From 769c7b28ffe1f899c06ba938fbcd2e7eab7f7aed Mon Sep 17 00:00:00 2001
From: Gabor Kiss-Vamosi <kisvegabor@gmail.com>
Date: Mon, 30 Jul 2018 06:52:29 +0200
Subject: [PATCH] add 'const' attribute to pointer where possible

---
 lv_core/lv_group.c      | 14 ++++-----
 lv_core/lv_group.h      | 14 ++++-----
 lv_core/lv_indev.c      | 10 +++---
 lv_core/lv_indev.h      | 10 +++---
 lv_core/lv_obj.c        | 70 ++++++++++++++++++++---------------------
 lv_core/lv_obj.h        | 60 +++++++++++++++++------------------
 lv_draw/lv_draw_rect.c  | 17 +++++++---
 lv_misc/lv_ll.c         | 12 +++----
 lv_misc/lv_ll.h         |  8 ++---
 lv_objx/lv_arc.c        |  4 +--
 lv_objx/lv_arc.h        |  4 +--
 lv_objx/lv_bar.c        | 10 +++---
 lv_objx/lv_bar.h        | 10 +++---
 lv_objx/lv_btn.c        | 14 ++++-----
 lv_objx/lv_btn.h        | 20 ++++++------
 lv_objx/lv_btnm.c       | 10 +++---
 lv_objx/lv_btnm.h       | 10 +++---
 lv_objx/lv_calendar.c   | 16 +++++-----
 lv_objx/lv_calendar.h   | 16 +++++-----
 lv_objx/lv_cb.c         |  6 ++--
 lv_objx/lv_cb.h         | 10 +++---
 lv_objx/lv_chart.c      | 12 +++----
 lv_objx/lv_chart.h      | 14 ++++-----
 lv_objx/lv_cont.c       |  8 ++---
 lv_objx/lv_cont.h       | 10 +++---
 lv_objx/lv_ddlist.c     | 16 +++++-----
 lv_objx/lv_ddlist.h     | 18 +++++------
 lv_objx/lv_gauge.c      |  8 ++---
 lv_objx/lv_gauge.h      | 20 ++++++------
 lv_objx/lv_img.c        |  6 ++--
 lv_objx/lv_img.h        | 10 +++---
 lv_objx/lv_kb.c         | 14 ++++-----
 lv_objx/lv_kb.h         | 14 ++++-----
 lv_objx/lv_label.c      | 18 +++++------
 lv_objx/lv_label.h      | 20 ++++++------
 lv_objx/lv_led.c        |  4 +--
 lv_objx/lv_led.h        |  6 ++--
 lv_objx/lv_line.c       |  6 ++--
 lv_objx/lv_line.h       | 10 +++---
 lv_objx/lv_list.c       | 26 +++++++--------
 lv_objx/lv_list.h       | 20 ++++++------
 lv_objx/lv_lmeter.c     | 12 +++----
 lv_objx/lv_lmeter.h     | 14 ++++-----
 lv_objx/lv_mbox.c       | 10 +++---
 lv_objx/lv_mbox.h       | 10 +++---
 lv_objx/lv_objx_templ.c |  4 +--
 lv_objx/lv_objx_templ.h |  4 +--
 lv_objx/lv_page.c       | 12 +++----
 lv_objx/lv_page.h       | 22 ++++++-------
 lv_objx/lv_preload.c    | 13 +++++---
 lv_objx/lv_preload.h    | 15 ++++++---
 lv_objx/lv_roller.c     |  6 ++--
 lv_objx/lv_roller.h     | 16 +++++-----
 lv_objx/lv_slider.c     | 12 +++----
 lv_objx/lv_slider.h     | 16 +++++-----
 lv_objx/lv_sw.c         |  4 +--
 lv_objx/lv_sw.h         |  8 ++---
 lv_objx/lv_ta.c         | 16 +++++-----
 lv_objx/lv_ta.h         | 20 ++++++------
 lv_objx/lv_tabview.c    | 18 +++++------
 lv_objx/lv_tabview.h    | 18 +++++------
 lv_objx/lv_win.c        | 16 +++++-----
 lv_objx/lv_win.h        | 16 +++++-----
 63 files changed, 454 insertions(+), 433 deletions(-)

diff --git a/lv_core/lv_group.c b/lv_core/lv_group.c
index 1c6f1850a..b2d6f4c93 100644
--- a/lv_core/lv_group.c
+++ b/lv_core/lv_group.c
@@ -348,7 +348,7 @@ lv_style_t * lv_group_mod_style(lv_group_t * group, const lv_style_t * style)
  * @param group pointer to a group
  * @return pointer to the focused object
  */
-lv_obj_t * lv_group_get_focused(lv_group_t * group)
+lv_obj_t * lv_group_get_focused(const lv_group_t * group)
 {
     if(!group) return NULL;
     if(group->obj_focus == NULL) return NULL;
@@ -361,7 +361,7 @@ lv_obj_t * lv_group_get_focused(lv_group_t * group)
  * @param group pointer to a group
  * @return pointer to the style modifier function
  */
-lv_group_style_mod_func_t lv_group_get_style_mod_cb(lv_group_t * group)
+lv_group_style_mod_func_t lv_group_get_style_mod_cb(const lv_group_t * group)
 {
 	if(!group) return false;
     return group->style_mod ;
@@ -372,7 +372,7 @@ lv_group_style_mod_func_t lv_group_get_style_mod_cb(lv_group_t * group)
  * @param group pointer to a group
  * @return pointer to the style modifier function
  */
-lv_group_style_mod_func_t lv_group_get_style_mod_edit_cb(lv_group_t * group)
+lv_group_style_mod_func_t lv_group_get_style_mod_edit_cb(const lv_group_t * group)
 {
 	if(!group) return false;
     return group->style_mod_edit;
@@ -383,7 +383,7 @@ lv_group_style_mod_func_t lv_group_get_style_mod_edit_cb(lv_group_t * group)
  * @param group pointer to a group
  * @return the call back function or NULL if not set
  */
-lv_group_focus_cb_t lv_group_get_focus_cb(lv_group_t * group)
+lv_group_focus_cb_t lv_group_get_focus_cb(const lv_group_t * group)
 {
 	if(!group) return false;
     return group->focus_cb;
@@ -394,7 +394,7 @@ lv_group_focus_cb_t lv_group_get_focus_cb(lv_group_t * group)
  * @param group pointer to group
  * @return true editing is enabled
  */
-bool lv_group_get_edit_enable(lv_group_t * group, bool en)
+bool lv_group_get_edit_enable(const lv_group_t * group, bool en)
 {
 	return group->edit_mode_en ? true : false;
 }
@@ -404,7 +404,7 @@ bool lv_group_get_edit_enable(lv_group_t * group, bool en)
  * @param group pointer to group
  * @return true: edit mode; false: navigate mode
  */
-bool lv_group_get_editing(lv_group_t * group)
+bool lv_group_get_editing(const lv_group_t * group)
 {
 	if(!group) return false;
 	return group->editing ? true : false;
@@ -415,7 +415,7 @@ bool lv_group_get_editing(lv_group_t * group)
  * @param group pointer to group
  * @return true: `click_focus` is enabled; false: disabled
  */
-bool lv_group_get_click_focus(lv_group_t * group)
+bool lv_group_get_click_focus(const lv_group_t * group)
 {
 	if(!group) return false;
 	return group->click_focus ? true : false;
diff --git a/lv_core/lv_group.h b/lv_core/lv_group.h
index c77afa86d..27b02e074 100644
--- a/lv_core/lv_group.h
+++ b/lv_core/lv_group.h
@@ -180,49 +180,49 @@ lv_style_t * lv_group_mod_style(lv_group_t * group, const lv_style_t * style);
  * @param group pointer to a group
  * @return pointer to the focused object
  */
-lv_obj_t * lv_group_get_focused(lv_group_t * group);
+lv_obj_t * lv_group_get_focused(const lv_group_t * group);
 
 /**
  * Get a the style modifier function of a group
  * @param group pointer to a group
  * @return pointer to the style modifier function
  */
-lv_group_style_mod_func_t lv_group_get_style_mod_cb(lv_group_t * group);
+lv_group_style_mod_func_t lv_group_get_style_mod_cb(const lv_group_t * group);
 
 /**
  * Get a the style modifier function of a group in edit mode
  * @param group pointer to a group
  * @return pointer to the style modifier function
  */
-lv_group_style_mod_func_t lv_group_get_style_mod_edit_cb(lv_group_t * group);
+lv_group_style_mod_func_t lv_group_get_style_mod_edit_cb(const lv_group_t * group);
 
 /**
  * Get the focus callback function of a group
  * @param group pointer to a group
  * @return the call back function or NULL if not set
  */
-lv_group_focus_cb_t lv_group_get_focus_cb(lv_group_t * group);
+lv_group_focus_cb_t lv_group_get_focus_cb(const lv_group_t * group);
 
 /**
  * Get the edit mode is enabled or not.
  * @param group pointer to group
  * @return true editing is enabled
  */
-bool lv_group_get_edit_enable(lv_group_t * group, bool en);
+bool lv_group_get_edit_enable(const lv_group_t * group, bool en);
 
 /**
  * Get the current mode (edit or navigate).
  * @param group pointer to group
  * @return true: edit mode; false: navigate mode
  */
-bool lv_group_get_editing(lv_group_t * group);
+bool lv_group_get_editing(const lv_group_t * group);
 
 /**
  * Get the `click_focus` attribute.
  * @param group pointer to group
  * @return true: `click_focus` is enabled; false: disabled
  */
-bool lv_group_get_click_focus(lv_group_t * group);
+bool lv_group_get_click_focus(const lv_group_t * group);
 
 
 /**********************
diff --git a/lv_core/lv_indev.c b/lv_core/lv_indev.c
index 1fb9727f5..cc862236c 100644
--- a/lv_core/lv_indev.c
+++ b/lv_core/lv_indev.c
@@ -80,7 +80,7 @@ lv_indev_t * lv_indev_get_act(void)
  * @param indev pointer to an input device
  * @return the type of the input device from `lv_hal_indev_type_t` (`LV_INDEV_TYPE_...`)
  */
-lv_hal_indev_type_t lv_indev_get_type(lv_indev_t * indev)
+lv_hal_indev_type_t lv_indev_get_type(const lv_indev_t * indev)
 {
 	if(indev == NULL) return LV_INDEV_TYPE_NONE;
 
@@ -170,7 +170,7 @@ void lv_indev_set_button_points(lv_indev_t * indev, lv_point_t * points)
  * @param indev pointer to an input device
  * @param point pointer to a point to store the result
  */
-void lv_indev_get_point(lv_indev_t * indev, lv_point_t * point)
+void lv_indev_get_point(const lv_indev_t * indev, lv_point_t * point)
 {
     if(indev->driver.type != LV_INDEV_TYPE_POINTER && indev->driver.type != LV_INDEV_TYPE_BUTTON) {
         point->x = -1;
@@ -186,7 +186,7 @@ void lv_indev_get_point(lv_indev_t * indev, lv_point_t * point)
  * @param indev pointer to an input device
  * @return true: drag is in progress
  */
-bool lv_indev_is_dragging(lv_indev_t * indev)
+bool lv_indev_is_dragging(const lv_indev_t * indev)
 {
     if(indev == NULL) return false;
     if(indev->driver.type != LV_INDEV_TYPE_POINTER && indev->driver.type != LV_INDEV_TYPE_BUTTON) return false;
@@ -198,7 +198,7 @@ bool lv_indev_is_dragging(lv_indev_t * indev)
  * @param indev pointer to an input device
  * @param point pointer to a point to store the vector
  */
-void lv_indev_get_vect(lv_indev_t * indev, lv_point_t * point)
+void lv_indev_get_vect(const lv_indev_t * indev, lv_point_t * point)
 {
     if(indev->driver.type != LV_INDEV_TYPE_POINTER && indev->driver.type != LV_INDEV_TYPE_BUTTON) {
         point->x = 0;
@@ -214,7 +214,7 @@ void lv_indev_get_vect(lv_indev_t * indev, lv_point_t * point)
  * @param indev pointer to an input device (NULL to get the overall smallest inactivity)
  * @return Elapsed ticks (milliseconds) since last press
  */
-uint32_t lv_indev_get_inactive_time(lv_indev_t * indev)
+uint32_t lv_indev_get_inactive_time(const lv_indev_t * indev)
 {
     uint32_t t;
 
diff --git a/lv_core/lv_indev.h b/lv_core/lv_indev.h
index 0ff4d1ebc..63ed1968e 100644
--- a/lv_core/lv_indev.h
+++ b/lv_core/lv_indev.h
@@ -46,7 +46,7 @@ lv_indev_t * lv_indev_get_act(void);
  * @param indev pointer to an input device
  * @return the type of the input device from `lv_hal_indev_type_t` (`LV_INDEV_TYPE_...`)
  */
-lv_hal_indev_type_t lv_indev_get_type(lv_indev_t * indev);
+lv_hal_indev_type_t lv_indev_get_type(const lv_indev_t * indev);
 
 /**
  * Reset one or all input devices
@@ -96,27 +96,27 @@ void lv_indev_set_button_points(lv_indev_t *indev, lv_point_t *points);
  * @param indev pointer to an input device
  * @param point pointer to a point to store the result
  */
-void lv_indev_get_point(lv_indev_t * indev, lv_point_t * point);
+void lv_indev_get_point(const lv_indev_t * indev, lv_point_t * point);
 
 /**
  * Check if there is dragging with an input device or not (for LV_INDEV_TYPE_POINTER and LV_INDEV_TYPE_BUTTON)
  * @param indev pointer to an input device
  * @return true: drag is in progress
  */
-bool lv_indev_is_dragging(lv_indev_t * indev);
+bool lv_indev_is_dragging(const lv_indev_t * indev);
 
 /**
  * Get the vector of dragging of an input device (for LV_INDEV_TYPE_POINTER and LV_INDEV_TYPE_BUTTON)
  * @param indev pointer to an input device
  * @param point pointer to a point to store the vector
  */
-void lv_indev_get_vect(lv_indev_t * indev, lv_point_t * point);
+void lv_indev_get_vect(const lv_indev_t * indev, lv_point_t * point);
 /**
  * Get elapsed time since last press
  * @param indev pointer to an input device (NULL to get the overall smallest inactivity)
  * @return Elapsed ticks (milliseconds) since last press
  */
-uint32_t lv_indev_get_inactive_time(lv_indev_t * indev);
+uint32_t lv_indev_get_inactive_time(const lv_indev_t * indev);
 
 /**
  * Do nothing until the next release
diff --git a/lv_core/lv_obj.c b/lv_core/lv_obj.c
index 99257e09a..77fc156ca 100644
--- a/lv_core/lv_obj.c
+++ b/lv_core/lv_obj.c
@@ -119,7 +119,7 @@ void lv_init(void)
  * @param copy pointer to a base object, if not NULL then the new object will be copied from it
  * @return pointer to the new object
  */
-lv_obj_t * lv_obj_create(lv_obj_t * parent, lv_obj_t * copy)
+lv_obj_t * lv_obj_create(lv_obj_t * parent,const  lv_obj_t * copy)
 {
 
     lv_obj_t * new_obj = NULL;
@@ -366,7 +366,7 @@ void lv_obj_clean(lv_obj_t * obj)
  * Mark the object as invalid therefore its current position will be redrawn by 'lv_refr_task'
  * @param obj pointer to an object
  */
-void lv_obj_invalidate(lv_obj_t * obj)
+void lv_obj_invalidate(const lv_obj_t * obj)
 {
     if(lv_obj_get_hidden(obj)) return;
 
@@ -1081,17 +1081,17 @@ lv_obj_t * lv_layer_sys(void)
  * @param obj pointer to an object
  * @return pointer to a screen
  */
-lv_obj_t * lv_obj_get_screen(lv_obj_t * obj)
+lv_obj_t * lv_obj_get_screen(const lv_obj_t * obj)
 {
-    lv_obj_t * par = obj;
-    lv_obj_t * act_p;
+	const lv_obj_t * par = obj;
+	const lv_obj_t * act_p;
 
     do {
         act_p = par;
         par = lv_obj_get_parent(act_p);
     } while(par != NULL);
 
-    return act_p;
+    return (lv_obj_t *)act_p;
 }
 
 /*---------------------
@@ -1103,7 +1103,7 @@ lv_obj_t * lv_obj_get_screen(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return pointer to the parent of  'obj'
  */
-lv_obj_t * lv_obj_get_parent(lv_obj_t * obj)
+lv_obj_t * lv_obj_get_parent(const lv_obj_t * obj)
 {
     return obj->par;
 }
@@ -1115,7 +1115,7 @@ lv_obj_t * lv_obj_get_parent(lv_obj_t * obj)
  *                  and the previous return value later
  * @return the child after 'act_child' or NULL if no more child
  */
-lv_obj_t * lv_obj_get_child(lv_obj_t * obj, lv_obj_t * child)
+lv_obj_t * lv_obj_get_child(const lv_obj_t * obj, const lv_obj_t * child)
 {
     if(child == NULL) {
         return lv_ll_get_head(&obj->child_ll);
@@ -1133,7 +1133,7 @@ lv_obj_t * lv_obj_get_child(lv_obj_t * obj, lv_obj_t * child)
  *                  and the previous return value later
  * @return the child after 'act_child' or NULL if no more child
  */
-lv_obj_t * lv_obj_get_child_back(lv_obj_t * obj, lv_obj_t * child)
+lv_obj_t * lv_obj_get_child_back(const lv_obj_t * obj, const lv_obj_t * child)
 {
     if(child == NULL) {
         return lv_ll_get_tail(&obj->child_ll);
@@ -1149,7 +1149,7 @@ lv_obj_t * lv_obj_get_child_back(lv_obj_t * obj, lv_obj_t * child)
  * @param obj pointer to an object
  * @return children number of 'obj'
  */
-uint16_t lv_obj_count_children(lv_obj_t * obj)
+uint16_t lv_obj_count_children(const lv_obj_t * obj)
 {
     lv_obj_t * i;
     uint16_t cnt = 0;
@@ -1168,7 +1168,7 @@ uint16_t lv_obj_count_children(lv_obj_t * obj)
  * @param obj pointer to an object
  * @param cords_p pointer to an area to store the coordinates
  */
-void lv_obj_get_coords(lv_obj_t * obj, lv_area_t * cords_p)
+void lv_obj_get_coords(const lv_obj_t * obj, lv_area_t * cords_p)
 {
     lv_area_copy(cords_p, &obj->coords);
 }
@@ -1179,7 +1179,7 @@ void lv_obj_get_coords(lv_obj_t * obj, lv_area_t * cords_p)
  * @param obj pointer to an object
  * @return distance of 'obj' from the left side of its parent
  */
-lv_coord_t lv_obj_get_x(lv_obj_t * obj)
+lv_coord_t lv_obj_get_x(const lv_obj_t * obj)
 {
     lv_coord_t rel_x;
     lv_obj_t * parent = lv_obj_get_parent(obj);
@@ -1193,7 +1193,7 @@ lv_coord_t lv_obj_get_x(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return distance of 'obj' from the top of its parent
  */
-lv_coord_t lv_obj_get_y(lv_obj_t * obj)
+lv_coord_t lv_obj_get_y(const lv_obj_t * obj)
 {
     lv_coord_t rel_y;
     lv_obj_t * parent = lv_obj_get_parent(obj);
@@ -1207,7 +1207,7 @@ lv_coord_t lv_obj_get_y(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return the width
  */
-lv_coord_t lv_obj_get_width(lv_obj_t * obj)
+lv_coord_t lv_obj_get_width(const lv_obj_t * obj)
 {
     return lv_area_get_width(&obj->coords);
 }
@@ -1217,7 +1217,7 @@ lv_coord_t lv_obj_get_width(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return the height
  */
-lv_coord_t lv_obj_get_height(lv_obj_t * obj)
+lv_coord_t lv_obj_get_height(const lv_obj_t * obj)
 {
     return lv_area_get_height(&obj->coords);
 }
@@ -1227,7 +1227,7 @@ lv_coord_t lv_obj_get_height(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return the extended size attribute
  */
-lv_coord_t lv_obj_get_ext_size(lv_obj_t * obj)
+lv_coord_t lv_obj_get_ext_size(const lv_obj_t * obj)
 {
     return obj->ext_size;
 }
@@ -1241,7 +1241,7 @@ lv_coord_t lv_obj_get_ext_size(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return pointer to a style
  */
-lv_style_t * lv_obj_get_style(lv_obj_t * obj)
+lv_style_t * lv_obj_get_style(const lv_obj_t * obj)
 {
     lv_style_t * style_act = obj->style_p;
     if(style_act == NULL) {
@@ -1289,7 +1289,7 @@ lv_style_t * lv_obj_get_style(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return true: the object is hidden
  */
-bool lv_obj_get_hidden(lv_obj_t * obj)
+bool lv_obj_get_hidden(const lv_obj_t * obj)
 {
     return obj->hidden == 0 ? false : true;
 }
@@ -1299,7 +1299,7 @@ bool lv_obj_get_hidden(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return true: the object is clickable
  */
-bool lv_obj_get_click(lv_obj_t * obj)
+bool lv_obj_get_click(const lv_obj_t * obj)
 {
     return obj->click == 0 ? false : true;
 }
@@ -1309,7 +1309,7 @@ bool lv_obj_get_click(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return true: the auto top feture is enabled
  */
-bool lv_obj_get_top(lv_obj_t * obj)
+bool lv_obj_get_top(const lv_obj_t * obj)
 {
     return obj->top == 0 ? false : true;
 }
@@ -1319,7 +1319,7 @@ bool lv_obj_get_top(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return true: the object is dragable
  */
-bool lv_obj_get_drag(lv_obj_t * obj)
+bool lv_obj_get_drag(const lv_obj_t * obj)
 {
     return obj->drag == 0 ? false : true;
 }
@@ -1329,7 +1329,7 @@ bool lv_obj_get_drag(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return true: drag throw is enabled
  */
-bool lv_obj_get_drag_throw(lv_obj_t * obj)
+bool lv_obj_get_drag_throw(const lv_obj_t * obj)
 {
     return obj->drag_throw == 0 ? false : true;
 }
@@ -1339,7 +1339,7 @@ bool lv_obj_get_drag_throw(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return true: drag parent is enabled
  */
-bool lv_obj_get_drag_parent(lv_obj_t * obj)
+bool lv_obj_get_drag_parent(const lv_obj_t * obj)
 {
     return obj->drag_parent == 0 ? false : true;
 }
@@ -1349,7 +1349,7 @@ bool lv_obj_get_drag_parent(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return true: opa scaling is enabled for this object and all children false: no opa scaling
  */
-lv_opa_t lv_obj_get_opa_scale_enable(lv_obj_t * obj)
+lv_opa_t lv_obj_get_opa_scale_enable(const lv_obj_t * obj)
 {
     return obj->opa_scale_en == 0 ? false : true;
 }
@@ -1359,9 +1359,9 @@ lv_opa_t lv_obj_get_opa_scale_enable(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return opa scale [0..255]
  */
-lv_opa_t lv_obj_get_opa_scale(lv_obj_t * obj)
+lv_opa_t lv_obj_get_opa_scale(const lv_obj_t * obj)
 {
-    lv_obj_t * parent = obj;
+	 const lv_obj_t * parent = obj;
 
     while(parent) {
         if(parent->opa_scale_en) return parent->opa_scale;
@@ -1376,7 +1376,7 @@ lv_opa_t lv_obj_get_opa_scale(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return protect field ('OR'ed values of lv_obj_prot_t)
  */
-uint8_t lv_obj_get_protect(lv_obj_t * obj)
+uint8_t lv_obj_get_protect(const lv_obj_t * obj)
 {
     return obj->protect ;
 }
@@ -1387,7 +1387,7 @@ uint8_t lv_obj_get_protect(lv_obj_t * obj)
  * @param prot protect bits to test ('OR'ed values of lv_obj_prot_t)
  * @return false: none of the given bits are set, true: at least one bit is set
  */
-bool lv_obj_is_protected(lv_obj_t * obj, uint8_t prot)
+bool lv_obj_is_protected(const lv_obj_t * obj, uint8_t prot)
 {
     return (obj->protect & prot) == 0 ? false : true ;
 }
@@ -1397,7 +1397,7 @@ bool lv_obj_is_protected(lv_obj_t * obj, uint8_t prot)
  * @param obj pointer to an object
  * @return the signal function
  */
-lv_signal_func_t   lv_obj_get_signal_func(lv_obj_t * obj)
+lv_signal_func_t   lv_obj_get_signal_func(const lv_obj_t * obj)
 {
     return obj->signal_func;
 }
@@ -1407,7 +1407,7 @@ lv_signal_func_t   lv_obj_get_signal_func(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return the design function
  */
-lv_design_func_t lv_obj_get_design_func(lv_obj_t * obj)
+lv_design_func_t lv_obj_get_design_func(const lv_obj_t * obj)
 {
     return obj->design_func;
 }
@@ -1422,7 +1422,7 @@ lv_design_func_t lv_obj_get_design_func(lv_obj_t * obj)
  * @return the ext pointer but not the dynamic version
  *         Use it as ext->data1, and NOT da(ext)->data1
  */
-void * lv_obj_get_ext_attr(lv_obj_t * obj)
+void * lv_obj_get_ext_attr(const lv_obj_t * obj)
 {
     return obj->ext_attr;
 }
@@ -1461,7 +1461,7 @@ void lv_obj_get_type(lv_obj_t * obj, lv_obj_type_t * buf)
  * @param obj pointer to an object
  * @return the free number
  */
-LV_OBJ_FREE_NUM_TYPE lv_obj_get_free_num(lv_obj_t * obj)
+LV_OBJ_FREE_NUM_TYPE lv_obj_get_free_num(const lv_obj_t * obj)
 {
     return obj->free_num;
 }
@@ -1473,7 +1473,7 @@ LV_OBJ_FREE_NUM_TYPE lv_obj_get_free_num(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return the free pointer
  */
-void * lv_obj_get_free_ptr(lv_obj_t * obj)
+void * lv_obj_get_free_ptr(const lv_obj_t * obj)
 {
     return obj->free_ptr;
 }
@@ -1486,7 +1486,7 @@ void * lv_obj_get_free_ptr(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return the pointer to group of the object
  */
-void * lv_obj_get_group(lv_obj_t * obj)
+void * lv_obj_get_group(const lv_obj_t * obj)
 {
     return obj->group_p;
 }
@@ -1496,7 +1496,7 @@ void * lv_obj_get_group(lv_obj_t * obj)
  * @param obj pointer to an object
  * @return true: the object is focused, false: the object is not focused or not in a group
  */
-bool lv_obj_is_focused(lv_obj_t * obj)
+bool lv_obj_is_focused(const lv_obj_t * obj)
 {
 	if(obj->group_p) {
 		if(lv_group_get_focused(obj->group_p) == obj) return true;
diff --git a/lv_core/lv_obj.h b/lv_core/lv_obj.h
index 8c4f1df5f..f450f8859 100644
--- a/lv_core/lv_obj.h
+++ b/lv_core/lv_obj.h
@@ -222,7 +222,7 @@ void lv_init(void);
  * @param copy pointer to a base object, if not NULL then the new object will be copied from it
  * @return pointer to the new object
  */
-lv_obj_t * lv_obj_create(lv_obj_t * parent, lv_obj_t * copy);
+lv_obj_t * lv_obj_create(lv_obj_t * parent,const  lv_obj_t * copy);
 
 /**
  * Delete 'obj' and all of its children
@@ -241,7 +241,7 @@ void lv_obj_clean(lv_obj_t *obj);
  * Mark the object as invalid therefore its current position will be redrawn by 'lv_refr_task'
  * @param obj pointer to an object
  */
-void lv_obj_invalidate(lv_obj_t * obj);
+void lv_obj_invalidate(const lv_obj_t * obj);
 
 /*=====================
  * Setter functions
@@ -532,7 +532,7 @@ lv_obj_t * lv_layer_sys(void);
  * @param obj pointer to an object
  * @return pointer to a screen
  */
-lv_obj_t * lv_obj_get_screen(lv_obj_t * obj);
+lv_obj_t * lv_obj_get_screen(const lv_obj_t * obj);
 
 /*---------------------
  * Parent/children get
@@ -543,7 +543,7 @@ lv_obj_t * lv_obj_get_screen(lv_obj_t * obj);
  * @param obj pointer to an object
  * @return pointer to the parent of  'obj'
  */
-lv_obj_t * lv_obj_get_parent(lv_obj_t * obj);
+lv_obj_t * lv_obj_get_parent(const lv_obj_t * obj);
 
 /**
  * Iterate through the children of an object (start from the "youngest, lastly created")
@@ -552,7 +552,7 @@ lv_obj_t * lv_obj_get_parent(lv_obj_t * obj);
  *                  and the previous return value later
  * @return the child after 'act_child' or NULL if no more child
  */
-lv_obj_t * lv_obj_get_child(lv_obj_t * obj, lv_obj_t * child);
+lv_obj_t * lv_obj_get_child(const lv_obj_t * obj, const lv_obj_t * child);
 
 /**
  * Iterate through the children of an object (start from the "oldest", firstly created)
@@ -561,14 +561,14 @@ lv_obj_t * lv_obj_get_child(lv_obj_t * obj, lv_obj_t * child);
  *                  and the previous return value later
  * @return the child after 'act_child' or NULL if no more child
  */
-lv_obj_t * lv_obj_get_child_back(lv_obj_t * obj, lv_obj_t * child);
+lv_obj_t * lv_obj_get_child_back(const lv_obj_t * obj, const lv_obj_t * child);
 
 /**
  * Count the children of an object (only children directly on 'obj')
  * @param obj pointer to an object
  * @return children number of 'obj'
  */
-uint16_t lv_obj_count_children(lv_obj_t * obj);
+uint16_t lv_obj_count_children(const lv_obj_t * obj);
 
 /*---------------------
  * Coordinate get
@@ -579,42 +579,42 @@ uint16_t lv_obj_count_children(lv_obj_t * obj);
  * @param obj pointer to an object
  * @param cords_p pointer to an area to store the coordinates
  */
-void lv_obj_get_coords(lv_obj_t * obj, lv_area_t * cords_p);
+void lv_obj_get_coords(const lv_obj_t * obj, lv_area_t * cords_p);
 
 /**
  * Get the x coordinate of object
  * @param obj pointer to an object
  * @return distance of 'obj' from the left side of its parent
  */
-lv_coord_t lv_obj_get_x(lv_obj_t * obj);
+lv_coord_t lv_obj_get_x(const lv_obj_t * obj);
 
 /**
  * Get the y coordinate of object
  * @param obj pointer to an object
  * @return distance of 'obj' from the top of its parent
  */
-lv_coord_t lv_obj_get_y(lv_obj_t * obj);
+lv_coord_t lv_obj_get_y(const lv_obj_t * obj);
 
 /**
  * Get the width of an object
  * @param obj pointer to an object
  * @return the width
  */
-lv_coord_t lv_obj_get_width(lv_obj_t * obj);
+lv_coord_t lv_obj_get_width(const lv_obj_t * obj);
 
 /**
  * Get the height of an object
  * @param obj pointer to an object
  * @return the height
  */
-lv_coord_t lv_obj_get_height(lv_obj_t * obj);
+lv_coord_t lv_obj_get_height(const lv_obj_t * obj);
 
 /**
  * Get the extended size attribute of an object
  * @param obj pointer to an object
  * @return the extended size attribute
  */
-lv_coord_t lv_obj_get_ext_size(lv_obj_t * obj);
+lv_coord_t lv_obj_get_ext_size(const lv_obj_t * obj);
 
 /*-----------------
  * Appearance get
@@ -625,7 +625,7 @@ lv_coord_t lv_obj_get_ext_size(lv_obj_t * obj);
  * @param obj pointer to an object
  * @return pointer to a style
  */
-lv_style_t * lv_obj_get_style(lv_obj_t * obj);
+lv_style_t * lv_obj_get_style(const lv_obj_t * obj);
 
 /*-----------------
  * Attribute get
@@ -636,56 +636,56 @@ lv_style_t * lv_obj_get_style(lv_obj_t * obj);
  * @param obj pointer to an object
  * @return true: the object is hidden
  */
-bool lv_obj_get_hidden(lv_obj_t * obj);
+bool lv_obj_get_hidden(const lv_obj_t * obj);
 
 /**
  * Get the click enable attribute of an object
  * @param obj pointer to an object
  * @return true: the object is clickable
  */
-bool lv_obj_get_click(lv_obj_t * obj);
+bool lv_obj_get_click(const lv_obj_t * obj);
 
 /**
  * Get the top enable attribute of an object
  * @param obj pointer to an object
  * @return true: the auto top feture is enabled
  */
-bool lv_obj_get_top(lv_obj_t * obj);
+bool lv_obj_get_top(const lv_obj_t * obj);
 
 /**
  * Get the drag enable attribute of an object
  * @param obj pointer to an object
  * @return true: the object is dragable
  */
-bool lv_obj_get_drag(lv_obj_t * obj);
+bool lv_obj_get_drag(const lv_obj_t * obj);
 
 /**
  * Get the drag thow enable attribute of an object
  * @param obj pointer to an object
  * @return true: drag throw is enabled
  */
-bool lv_obj_get_drag_throw(lv_obj_t * obj);
+bool lv_obj_get_drag_throw(const lv_obj_t * obj);
 
 /**
  * Get the drag parent attribute of an object
  * @param obj pointer to an object
  * @return true: drag parent is enabled
  */
-bool lv_obj_get_drag_parent(lv_obj_t * obj);
+bool lv_obj_get_drag_parent(const lv_obj_t * obj);
 
 /**
  * Get the opa scale parameter of an object
  * @param obj pointer to an object
  * @return opa scale [0..255]
  */
-lv_opa_t lv_obj_get_opa_scale(lv_obj_t * obj);
+lv_opa_t lv_obj_get_opa_scale(const lv_obj_t * obj);
 
 /**
  * Get the protect field of an object
  * @param obj pointer to an object
  * @return protect field ('OR'ed values of lv_obj_prot_t)
  */
-uint8_t lv_obj_get_protect(lv_obj_t * obj);
+uint8_t lv_obj_get_protect(const lv_obj_t * obj);
 
 /**
  * Check at least one bit of a given protect bitfield is set
@@ -693,21 +693,21 @@ uint8_t lv_obj_get_protect(lv_obj_t * obj);
  * @param prot protect bits to test ('OR'ed values of lv_obj_prot_t)
  * @return false: none of the given bits are set, true: at least one bit is set
  */
-bool lv_obj_is_protected(lv_obj_t * obj, uint8_t prot);
+bool lv_obj_is_protected(const lv_obj_t * obj, uint8_t prot);
 
 /**
  * Get the signal function of an object
  * @param obj pointer to an object
  * @return the signal function
  */
-lv_signal_func_t   lv_obj_get_signal_func(lv_obj_t * obj);
+lv_signal_func_t   lv_obj_get_signal_func(const lv_obj_t * obj);
 
 /**
  * Get the design function of an object
  * @param obj pointer to an object
  * @return the design function
  */
-lv_design_func_t lv_obj_get_design_func(lv_obj_t * obj);
+lv_design_func_t lv_obj_get_design_func(const lv_obj_t * obj);
 
 /*------------------
  * Other get
@@ -719,7 +719,7 @@ lv_design_func_t lv_obj_get_design_func(lv_obj_t * obj);
  * @return the ext pointer but not the dynamic version
  *         Use it as ext->data1, and NOT da(ext)->data1
  */
-void * lv_obj_get_ext_attr(lv_obj_t * obj);
+void * lv_obj_get_ext_attr(const lv_obj_t * obj);
 
 /**
  * Get object's and its ancestors type. Put their name in `type_buf` starting with the current type.
@@ -735,7 +735,7 @@ void lv_obj_get_type(lv_obj_t * obj, lv_obj_type_t * buf);
  * @param obj pointer to an object
  * @return the free number
  */
-LV_OBJ_FREE_NUM_TYPE lv_obj_get_free_num(lv_obj_t * obj);
+LV_OBJ_FREE_NUM_TYPE lv_obj_get_free_num(const lv_obj_t * obj);
 #endif
 
 #if LV_OBJ_FREE_PTR != 0
@@ -744,7 +744,7 @@ LV_OBJ_FREE_NUM_TYPE lv_obj_get_free_num(lv_obj_t * obj);
  * @param obj pointer to an object
  * @return the free pointer
  */
-void * lv_obj_get_free_ptr(lv_obj_t * obj);
+void * lv_obj_get_free_ptr(const lv_obj_t * obj);
 #endif
 
 #if USE_LV_GROUP
@@ -753,7 +753,7 @@ void * lv_obj_get_free_ptr(lv_obj_t * obj);
  * @param obj pointer to an object
  * @return the pointer to group of the object
  */
-void * lv_obj_get_group(lv_obj_t * obj);
+void * lv_obj_get_group(const lv_obj_t * obj);
 
 
 /**
@@ -761,7 +761,7 @@ void * lv_obj_get_group(lv_obj_t * obj);
  * @param obj pointer to an object
  * @return true: the object is focused, false: the object is not focused or not in a group
  */
-bool lv_obj_is_focused(lv_obj_t * obj);
+bool lv_obj_is_focused(const lv_obj_t * obj);
 
 #endif
 
diff --git a/lv_draw/lv_draw_rect.c b/lv_draw/lv_draw_rect.c
index 30996bc53..269999dcc 100644
--- a/lv_draw/lv_draw_rect.c
+++ b/lv_draw/lv_draw_rect.c
@@ -29,15 +29,20 @@ static void lv_draw_rect_main_mid(const lv_area_t * coords, const lv_area_t * ma
 static void lv_draw_rect_main_corner(const lv_area_t * coords, const lv_area_t * mask, const lv_style_t * style, lv_opa_t opa_scale);
 static void lv_draw_rect_border_straight(const lv_area_t * coords, const lv_area_t * mask, const lv_style_t * style, lv_opa_t opa_scale);
 static void lv_draw_rect_border_corner(const lv_area_t * coords, const lv_area_t * mask, const lv_style_t * style, lv_opa_t opa_scale);
+
 #if USE_LV_SHADOW && LV_VDB_SIZE
 static void lv_draw_shadow(const lv_area_t * coords, const lv_area_t * mask, const lv_style_t * style, lv_opa_t opa_scale);
 static void lv_draw_shadow_full(const lv_area_t * coords, const lv_area_t * mask, const  lv_style_t * style, lv_opa_t opa_scale);
 static void lv_draw_shadow_bottom(const lv_area_t * coords, const lv_area_t * mask, const lv_style_t * style, lv_opa_t opa_scale);
 static void lv_draw_shadow_full_straight(const lv_area_t * coords, const lv_area_t * mask, const lv_style_t * style, const lv_opa_t * map);
 #endif
+
 static uint16_t lv_draw_cont_radius_corr(uint16_t r, lv_coord_t w, lv_coord_t h);
 
+#if LV_ANTIALIAS
 static lv_opa_t antialias_get_opa_circ(lv_coord_t seg, lv_coord_t px_id, lv_opa_t opa);
+#endif
+
 /**********************
  *  STATIC VARIABLES
  **********************/
@@ -1391,13 +1396,15 @@ static uint16_t lv_draw_cont_radius_corr(uint16_t r, lv_coord_t w, lv_coord_t h)
     return r;
 }
 
+#if LV_ANTIALIAS
+
 /**
  * Approximate the opacity for anti-aliasing.
  * Used  the first segment of a circle which is the longest and have the most non-linearity (cos)
- * @param seg
- * @param px_id
- * @param line_opa
- * @return
+ * @param seg length of the line segment
+ * @param px_id index of pixel on the line segment
+ * @param line_opa opacity of the lien (it will be the max opacity)
+ * @return the desired opacity of the pixel
  */
 static lv_opa_t antialias_get_opa_circ(lv_coord_t seg, lv_coord_t px_id, lv_opa_t opa)
 {
@@ -1413,3 +1420,5 @@ static lv_opa_t antialias_get_opa_circ(lv_coord_t seg, lv_coord_t px_id, lv_opa_
     }
 
 }
+
+#endif
diff --git a/lv_misc/lv_ll.c b/lv_misc/lv_ll.c
index 185157d9f..0ebea4922 100644
--- a/lv_misc/lv_ll.c
+++ b/lv_misc/lv_ll.c
@@ -231,7 +231,7 @@ void lv_ll_chg_list(lv_ll_t * ll_ori_p, lv_ll_t * ll_new_p, void * node)
  * @param ll_p pointer to linked list
  * @return pointer to the head of 'll_p'
  */
-void * lv_ll_get_head(lv_ll_t * ll_p)
+void * lv_ll_get_head(const lv_ll_t * ll_p)
 {
     void * head = NULL;
 
@@ -247,7 +247,7 @@ void * lv_ll_get_head(lv_ll_t * ll_p)
  * @param ll_p pointer to linked list
  * @return pointer to the head of 'll_p'
  */
-void * lv_ll_get_tail(lv_ll_t * ll_p)
+void * lv_ll_get_tail(const lv_ll_t * ll_p)
 {
     void * tail = NULL;
 
@@ -264,12 +264,12 @@ void * lv_ll_get_tail(lv_ll_t * ll_p)
  * @param n_act pointer a node
  * @return pointer to the next node
  */
-void * lv_ll_get_next(lv_ll_t * ll_p, void * n_act)
+void * lv_ll_get_next(const lv_ll_t * ll_p,const  void * n_act)
 {
     void * next = NULL;
 
     if(ll_p != NULL)    {
-        lv_ll_node_t * n_act_d = n_act;
+    	const lv_ll_node_t * n_act_d = n_act;
         memcpy(&next, n_act_d + LL_NEXT_P_OFFSET(ll_p), sizeof(void *));
     }
 
@@ -282,12 +282,12 @@ void * lv_ll_get_next(lv_ll_t * ll_p, void * n_act)
  * @param n_act pointer a node
  * @return pointer to the previous node
  */
-void * lv_ll_get_prev(lv_ll_t * ll_p, void * n_act)
+void * lv_ll_get_prev(const lv_ll_t * ll_p,const  void * n_act)
 {
     void * prev = NULL;
 
     if(ll_p != NULL) {
-        lv_ll_node_t * n_act_d = n_act;
+    	const lv_ll_node_t * n_act_d = n_act;
         memcpy(&prev, n_act_d + LL_PREV_P_OFFSET(ll_p), sizeof(void *));
     }
 
diff --git a/lv_misc/lv_ll.h b/lv_misc/lv_ll.h
index e472f8e06..43f865182 100644
--- a/lv_misc/lv_ll.h
+++ b/lv_misc/lv_ll.h
@@ -97,14 +97,14 @@ void lv_ll_chg_list(lv_ll_t * ll_ori_p, lv_ll_t * ll_new_p, void * node);
  * @param ll_p pointer to linked list
  * @return pointer to the head of 'll_p'
  */
-void * lv_ll_get_head(lv_ll_t * ll_p);
+void * lv_ll_get_head(const lv_ll_t * ll_p);
 
 /**
  * Return with tail node of the linked list
  * @param ll_p pointer to linked list
  * @return pointer to the head of 'll_p'
  */
-void * lv_ll_get_tail(lv_ll_t * ll_p);
+void * lv_ll_get_tail(const lv_ll_t * ll_p);
 
 /**
  * Return with the pointer of the next node after 'n_act'
@@ -112,7 +112,7 @@ void * lv_ll_get_tail(lv_ll_t * ll_p);
  * @param n_act pointer a node
  * @return pointer to the next node
  */
-void * lv_ll_get_next(lv_ll_t * ll_p, void * n_act);
+void * lv_ll_get_next(const lv_ll_t * ll_p, const void * n_act);
 
 /**
  * Return with the pointer of the previous node after 'n_act'
@@ -120,7 +120,7 @@ void * lv_ll_get_next(lv_ll_t * ll_p, void * n_act);
  * @param n_act pointer a node
  * @return pointer to the previous node
  */
-void * lv_ll_get_prev(lv_ll_t * ll_p, void * n_act);
+void * lv_ll_get_prev(const lv_ll_t * ll_p, const void * n_act);
 
 /**
  * Move a nodw before an other node in the same linked list
diff --git a/lv_objx/lv_arc.c b/lv_objx/lv_arc.c
index 9dabd7e4a..53494d5c7 100644
--- a/lv_objx/lv_arc.c
+++ b/lv_objx/lv_arc.c
@@ -48,7 +48,7 @@ static lv_design_func_t ancestor_design;
  * @param copy pointer to a arc object, if not NULL then the new object will be copied from it
  * @return pointer to the created arc
  */
-lv_obj_t * lv_arc_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_arc_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 
 	LV_LOG_TRACE("arc create started");
@@ -174,7 +174,7 @@ uint16_t lv_arc_get_angle_end(lv_obj_t * arc)
  * @param type which style should be get
  * @return style pointer to the style
  *  */
-lv_style_t * lv_arc_get_style(lv_obj_t * arc, lv_arc_style_t type)
+lv_style_t * lv_arc_get_style(const lv_obj_t * arc, lv_arc_style_t type)
 {
 
     switch(type) {
diff --git a/lv_objx/lv_arc.h b/lv_objx/lv_arc.h
index acf3976de..e9f97e9ce 100644
--- a/lv_objx/lv_arc.h
+++ b/lv_objx/lv_arc.h
@@ -55,7 +55,7 @@ typedef enum {
  * @param copy pointer to a arc object, if not NULL then the new object will be copied from it
  * @return pointer to the created arc
  */
-lv_obj_t * lv_arc_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_arc_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*======================
  * Add/remove functions
@@ -106,7 +106,7 @@ uint16_t lv_arc_get_angle_end(lv_obj_t * arc);
  * @param type which style should be get
  * @return style pointer to the style
  *  */
-lv_style_t * lv_arc_get_style(lv_obj_t * arc, lv_arc_style_t type);
+lv_style_t * lv_arc_get_style(const lv_obj_t * arc, lv_arc_style_t type);
 
 /*=====================
  * Other functions
diff --git a/lv_objx/lv_bar.c b/lv_objx/lv_bar.c
index 975c9b9bd..aca32328a 100644
--- a/lv_objx/lv_bar.c
+++ b/lv_objx/lv_bar.c
@@ -50,7 +50,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a bar object, if not NULL then the new object will be copied from it
  * @return pointer to the created bar
  */
-lv_obj_t * lv_bar_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_bar_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("lv_bar create started");
 
@@ -214,7 +214,7 @@ void lv_bar_set_style(lv_obj_t * bar, lv_bar_style_t type, lv_style_t * style)
  * @param bar pointer to a bar object
  * @return the value of the bar
  */
-int16_t lv_bar_get_value(lv_obj_t * bar)
+int16_t lv_bar_get_value(const lv_obj_t * bar)
 {
     lv_bar_ext_t * ext = lv_obj_get_ext_attr(bar);
     return ext->cur_value;
@@ -225,7 +225,7 @@ int16_t lv_bar_get_value(lv_obj_t * bar)
  * @param bar pointer to a bar object
  * @return the minimum value of the bar
  */
-int16_t lv_bar_get_min_value(lv_obj_t * bar)
+int16_t lv_bar_get_min_value(const lv_obj_t * bar)
 {
     lv_bar_ext_t * ext = lv_obj_get_ext_attr(bar);
     return ext->min_value;
@@ -236,7 +236,7 @@ int16_t lv_bar_get_min_value(lv_obj_t * bar)
  * @param bar pointer to a bar object
  * @return the maximum value of the bar
  */
-int16_t lv_bar_get_max_value(lv_obj_t * bar)
+int16_t lv_bar_get_max_value(const lv_obj_t * bar)
 {
     lv_bar_ext_t * ext = lv_obj_get_ext_attr(bar);
     return ext->max_value;
@@ -248,7 +248,7 @@ int16_t lv_bar_get_max_value(lv_obj_t * bar)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_bar_get_style(lv_obj_t * bar, lv_bar_style_t type)
+lv_style_t * lv_bar_get_style(const lv_obj_t * bar, lv_bar_style_t type)
 {
     lv_bar_ext_t * ext = lv_obj_get_ext_attr(bar);
 
diff --git a/lv_objx/lv_bar.h b/lv_objx/lv_bar.h
index 1a9ef5c2f..2c0de508d 100644
--- a/lv_objx/lv_bar.h
+++ b/lv_objx/lv_bar.h
@@ -60,7 +60,7 @@ typedef enum {
  * @param copy pointer to a bar object, if not NULL then the new object will be copied from it
  * @return pointer to the created bar
  */
-lv_obj_t * lv_bar_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_bar_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -107,21 +107,21 @@ void lv_bar_set_style(lv_obj_t *bar, lv_bar_style_t type, lv_style_t *style);
  * @param bar pointer to a bar object
  * @return the value of the bar
  */
-int16_t lv_bar_get_value(lv_obj_t * bar);
+int16_t lv_bar_get_value(const lv_obj_t * bar);
 
 /**
  * Get the minimum value of a bar
  * @param bar pointer to a bar object
  * @return the minimum value of the bar
  */
-int16_t lv_bar_get_min_value(lv_obj_t * bar);
+int16_t lv_bar_get_min_value(const lv_obj_t * bar);
 
 /**
  * Get the maximum value of a bar
  * @param bar pointer to a bar object
  * @return the maximum value of the bar
  */
-int16_t lv_bar_get_max_value(lv_obj_t * bar);
+int16_t lv_bar_get_max_value(const lv_obj_t * bar);
 
 
 /**
@@ -130,7 +130,7 @@ int16_t lv_bar_get_max_value(lv_obj_t * bar);
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_bar_get_style(lv_obj_t *bar, lv_bar_style_t type);
+lv_style_t * lv_bar_get_style(const lv_obj_t *bar, lv_bar_style_t type);
 
 /**********************
  *      MACROS
diff --git a/lv_objx/lv_btn.c b/lv_objx/lv_btn.c
index ecdef4c4d..409d2c123 100644
--- a/lv_objx/lv_btn.c
+++ b/lv_objx/lv_btn.c
@@ -65,7 +65,7 @@ static lv_point_t ink_point;
  * @param copy pointer to a button object, if not NULL then the new object will be copied from it
  * @return pointer to the created button
  */
-lv_obj_t * lv_btn_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_btn_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("button create started");
 
@@ -284,7 +284,7 @@ void lv_btn_set_style(lv_obj_t * btn, lv_btn_style_t type, lv_style_t * style)
  * @param btn pointer to a button object
  * @return the state of the button (from lv_btn_state_t enum)
  */
-lv_btn_state_t lv_btn_get_state(lv_obj_t * btn)
+lv_btn_state_t lv_btn_get_state(const lv_obj_t * btn)
 {
     lv_btn_ext_t * ext = lv_obj_get_ext_attr(btn);
     return ext->state;
@@ -295,7 +295,7 @@ lv_btn_state_t lv_btn_get_state(lv_obj_t * btn)
  * @param btn pointer to a button object
  * @return ture: toggle enabled, false: disabled
  */
-bool lv_btn_get_toggle(lv_obj_t * btn)
+bool lv_btn_get_toggle(const lv_obj_t * btn)
 {
     lv_btn_ext_t * ext = lv_obj_get_ext_attr(btn);
 
@@ -307,7 +307,7 @@ bool lv_btn_get_toggle(lv_obj_t * btn)
  * @param btn pointer to a button object
  * @return pointer to the release action function
  */
-lv_action_t lv_btn_get_action(lv_obj_t * btn, lv_btn_action_t type)
+lv_action_t lv_btn_get_action(const lv_obj_t * btn, lv_btn_action_t type)
 {
     if(type >= LV_BTN_ACTION_NUM) return NULL;
 
@@ -320,7 +320,7 @@ lv_action_t lv_btn_get_action(lv_obj_t * btn, lv_btn_action_t type)
  * @param btn pointer to a button object
  * @return the time of the ink animation
  */
-uint16_t lv_btn_get_ink_fill_time(lv_obj_t * btn, uint16_t time)
+uint16_t lv_btn_get_ink_fill_time(const lv_obj_t * btn, uint16_t time)
 {
     lv_btn_ext_t * ext = lv_obj_get_ext_attr(btn);
     return ext->ink_fill_time;
@@ -332,7 +332,7 @@ uint16_t lv_btn_get_ink_fill_time(lv_obj_t * btn, uint16_t time)
  * @param btn pointer to a button object
  * @return the time of the ink animation
  */
-uint16_t lv_btn_get_ink_wait_time(lv_obj_t * btn, uint16_t time)
+uint16_t lv_btn_get_ink_wait_time(const lv_obj_t * btn, uint16_t time)
 {
     lv_btn_ext_t * ext = lv_obj_get_ext_attr(btn);
     return ext->ink_wait_time;
@@ -344,7 +344,7 @@ uint16_t lv_btn_get_ink_wait_time(lv_obj_t * btn, uint16_t time)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_btn_get_style(lv_obj_t * btn, lv_btn_style_t type)
+lv_style_t * lv_btn_get_style(const lv_obj_t * btn, lv_btn_style_t type)
 {
     lv_btn_ext_t * ext = lv_obj_get_ext_attr(btn);
 
diff --git a/lv_objx/lv_btn.h b/lv_objx/lv_btn.h
index 2ccd7aae6..0fed43676 100644
--- a/lv_objx/lv_btn.h
+++ b/lv_objx/lv_btn.h
@@ -90,7 +90,7 @@ typedef enum {
  * @param copy pointer to a button object, if not NULL then the new object will be copied from it
  * @return pointer to the created button
  */
-lv_obj_t * lv_btn_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_btn_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -178,28 +178,28 @@ void lv_btn_set_style(lv_obj_t * btn, lv_btn_style_t type, lv_style_t *style);
  * @param btn pointer to a button object
  * @return the state of the button (from lv_btn_state_t enum)
  */
-lv_btn_state_t lv_btn_get_state(lv_obj_t * btn);
+lv_btn_state_t lv_btn_get_state(const lv_obj_t * btn);
 
 /**
  * Get the toggle enable attribute of the button
  * @param btn pointer to a button object
  * @return ture: toggle enabled, false: disabled
  */
-bool lv_btn_get_toggle(lv_obj_t * btn);
+bool lv_btn_get_toggle(const lv_obj_t * btn);
 
 /**
  * Get the release action of a button
  * @param btn pointer to a button object
  * @return pointer to the release action function
  */
-lv_action_t lv_btn_get_action(lv_obj_t * btn, lv_btn_action_t type);
+lv_action_t lv_btn_get_action(const lv_obj_t * btn, lv_btn_action_t type);
 
 /**
  * Get the layout of a button
  * @param btn pointer to button object
  * @return the layout from 'lv_cont_layout_t'
  */
-static inline lv_layout_t lv_btn_get_layout(lv_obj_t * btn)
+static inline lv_layout_t lv_btn_get_layout(const lv_obj_t * btn)
 {
     return lv_cont_get_layout(btn);
 }
@@ -209,7 +209,7 @@ static inline lv_layout_t lv_btn_get_layout(lv_obj_t * btn)
  * @param btn pointer to a button object
  * @return true: horizontal fit is enabled; false: disabled
  */
-static inline bool lv_btn_get_hor_fit(lv_obj_t * btn)
+static inline bool lv_btn_get_hor_fit(const lv_obj_t * btn)
 {
     return lv_cont_get_hor_fit(btn);
 }
@@ -219,7 +219,7 @@ static inline bool lv_btn_get_hor_fit(lv_obj_t * btn)
  * @param btn pointer to a button object
  * @return true: vertical fit is enabled; false: disabled
  */
-static inline bool lv_btn_get_ver_fit(lv_obj_t * btn)
+static inline bool lv_btn_get_ver_fit(const lv_obj_t * btn)
 {
     return lv_cont_get_ver_fit(btn);
 }
@@ -228,14 +228,14 @@ static inline bool lv_btn_get_ver_fit(lv_obj_t * btn)
  * @param btn pointer to a button object
  * @return the time of the ink animation
  */
-uint16_t lv_btn_get_ink_fill_time(lv_obj_t * btn, uint16_t time);
+uint16_t lv_btn_get_ink_fill_time(const lv_obj_t * btn, uint16_t time);
 
 /**
  * Get the wait time before the ink disappears
  * @param btn pointer to a button object
  * @return the time of the ink animation
  */
-uint16_t lv_btn_get_ink_wait_time(lv_obj_t * btn, uint16_t time);
+uint16_t lv_btn_get_ink_wait_time(const lv_obj_t * btn, uint16_t time);
 
 /**
  * Get style of a button.
@@ -243,7 +243,7 @@ uint16_t lv_btn_get_ink_wait_time(lv_obj_t * btn, uint16_t time);
  * @param type which style should be get
  * @return style pointer to the style
  *  */
-lv_style_t * lv_btn_get_style(lv_obj_t * btn, lv_btn_style_t type);
+lv_style_t * lv_btn_get_style(const lv_obj_t * btn, lv_btn_style_t type);
 
 /**********************
  *      MACROS
diff --git a/lv_objx/lv_btnm.c b/lv_objx/lv_btnm.c
index a488923c3..43a7fa647 100644
--- a/lv_objx/lv_btnm.c
+++ b/lv_objx/lv_btnm.c
@@ -62,7 +62,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a button matrix object, if not NULL then the new object will be copied from it
  * @return pointer to the created button matrix
  */
-lv_obj_t * lv_btnm_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_btnm_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("button matrix create started");
 
@@ -324,7 +324,7 @@ void lv_btnm_set_style(lv_obj_t * btnm, lv_btnm_style_t type, lv_style_t * style
  * @param btnm pointer to a button matrix object
  * @return the current map
  */
-const char ** lv_btnm_get_map(lv_obj_t * btnm)
+const char ** lv_btnm_get_map(const lv_obj_t * btnm)
 {
     lv_btnm_ext_t * ext = lv_obj_get_ext_attr(btnm);
     return ext->map_p;
@@ -335,7 +335,7 @@ const char ** lv_btnm_get_map(lv_obj_t * btnm)
  * @param btnm: pointer to button matrix object
  * @return pointer to the callback function
  */
-lv_btnm_action_t lv_btnm_get_action(lv_obj_t * btnm)
+lv_btnm_action_t lv_btnm_get_action(const lv_obj_t * btnm)
 {
     lv_btnm_ext_t * ext = lv_obj_get_ext_attr(btnm);
     return ext->action;
@@ -346,7 +346,7 @@ lv_btnm_action_t lv_btnm_get_action(lv_obj_t * btnm)
  * @param btnm pointer to button matrix object
  * @return  index of the currently toggled button (0: if unset)
  */
-uint16_t lv_btnm_get_toggled(lv_obj_t * btnm)
+uint16_t lv_btnm_get_toggled(const lv_obj_t * btnm)
 {
     lv_btnm_ext_t * ext = lv_obj_get_ext_attr(btnm);
 
@@ -360,7 +360,7 @@ uint16_t lv_btnm_get_toggled(lv_obj_t * btnm)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_btnm_get_style(lv_obj_t * btnm, lv_btnm_style_t type)
+lv_style_t * lv_btnm_get_style(const lv_obj_t * btnm, lv_btnm_style_t type)
 {
     lv_btnm_ext_t * ext = lv_obj_get_ext_attr(btnm);
 
diff --git a/lv_objx/lv_btnm.h b/lv_objx/lv_btnm.h
index 03e62ade6..47f567193 100644
--- a/lv_objx/lv_btnm.h
+++ b/lv_objx/lv_btnm.h
@@ -81,7 +81,7 @@ typedef enum {
  * @param copy pointer to a button matrix object, if not NULL then the new object will be copied from it
  * @return pointer to the created button matrix
  */
-lv_obj_t * lv_btnm_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_btnm_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -135,14 +135,14 @@ void lv_btnm_set_style(lv_obj_t *btnm, lv_btnm_style_t type, lv_style_t *style);
  * @param btnm pointer to a button matrix object
  * @return the current map
  */
-const char ** lv_btnm_get_map(lv_obj_t * btnm);
+const char ** lv_btnm_get_map(const lv_obj_t * btnm);
 
 /**
  * Get a the callback function of the buttons on a button matrix
  * @param btnm: pointer to button matrix object
  * @return pointer to the callback function
  */
-lv_btnm_action_t lv_btnm_get_action(lv_obj_t * btnm);
+lv_btnm_action_t lv_btnm_get_action(const lv_obj_t * btnm);
 
 
 /**
@@ -150,7 +150,7 @@ lv_btnm_action_t lv_btnm_get_action(lv_obj_t * btnm);
  * @param btnm pointer to button matrix object
  * @return  index of the currently toggled button (0: if unset)
  */
-uint16_t lv_btnm_get_toggled(lv_obj_t * btnm);
+uint16_t lv_btnm_get_toggled(const lv_obj_t * btnm);
 
 /**
  * Get a style of a button matrix
@@ -158,7 +158,7 @@ uint16_t lv_btnm_get_toggled(lv_obj_t * btnm);
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_btnm_get_style(lv_obj_t *btnm, lv_btnm_style_t type);
+lv_style_t * lv_btnm_get_style(const lv_obj_t *btnm, lv_btnm_style_t type);
 
 /**********************
  *      MACROS
diff --git a/lv_objx/lv_calendar.c b/lv_objx/lv_calendar.c
index 2b778b850..a06cdb55a 100644
--- a/lv_objx/lv_calendar.c
+++ b/lv_objx/lv_calendar.c
@@ -68,7 +68,7 @@ static const char * month_name[12] = {"January",   "February",   "March",    "Ap
  * @param copy pointer to a calendar object, if not NULL then the new object will be copied from it
  * @return pointer to the created calendar
  */
-lv_obj_t * lv_calendar_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_calendar_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("calendar create started");
 
@@ -281,7 +281,7 @@ void lv_calendar_set_style(lv_obj_t * calendar, lv_calendar_style_t type, lv_sty
  * @param calendar pointer to a calendar object
  * @return return pointer to an `lv_calendar_date_t` variable containing the date of today.
  */
-lv_calendar_date_t * lv_calendar_get_today_date(lv_obj_t * calendar)
+lv_calendar_date_t * lv_calendar_get_today_date(const lv_obj_t * calendar)
 {
     lv_calendar_ext_t * ext = lv_obj_get_ext_attr(calendar);
     return &ext->today;
@@ -292,7 +292,7 @@ lv_calendar_date_t * lv_calendar_get_today_date(lv_obj_t * calendar)
  * @param calendar pointer to a calendar object
  * @return pointer to an `lv_calendar_date_t` variable containing the date is being shown.
  */
-lv_calendar_date_t * lv_calendar_get_showed_date(lv_obj_t * calendar)
+lv_calendar_date_t * lv_calendar_get_showed_date(const lv_obj_t * calendar)
 {
     lv_calendar_ext_t * ext = lv_obj_get_ext_attr(calendar);
     return &ext->showed_date;
@@ -303,7 +303,7 @@ lv_calendar_date_t * lv_calendar_get_showed_date(lv_obj_t * calendar)
  * @param calendar pointer to a calendar object
  * @return pointer to an `lv_calendar_date_t` array containing the dates.
  */
-lv_calendar_date_t * lv_calendar_get_highlighted_dates(lv_obj_t * calendar)
+lv_calendar_date_t * lv_calendar_get_highlighted_dates(const lv_obj_t * calendar)
 {
     lv_calendar_ext_t * ext = lv_obj_get_ext_attr(calendar);
     return ext->highlighted_dates;
@@ -314,7 +314,7 @@ lv_calendar_date_t * lv_calendar_get_highlighted_dates(lv_obj_t * calendar)
  * @param calendar pointer to a calendar object
  * @return number of highlighted days
  */
-uint16_t lv_calendar_get_highlighted_dates_num(lv_obj_t * calendar)
+uint16_t lv_calendar_get_highlighted_dates_num(const lv_obj_t * calendar)
 {
     lv_calendar_ext_t * ext = lv_obj_get_ext_attr(calendar);
     return ext->highlighted_dates_num;
@@ -325,7 +325,7 @@ uint16_t lv_calendar_get_highlighted_dates_num(lv_obj_t * calendar)
  * @param calendar pointer to a calendar object
  * @return pointer to the array of day names
  */
-const char ** lv_calendar_get_day_names(lv_obj_t * calendar, const char ** day_names)
+const char ** lv_calendar_get_day_names(const lv_obj_t * calendar, const char ** day_names)
 {
     lv_calendar_ext_t * ext = lv_obj_get_ext_attr(calendar);
     return ext->day_names;
@@ -336,7 +336,7 @@ const char ** lv_calendar_get_day_names(lv_obj_t * calendar, const char ** day_n
  * @param calendar pointer to a calendar object
  * @return pointer to the array of month names
  */
-const char ** lv_calendar_get_month_names(lv_obj_t * calendar, const char ** day_names)
+const char ** lv_calendar_get_month_names(const lv_obj_t * calendar, const char ** day_names)
 {
     lv_calendar_ext_t * ext = lv_obj_get_ext_attr(calendar);
     return ext->month_names;
@@ -348,7 +348,7 @@ const char ** lv_calendar_get_month_names(lv_obj_t * calendar, const char ** day
  * @param type which style should be get
  * @return style pointer to the style
  *  */
-lv_style_t * lv_calendar_get_style(lv_obj_t * calendar, lv_calendar_style_t type)
+lv_style_t * lv_calendar_get_style(const lv_obj_t * calendar, lv_calendar_style_t type)
 {
     lv_calendar_ext_t * ext = lv_obj_get_ext_attr(calendar);
 
diff --git a/lv_objx/lv_calendar.h b/lv_objx/lv_calendar.h
index 78c26f95d..2c3262b60 100644
--- a/lv_objx/lv_calendar.h
+++ b/lv_objx/lv_calendar.h
@@ -82,7 +82,7 @@ typedef enum {
  * @param copy pointer to a calendar object, if not NULL then the new object will be copied from it
  * @return pointer to the created calendar
  */
-lv_obj_t * lv_calendar_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_calendar_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*======================
  * Add/remove functions
@@ -149,28 +149,28 @@ void lv_calendar_set_style(lv_obj_t * calendar, lv_calendar_style_t type, lv_sty
  * @param calendar pointer to a calendar object
  * @return return pointer to an `lv_calendar_date_t` variable containing the date of today.
  */
-lv_calendar_date_t * lv_calendar_get_today_date(lv_obj_t * calendar);
+lv_calendar_date_t * lv_calendar_get_today_date(const lv_obj_t * calendar);
 
 /**
  * Get the currently showed
  * @param calendar pointer to a calendar object
  * @return pointer to an `lv_calendar_date_t` variable containing the date is being shown.
  */
-lv_calendar_date_t * lv_calendar_get_showed_date(lv_obj_t * calendar);
+lv_calendar_date_t * lv_calendar_get_showed_date(const lv_obj_t * calendar);
 
 /**
  * Get the the highlighted dates
  * @param calendar pointer to a calendar object
  * @return pointer to an `lv_calendar_date_t` array containing the dates.
  */
-lv_calendar_date_t * lv_calendar_get_highlighted_dates(lv_obj_t * calendar);
+lv_calendar_date_t * lv_calendar_get_highlighted_dates(const lv_obj_t * calendar);
 
 /**
  * Get the number of the highlighted dates
  * @param calendar pointer to a calendar object
  * @return number of highlighted days
  */
-uint16_t lv_calendar_get_highlighted_dates_num(lv_obj_t * calendar);
+uint16_t lv_calendar_get_highlighted_dates_num(const lv_obj_t * calendar);
 
 
 /**
@@ -178,14 +178,14 @@ uint16_t lv_calendar_get_highlighted_dates_num(lv_obj_t * calendar);
  * @param calendar pointer to a calendar object
  * @return pointer to the array of day names
  */
-const char ** lv_calendar_get_day_names(lv_obj_t * calendar, const char ** day_names);
+const char ** lv_calendar_get_day_names(const lv_obj_t * calendar, const char ** day_names);
 
 /**
  * Get the name of the month
  * @param calendar pointer to a calendar object
  * @return pointer to the array of month names
  */
-const char ** lv_calendar_get_month_names(lv_obj_t * calendar, const char ** day_names);
+const char ** lv_calendar_get_month_names(const lv_obj_t * calendar, const char ** day_names);
 
 /**
  * Get style of a calendar.
@@ -193,7 +193,7 @@ const char ** lv_calendar_get_month_names(lv_obj_t * calendar, const char ** day
  * @param type which style should be get
  * @return style pointer to the style
  *  */
-lv_style_t * lv_calendar_get_style(lv_obj_t * calendar, lv_calendar_style_t type);
+lv_style_t * lv_calendar_get_style(const lv_obj_t * calendar, lv_calendar_style_t type);
 
 /*=====================
  * Other functions
diff --git a/lv_objx/lv_cb.c b/lv_objx/lv_cb.c
index 19699560f..21befa0f9 100644
--- a/lv_objx/lv_cb.c
+++ b/lv_objx/lv_cb.c
@@ -48,7 +48,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a check box object, if not NULL then the new object will be copied from it
  * @return pointer to the created check box
  */
-lv_obj_t * lv_cb_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_cb_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 
 	LV_LOG_TRACE("check box create started");
@@ -176,7 +176,7 @@ void lv_cb_set_style(lv_obj_t * cb, lv_cb_style_t type, lv_style_t * style)
  * @param cb pointer to check box object
  * @return pointer to the text of the check box
  */
-const char * lv_cb_get_text(lv_obj_t * cb)
+const char * lv_cb_get_text(const lv_obj_t * cb)
 {
     lv_cb_ext_t * ext = lv_obj_get_ext_attr(cb);
     return lv_label_get_text(ext->label);
@@ -189,7 +189,7 @@ const char * lv_cb_get_text(lv_obj_t * cb)
  * @param type which style should be get
  * @return style pointer to the style
  *  */
-lv_style_t * lv_cb_get_style(lv_obj_t * cb, lv_cb_style_t type)
+lv_style_t * lv_cb_get_style(const lv_obj_t * cb, lv_cb_style_t type)
 {
     lv_cb_ext_t * ext = lv_obj_get_ext_attr(cb);
 
diff --git a/lv_objx/lv_cb.h b/lv_objx/lv_cb.h
index f80b300d3..1d3b89da5 100644
--- a/lv_objx/lv_cb.h
+++ b/lv_objx/lv_cb.h
@@ -70,7 +70,7 @@ typedef enum {
  * @param copy pointer to a check box object, if not NULL then the new object will be copied from it
  * @return pointer to the created check box
  */
-lv_obj_t * lv_cb_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_cb_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -129,14 +129,14 @@ void lv_cb_set_style(lv_obj_t * cb, lv_cb_style_t type, lv_style_t *style);
  * @param cb pointer to check box object
  * @return pointer to the text of the check box
  */
-const char * lv_cb_get_text(lv_obj_t * cb);
+const char * lv_cb_get_text(const lv_obj_t * cb);
 
 /**
  * Get the current state of the check box
  * @param cb pointer to a check box object
  * @return true: checked; false: not checked
  */
-static inline bool lv_cb_is_checked(lv_obj_t * cb)
+static inline bool lv_cb_is_checked(const lv_obj_t * cb)
 {
     return lv_btn_get_state(cb) == LV_BTN_STATE_REL ? false : true;
 }
@@ -146,7 +146,7 @@ static inline bool lv_cb_is_checked(lv_obj_t * cb)
  * @param cb pointer to a button object
  * @return pointer to the action function
  */
-static inline lv_action_t lv_cb_get_action(lv_obj_t * cb)
+static inline lv_action_t lv_cb_get_action(const lv_obj_t * cb)
 {
     return lv_btn_get_action(cb, LV_BTN_ACTION_CLICK);
 }
@@ -158,7 +158,7 @@ static inline lv_action_t lv_cb_get_action(lv_obj_t * cb)
  * @param type which style should be get
  * @return style pointer to the style
  *  */
-lv_style_t * lv_cb_get_style(lv_obj_t * cb, lv_cb_style_t type);
+lv_style_t * lv_cb_get_style(const lv_obj_t * cb, lv_cb_style_t type);
 
 /**********************
  *      MACROS
diff --git a/lv_objx/lv_chart.c b/lv_objx/lv_chart.c
index b4d1f983c..4d9e95831 100644
--- a/lv_objx/lv_chart.c
+++ b/lv_objx/lv_chart.c
@@ -55,7 +55,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a chart background object, if not NULL then the new object will be copied from it
  * @return pointer to the created chart background
  */
-lv_obj_t * lv_chart_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_chart_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 
 
@@ -349,7 +349,7 @@ void lv_chart_set_next(lv_obj_t * chart, lv_chart_series_t * ser, lv_coord_t y)
  * @param chart pointer to chart object
  * @return type of the chart (from 'lv_chart_t' enum)
  */
-lv_chart_type_t lv_chart_get_type(lv_obj_t * chart)
+lv_chart_type_t lv_chart_get_type(const lv_obj_t * chart)
 {
     lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
     return ext->type;
@@ -360,7 +360,7 @@ lv_chart_type_t lv_chart_get_type(lv_obj_t * chart)
  * @param chart pointer to chart object
  * @return point number on each data line
  */
-uint16_t lv_chart_get_point_cnt(lv_obj_t * chart)
+uint16_t lv_chart_get_point_cnt(const lv_obj_t * chart)
 {
     lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
     return ext->point_cnt;
@@ -371,7 +371,7 @@ uint16_t lv_chart_get_point_cnt(lv_obj_t * chart)
  * @param chart pointer to chart object
  * @return the opacity of the data series
  */
-lv_opa_t lv_chart_get_series_opa(lv_obj_t * chart)
+lv_opa_t lv_chart_get_series_opa(const lv_obj_t * chart)
 {
     lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
     return ext->series.opa;
@@ -382,7 +382,7 @@ lv_opa_t lv_chart_get_series_opa(lv_obj_t * chart)
  * @param chart pointer to chart object
  * @return the width the data series (lines or points)
  */
-lv_coord_t lv_chart_get_series_width(lv_obj_t * chart)
+lv_coord_t lv_chart_get_series_width(const lv_obj_t * chart)
 {
     lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
     return ext->series.width;
@@ -393,7 +393,7 @@ lv_coord_t lv_chart_get_series_width(lv_obj_t * chart)
  * @param chart pointer to chart object
  * @return dark effect level (LV_OPA_TRANSP to turn off)
  */
-lv_opa_t lv_chart_get_series_darking(lv_obj_t * chart)
+lv_opa_t lv_chart_get_series_darking(const lv_obj_t * chart)
 {
     lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
     return ext->series.dark;
diff --git a/lv_objx/lv_chart.h b/lv_objx/lv_chart.h
index 84a393142..07f5a380c 100644
--- a/lv_objx/lv_chart.h
+++ b/lv_objx/lv_chart.h
@@ -76,7 +76,7 @@ typedef enum
  * @param copy pointer to a chart background object, if not NULL then the new object will be copied from it
  * @return pointer to the created chart background
  */
-lv_obj_t * lv_chart_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_chart_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*======================
  * Add/remove functions
@@ -188,42 +188,42 @@ static inline void lv_chart_set_style(lv_obj_t *chart, lv_style_t *style)
  * @param chart pointer to chart object
  * @return type of the chart (from 'lv_chart_t' enum)
  */
-lv_chart_type_t lv_chart_get_type(lv_obj_t * chart);
+lv_chart_type_t lv_chart_get_type(const lv_obj_t * chart);
 
 /**
  * Get the data point number per data line on chart
  * @param chart pointer to chart object
  * @return point number on each data line
  */
-uint16_t lv_chart_get_point_cnt(lv_obj_t * chart);
+uint16_t lv_chart_get_point_cnt(const lv_obj_t * chart);
 
 /**
  * Get the opacity of the data series
  * @param chart pointer to chart object
  * @return the opacity of the data series
  */
-lv_opa_t lv_chart_get_series_opa(lv_obj_t * chart);
+lv_opa_t lv_chart_get_series_opa(const lv_obj_t * chart);
 
 /**
  * Get the data series width
  * @param chart pointer to chart object
  * @return the width the data series (lines or points)
  */
-lv_coord_t lv_chart_get_series_width(lv_obj_t * chart);
+lv_coord_t lv_chart_get_series_width(const lv_obj_t * chart);
 
 /**
  * Get the dark effect level on the bottom of the points or columns
  * @param chart pointer to chart object
  * @return dark effect level (LV_OPA_TRANSP to turn off)
  */
-lv_opa_t lv_chart_get_series_darking(lv_obj_t * chart);
+lv_opa_t lv_chart_get_series_darking(const lv_obj_t * chart);
 
 /**
  * Get the style of an chart object
  * @param chart pointer to an chart object
  * @return pointer to the chart's style
  */
-static inline lv_style_t* lv_chart_get_style(lv_obj_t *chart)
+static inline lv_style_t* lv_chart_get_style(const lv_obj_t *chart)
 {
     return lv_obj_get_style(chart);
 }
diff --git a/lv_objx/lv_cont.c b/lv_objx/lv_cont.c
index d8c72f840..e4a486e78 100644
--- a/lv_objx/lv_cont.c
+++ b/lv_objx/lv_cont.c
@@ -60,7 +60,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a container object, if not NULL then the new object will be copied from it
  * @return pointer to the created container
  */
-lv_obj_t * lv_cont_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_cont_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 
 
@@ -163,7 +163,7 @@ void lv_cont_set_fit(lv_obj_t * cont, bool hor_en, bool ver_en)
  * @param cont pointer to container object
  * @return the layout from 'lv_cont_layout_t'
  */
-lv_layout_t lv_cont_get_layout(lv_obj_t * cont)
+lv_layout_t lv_cont_get_layout(const lv_obj_t * cont)
 {
     lv_cont_ext_t * ext = lv_obj_get_ext_attr(cont);
     return ext->layout;
@@ -174,7 +174,7 @@ lv_layout_t lv_cont_get_layout(lv_obj_t * cont)
  * @param cont pointer to a container object
  * @return true: horizontal fit is enabled; false: disabled
  */
-bool lv_cont_get_hor_fit(lv_obj_t * cont)
+bool lv_cont_get_hor_fit(const lv_obj_t * cont)
 {
     lv_cont_ext_t * ext = lv_obj_get_ext_attr(cont);
     return ext->hor_fit == 0 ? false : true;
@@ -185,7 +185,7 @@ bool lv_cont_get_hor_fit(lv_obj_t * cont)
  * @param cont pointer to a container object
  * @return true: vertical fit is enabled; false: disabled
  */
-bool lv_cont_get_ver_fit(lv_obj_t * cont)
+bool lv_cont_get_ver_fit(const lv_obj_t * cont)
 {
     lv_cont_ext_t * ext = lv_obj_get_ext_attr(cont);
     return ext->ver_fit == 0 ? false : true;
diff --git a/lv_objx/lv_cont.h b/lv_objx/lv_cont.h
index 335b8c282..8b6835c47 100644
--- a/lv_objx/lv_cont.h
+++ b/lv_objx/lv_cont.h
@@ -65,7 +65,7 @@ typedef struct
  * @param copy pointer to a container object, if not NULL then the new object will be copied from it
  * @return pointer to the created container
  */
-lv_obj_t * lv_cont_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_cont_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -107,28 +107,28 @@ static inline void lv_cont_set_style(lv_obj_t *cont, lv_style_t * style)
  * @param cont pointer to container object
  * @return the layout from 'lv_cont_layout_t'
  */
-lv_layout_t lv_cont_get_layout(lv_obj_t * cont);
+lv_layout_t lv_cont_get_layout(const lv_obj_t * cont);
 
 /**
  * Get horizontal fit enable attribute of a container
  * @param cont pointer to a container object
  * @return true: horizontal fit is enabled; false: disabled
  */
-bool lv_cont_get_hor_fit(lv_obj_t * cont);
+bool lv_cont_get_hor_fit(const lv_obj_t * cont);
 
 /**
  * Get vertical fit enable attribute of a container
  * @param cont pointer to a container object
  * @return true: vertical fit is enabled; false: disabled
  */
-bool lv_cont_get_ver_fit(lv_obj_t * cont);
+bool lv_cont_get_ver_fit(const lv_obj_t * cont);
 
 /**
  * Get the style of a container
  * @param cont pointer to a container object
  * @return pointer to the container's style
  */
-static inline lv_style_t * lv_cont_get_style(lv_obj_t *cont)
+static inline lv_style_t * lv_cont_get_style(const lv_obj_t *cont)
 {
     return lv_obj_get_style(cont);
 }
diff --git a/lv_objx/lv_ddlist.c b/lv_objx/lv_ddlist.c
index 5197e27f6..c7a4400f9 100644
--- a/lv_objx/lv_ddlist.c
+++ b/lv_objx/lv_ddlist.c
@@ -64,7 +64,7 @@ static lv_design_func_t  ancestor_design;
  * @param copy pointer to a drop down list object, if not NULL then the new object will be copied from it
  * @return pointer to the created drop down list
  */
-lv_obj_t * lv_ddlist_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_ddlist_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("drop down list create started");
 
@@ -280,7 +280,7 @@ void lv_ddlist_set_style(lv_obj_t * ddlist, lv_ddlist_style_t type, lv_style_t *
  * @param ddlist pointer to drop down list object
  * @return the options separated by '\n'-s (E.g. "Option1\nOption2\nOption3")
  */
-const char * lv_ddlist_get_options(lv_obj_t * ddlist)
+const char * lv_ddlist_get_options(const lv_obj_t * ddlist)
 {
     lv_ddlist_ext_t * ext = lv_obj_get_ext_attr(ddlist);
     return lv_label_get_text(ext->label);
@@ -291,7 +291,7 @@ const char * lv_ddlist_get_options(lv_obj_t * ddlist)
  * @param ddlist pointer to drop down list object
  * @return id of the selected option (0 ... number of option - 1);
  */
-uint16_t lv_ddlist_get_selected(lv_obj_t * ddlist)
+uint16_t lv_ddlist_get_selected(const lv_obj_t * ddlist)
 {
     lv_ddlist_ext_t * ext = lv_obj_get_ext_attr(ddlist);
 
@@ -303,7 +303,7 @@ uint16_t lv_ddlist_get_selected(lv_obj_t * ddlist)
  * @param ddlist pointer to ddlist object
  * @param buf pointer to an array to store the string
  */
-void lv_ddlist_get_selected_str(lv_obj_t * ddlist, char * buf)
+void lv_ddlist_get_selected_str(const lv_obj_t * ddlist, char * buf)
 {
     lv_ddlist_ext_t * ext = lv_obj_get_ext_attr(ddlist);
 
@@ -328,7 +328,7 @@ void lv_ddlist_get_selected_str(lv_obj_t * ddlist, char * buf)
  * @param ddlist pointer to a drop down list
  * @return  pointer to the call back function
  */
-lv_action_t lv_ddlist_get_action(lv_obj_t * ddlist)
+lv_action_t lv_ddlist_get_action(const lv_obj_t * ddlist)
 {
     lv_ddlist_ext_t * ext = lv_obj_get_ext_attr(ddlist);
     return ext->action;
@@ -339,7 +339,7 @@ lv_action_t lv_ddlist_get_action(lv_obj_t * ddlist)
  * @param ddlist pointer to a drop down list object
  * @return the height if the ddlist is opened (0: auto size)
  */
-lv_coord_t lv_ddlist_get_fix_height(lv_obj_t * ddlist)
+lv_coord_t lv_ddlist_get_fix_height(const lv_obj_t * ddlist)
 {
     lv_ddlist_ext_t * ext = lv_obj_get_ext_attr(ddlist);
     return ext->fix_height;
@@ -350,7 +350,7 @@ lv_coord_t lv_ddlist_get_fix_height(lv_obj_t * ddlist)
  * @param ddlist pointer to a drop down list
  * @return open/close animation time [ms]
  */
-uint16_t lv_ddlist_get_anim_time(lv_obj_t * ddlist)
+uint16_t lv_ddlist_get_anim_time(const lv_obj_t * ddlist)
 {
     lv_ddlist_ext_t * ext = lv_obj_get_ext_attr(ddlist);
     return ext->anim_time;
@@ -363,7 +363,7 @@ uint16_t lv_ddlist_get_anim_time(lv_obj_t * ddlist)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_ddlist_get_style(lv_obj_t * ddlist, lv_ddlist_style_t type)
+lv_style_t * lv_ddlist_get_style(const lv_obj_t * ddlist, lv_ddlist_style_t type)
 {
     lv_ddlist_ext_t * ext = lv_obj_get_ext_attr(ddlist);
 
diff --git a/lv_objx/lv_ddlist.h b/lv_objx/lv_ddlist.h
index e6f27b194..b1bb044b8 100644
--- a/lv_objx/lv_ddlist.h
+++ b/lv_objx/lv_ddlist.h
@@ -72,7 +72,7 @@ typedef enum {
  * @param copy pointer to a drop down list object, if not NULL then the new object will be copied from it
  * @return pointer to the created drop down list
  */
-lv_obj_t * lv_ddlist_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_ddlist_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -149,42 +149,42 @@ void lv_ddlist_set_style(lv_obj_t *ddlist, lv_ddlist_style_t type, lv_style_t *s
  * @param ddlist pointer to drop down list object
  * @return the options separated by '\n'-s (E.g. "Option1\nOption2\nOption3")
  */
-const char * lv_ddlist_get_options(lv_obj_t * ddlist);
+const char * lv_ddlist_get_options(const lv_obj_t * ddlist);
 
 /**
  * Get the selected option
  * @param ddlist pointer to drop down list object
  * @return id of the selected option (0 ... number of option - 1);
  */
-uint16_t lv_ddlist_get_selected(lv_obj_t * ddlist);
+uint16_t lv_ddlist_get_selected(const lv_obj_t * ddlist);
 
 /**
  * Get the current selected option as a string
  * @param ddlist pointer to ddlist object
  * @param buf pointer to an array to store the string
  */
-void lv_ddlist_get_selected_str(lv_obj_t * ddlist, char * buf);
+void lv_ddlist_get_selected_str(const lv_obj_t * ddlist, char * buf);
 
 /**
  * Get the "option selected" callback function
  * @param ddlist pointer to a drop down list
  * @return  pointer to the call back function
  */
-lv_action_t lv_ddlist_get_action(lv_obj_t * ddlist);
+lv_action_t lv_ddlist_get_action(const lv_obj_t * ddlist);
 
 /**
  * Get the fix height value.
  * @param ddlist pointer to a drop down list object
  * @return the height if the ddlist is opened (0: auto size)
  */
-lv_coord_t lv_ddlist_get_fix_height(lv_obj_t * ddlist);
+lv_coord_t lv_ddlist_get_fix_height(const lv_obj_t * ddlist);
 
 /**
  * Get the scroll bar mode of a drop down list
  * @param ddlist pointer to a  drop down list object
  * @return scrollbar mode from 'lv_page_sb_mode_t' enum
  */
-static inline lv_sb_mode_t lv_ddlist_get_sb_mode(lv_obj_t * ddlist)
+static inline lv_sb_mode_t lv_ddlist_get_sb_mode(const lv_obj_t * ddlist)
 {
     return lv_page_get_sb_mode(ddlist);
 }
@@ -194,7 +194,7 @@ static inline lv_sb_mode_t lv_ddlist_get_sb_mode(lv_obj_t * ddlist)
  * @param ddlist pointer to a drop down list
  * @return open/close animation time [ms]
  */
-uint16_t lv_ddlist_get_anim_time(lv_obj_t * ddlist);
+uint16_t lv_ddlist_get_anim_time(const lv_obj_t * ddlist);
 
 /**
  * Get a style of a drop down list
@@ -202,7 +202,7 @@ uint16_t lv_ddlist_get_anim_time(lv_obj_t * ddlist);
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_ddlist_get_style(lv_obj_t *ddlist, lv_ddlist_style_t type);
+lv_style_t * lv_ddlist_get_style(const lv_obj_t *ddlist, lv_ddlist_style_t type);
 
 /*=====================
  * Other functions
diff --git a/lv_objx/lv_gauge.c b/lv_objx/lv_gauge.c
index 7cd3af3ef..66ee2c78e 100644
--- a/lv_objx/lv_gauge.c
+++ b/lv_objx/lv_gauge.c
@@ -58,7 +58,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a gauge object, if not NULL then the new object will be copied from it
  * @return pointer to the created gauge
  */
-lv_obj_t * lv_gauge_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_gauge_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("gauge create started");
 
@@ -208,7 +208,7 @@ void lv_gauge_set_scale(lv_obj_t * gauge, uint16_t angle, uint8_t line_cnt, uint
  * @param needle the id of the needle
  * @return the value of the needle [min,max]
  */
-int16_t lv_gauge_get_value(lv_obj_t * gauge,  uint8_t needle)
+int16_t lv_gauge_get_value(const lv_obj_t * gauge,  uint8_t needle)
 {
     lv_gauge_ext_t * ext = lv_obj_get_ext_attr(gauge);
     int16_t min = lv_gauge_get_min_value(gauge);
@@ -223,7 +223,7 @@ int16_t lv_gauge_get_value(lv_obj_t * gauge,  uint8_t needle)
  * @param gauge pointer to gauge
  * @return count of needles
  */
-uint8_t lv_gauge_get_needle_count(lv_obj_t * gauge)
+uint8_t lv_gauge_get_needle_count(const lv_obj_t * gauge)
 {
     lv_gauge_ext_t * ext = lv_obj_get_ext_attr(gauge);
     return ext->needle_count;
@@ -234,7 +234,7 @@ uint8_t lv_gauge_get_needle_count(lv_obj_t * gauge)
  * @param gauge pointer to a gauge object
  * @return count of labels
  */
-uint8_t lv_gauge_get_label_count(lv_obj_t * gauge)
+uint8_t lv_gauge_get_label_count(const lv_obj_t * gauge)
 {
     lv_gauge_ext_t * ext = lv_obj_get_ext_attr(gauge);
     return ext->label_count;
diff --git a/lv_objx/lv_gauge.h b/lv_objx/lv_gauge.h
index 3ac1908fc..4542c4c91 100644
--- a/lv_objx/lv_gauge.h
+++ b/lv_objx/lv_gauge.h
@@ -60,7 +60,7 @@ typedef struct
  * @param copy pointer to a gauge object, if not NULL then the new object will be copied from it
  * @return pointer to the created gauge
  */
-lv_obj_t * lv_gauge_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_gauge_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -132,21 +132,21 @@ static inline void lv_gauge_set_style(lv_obj_t *gauge, lv_style_t *bg)
  * @param needle the id of the needle
  * @return the value of the needle [min,max]
  */
-int16_t lv_gauge_get_value(lv_obj_t * gauge,  uint8_t needle);
+int16_t lv_gauge_get_value(const lv_obj_t * gauge,  uint8_t needle);
 
 /**
  * Get the count of needles on a gauge
  * @param gauge pointer to gauge
  * @return count of needles
  */
-uint8_t lv_gauge_get_needle_count(lv_obj_t * gauge);
+uint8_t lv_gauge_get_needle_count(const lv_obj_t * gauge);
 
 /**
  * Get the minimum value of a gauge
  * @param gauge pointer to a gauge object
  * @return the minimum value of the gauge
  */
-static inline int16_t lv_gauge_get_min_value(lv_obj_t * lmeter)
+static inline int16_t lv_gauge_get_min_value(const lv_obj_t * lmeter)
 {
     return lv_lmeter_get_min_value(lmeter);
 }
@@ -156,7 +156,7 @@ static inline int16_t lv_gauge_get_min_value(lv_obj_t * lmeter)
  * @param gauge pointer to a gauge object
  * @return the maximum value of the gauge
  */
-static inline int16_t lv_gauge_get_max_value(lv_obj_t * lmeter)
+static inline int16_t lv_gauge_get_max_value(const lv_obj_t * lmeter)
 {
     return lv_lmeter_get_max_value(lmeter);
 }
@@ -166,7 +166,7 @@ static inline int16_t lv_gauge_get_max_value(lv_obj_t * lmeter)
  * @param gauge pointer to a gauge object
  * @return the critical value
  */
-static inline int16_t lv_gauge_get_critical_value(lv_obj_t * gauge)
+static inline int16_t lv_gauge_get_critical_value(const lv_obj_t * gauge)
 {
     return lv_lmeter_get_value(gauge);
 }
@@ -176,14 +176,14 @@ static inline int16_t lv_gauge_get_critical_value(lv_obj_t * gauge)
  * @param gauge pointer to a gauge object
  * @return count of labels
  */
-uint8_t lv_gauge_get_label_count(lv_obj_t * gauge);
+uint8_t lv_gauge_get_label_count(const lv_obj_t * gauge);
 
 /**
  * Get the scale number of a gauge
  * @param gauge pointer to a gauge object
  * @return number of the scale units
  */
-static inline uint8_t lv_gauge_get_line_count(lv_obj_t * gauge)
+static inline uint8_t lv_gauge_get_line_count(const lv_obj_t * gauge)
 {
     return lv_lmeter_get_line_count(gauge);
 }
@@ -193,7 +193,7 @@ static inline uint8_t lv_gauge_get_line_count(lv_obj_t * gauge)
  * @param gauge pointer to a gauge object
  * @return angle of the scale
  */
-static inline uint16_t lv_gauge_get_scale_angle(lv_obj_t * gauge)
+static inline uint16_t lv_gauge_get_scale_angle(const lv_obj_t * gauge)
 {
     return lv_lmeter_get_scale_angle(gauge);
 }
@@ -203,7 +203,7 @@ static inline uint16_t lv_gauge_get_scale_angle(lv_obj_t * gauge)
  * @param gauge pointer to a gauge object
  * @return pointer to the gauge's style
  */
-static inline lv_style_t * lv_gauge_get_style(lv_obj_t *gauge)
+static inline lv_style_t * lv_gauge_get_style(const lv_obj_t *gauge)
 {
     return lv_obj_get_style(gauge);
 }
diff --git a/lv_objx/lv_img.c b/lv_objx/lv_img.c
index c9e914e72..81b357270 100644
--- a/lv_objx/lv_img.c
+++ b/lv_objx/lv_img.c
@@ -52,7 +52,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a image object, if not NULL then the new object will be copied from it
  * @return pointer to the created image
  */
-lv_obj_t * lv_img_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_img_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("image create started");
 
@@ -254,7 +254,7 @@ lv_img_src_t lv_img_get_src_type(const void * src)
  * @param img pointer to an image
  * @return file name
  */
-const char * lv_img_get_file_name(lv_obj_t * img)
+const char * lv_img_get_file_name(const lv_obj_t * img)
 {
     lv_img_ext_t * ext = lv_obj_get_ext_attr(img);
 
@@ -268,7 +268,7 @@ const char * lv_img_get_file_name(lv_obj_t * img)
  * @param img pointer to an image
  * @return true: auto size is enabled, false: auto size is disabled
  */
-bool lv_img_get_auto_size(lv_obj_t * img)
+bool lv_img_get_auto_size(const lv_obj_t * img)
 {
     lv_img_ext_t * ext = lv_obj_get_ext_attr(img);
 
diff --git a/lv_objx/lv_img.h b/lv_objx/lv_img.h
index 4922af074..861ff56dc 100644
--- a/lv_objx/lv_img.h
+++ b/lv_objx/lv_img.h
@@ -59,7 +59,7 @@ typedef struct
  * @param copy pointer to a image object, if not NULL then the new object will be copied from it
  * @return pointer to the created image
  */
-lv_obj_t * lv_img_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_img_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -131,21 +131,21 @@ lv_img_src_t lv_img_get_src_type(const void * src);
  * @param img pointer to an image
  * @return file name
  */
-const char * lv_img_get_file_name(lv_obj_t * img);
+const char * lv_img_get_file_name(const lv_obj_t * img);
 
 /**
  * Get the auto size enable attribute
  * @param img pointer to an image
  * @return true: auto size is enabled, false: auto size is disabled
  */
-bool lv_img_get_auto_size(lv_obj_t * img);
+bool lv_img_get_auto_size(const lv_obj_t * img);
 
 /**
  * Get the style of an image object
  * @param img pointer to an image object
  * @return pointer to the image's style
  */
-static inline lv_style_t* lv_img_get_style(lv_obj_t *img)
+static inline lv_style_t* lv_img_get_style(const lv_obj_t *img)
 {
     return lv_obj_get_style(img);
 }
@@ -155,7 +155,7 @@ static inline lv_style_t* lv_img_get_style(lv_obj_t *img)
  * @param img -
  * @return false
  */
-static inline bool lv_img_get_upscale(lv_obj_t * img)
+static inline bool lv_img_get_upscale(const lv_obj_t * img)
 {
     return false;
 }
diff --git a/lv_objx/lv_kb.c b/lv_objx/lv_kb.c
index 940b69abc..a19c4a38a 100644
--- a/lv_objx/lv_kb.c
+++ b/lv_objx/lv_kb.c
@@ -73,7 +73,7 @@ static const char * kb_map_num[] = {
  * @param copy pointer to a keyboard object, if not NULL then the new object will be copied from it
  * @return pointer to the created keyboard
  */
-lv_obj_t * lv_kb_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_kb_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("keyboard create started");
 
@@ -271,7 +271,7 @@ void lv_kb_set_style(lv_obj_t * kb, lv_kb_style_t type, lv_style_t * style)
  * @param kb pointer to a Keyboard object
  * @return pointer to the assigned Text Area object
  */
-lv_obj_t * lv_kb_get_ta(lv_obj_t * kb)
+lv_obj_t * lv_kb_get_ta(const lv_obj_t * kb)
 {
     lv_kb_ext_t * ext = lv_obj_get_ext_attr(kb);
     return ext->ta;
@@ -282,7 +282,7 @@ lv_obj_t * lv_kb_get_ta(lv_obj_t * kb)
  * @param kb pointer to a Keyboard object
  * @return the current mode from 'lv_kb_mode_t'
  */
-lv_kb_mode_t lv_kb_get_mode(lv_obj_t * kb)
+lv_kb_mode_t lv_kb_get_mode(const lv_obj_t * kb)
 {
     lv_kb_ext_t * ext = lv_obj_get_ext_attr(kb);
     return ext->mode;
@@ -294,7 +294,7 @@ lv_kb_mode_t lv_kb_get_mode(lv_obj_t * kb)
  * @param kb pointer to a Keyboard object
  * @return true: show cursor on the current text area, false: hide cursor
  */
-bool lv_kb_get_cursor_manage(lv_obj_t * kb)
+bool lv_kb_get_cursor_manage(const lv_obj_t * kb)
 {
     lv_kb_ext_t * ext = lv_obj_get_ext_attr(kb);
     return ext->cursor_mng == 0 ? false : true;
@@ -305,7 +305,7 @@ bool lv_kb_get_cursor_manage(lv_obj_t * kb)
  * @param kb pointer to Keyboard object
  * @return the ok callback
  */
-lv_action_t lv_kb_get_ok_action(lv_obj_t * kb)
+lv_action_t lv_kb_get_ok_action(const lv_obj_t * kb)
 {
     lv_kb_ext_t * ext = lv_obj_get_ext_attr(kb);
     return ext->ok_action;
@@ -316,7 +316,7 @@ lv_action_t lv_kb_get_ok_action(lv_obj_t * kb)
  * @param kb pointer to Keyboard object
  * @return the close callback
  */
-lv_action_t lv_kb_get_hide_action(lv_obj_t * kb)
+lv_action_t lv_kb_get_hide_action(const lv_obj_t * kb)
 {
     lv_kb_ext_t * ext = lv_obj_get_ext_attr(kb);
     return ext->hide_action;
@@ -328,7 +328,7 @@ lv_action_t lv_kb_get_hide_action(lv_obj_t * kb)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_kb_get_style(lv_obj_t * kb, lv_kb_style_t type)
+lv_style_t * lv_kb_get_style(const lv_obj_t * kb, lv_kb_style_t type)
 {
     switch(type) {
         case LV_KB_STYLE_BG:
diff --git a/lv_objx/lv_kb.h b/lv_objx/lv_kb.h
index 5042432c5..c4984807a 100644
--- a/lv_objx/lv_kb.h
+++ b/lv_objx/lv_kb.h
@@ -77,7 +77,7 @@ typedef enum {
  * @param copy pointer to a keyboard object, if not NULL then the new object will be copied from it
  * @return pointer to the created keyboard
  */
-lv_obj_t * lv_kb_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_kb_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -146,35 +146,35 @@ void lv_kb_set_style(lv_obj_t *kb, lv_kb_style_t type, lv_style_t *style);
  * @param kb pointer to a Keyboard object
  * @return pointer to the assigned Text Area object
  */
-lv_obj_t * lv_kb_get_ta(lv_obj_t * kb);
+lv_obj_t * lv_kb_get_ta(const lv_obj_t * kb);
 
 /**
  * Set a new a mode (text or number map)
  * @param kb pointer to a Keyboard object
  * @return the current mode from 'lv_kb_mode_t'
  */
-lv_kb_mode_t lv_kb_get_mode(lv_obj_t * kb);
+lv_kb_mode_t lv_kb_get_mode(const lv_obj_t * kb);
 
 /**
  * Get the current cursor manage mode.
  * @param kb pointer to a Keyboard object
  * @return true: show cursor on the current text area, false: hide cursor
  */
-bool lv_kb_get_cursor_manage(lv_obj_t * kb);
+bool lv_kb_get_cursor_manage(const lv_obj_t * kb);
 
 /**
  * Get the callback to call when the "Ok" button is pressed
  * @param kb pointer to Keyboard object
  * @return the ok callback
  */
-lv_action_t lv_kb_get_ok_action(lv_obj_t * kb);
+lv_action_t lv_kb_get_ok_action(const lv_obj_t * kb);
 
 /**
  * Get the callback to call when the "Hide" button is pressed
  * @param kb pointer to Keyboard object
  * @return the close callback
  */
-lv_action_t lv_kb_get_hide_action(lv_obj_t * kb);
+lv_action_t lv_kb_get_hide_action(const lv_obj_t * kb);
 
 /**
  * Get a style of a keyboard
@@ -182,7 +182,7 @@ lv_action_t lv_kb_get_hide_action(lv_obj_t * kb);
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_kb_get_style(lv_obj_t *kb, lv_kb_style_t type);
+lv_style_t * lv_kb_get_style(const lv_obj_t *kb, lv_kb_style_t type);
 
 /**********************
  *      MACROS
diff --git a/lv_objx/lv_label.c b/lv_objx/lv_label.c
index b8ccb4184..95eec4516 100644
--- a/lv_objx/lv_label.c
+++ b/lv_objx/lv_label.c
@@ -62,7 +62,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a button object, if not NULL then the new object will be copied from it
  * @return pointer to the created button
  */
-lv_obj_t * lv_label_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_label_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("label create started");
 
@@ -337,7 +337,7 @@ void lv_label_set_anim_speed(lv_obj_t * label, uint16_t anim_speed)
  * @param label pointer to a label object
  * @return the text of the label
  */
-char * lv_label_get_text(lv_obj_t * label)
+char * lv_label_get_text(const lv_obj_t * label)
 {
     lv_label_ext_t * ext = lv_obj_get_ext_attr(label);
 
@@ -349,7 +349,7 @@ char * lv_label_get_text(lv_obj_t * label)
  * @param label pointer to a label object
  * @return the long mode
  */
-lv_label_long_mode_t lv_label_get_long_mode(lv_obj_t * label)
+lv_label_long_mode_t lv_label_get_long_mode(const lv_obj_t * label)
 {
     lv_label_ext_t * ext = lv_obj_get_ext_attr(label);
     return ext->long_mode;
@@ -360,7 +360,7 @@ lv_label_long_mode_t lv_label_get_long_mode(lv_obj_t * label)
  * @param label pointer to a label object
  * @return LV_LABEL_ALIGN_LEFT or LV_LABEL_ALIGN_CENTER
  */
-lv_label_align_t lv_label_get_align(lv_obj_t * label)
+lv_label_align_t lv_label_get_align(const lv_obj_t * label)
 {
     lv_label_ext_t * ext = lv_obj_get_ext_attr(label);
     return ext->align;
@@ -371,7 +371,7 @@ lv_label_align_t lv_label_get_align(lv_obj_t * label)
  * @param label pointer to a label object
  * @return true: recoloring is enabled, false: disable
  */
-bool lv_label_get_recolor(lv_obj_t * label)
+bool lv_label_get_recolor(const lv_obj_t * label)
 {
     lv_label_ext_t * ext = lv_obj_get_ext_attr(label);
     return ext->recolor == 0 ? false : true;
@@ -382,7 +382,7 @@ bool lv_label_get_recolor(lv_obj_t * label)
  * @param label pointer to a label object
  * @return true: draw body; false: don't draw body
  */
-bool lv_label_get_body_draw(lv_obj_t * label)
+bool lv_label_get_body_draw(const lv_obj_t * label)
 {
     lv_label_ext_t * ext = lv_obj_get_ext_attr(label);
     return ext->body_draw == 0 ? false : true;
@@ -393,7 +393,7 @@ bool lv_label_get_body_draw(lv_obj_t * label)
  * @param label pointer to a label object
  * @return speed of animation in px/sec unit
  */
-uint16_t lv_label_get_anim_speed(lv_obj_t * label)
+uint16_t lv_label_get_anim_speed(const lv_obj_t * label)
 {
     lv_label_ext_t * ext = lv_obj_get_ext_attr(label);
     return ext->anim_speed;
@@ -405,7 +405,7 @@ uint16_t lv_label_get_anim_speed(lv_obj_t * label)
  * @param index index of the letter [0 ... text length]. Expressed in character index, not byte index (different in UTF-8)
  * @param pos store the result here (E.g. index = 0 gives 0;0 coordinates)
  */
-void lv_label_get_letter_pos(lv_obj_t * label, uint16_t index, lv_point_t * pos)
+void lv_label_get_letter_pos(const lv_obj_t * label, uint16_t index, lv_point_t * pos)
 {
     const char * txt = lv_label_get_text(label);
     lv_label_ext_t * ext = lv_obj_get_ext_attr(label);
@@ -487,7 +487,7 @@ void lv_label_get_letter_pos(lv_obj_t * label, uint16_t index, lv_point_t * pos)
  * @return the index of the letter on the 'pos_p' point (E.g. on 0;0 is the 0. letter)
  * Expressed in character index and not byte index (different in UTF-8)
  */
-uint16_t lv_label_get_letter_on(lv_obj_t * label, lv_point_t * pos)
+uint16_t lv_label_get_letter_on(const lv_obj_t * label, lv_point_t * pos)
 {
     const char * txt = lv_label_get_text(label);
     lv_label_ext_t * ext = lv_obj_get_ext_attr(label);
diff --git a/lv_objx/lv_label.h b/lv_objx/lv_label.h
index fefc4db15..e6363da14 100644
--- a/lv_objx/lv_label.h
+++ b/lv_objx/lv_label.h
@@ -86,7 +86,7 @@ typedef struct
  * @param copy pointer to a button object, if not NULL then the new object will be copied from it
  * @return pointer to the created button
  */
-lv_obj_t * lv_label_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_label_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -169,42 +169,42 @@ static inline void lv_label_set_style(lv_obj_t *label, lv_style_t *style)
  * @param label pointer to a label object
  * @return the text of the label
  */
-char * lv_label_get_text(lv_obj_t * label);
+char * lv_label_get_text(const lv_obj_t * label);
 
 /**
  * Get the long mode of a label
  * @param label pointer to a label object
  * @return the long mode
  */
-lv_label_long_mode_t lv_label_get_long_mode(lv_obj_t * label);
+lv_label_long_mode_t lv_label_get_long_mode(const lv_obj_t * label);
 
 /**
  * Get the align attribute
  * @param label pointer to a label object
  * @return LV_LABEL_ALIGN_LEFT or LV_LABEL_ALIGN_CENTER
  */
-lv_label_align_t lv_label_get_align(lv_obj_t * label);
+lv_label_align_t lv_label_get_align(const lv_obj_t * label);
 
 /**
  * Get the recoloring attribute
  * @param label pointer to a label object
  * @return true: recoloring is enabled, false: disable
  */
-bool lv_label_get_recolor(lv_obj_t * label);
+bool lv_label_get_recolor(const lv_obj_t * label);
 
 /**
  * Get the body draw attribute
  * @param label pointer to a label object
  * @return true: draw body; false: don't draw body
  */
-bool lv_label_get_body_draw(lv_obj_t *label);
+bool lv_label_get_body_draw(const lv_obj_t *label);
 
 /**
  * Get the label's animation speed in LV_LABEL_LONG_ROLL and SCROLL modes
  * @param label pointer to a label object
  * @return speed of animation in px/sec unit
  */
-uint16_t lv_label_get_anim_speed(lv_obj_t *label);
+uint16_t lv_label_get_anim_speed(const lv_obj_t *label);
 
 /**
  * Get the relative x and y coordinates of a letter
@@ -212,7 +212,7 @@ uint16_t lv_label_get_anim_speed(lv_obj_t *label);
  * @param index index of the letter [0 ... text length]. Expressed in character index, not byte index (different in UTF-8)
  * @param pos store the result here (E.g. index = 0 gives 0;0 coordinates)
  */
-void lv_label_get_letter_pos(lv_obj_t * label, uint16_t index, lv_point_t * pos);
+void lv_label_get_letter_pos(const lv_obj_t * label, uint16_t index, lv_point_t * pos);
 
 /**
  * Get the index of letter on a relative point of a label
@@ -221,14 +221,14 @@ void lv_label_get_letter_pos(lv_obj_t * label, uint16_t index, lv_point_t * pos)
  * @return the index of the letter on the 'pos_p' point (E.g. on 0;0 is the 0. letter)
  * Expressed in character index and not byte index (different in UTF-8)
  */
-uint16_t lv_label_get_letter_on(lv_obj_t * label, lv_point_t * pos);
+uint16_t lv_label_get_letter_on(const lv_obj_t * label, lv_point_t * pos);
 
 /**
  * Get the style of an label object
  * @param label pointer to an label object
  * @return pointer to the label's style
  */
-static inline lv_style_t* lv_label_get_style(lv_obj_t *label)
+static inline lv_style_t* lv_label_get_style(const lv_obj_t *label)
 {
     return lv_obj_get_style(label);
 }
diff --git a/lv_objx/lv_led.c b/lv_objx/lv_led.c
index f50e4778d..75773c29d 100644
--- a/lv_objx/lv_led.c
+++ b/lv_objx/lv_led.c
@@ -50,7 +50,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a led object, if not NULL then the new object will be copied from it
  * @return pointer to the created led
  */
-lv_obj_t * lv_led_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_led_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("led create started");
 
@@ -159,7 +159,7 @@ void lv_led_toggle(lv_obj_t * led)
  * @param led pointer to LED object
  * @return bright 0 (max. dark) ... 255 (max. light)
  */
-uint8_t lv_led_get_bright(lv_obj_t * led)
+uint8_t lv_led_get_bright(const lv_obj_t * led)
 {
     lv_led_ext_t * ext = lv_obj_get_ext_attr(led);
     return ext->bright;
diff --git a/lv_objx/lv_led.h b/lv_objx/lv_led.h
index 63f7898fb..25e48a79c 100644
--- a/lv_objx/lv_led.h
+++ b/lv_objx/lv_led.h
@@ -49,7 +49,7 @@ typedef struct
  * @param copy pointer to a led object, if not NULL then the new object will be copied from it
  * @return pointer to the created led
  */
-lv_obj_t * lv_led_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_led_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /**
  * Set the brightness of a LED object
@@ -91,14 +91,14 @@ static inline void lv_led_set_style(lv_obj_t *led, lv_style_t *style)
  * @param led pointer to LED object
  * @return bright 0 (max. dark) ... 255 (max. light)
  */
-uint8_t lv_led_get_bright(lv_obj_t * led);
+uint8_t lv_led_get_bright(const lv_obj_t * led);
 
 /**
  * Get the style of an led object
  * @param led pointer to an led object
  * @return pointer to the led's style
  */
-static inline lv_style_t* lv_led_get_style(lv_obj_t *led)
+static inline lv_style_t* lv_led_get_style(const lv_obj_t *led)
 {
     return lv_obj_get_style(led);
 }
diff --git a/lv_objx/lv_line.c b/lv_objx/lv_line.c
index b2bb17334..c5d802255 100644
--- a/lv_objx/lv_line.c
+++ b/lv_objx/lv_line.c
@@ -48,7 +48,7 @@ static lv_signal_func_t ancestor_signal;
  * @param par pointer to an object, it will be the parent of the new line
  * @return pointer to the created line
  */
-lv_obj_t * lv_line_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_line_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("line create started");
 
@@ -171,7 +171,7 @@ void lv_line_set_y_invert(lv_obj_t * line, bool yinv_en)
  * @param line pointer to a line object
  * @return true: auto size is enabled, false: disabled
  */
-bool lv_line_get_auto_size(lv_obj_t * line)
+bool lv_line_get_auto_size(const lv_obj_t * line)
 {
     lv_line_ext_t * ext = lv_obj_get_ext_attr(line);
 
@@ -183,7 +183,7 @@ bool lv_line_get_auto_size(lv_obj_t * line)
  * @param line pointer to a line object
  * @return true: y inversion is enabled, false: disabled
  */
-bool lv_line_get_y_inv(lv_obj_t * line)
+bool lv_line_get_y_inv(const lv_obj_t * line)
 {
     lv_line_ext_t * ext = lv_obj_get_ext_attr(line);
 
diff --git a/lv_objx/lv_line.h b/lv_objx/lv_line.h
index 70883bac5..9ba153ce7 100644
--- a/lv_objx/lv_line.h
+++ b/lv_objx/lv_line.h
@@ -51,7 +51,7 @@ typedef struct
  * @param par pointer to an object, it will be the parent of the new line
  * @return pointer to the created line
  */
-lv_obj_t * lv_line_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_line_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -111,21 +111,21 @@ static inline void lv_line_set_upscale(lv_obj_t * line, bool upcale)
  * @param line pointer to a line object
  * @return true: auto size is enabled, false: disabled
  */
-bool lv_line_get_auto_size(lv_obj_t * line);
+bool lv_line_get_auto_size(const lv_obj_t * line);
 
 /**
  * Get the y inversion attribute
  * @param line pointer to a line object
  * @return true: y inversion is enabled, false: disabled
  */
-bool lv_line_get_y_inv(lv_obj_t * line);
+bool lv_line_get_y_inv(const lv_obj_t * line);
 
 /**
  * Get the style of an line object
  * @param line pointer to an line object
  * @return pointer to the line's style
  */
-static inline lv_style_t* lv_line_get_style(lv_obj_t *line)
+static inline lv_style_t* lv_line_get_style(const lv_obj_t *line)
 {
     return lv_obj_get_style(line);
 }
@@ -135,7 +135,7 @@ static inline lv_style_t* lv_line_get_style(lv_obj_t *line)
  * @param line -
  * @return false
  */
-static inline bool lv_line_get_upscale(lv_obj_t * line)
+static inline bool lv_line_get_upscale(const lv_obj_t * line)
 {
     return false;
 }
diff --git a/lv_objx/lv_list.c b/lv_objx/lv_list.c
index a2fa39d20..8ab000725 100644
--- a/lv_objx/lv_list.c
+++ b/lv_objx/lv_list.c
@@ -37,8 +37,8 @@
  **********************/
 static lv_res_t lv_list_signal(lv_obj_t * list, lv_signal_t sign, void * param);
 static lv_res_t lv_list_btn_signal(lv_obj_t * btn, lv_signal_t sign, void * param);
-static lv_obj_t * get_next_btn(lv_obj_t * list, lv_obj_t * prev_btn);
-static lv_obj_t * get_prev_btn(lv_obj_t * list, lv_obj_t * prev_btn);
+static lv_obj_t * get_next_btn(const lv_obj_t * list, lv_obj_t * prev_btn);
+static lv_obj_t * get_prev_btn(const lv_obj_t * list, lv_obj_t * prev_btn);
 static void refr_btn_width(lv_obj_t * list);
 
 /**********************
@@ -69,7 +69,7 @@ static lv_obj_t * last_clicked_btn;
  * @param copy pointer to a list object, if not NULL then the new object will be copied from it
  * @return pointer to the created list
  */
-lv_obj_t * lv_list_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_list_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("list create started");
 
@@ -312,7 +312,7 @@ void lv_list_set_style(lv_obj_t * list, lv_list_style_t type, lv_style_t * style
  * @param btn pointer to list element
  * @return pointer to the text
  */
-const char * lv_list_get_btn_text(lv_obj_t * btn)
+const char * lv_list_get_btn_text(const lv_obj_t * btn)
 {
     lv_obj_t * label = lv_list_get_btn_label(btn);
     if(label == NULL) return "";
@@ -324,7 +324,7 @@ const char * lv_list_get_btn_text(lv_obj_t * btn)
  * @param btn pointer to a list element (button)
  * @return pointer to the label from the list element or NULL if not found
  */
-lv_obj_t * lv_list_get_btn_label(lv_obj_t * btn)
+lv_obj_t * lv_list_get_btn_label(const lv_obj_t * btn)
 {
     lv_obj_t * label = lv_obj_get_child(btn, NULL);
     if(label == NULL) return NULL;
@@ -342,7 +342,7 @@ lv_obj_t * lv_list_get_btn_label(lv_obj_t * btn)
  * @param btn pointer to a list element (button)
  * @return pointer to the image from the list element or NULL if not found
  */
-lv_obj_t * lv_list_get_btn_img(lv_obj_t * btn)
+lv_obj_t * lv_list_get_btn_img(const lv_obj_t * btn)
 {
 #if USE_LV_IMG != 0
     lv_obj_t * img = lv_obj_get_child(btn, NULL);
@@ -364,7 +364,7 @@ lv_obj_t * lv_list_get_btn_img(lv_obj_t * btn)
  * @param list pointer to a list object
  * @return duration of animation [ms]
  */
-uint16_t lv_list_get_anim_time(lv_obj_t * list)
+uint16_t lv_list_get_anim_time(const lv_obj_t * list)
 {
     lv_list_ext_t * ext = lv_obj_get_ext_attr(list);
     return ext->anim_time;
@@ -376,7 +376,7 @@ uint16_t lv_list_get_anim_time(lv_obj_t * list)
  * @param type which style should be get
  * @return style pointer to a style
  *  */
-lv_style_t * lv_list_get_style(lv_obj_t * list, lv_list_style_t type)
+lv_style_t * lv_list_get_style(const lv_obj_t * list, lv_list_style_t type)
 {
     lv_list_ext_t * ext = lv_obj_get_ext_attr(list);
 
@@ -412,7 +412,7 @@ lv_style_t * lv_list_get_style(lv_obj_t * list, lv_list_style_t type)
  * Move the list elements up by one
  * @param list pointer a to list object
  */
-void lv_list_up(lv_obj_t * list)
+void lv_list_up(const lv_obj_t * list)
 {
     /*Search the first list element which 'y' coordinate is below the parent
      * and position the list to show this element on the bottom*/
@@ -457,7 +457,7 @@ void lv_list_up(lv_obj_t * list)
  * Move the list elements down by one
  * @param list pointer to a list object
  */
-void lv_list_down(lv_obj_t * list)
+void lv_list_down(const lv_obj_t * list)
 {
     /*Search the first list element which 'y' coordinate is above the parent
      * and position the list to show this element on the top*/
@@ -500,7 +500,7 @@ void lv_list_down(lv_obj_t * list)
  * @param btn pointer to a list button to focus
  * @param anim_en true: scroll with animation, false: without animation
  */
-void lv_list_focus(lv_obj_t * btn, bool anim_en)
+void lv_list_focus(const lv_obj_t * btn, bool anim_en)
 {
 
 #if USE_LV_ANIMATION == 0
@@ -701,7 +701,7 @@ static lv_res_t lv_list_btn_signal(lv_obj_t * btn, lv_signal_t sign, void * para
  * @param prev_btn pointer to button. Search the next after it.
  * @return pointer to the next button or NULL when no more buttons
  */
-static lv_obj_t * get_next_btn(lv_obj_t * list, lv_obj_t * prev_btn)
+static lv_obj_t * get_next_btn(const lv_obj_t * list, lv_obj_t * prev_btn)
 {
     /* Not a good practice but user can add/create objects to the lists manually.
      * When getting the next button try to be sure that it is at least a button */
@@ -727,7 +727,7 @@ static lv_obj_t * get_next_btn(lv_obj_t * list, lv_obj_t * prev_btn)
  * @param prev_btn pointer to button. Search the previous before it.
  * @return pointer to the previous button or NULL when no more buttons
  */
-static lv_obj_t * get_prev_btn(lv_obj_t * list, lv_obj_t * prev_btn)
+static lv_obj_t * get_prev_btn(const lv_obj_t * list, lv_obj_t * prev_btn)
 {
     /* Not a good practice but user can add/create objects to the lists manually.
      * When getting the next button try to be sure that it is at least a button */
diff --git a/lv_objx/lv_list.h b/lv_objx/lv_list.h
index 2b40f7ffe..1acd9df06 100644
--- a/lv_objx/lv_list.h
+++ b/lv_objx/lv_list.h
@@ -79,7 +79,7 @@ typedef enum {
  * @param copy pointer to a list object, if not NULL then the new object will be copied from it
  * @return pointer to the created list
  */
-lv_obj_t * lv_list_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_list_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /**
  * Delete all children of the scrl object, without deleting scrl child.
@@ -139,34 +139,34 @@ void lv_list_set_style(lv_obj_t *list, lv_list_style_t type, lv_style_t *style);
  * @param btn pointer to list element
  * @return pointer to the text
  */
-const char * lv_list_get_btn_text(lv_obj_t * btn);
+const char * lv_list_get_btn_text(const lv_obj_t * btn);
 /**
  * Get the label object from a list element
  * @param btn pointer to a list element (button)
  * @return pointer to the label from the list element or NULL if not found
  */
-lv_obj_t * lv_list_get_btn_label(lv_obj_t * btn);
+lv_obj_t * lv_list_get_btn_label(const lv_obj_t * btn);
 
 /**
  * Get the image object from a list element
  * @param btn pointer to a list element (button)
  * @return pointer to the image from the list element or NULL if not found
  */
-lv_obj_t * lv_list_get_btn_img(lv_obj_t * btn);
+lv_obj_t * lv_list_get_btn_img(const lv_obj_t * btn);
 
 /**
  * Get scroll animation duration
  * @param list pointer to a list object
  * @return duration of animation [ms]
  */
-uint16_t lv_list_get_anim_time(lv_obj_t *list);
+uint16_t lv_list_get_anim_time(const lv_obj_t *list);
 
 /**
  * Get the scroll bar mode of a list
  * @param list pointer to a list object
  * @return scrollbar mode from 'lv_page_sb_mode_t' enum
  */
-static inline lv_sb_mode_t lv_list_get_sb_mode(lv_obj_t * list)
+static inline lv_sb_mode_t lv_list_get_sb_mode(const lv_obj_t * list)
 {
     return lv_page_get_sb_mode(list);
 }
@@ -177,7 +177,7 @@ static inline lv_sb_mode_t lv_list_get_sb_mode(lv_obj_t * list)
  * @param type which style should be get
  * @return style pointer to a style
  *  */
-lv_style_t * lv_list_get_style(lv_obj_t *list, lv_list_style_t type);
+lv_style_t * lv_list_get_style(const lv_obj_t *list, lv_list_style_t type);
 
 /*=====================
  * Other functions
@@ -187,19 +187,19 @@ lv_style_t * lv_list_get_style(lv_obj_t *list, lv_list_style_t type);
  * Move the list elements up by one
  * @param list pointer a to list object
  */
-void lv_list_up(lv_obj_t * list);
+void lv_list_up(const lv_obj_t * list);
 /**
  * Move the list elements down by one
  * @param list pointer to a list object
  */
-void lv_list_down(lv_obj_t * list);
+void lv_list_down(const lv_obj_t * list);
 
 /**
  * Focus on a list button. It ensures that the button will be visible on the list.
  * @param btn pointer to a list button to focus
  * @param anim_en true: scroll with animation, false: without animation
  */
-void lv_list_focus(lv_obj_t *btn, bool anim_en);
+void lv_list_focus(const lv_obj_t *btn, bool anim_en);
 
 /**********************
  *      MACROS
diff --git a/lv_objx/lv_lmeter.c b/lv_objx/lv_lmeter.c
index d80840700..455d4e6b2 100644
--- a/lv_objx/lv_lmeter.c
+++ b/lv_objx/lv_lmeter.c
@@ -50,7 +50,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a line meter object, if not NULL then the new object will be copied from it
  * @return pointer to the created line meter
  */
-lv_obj_t * lv_lmeter_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_lmeter_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("line meter create started");
 
@@ -177,7 +177,7 @@ void lv_lmeter_set_scale(lv_obj_t * lmeter, uint16_t angle, uint8_t line_cnt)
  * @param lmeter pointer to a line meter object
  * @return the value of the line meter
  */
-int16_t lv_lmeter_get_value(lv_obj_t * lmeter)
+int16_t lv_lmeter_get_value(const lv_obj_t * lmeter)
 {
     lv_lmeter_ext_t * ext = lv_obj_get_ext_attr(lmeter);
     return ext->cur_value;
@@ -188,7 +188,7 @@ int16_t lv_lmeter_get_value(lv_obj_t * lmeter)
  * @param lmeter pointer to a line meter object
  * @return the minimum value of the line meter
  */
-int16_t lv_lmeter_get_min_value(lv_obj_t * lmeter)
+int16_t lv_lmeter_get_min_value(const lv_obj_t * lmeter)
 {
     lv_lmeter_ext_t * ext = lv_obj_get_ext_attr(lmeter);
     return ext->min_value;
@@ -199,7 +199,7 @@ int16_t lv_lmeter_get_min_value(lv_obj_t * lmeter)
  * @param lmeter pointer to a line meter object
  * @return the maximum value of the line meter
  */
-int16_t lv_lmeter_get_max_value(lv_obj_t * lmeter)
+int16_t lv_lmeter_get_max_value(const lv_obj_t * lmeter)
 {
     lv_lmeter_ext_t * ext = lv_obj_get_ext_attr(lmeter);
     return ext->max_value;
@@ -210,7 +210,7 @@ int16_t lv_lmeter_get_max_value(lv_obj_t * lmeter)
  * @param lmeter pointer to a line meter object
  * @return number of the scale units
  */
-uint8_t lv_lmeter_get_line_count(lv_obj_t * lmeter)
+uint8_t lv_lmeter_get_line_count(const lv_obj_t * lmeter)
 {
     lv_lmeter_ext_t * ext = lv_obj_get_ext_attr(lmeter);
     return ext->line_cnt ;
@@ -221,7 +221,7 @@ uint8_t lv_lmeter_get_line_count(lv_obj_t * lmeter)
  * @param lmeter pointer to a line meter object
  * @return angle of the scale
  */
-uint16_t lv_lmeter_get_scale_angle(lv_obj_t * lmeter)
+uint16_t lv_lmeter_get_scale_angle(const lv_obj_t * lmeter)
 {
     lv_lmeter_ext_t * ext = lv_obj_get_ext_attr(lmeter);
     return ext->scale_angle;
diff --git a/lv_objx/lv_lmeter.h b/lv_objx/lv_lmeter.h
index f33acbe57..0235d34f9 100644
--- a/lv_objx/lv_lmeter.h
+++ b/lv_objx/lv_lmeter.h
@@ -52,7 +52,7 @@ typedef struct
  * @param copy pointer to a line meter object, if not NULL then the new object will be copied from it
  * @return pointer to the created line meter
  */
-lv_obj_t * lv_lmeter_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_lmeter_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -100,42 +100,42 @@ static inline void lv_lmeter_set_style(lv_obj_t *lmeter, lv_style_t *bg)
  * @param lmeter pointer to a line meter object
  * @return the value of the line meter
  */
-int16_t lv_lmeter_get_value(lv_obj_t *lmeter);
+int16_t lv_lmeter_get_value(const lv_obj_t *lmeter);
 
 /**
  * Get the minimum value of a line meter
  * @param lmeter pointer to a line meter object
  * @return the minimum value of the line meter
  */
-int16_t lv_lmeter_get_min_value(lv_obj_t * lmeter);
+int16_t lv_lmeter_get_min_value(const lv_obj_t * lmeter);
 
 /**
  * Get the maximum value of a line meter
  * @param lmeter pointer to a line meter object
  * @return the maximum value of the line meter
  */
-int16_t lv_lmeter_get_max_value(lv_obj_t * lmeter);
+int16_t lv_lmeter_get_max_value(const lv_obj_t * lmeter);
 
 /**
  * Get the scale number of a line meter
  * @param lmeter pointer to a line meter object
  * @return number of the scale units
  */
-uint8_t lv_lmeter_get_line_count(lv_obj_t * lmeter);
+uint8_t lv_lmeter_get_line_count(const lv_obj_t * lmeter);
 
 /**
  * Get the scale angle of a line meter
  * @param lmeter pointer to a line meter object
  * @return angle of the scale
  */
-uint16_t lv_lmeter_get_scale_angle(lv_obj_t * lmeter);
+uint16_t lv_lmeter_get_scale_angle(const lv_obj_t * lmeter);
 
 /**
  * Get the style of a line meter
  * @param lmeter pointer to a line meter object
  * @return pointer to the line meter's style
  */
-static inline lv_style_t * lv_lmeter_get_style(lv_obj_t * lmeter)
+static inline lv_style_t * lv_lmeter_get_style(const lv_obj_t * lmeter)
 {
     return lv_obj_get_style(lmeter);
 }
diff --git a/lv_objx/lv_mbox.c b/lv_objx/lv_mbox.c
index a3fc331e8..b4ddc26ee 100644
--- a/lv_objx/lv_mbox.c
+++ b/lv_objx/lv_mbox.c
@@ -58,7 +58,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a message box object, if not NULL then the new object will be copied from it
  * @return pointer to the created message box
  */
-lv_obj_t * lv_mbox_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_mbox_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("mesasge box create started");
 
@@ -285,7 +285,7 @@ void lv_mbox_set_style(lv_obj_t * mbox, lv_mbox_style_t type, lv_style_t * style
  * @param mbox pointer to a message box object
  * @return pointer to the text of the message box
  */
-const char * lv_mbox_get_text(lv_obj_t * mbox)
+const char * lv_mbox_get_text(const lv_obj_t * mbox)
 {
     lv_mbox_ext_t * ext = lv_obj_get_ext_attr(mbox);
 
@@ -298,7 +298,7 @@ const char * lv_mbox_get_text(lv_obj_t * mbox)
  * @param btn pointer to a button of a message box
  * @return pointer to the button's message box
  */
-lv_obj_t * lv_mbox_get_from_btn(lv_obj_t * btn)
+lv_obj_t * lv_mbox_get_from_btn(const lv_obj_t * btn)
 {
     lv_obj_t * mbox = lv_obj_get_parent(btn);
 
@@ -310,7 +310,7 @@ lv_obj_t * lv_mbox_get_from_btn(lv_obj_t * btn)
  * @param mbox pointer to a message box object
  * @return animation length in  milliseconds (0: no animation)
  */
-uint16_t lv_mbox_get_anim_time(lv_obj_t * mbox)
+uint16_t lv_mbox_get_anim_time(const lv_obj_t * mbox)
 {
     lv_mbox_ext_t * ext = lv_obj_get_ext_attr(mbox);
     return ext->anim_time;
@@ -322,7 +322,7 @@ uint16_t lv_mbox_get_anim_time(lv_obj_t * mbox)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_mbox_get_style(lv_obj_t * mbox, lv_mbox_style_t type)
+lv_style_t * lv_mbox_get_style(const lv_obj_t * mbox, lv_mbox_style_t type)
 {
     lv_mbox_ext_t * ext = lv_obj_get_ext_attr(mbox);
 
diff --git a/lv_objx/lv_mbox.h b/lv_objx/lv_mbox.h
index 66588b3c3..1f4b21505 100644
--- a/lv_objx/lv_mbox.h
+++ b/lv_objx/lv_mbox.h
@@ -78,7 +78,7 @@ typedef enum {
  * @param copy pointer to a message box object, if not NULL then the new object will be copied from it
  * @return pointer to the created message box
  */
-lv_obj_t * lv_mbox_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_mbox_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*======================
  * Add/remove functions
@@ -148,7 +148,7 @@ void lv_mbox_set_style(lv_obj_t *mbox, lv_mbox_style_t type, lv_style_t *style);
  * @param mbox pointer to a message box object
  * @return pointer to the text of the message box
  */
-const char * lv_mbox_get_text(lv_obj_t * mbox);
+const char * lv_mbox_get_text(const lv_obj_t * mbox);
 
 /**
  * Get the message box object from one of its button.
@@ -156,14 +156,14 @@ const char * lv_mbox_get_text(lv_obj_t * mbox);
  * @param btn pointer to a button of a message box
  * @return pointer to the button's message box
  */
-lv_obj_t * lv_mbox_get_from_btn(lv_obj_t * btn);
+lv_obj_t * lv_mbox_get_from_btn(const lv_obj_t * btn);
 
 /**
  * Get the animation duration (close animation time)
  * @param mbox pointer to a message box object
  * @return animation length in  milliseconds (0: no animation)
  */
-uint16_t lv_mbox_get_anim_time(lv_obj_t * mbox);
+uint16_t lv_mbox_get_anim_time(const lv_obj_t * mbox);
 
 
 /**
@@ -172,7 +172,7 @@ uint16_t lv_mbox_get_anim_time(lv_obj_t * mbox);
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_mbox_get_style(lv_obj_t *mbox, lv_mbox_style_t type);
+lv_style_t * lv_mbox_get_style(const lv_obj_t *mbox, lv_mbox_style_t type);
 
 /**********************
  *      MACROS
diff --git a/lv_objx/lv_objx_templ.c b/lv_objx/lv_objx_templ.c
index 2c7bf0396..8947ad66f 100644
--- a/lv_objx/lv_objx_templ.c
+++ b/lv_objx/lv_objx_templ.c
@@ -51,7 +51,7 @@ static lv_design_func_t ancestor_design;
  * @param copy pointer to a template object, if not NULL then the new object will be copied from it
  * @return pointer to the created template
  */
-lv_obj_t * lv_templ_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_templ_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("template create started");
 
@@ -141,7 +141,7 @@ void lv_templ_set_style(lv_obj_t * templ, lv_templ_style_t type, lv_style_t * st
  * @param type which style should be get
  * @return style pointer to the style
  *  */
-lv_style_t * lv_templ_get_style(lv_obj_t * templ, lv_templ_style_t type)
+lv_style_t * lv_templ_get_style(const lv_obj_t * templ, lv_templ_style_t type)
 {
     lv_templ_ext_t * ext = lv_obj_get_ext_attr(templ);
 
diff --git a/lv_objx/lv_objx_templ.h b/lv_objx/lv_objx_templ.h
index b921a24c0..afe20b90b 100644
--- a/lv_objx/lv_objx_templ.h
+++ b/lv_objx/lv_objx_templ.h
@@ -62,7 +62,7 @@ typedef enum {
  * @param copy pointer to a template object, if not NULL then the new object will be copied from it
  * @return pointer to the created template
  */
-lv_obj_t * lv_templ_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_templ_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*======================
  * Add/remove functions
@@ -91,7 +91,7 @@ void lv_templ_set_style(lv_obj_t * templ, lv_templ_style_t type, lv_style_t *sty
  * @param type which style should be get
  * @return style pointer to the style
  *  */
-lv_style_t * lv_templ_get_style(lv_obj_t * templ, lv_templ_style_t type);
+lv_style_t * lv_templ_get_style(const lv_obj_t * templ, lv_templ_style_t type);
 
 /*=====================
  * Other functions
diff --git a/lv_objx/lv_page.c b/lv_objx/lv_page.c
index eb8b48788..e126da5f6 100644
--- a/lv_objx/lv_page.c
+++ b/lv_objx/lv_page.c
@@ -55,7 +55,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a page object, if not NULL then the new object will be copied from it
  * @return pointer to the created page
  */
-lv_obj_t * lv_page_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_page_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("page create started");
 
@@ -248,7 +248,7 @@ void lv_page_set_style(lv_obj_t * page, lv_page_style_t type, lv_style_t * style
  * @param page pointer to a page object
  * @return pointer to a container which is the scrollable part of the page
  */
-lv_obj_t * lv_page_get_scrl(lv_obj_t * page)
+lv_obj_t * lv_page_get_scrl(const lv_obj_t * page)
 {
     lv_page_ext_t * ext = lv_obj_get_ext_attr(page);
 
@@ -260,7 +260,7 @@ lv_obj_t * lv_page_get_scrl(lv_obj_t * page)
  * @param page pointer to a page object
  * @return the mode from 'lv_page_sb.mode_t' enum
  */
-lv_sb_mode_t lv_page_get_sb_mode(lv_obj_t * page)
+lv_sb_mode_t lv_page_get_sb_mode(const lv_obj_t * page)
 {
     lv_page_ext_t * ext = lv_obj_get_ext_attr(page);
     return ext->sb.mode;
@@ -271,7 +271,7 @@ lv_sb_mode_t lv_page_get_sb_mode(lv_obj_t * page)
  * @param page pointer to a page object
  * @return true: scrolling with arrows is enabled
  */
-bool lv_page_get_arrow_scroll(lv_obj_t * page)
+bool lv_page_get_arrow_scroll(const lv_obj_t * page)
 {
     lv_page_ext_t * ext = lv_obj_get_ext_attr(page);
     return ext->arrow_scroll ? true : false;
@@ -283,7 +283,7 @@ bool lv_page_get_arrow_scroll(lv_obj_t * page)
  * @param type which style should be get
  * @return style pointer to a style
  *  */
-lv_style_t * lv_page_get_style(lv_obj_t * page, lv_page_style_t type)
+lv_style_t * lv_page_get_style(const lv_obj_t * page, lv_page_style_t type)
 {
     lv_page_ext_t * ext = lv_obj_get_ext_attr(page);
 
@@ -323,7 +323,7 @@ void lv_page_glue_obj(lv_obj_t * obj, bool glue)
  * @param obj pointer to an object to focus (must be on the page)
  * @param anim_time scroll animation time in milliseconds (0: no animation)
  */
-void lv_page_focus(lv_obj_t * page, lv_obj_t * obj, uint16_t anim_time)
+void lv_page_focus(lv_obj_t * page, const lv_obj_t * obj, uint16_t anim_time)
 {
 
 #if USE_LV_ANIMATION == 0
diff --git a/lv_objx/lv_page.h b/lv_objx/lv_page.h
index 773a2e306..070fd1f6f 100644
--- a/lv_objx/lv_page.h
+++ b/lv_objx/lv_page.h
@@ -83,7 +83,7 @@ typedef enum {
  * @param copy pointer to a page object, if not NULL then the new object will be copied from it
  * @return pointer to the created page
  */
-lv_obj_t * lv_page_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_page_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /**
  * Delete all children of the scrl object, without deleting scrl child.
@@ -96,7 +96,7 @@ void lv_page_clean(lv_obj_t *obj);
  * @param page pointer to a page object
  * @return pointer to a container which is the scrollable part of the page
  */
-lv_obj_t * lv_page_get_scrl(lv_obj_t * page);
+lv_obj_t * lv_page_get_scrl(const lv_obj_t * page);
 
 /*=====================
  * Setter functions
@@ -191,7 +191,7 @@ void lv_page_set_style(lv_obj_t *page, lv_page_style_t type, lv_style_t *style);
  * @param page pointer to a page object
  * @return the mode from 'lv_page_sb.mode_t' enum
  */
-lv_sb_mode_t lv_page_get_sb_mode(lv_obj_t * page);
+lv_sb_mode_t lv_page_get_sb_mode(const lv_obj_t * page);
 
 
 /**
@@ -199,14 +199,14 @@ lv_sb_mode_t lv_page_get_sb_mode(lv_obj_t * page);
  * @param page pointer to a page object
  * @return true: scrolling with arrows is enabled
  */
-bool lv_page_get_arrow_scroll(lv_obj_t * page);
+bool lv_page_get_arrow_scroll(const lv_obj_t * page);
 
 /**
  * Get width of the scrollable part of a page
  * @param page pointer to a page object
  * @return the width of the scrollable
  */
-static inline lv_coord_t lv_page_get_scrl_width(lv_obj_t *page)
+static inline lv_coord_t lv_page_get_scrl_width(const lv_obj_t *page)
 {
     return lv_obj_get_width(lv_page_get_scrl(page));
 }
@@ -216,7 +216,7 @@ static inline lv_coord_t lv_page_get_scrl_width(lv_obj_t *page)
  * @param page pointer to a page object
  * @return the height of the scrollable
  */
-static inline lv_coord_t lv_page_get_scrl_height(lv_obj_t *page)
+static inline lv_coord_t lv_page_get_scrl_height(const lv_obj_t *page)
 {
     return lv_obj_get_height(lv_page_get_scrl(page));
 }
@@ -226,7 +226,7 @@ static inline lv_coord_t lv_page_get_scrl_height(lv_obj_t *page)
 * @param page pointer to page object
 * @return the layout from 'lv_cont_layout_t'
 */
-static inline lv_layout_t lv_page_get_scrl_layout(lv_obj_t * page)
+static inline lv_layout_t lv_page_get_scrl_layout(const lv_obj_t * page)
 {
     return lv_cont_get_layout(lv_page_get_scrl(page));
 }
@@ -236,7 +236,7 @@ static inline lv_layout_t lv_page_get_scrl_layout(lv_obj_t * page)
 * @param page pointer to a page object
 * @return true: horizontal fit is enabled; false: disabled
 */
-static inline bool lv_page_get_scrl_hor_fit(lv_obj_t * page)
+static inline bool lv_page_get_scrl_hor_fit(const lv_obj_t * page)
 {
     return lv_cont_get_hor_fit(lv_page_get_scrl(page));
 }
@@ -246,7 +246,7 @@ static inline bool lv_page_get_scrl_hor_fit(lv_obj_t * page)
 * @param page pointer to a page object
 * @return true: vertical fit is enabled; false: disabled
 */
-static inline bool lv_page_get_scrl_fit_ver(lv_obj_t * page)
+static inline bool lv_page_get_scrl_fit_ver(const lv_obj_t * page)
 {
     return lv_cont_get_ver_fit(lv_page_get_scrl(page));
 }
@@ -257,7 +257,7 @@ static inline bool lv_page_get_scrl_fit_ver(lv_obj_t * page)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_page_get_style(lv_obj_t *page, lv_page_style_t type);
+lv_style_t * lv_page_get_style(const lv_obj_t *page, lv_page_style_t type);
 
 /*=====================
  * Other functions
@@ -276,7 +276,7 @@ void lv_page_glue_obj(lv_obj_t * obj, bool glue);
  * @param obj pointer to an object to focus (must be on the page)
  * @param anim_time scroll animation time in milliseconds (0: no animation)
  */
-void lv_page_focus(lv_obj_t * page, lv_obj_t * obj, uint16_t anim_time);
+void lv_page_focus(lv_obj_t * page, const lv_obj_t * obj, uint16_t anim_time);
 
 /**********************
  *      MACROS
diff --git a/lv_objx/lv_preload.c b/lv_objx/lv_preload.c
index 9de13a13d..d84023a37 100644
--- a/lv_objx/lv_preload.c
+++ b/lv_objx/lv_preload.c
@@ -53,7 +53,7 @@ static lv_design_func_t ancestor_design;
  * @param copy pointer to a pre loader object, if not NULL then the new object will be copied from it
  * @return pointer to the created pre loader
  */
-lv_obj_t * lv_preload_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_preload_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("preload create started");
 
@@ -182,7 +182,7 @@ void lv_preload_set_style(lv_obj_t * preload, lv_preload_style_t type, lv_style_
  * Get the arc length [degree] of the a pre loader
  * @param preload pointer to a pre loader object
  */
-uint16_t lv_preload_get_arc_length(lv_obj_t * preload)
+uint16_t lv_preload_get_arc_length(const lv_obj_t * preload)
 {
     lv_preload_ext_t * ext = lv_obj_get_ext_attr(preload);
     return ext->arc_length;
@@ -193,7 +193,7 @@ uint16_t lv_preload_get_arc_length(lv_obj_t * preload)
  * Get the spin time of the arc
  * @param preload pointer to a pre loader object [milliseconds]
  */
-uint16_t lv_preload_get_spin_time(lv_obj_t * preload)
+uint16_t lv_preload_get_spin_time(const lv_obj_t * preload)
 {
     lv_preload_ext_t * ext = lv_obj_get_ext_attr(preload);
     return ext->time;
@@ -205,7 +205,7 @@ uint16_t lv_preload_get_spin_time(lv_obj_t * preload)
  * @param type which style should be get
  * @return style pointer to the style
  *  */
-lv_style_t * lv_preload_get_style(lv_obj_t * preload, lv_preload_style_t type)
+lv_style_t * lv_preload_get_style(const lv_obj_t * preload, lv_preload_style_t type)
 {
 
     switch(type) {
@@ -223,6 +223,11 @@ lv_style_t * lv_preload_get_style(lv_obj_t * preload, lv_preload_style_t type)
  * Other functions
  *====================*/
 
+/**
+ * Automatically in an animation to rotate the arc of spinner.
+ * @param ptr pointer to preloader
+ * @param val the current desired value [0..360]
+ */
 void lv_preload_spinner_animation(void * ptr, int32_t val)
 {
     lv_obj_t * preload = ptr;
diff --git a/lv_objx/lv_preload.h b/lv_objx/lv_preload.h
index 224dcb6f9..b6200a5fb 100644
--- a/lv_objx/lv_preload.h
+++ b/lv_objx/lv_preload.h
@@ -70,7 +70,7 @@ typedef enum {
  * @param copy pointer to a pre loader object, if not NULL then the new object will be copied from it
  * @return pointer to the created pre loader
  */
-lv_obj_t * lv_preload_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_preload_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*======================
  * Add/remove functions
@@ -110,13 +110,13 @@ void lv_preload_set_style(lv_obj_t * preload, lv_preload_style_t type, lv_style_
  * Get the arc length [degree] of the a pre loader
  * @param preload pointer to a pre loader object
  */
-uint16_t lv_preload_get_arc_length(lv_obj_t * preload);
+uint16_t lv_preload_get_arc_length(const lv_obj_t * preload);
 
 /**
  * Get the spin time of the arc
  * @param preload pointer to a pre loader object [milliseconds]
  */
-uint16_t lv_preload_get_spin_time(lv_obj_t * preload);
+uint16_t lv_preload_get_spin_time(const lv_obj_t * preload);
 
 /**
  * Get style of a pre loader.
@@ -124,11 +124,18 @@ uint16_t lv_preload_get_spin_time(lv_obj_t * preload);
  * @param type which style should be get
  * @return style pointer to the style
  *  */
-lv_style_t * lv_preload_get_style(lv_obj_t * preload, lv_preload_style_t type);
+lv_style_t * lv_preload_get_style(const lv_obj_t * preload, lv_preload_style_t type);
 
 /*=====================
  * Other functions
  *====================*/
+
+/**
+ * Get style of a pre loader.
+ * @param preload pointer to pre loader object
+ * @param type which style should be get
+ * @return style pointer to the style
+ *  */
 void lv_preload_spinner_animation(void * ptr, int32_t val);
 
 /**********************
diff --git a/lv_objx/lv_roller.c b/lv_objx/lv_roller.c
index 32c22eec7..55219c467 100644
--- a/lv_objx/lv_roller.c
+++ b/lv_objx/lv_roller.c
@@ -58,7 +58,7 @@ static lv_signal_func_t ancestor_scrl_signal;
  * @param copy pointer to a roller object, if not NULL then the new object will be copied from it
  * @return pointer to the created roller
  */
-lv_obj_t * lv_roller_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_roller_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("roller create started");
 
@@ -179,7 +179,7 @@ void lv_roller_set_style(lv_obj_t * roller, lv_roller_style_t type, lv_style_t *
  * @param roller pointer to a roller object
  * @return true: auto size enabled; false: manual width settings enabled
  */
-bool lv_roller_get_hor_fit(lv_obj_t * roller)
+bool lv_roller_get_hor_fit(const lv_obj_t * roller)
 {
     return lv_page_get_scrl_hor_fit(roller);
 }
@@ -190,7 +190,7 @@ bool lv_roller_get_hor_fit(lv_obj_t * roller)
  * @param type which style should be get
  * @return style pointer to a style
  *  */
-lv_style_t * lv_roller_get_style(lv_obj_t * roller, lv_roller_style_t type)
+lv_style_t * lv_roller_get_style(const lv_obj_t * roller, lv_roller_style_t type)
 {
     switch(type) {
         case LV_ROLLER_STYLE_BG:
diff --git a/lv_objx/lv_roller.h b/lv_objx/lv_roller.h
index 71c5d9543..c99f9b9e4 100644
--- a/lv_objx/lv_roller.h
+++ b/lv_objx/lv_roller.h
@@ -57,7 +57,7 @@ typedef enum {
  * @param copy pointer to a roller object, if not NULL then the new object will be copied from it
  * @return pointer to the created roller
  */
-lv_obj_t * lv_roller_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_roller_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -137,7 +137,7 @@ void lv_roller_set_style(lv_obj_t *roller, lv_roller_style_t type, lv_style_t *s
  * @param roller pointer to roller object
  * @return the options separated by '\n'-s (E.g. "Option1\nOption2\nOption3")
  */
-static inline const char * lv_roller_get_options(lv_obj_t *roller)
+static inline const char * lv_roller_get_options(const lv_obj_t *roller)
 {
     return lv_ddlist_get_options(roller);
 }
@@ -147,7 +147,7 @@ static inline const char * lv_roller_get_options(lv_obj_t *roller)
  * @param roller pointer to a roller object
  * @return id of the selected option (0 ... number of option - 1);
  */
-static inline uint16_t lv_roller_get_selected(lv_obj_t *roller)
+static inline uint16_t lv_roller_get_selected(const lv_obj_t *roller)
 {
     return lv_ddlist_get_selected(roller);
 }
@@ -157,7 +157,7 @@ static inline uint16_t lv_roller_get_selected(lv_obj_t *roller)
  * @param roller pointer to roller object
  * @param buf pointer to an array to store the string
  */
-static inline void lv_roller_get_selected_str(lv_obj_t * roller, char * buf)
+static inline void lv_roller_get_selected_str(const lv_obj_t * roller, char * buf)
 {
     lv_ddlist_get_selected_str(roller, buf);
 }
@@ -167,7 +167,7 @@ static inline void lv_roller_get_selected_str(lv_obj_t * roller, char * buf)
  * @param roller pointer to a roller
  * @return  pointer to the call back function
  */
-static inline lv_action_t lv_roller_get_action(lv_obj_t * roller)
+static inline lv_action_t lv_roller_get_action(const lv_obj_t * roller)
 {
     return lv_ddlist_get_action(roller);
 }
@@ -177,7 +177,7 @@ static inline lv_action_t lv_roller_get_action(lv_obj_t * roller)
  * @param roller pointer to a roller
  * @return open/close animation time [ms]
  */
-static inline uint16_t lv_roller_get_anim_time(lv_obj_t * roller)
+static inline uint16_t lv_roller_get_anim_time(const lv_obj_t * roller)
 {
     return lv_ddlist_get_anim_time(roller);
 }
@@ -187,7 +187,7 @@ static inline uint16_t lv_roller_get_anim_time(lv_obj_t * roller)
  * @param roller pointer to a roller object
  * @return true: auto size enabled; false: manual width settings enabled
  */
-bool lv_roller_get_hor_fit(lv_obj_t *roller);
+bool lv_roller_get_hor_fit(const lv_obj_t *roller);
 
 /**
  * Get a style of a roller
@@ -195,7 +195,7 @@ bool lv_roller_get_hor_fit(lv_obj_t *roller);
  * @param type which style should be get
  * @return style pointer to a style
  *  */
-lv_style_t * lv_roller_get_style(lv_obj_t *roller, lv_roller_style_t type);
+lv_style_t * lv_roller_get_style(const lv_obj_t *roller, lv_roller_style_t type);
 
 /**********************
  *      MACROS
diff --git a/lv_objx/lv_slider.c b/lv_objx/lv_slider.c
index 2dcc8db02..17e53b5ac 100644
--- a/lv_objx/lv_slider.c
+++ b/lv_objx/lv_slider.c
@@ -51,7 +51,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a slider object, if not NULL then the new object will be copied from it
  * @return pointer to the created slider
  */
-lv_obj_t * lv_slider_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_slider_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("slider create started");
 
@@ -173,7 +173,7 @@ void lv_slider_set_style(lv_obj_t * slider, lv_slider_style_t type, lv_style_t *
  * @param slider pointer to a slider object
  * @return the value of the slider
  */
-int16_t lv_slider_get_value(lv_obj_t * slider)
+int16_t lv_slider_get_value(const lv_obj_t * slider)
 {
     lv_slider_ext_t * ext = lv_obj_get_ext_attr(slider);
 
@@ -186,7 +186,7 @@ int16_t lv_slider_get_value(lv_obj_t * slider)
  * @param slider pointer to slider object
  * @return the callback function
  */
-lv_action_t lv_slider_get_action(lv_obj_t * slider)
+lv_action_t lv_slider_get_action(const lv_obj_t * slider)
 {
     lv_slider_ext_t * ext = lv_obj_get_ext_attr(slider);
     return ext->action;
@@ -197,7 +197,7 @@ lv_action_t lv_slider_get_action(lv_obj_t * slider)
  * @param slider pointer to a slider object
  * @return true: drag in progress false: not dragged
  */
-bool lv_slider_is_dragged(lv_obj_t * slider)
+bool lv_slider_is_dragged(const lv_obj_t * slider)
 {
     lv_slider_ext_t * ext = lv_obj_get_ext_attr(slider);
     return ext->drag_value == LV_SLIDER_NOT_PRESSED ? false : true;
@@ -209,7 +209,7 @@ bool lv_slider_is_dragged(lv_obj_t * slider)
  * @return true: the knob is drawn always in the slider;
  *         false: the knob can be out on the edges
  */
-bool lv_slider_get_knob_in(lv_obj_t * slider)
+bool lv_slider_get_knob_in(const lv_obj_t * slider)
 {
     lv_slider_ext_t * ext = lv_obj_get_ext_attr(slider);
     return ext->knob_in == 0 ? false : true;
@@ -221,7 +221,7 @@ bool lv_slider_get_knob_in(lv_obj_t * slider)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_slider_get_style(lv_obj_t * slider, lv_slider_style_t type)
+lv_style_t * lv_slider_get_style(const lv_obj_t * slider, lv_slider_style_t type)
 {
     lv_slider_ext_t * ext = lv_obj_get_ext_attr(slider);
 
diff --git a/lv_objx/lv_slider.h b/lv_objx/lv_slider.h
index 1cae9b00e..8eb2bd2d7 100644
--- a/lv_objx/lv_slider.h
+++ b/lv_objx/lv_slider.h
@@ -65,7 +65,7 @@ typedef enum
  * @param copy pointer to a slider object, if not NULL then the new object will be copied from it
  * @return pointer to the created slider
  */
-lv_obj_t * lv_slider_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_slider_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -135,14 +135,14 @@ void lv_slider_set_style(lv_obj_t *slider, lv_slider_style_t type, lv_style_t *s
  * @param slider pointer to a slider object
  * @return the value of the slider
  */
-int16_t lv_slider_get_value(lv_obj_t * slider);
+int16_t lv_slider_get_value(const lv_obj_t * slider);
 
 /**
  * Get the minimum value of a slider
  * @param slider pointer to a slider object
  * @return the minimum value of the slider
  */
-static inline int16_t lv_slider_get_min_value(lv_obj_t * slider)
+static inline int16_t lv_slider_get_min_value(const lv_obj_t * slider)
 {
     return lv_bar_get_min_value(slider);
 }
@@ -152,7 +152,7 @@ static inline int16_t lv_slider_get_min_value(lv_obj_t * slider)
  * @param slider pointer to a slider object
  * @return the maximum value of the slider
  */
-static inline int16_t lv_slider_get_max_value(lv_obj_t * slider)
+static inline int16_t lv_slider_get_max_value(const lv_obj_t * slider)
 {
     return lv_bar_get_max_value(slider);
 }
@@ -162,14 +162,14 @@ static inline int16_t lv_slider_get_max_value(lv_obj_t * slider)
  * @param slider pointer to slider object
  * @return the callback function
  */
-lv_action_t lv_slider_get_action(lv_obj_t * slider);
+lv_action_t lv_slider_get_action(const lv_obj_t * slider);
 
 /**
  * Give the slider is being dragged or not
  * @param slider pointer to a slider object
  * @return true: drag in progress false: not dragged
  */
-bool lv_slider_is_dragged(lv_obj_t * slider);
+bool lv_slider_is_dragged(const lv_obj_t * slider);
 
 /**
  * Get the 'knob in' attribute of a slider
@@ -177,7 +177,7 @@ bool lv_slider_is_dragged(lv_obj_t * slider);
  * @return true: the knob is drawn always in the slider;
  *         false: the knob can be out on the edges
  */
-bool lv_slider_get_knob_in(lv_obj_t * slider);
+bool lv_slider_get_knob_in(const lv_obj_t * slider);
 
 
 /**
@@ -186,7 +186,7 @@ bool lv_slider_get_knob_in(lv_obj_t * slider);
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_slider_get_style(lv_obj_t *slider, lv_slider_style_t type);
+lv_style_t * lv_slider_get_style(const lv_obj_t *slider, lv_slider_style_t type);
 
 /**********************
  *      MACROS
diff --git a/lv_objx/lv_sw.c b/lv_objx/lv_sw.c
index 47954f089..a39021f42 100644
--- a/lv_objx/lv_sw.c
+++ b/lv_objx/lv_sw.c
@@ -48,7 +48,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a switch object, if not NULL then the new object will be copied from it
  * @return pointer to the created switch
  */
-lv_obj_t * lv_sw_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_sw_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("switch create started");
 
@@ -175,7 +175,7 @@ void lv_sw_set_style(lv_obj_t * sw, lv_sw_style_t type, lv_style_t * style)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_sw_get_style(lv_obj_t * sw, lv_sw_style_t type)
+lv_style_t * lv_sw_get_style(const lv_obj_t * sw, lv_sw_style_t type)
 {
     lv_sw_ext_t * ext = lv_obj_get_ext_attr(sw);
 
diff --git a/lv_objx/lv_sw.h b/lv_objx/lv_sw.h
index 898b4efe0..9a2bb8a5a 100644
--- a/lv_objx/lv_sw.h
+++ b/lv_objx/lv_sw.h
@@ -63,7 +63,7 @@ typedef enum {
  * @param copy pointer to a switch object, if not NULL then the new object will be copied from it
  * @return pointer to the created switch
  */
-lv_obj_t * lv_sw_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_sw_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /*=====================
  * Setter functions
@@ -108,7 +108,7 @@ void lv_sw_set_style(lv_obj_t *sw, lv_sw_style_t type, lv_style_t *style);
  * @param sw pointer to a switch object
  * @return false: OFF; true: ON
  */
-static inline bool lv_sw_get_state(lv_obj_t *sw)
+static inline bool lv_sw_get_state(const lv_obj_t *sw)
 {
     return lv_bar_get_value(sw) == 0 ? false : true;
 }
@@ -118,7 +118,7 @@ static inline bool lv_sw_get_state(lv_obj_t *sw)
  * @param slider pointer to a switch object
  * @return the callback function
  */
-static inline lv_action_t lv_sw_get_action(lv_obj_t * slider)
+static inline lv_action_t lv_sw_get_action(const lv_obj_t * slider)
 {
     return lv_slider_get_action(slider);
 }
@@ -129,7 +129,7 @@ static inline lv_action_t lv_sw_get_action(lv_obj_t * slider)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_sw_get_style(lv_obj_t *sw, lv_sw_style_t type);
+lv_style_t * lv_sw_get_style(const lv_obj_t *sw, lv_sw_style_t type);
 
 /**********************
  *      MACROS
diff --git a/lv_objx/lv_ta.c b/lv_objx/lv_ta.c
index d871fe815..b939a08e3 100644
--- a/lv_objx/lv_ta.c
+++ b/lv_objx/lv_ta.c
@@ -72,7 +72,7 @@ static lv_signal_func_t scrl_signal;
  * @param copy pointer to a text area object, if not NULL then the new object will be copied from it
  * @return pointer to the created text area
  */
-lv_obj_t * lv_ta_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_ta_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("text area create started");
 
@@ -551,7 +551,7 @@ void lv_ta_set_style(lv_obj_t * ta, lv_ta_style_t type, lv_style_t * style)
  * @param ta pointer to a text area object
  * @return pointer to the text
  */
-const char * lv_ta_get_text(lv_obj_t * ta)
+const char * lv_ta_get_text(const lv_obj_t * ta)
 {
     lv_ta_ext_t * ext = lv_obj_get_ext_attr(ta);
 
@@ -571,7 +571,7 @@ const char * lv_ta_get_text(lv_obj_t * ta)
  * @param ta pointer to a text area object
  * @return pointer to the label object
  */
-lv_obj_t * lv_ta_get_label(lv_obj_t * ta)
+lv_obj_t * lv_ta_get_label(const lv_obj_t * ta)
 {
     lv_ta_ext_t * ext = lv_obj_get_ext_attr(ta);
     return ext->label;
@@ -583,7 +583,7 @@ lv_obj_t * lv_ta_get_label(lv_obj_t * ta)
  * @param ta pointer to a text area object
  * @return the cursor position
  */
-uint16_t lv_ta_get_cursor_pos(lv_obj_t * ta)
+uint16_t lv_ta_get_cursor_pos(const lv_obj_t * ta)
 {
     lv_ta_ext_t * ext = lv_obj_get_ext_attr(ta);
     return ext->cursor.pos;
@@ -594,7 +594,7 @@ uint16_t lv_ta_get_cursor_pos(lv_obj_t * ta)
  * @param ta pointer to a text area object
  * @return element of 'lv_ta_cursor_type_t'
  */
-lv_cursor_type_t lv_ta_get_cursor_type(lv_obj_t * ta)
+lv_cursor_type_t lv_ta_get_cursor_type(const lv_obj_t * ta)
 {
     lv_ta_ext_t * ext = lv_obj_get_ext_attr(ta);
     return ext->cursor.type;
@@ -605,7 +605,7 @@ lv_cursor_type_t lv_ta_get_cursor_type(lv_obj_t * ta)
  * @param ta pointer to a text area object
  * @return true: password mode is enabled, false: disabled
  */
-bool lv_ta_get_pwd_mode(lv_obj_t * ta)
+bool lv_ta_get_pwd_mode(const lv_obj_t * ta)
 {
     lv_ta_ext_t * ext = lv_obj_get_ext_attr(ta);
     return ext->pwd_mode == 0 ? false : true;
@@ -616,7 +616,7 @@ bool lv_ta_get_pwd_mode(lv_obj_t * ta)
  * @param ta pointer to a text area object
  * @return true: one line configuration is enabled, false: disabled
  */
-bool lv_ta_get_one_line(lv_obj_t * ta)
+bool lv_ta_get_one_line(const lv_obj_t * ta)
 {
     lv_ta_ext_t * ext = lv_obj_get_ext_attr(ta);
     return ext->one_line == 0 ? false : true;
@@ -628,7 +628,7 @@ bool lv_ta_get_one_line(lv_obj_t * ta)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_ta_get_style(lv_obj_t * ta, lv_ta_style_t type)
+lv_style_t * lv_ta_get_style(const lv_obj_t * ta, lv_ta_style_t type)
 {
     lv_ta_ext_t * ext = lv_obj_get_ext_attr(ta);
 
diff --git a/lv_objx/lv_ta.h b/lv_objx/lv_ta.h
index a89383d7c..a7d5525ed 100644
--- a/lv_objx/lv_ta.h
+++ b/lv_objx/lv_ta.h
@@ -87,7 +87,7 @@ typedef enum {
  * @param copy pointer to a text area object, if not NULL then the new object will be copied from it
  * @return pointer to the created text area
  */
-lv_obj_t * lv_ta_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_ta_create(lv_obj_t * par, const lv_obj_t * copy);
 
 
 /*======================
@@ -181,56 +181,56 @@ void lv_ta_set_style(lv_obj_t *ta, lv_ta_style_t type, lv_style_t *style);
  * @param ta pointer to a text area object
  * @return pointer to the text
  */
-const char * lv_ta_get_text(lv_obj_t * ta);
+const char * lv_ta_get_text(const lv_obj_t * ta);
 
 /**
  * Get the label of a text area
  * @param ta pointer to a text area object
  * @return pointer to the label object
  */
-lv_obj_t * lv_ta_get_label(lv_obj_t * ta);
+lv_obj_t * lv_ta_get_label(const lv_obj_t * ta);
 
 /**
  * Get the current cursor position in character index
  * @param ta pointer to a text area object
  * @return the cursor position
  */
-uint16_t lv_ta_get_cursor_pos(lv_obj_t * ta);
+uint16_t lv_ta_get_cursor_pos(const lv_obj_t * ta);
 
 /**
  * Get the current cursor visibility.
  * @param ta pointer to a text area object
  * @return true: the cursor is drawn, false: the cursor is hidden
  */
-bool lv_ta_get_cursor_show(lv_obj_t * ta);
+bool lv_ta_get_cursor_show(const lv_obj_t * ta);
 
 /**
  * Get the current cursor type.
  * @param ta pointer to a text area object
  * @return element of 'lv_cursor_type_t'
  */
-lv_cursor_type_t lv_ta_get_cursor_type(lv_obj_t * ta);
+lv_cursor_type_t lv_ta_get_cursor_type(const lv_obj_t * ta);
 
 /**
  * Get the password mode attribute
  * @param ta pointer to a text area object
  * @return true: password mode is enabled, false: disabled
  */
-bool lv_ta_get_pwd_mode(lv_obj_t * ta);
+bool lv_ta_get_pwd_mode(const lv_obj_t * ta);
 
 /**
  * Get the one line configuration attribute
  * @param ta pointer to a text area object
  * @return true: one line configuration is enabled, false: disabled
  */
-bool lv_ta_get_one_line(lv_obj_t * ta);
+bool lv_ta_get_one_line(const lv_obj_t * ta);
 
 /**
  * Get the scroll bar mode of a text area
  * @param ta pointer to a text area object
  * @return scrollbar mode from 'lv_page_sb_mode_t' enum
  */
-static inline lv_sb_mode_t lv_ta_get_sb_mode(lv_obj_t * ta)
+static inline lv_sb_mode_t lv_ta_get_sb_mode(const lv_obj_t * ta)
 {
     return lv_page_get_sb_mode(ta);
 }
@@ -241,7 +241,7 @@ static inline lv_sb_mode_t lv_ta_get_sb_mode(lv_obj_t * ta)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_ta_get_style(lv_obj_t *ta, lv_ta_style_t type);
+lv_style_t * lv_ta_get_style(const lv_obj_t *ta, lv_ta_style_t type);
 
 /*=====================
  * Other functions
diff --git a/lv_objx/lv_tabview.c b/lv_objx/lv_tabview.c
index 9d76c43bc..e7f90618a 100644
--- a/lv_objx/lv_tabview.c
+++ b/lv_objx/lv_tabview.c
@@ -64,7 +64,7 @@ static const char * tab_def[] = {""};
  * @param copy pointer to a tab object, if not NULL then the new object will be copied from it
  * @return pointer to the created tab
  */
-lv_obj_t * lv_tabview_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_tabview_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("tab view create started");
 
@@ -428,7 +428,7 @@ void lv_tabview_set_btns_pos(lv_obj_t * tabview, lv_tabview_btns_pos_t btns_pos)
  * @param tabview pointer to Tab view object
  * @return the active btn index
  */
-uint16_t lv_tabview_get_tab_act(lv_obj_t * tabview)
+uint16_t lv_tabview_get_tab_act(const lv_obj_t * tabview)
 {
     lv_tabview_ext_t  * ext = lv_obj_get_ext_attr(tabview);
     return ext->tab_cur;
@@ -439,7 +439,7 @@ uint16_t lv_tabview_get_tab_act(lv_obj_t * tabview)
  * @param tabview pointer to Tab view object
  * @return btn count
  */
-uint16_t lv_tabview_get_tab_count(lv_obj_t * tabview)
+uint16_t lv_tabview_get_tab_count(const lv_obj_t * tabview)
 {
     lv_tabview_ext_t  * ext = lv_obj_get_ext_attr(tabview);
     return ext->tab_cnt;
@@ -451,7 +451,7 @@ uint16_t lv_tabview_get_tab_count(lv_obj_t * tabview)
  * @param id index of the btn (>= 0)
  * @return pointer to page (lv_page) object
  */
-lv_obj_t * lv_tabview_get_tab(lv_obj_t * tabview, uint16_t id)
+lv_obj_t * lv_tabview_get_tab(const lv_obj_t * tabview, uint16_t id)
 {
     lv_tabview_ext_t * ext = lv_obj_get_ext_attr(tabview);
     uint16_t i = 0;
@@ -472,7 +472,7 @@ lv_obj_t * lv_tabview_get_tab(lv_obj_t * tabview, uint16_t id)
  * @param tabview pointer to a tabview object
  * @param return the current btn load action
  */
-lv_tabview_action_t lv_tabview_get_tab_load_action(lv_obj_t * tabview)
+lv_tabview_action_t lv_tabview_get_tab_load_action(const lv_obj_t * tabview)
 {
     lv_tabview_ext_t  * ext = lv_obj_get_ext_attr(tabview);
     return ext->tab_load_action;
@@ -483,7 +483,7 @@ lv_tabview_action_t lv_tabview_get_tab_load_action(lv_obj_t * tabview)
  * @param tabview pointer to Tab view object
  * @return true: enable sliding; false: disable sliding
  */
-bool lv_tabview_get_sliding(lv_obj_t * tabview)
+bool lv_tabview_get_sliding(const lv_obj_t * tabview)
 {
     lv_tabview_ext_t * ext = lv_obj_get_ext_attr(tabview);
     return ext->slide_enable ? true : false;
@@ -494,7 +494,7 @@ bool lv_tabview_get_sliding(lv_obj_t * tabview)
  * @param tabview pointer to Tab view object
  * @return time of animation in milliseconds
  */
-uint16_t lv_tabview_get_anim_time(lv_obj_t * tabview)
+uint16_t lv_tabview_get_anim_time(const lv_obj_t * tabview)
 {
     lv_tabview_ext_t  * ext = lv_obj_get_ext_attr(tabview);
     return ext->anim_time;
@@ -506,7 +506,7 @@ uint16_t lv_tabview_get_anim_time(lv_obj_t * tabview)
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_tabview_get_style(lv_obj_t * tabview, lv_tabview_style_t type)
+lv_style_t * lv_tabview_get_style(const lv_obj_t * tabview, lv_tabview_style_t type)
 {
     lv_tabview_ext_t * ext = lv_obj_get_ext_attr(tabview);
 
@@ -535,7 +535,7 @@ lv_style_t * lv_tabview_get_style(lv_obj_t * tabview, lv_tabview_style_t type)
  * Get position of tab select buttons
  * @param tabview pointer to a ab view object
  */
-lv_tabview_btns_pos_t lv_tabview_get_btns_pos(lv_obj_t * tabview)
+lv_tabview_btns_pos_t lv_tabview_get_btns_pos(const lv_obj_t * tabview)
 {
     lv_tabview_ext_t * ext = lv_obj_get_ext_attr(tabview);
     return ext->btns_pos;
diff --git a/lv_objx/lv_tabview.h b/lv_objx/lv_tabview.h
index beee8e112..67838a826 100644
--- a/lv_objx/lv_tabview.h
+++ b/lv_objx/lv_tabview.h
@@ -91,7 +91,7 @@ typedef enum {
  * @param copy pointer to a tab object, if not NULL then the new object will be copied from it
  * @return pointer to the created tab
  */
-lv_obj_t * lv_tabview_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_tabview_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /**
  * Delete all children of the scrl object, without deleting scrl child.
@@ -169,42 +169,42 @@ void lv_tabview_set_btns_pos(lv_obj_t *tabview, lv_tabview_btns_pos_t btns_pos);
  * @param tabview pointer to Tab view object
  * @return the active tab index
  */
-uint16_t lv_tabview_get_tab_act(lv_obj_t * tabview);
+uint16_t lv_tabview_get_tab_act(const lv_obj_t * tabview);
 
 /**
  * Get the number of tabs
  * @param tabview pointer to Tab view object
  * @return tab count
  */
-uint16_t lv_tabview_get_tab_count(lv_obj_t * tabview);
+uint16_t lv_tabview_get_tab_count(const lv_obj_t * tabview);
 /**
  * Get the page (content area) of a tab
  * @param tabview pointer to Tab view object
  * @param id index of the tab (>= 0)
  * @return pointer to page (lv_page) object
  */
-lv_obj_t * lv_tabview_get_tab(lv_obj_t * tabview, uint16_t id);
+lv_obj_t * lv_tabview_get_tab(const lv_obj_t * tabview, uint16_t id);
 
 /**
  * Get the tab load action
  * @param tabview pointer to a tabview object
  * @param return the current tab load action
  */
-lv_tabview_action_t lv_tabview_get_tab_load_action(lv_obj_t *tabview);
+lv_tabview_action_t lv_tabview_get_tab_load_action(const lv_obj_t *tabview);
 
 /**
  * Get horizontal sliding is enabled or not
  * @param tabview pointer to Tab view object
  * @return true: enable sliding; false: disable sliding
  */
-bool lv_tabview_get_sliding(lv_obj_t * tabview);
+bool lv_tabview_get_sliding(const lv_obj_t * tabview);
 
 /**
  * Get the animation time of tab view when a new tab is loaded
  * @param tabview pointer to Tab view object
  * @return time of animation in milliseconds
  */
-uint16_t lv_tabview_get_anim_time(lv_obj_t * tabview);
+uint16_t lv_tabview_get_anim_time(const lv_obj_t * tabview);
 
 /**
  * Get a style of a tab view
@@ -212,13 +212,13 @@ uint16_t lv_tabview_get_anim_time(lv_obj_t * tabview);
  * @param type which style should be get
  * @return style pointer to a style
  */
-lv_style_t * lv_tabview_get_style(lv_obj_t *tabview, lv_tabview_style_t type);
+lv_style_t * lv_tabview_get_style(const lv_obj_t *tabview, lv_tabview_style_t type);
 
 /**
  * Get position of tab select buttons
  * @param tabview pointer to a ab view object
  */
-lv_tabview_btns_pos_t lv_tabview_get_btns_pos(lv_obj_t *tabview);
+lv_tabview_btns_pos_t lv_tabview_get_btns_pos(const lv_obj_t *tabview);
 
 
 /**********************
diff --git a/lv_objx/lv_win.c b/lv_objx/lv_win.c
index 87feea42a..1d8d6fcbc 100644
--- a/lv_objx/lv_win.c
+++ b/lv_objx/lv_win.c
@@ -44,7 +44,7 @@ static lv_signal_func_t ancestor_signal;
  * @param copy pointer to a window object, if not NULL then the new object will be copied from it
  * @return pointer to the created window
  */
-lv_obj_t * lv_win_create(lv_obj_t * par, lv_obj_t * copy)
+lv_obj_t * lv_win_create(lv_obj_t * par, const lv_obj_t * copy)
 {
 	LV_LOG_TRACE("window create started");
 
@@ -309,7 +309,7 @@ void lv_win_set_style(lv_obj_t * win, lv_win_style_t type, lv_style_t * style)
  * @param win pointer to a window object
  * @return title string of the window
  */
-const char * lv_win_get_title(lv_obj_t * win)
+const char * lv_win_get_title(const lv_obj_t * win)
 {
     lv_win_ext_t * ext = lv_obj_get_ext_attr(win);
     return lv_label_get_text(ext->title);
@@ -320,7 +320,7 @@ const char * lv_win_get_title(lv_obj_t * win)
  * @param win pointer to a window object
  * @return control button size
  */
-lv_coord_t lv_win_get_btn_size(lv_obj_t * win)
+lv_coord_t lv_win_get_btn_size(const lv_obj_t * win)
 {
     lv_win_ext_t * ext = lv_obj_get_ext_attr(win);
     return ext->btn_size;
@@ -331,7 +331,7 @@ lv_coord_t lv_win_get_btn_size(lv_obj_t * win)
  * @param win pointer to a window object
  * @return the layout of the window (from 'lv_layout_t')
  */
-lv_layout_t lv_win_get_layout(lv_obj_t * win)
+lv_layout_t lv_win_get_layout(const lv_obj_t * win)
 {
     lv_win_ext_t * ext = lv_obj_get_ext_attr(win);
     return lv_page_get_scrl_layout(ext->page);
@@ -342,7 +342,7 @@ lv_layout_t lv_win_get_layout(lv_obj_t * win)
  * @param win pointer to a window object
  * @return the scroll bar mode of the window (from 'lv_sb_mode_t')
  */
-lv_sb_mode_t lv_win_get_sb_mode(lv_obj_t * win)
+lv_sb_mode_t lv_win_get_sb_mode(const lv_obj_t * win)
 {
     lv_win_ext_t * ext = lv_obj_get_ext_attr(win);
     return lv_page_get_sb_mode(ext->page);
@@ -353,7 +353,7 @@ lv_sb_mode_t lv_win_get_sb_mode(lv_obj_t * win)
  * @param win pointer to a window object
  * @return the width of the content_bg area
  */
-lv_coord_t lv_win_get_width(lv_obj_t * win)
+lv_coord_t lv_win_get_width(const lv_obj_t * win)
 {
     lv_win_ext_t * ext = lv_obj_get_ext_attr(win);
     lv_obj_t * scrl = lv_page_get_scrl(ext->page);
@@ -368,7 +368,7 @@ lv_coord_t lv_win_get_width(lv_obj_t * win)
  * @param ctrl_btn pointer to a control button of a window
  * @return pointer to the window of 'ctrl_btn'
  */
-lv_obj_t * lv_win_get_from_btn(lv_obj_t * ctrl_btn)
+lv_obj_t * lv_win_get_from_btn(const lv_obj_t * ctrl_btn)
 {
     lv_obj_t * header = lv_obj_get_parent(ctrl_btn);
     lv_obj_t * win = lv_obj_get_parent(header);
@@ -382,7 +382,7 @@ lv_obj_t * lv_win_get_from_btn(lv_obj_t * ctrl_btn)
  * @param type which style window be get
  * @return style pointer to a style
  */
-lv_style_t * lv_win_get_style(lv_obj_t * win, lv_win_style_t type)
+lv_style_t * lv_win_get_style(const lv_obj_t * win, lv_win_style_t type)
 {
     lv_win_ext_t * ext = lv_obj_get_ext_attr(win);
 
diff --git a/lv_objx/lv_win.h b/lv_objx/lv_win.h
index 94be309de..8032a3982 100644
--- a/lv_objx/lv_win.h
+++ b/lv_objx/lv_win.h
@@ -88,7 +88,7 @@ typedef enum {
  * @param copy pointer to a window object, if not NULL then the new object will be copied from it
  * @return pointer to the created window
  */
-lv_obj_t * lv_win_create(lv_obj_t * par, lv_obj_t * copy);
+lv_obj_t * lv_win_create(lv_obj_t * par, const lv_obj_t * copy);
 
 /**
  * Delete all children of the scrl object, without deleting scrl child.
@@ -165,35 +165,35 @@ void lv_win_set_style(lv_obj_t *win, lv_win_style_t type, lv_style_t *style);
  * @param win pointer to a window object
  * @return title string of the window
  */
-const char * lv_win_get_title(lv_obj_t * win);
+const char * lv_win_get_title(const lv_obj_t * win);
 
 /**
  * Get the control button size of a window
  * @param win pointer to a window object
  * @return control button size
  */
-lv_coord_t lv_win_get_btn_size(lv_obj_t * win);
+lv_coord_t lv_win_get_btn_size(const lv_obj_t * win);
 
 /**
  * Get the layout of a window
  * @param win pointer to a window object
  * @return the layout of the window (from 'lv_layout_t')
  */
-lv_layout_t lv_win_get_layout(lv_obj_t *win);
+lv_layout_t lv_win_get_layout(const lv_obj_t *win);
 
 /**
  * Get the scroll bar mode of a window
  * @param win pointer to a window object
  * @return the scroll bar mode of the window (from 'lv_sb_mode_t')
  */
-lv_sb_mode_t lv_win_get_sb_mode(lv_obj_t *win);
+lv_sb_mode_t lv_win_get_sb_mode(const lv_obj_t *win);
 
 /**
  * Get width of the content area (page scrollable) of the window
  * @param win pointer to a window object
  * @return the width of the content area
  */
-lv_coord_t lv_win_get_width(lv_obj_t * win);
+lv_coord_t lv_win_get_width(const lv_obj_t * win);
 
 /**
  * Get the pointer of a widow from one of  its control button.
@@ -201,7 +201,7 @@ lv_coord_t lv_win_get_width(lv_obj_t * win);
  * @param ctrl_btn pointer to a control button of a window
  * @return pointer to the window of 'ctrl_btn'
  */
-lv_obj_t * lv_win_get_from_btn(lv_obj_t * ctrl_btn);
+lv_obj_t * lv_win_get_from_btn(const lv_obj_t * ctrl_btn);
 
 /**
  * Get a style of a window
@@ -209,7 +209,7 @@ lv_obj_t * lv_win_get_from_btn(lv_obj_t * ctrl_btn);
  * @param type which style window be get
  * @return style pointer to a style
  */
-lv_style_t * lv_win_get_style(lv_obj_t *win, lv_win_style_t type);
+lv_style_t * lv_win_get_style(const lv_obj_t *win, lv_win_style_t type);
 
 /*=====================
  * Other functions