feat(obj) add lv_obj_move_to_index(obj, index), renamed lv_obj_get_child_id(obj) to lv_obj_get_index(obj) (#2514)

* - renamed lv_obj_get_id(obj) to lv_obj_get_index(obj).

- added lv_obj_move_to_index(obj, index).

* automatic review comment fixed

* removed unused variable

* review issue

* restored deprecated function in header, otherwise Build Micropython with LVGL submodule / build (pull_request)  failes

* moved deprecated lv_obj_get_child_id() back to lv_obj_tree.h, otherwise Micropython will not build

* inline function did not work

* made deprecated function 'static inline'

* and now also inline

* move static inline function to lv_api_map.h again

* removed lv_obj_move_up/down

* changed log to warning for deprecated function

* redefined lv_obj_move_foreground(obj) and lv_obj_move_background(obj) as inline functions now calling lv_obj_move_to_index(obj, index).

- lv_obj_swap(obj1, obj2) added. (#2461)

docs/CHANGELOG.md

@@ -1,7 +1,9 @@
 # Changelog
 
 ## v8.1.0 (In progress)
-- lv_obj_move_up(obj) and lv_obj_move_down(obj) added. (#2461)
+- renamed lv_obj_get_child_id(obj) to lv_obj_get_index(obj).
+- added lv_obj_move_to_index(obj, index). (#2461)
+- redefined lv_obj_move_foreground(obj) and lv_obj_move_background(obj) as inline functions now calling lv_obj_move_to_index(obj, index).
 - lv_obj_swap(obj1, obj2) added. (#2461)
 - feat(anim) add interface for handling lv_anim user data. (#2415)
 - feat(obj) add lv_is_initialized (#2402)

docs/overview/layer.md

@@ -42,7 +42,7 @@ lv_obj_del(label2);
 
 There are 4 explicit way to bring an object to the foreground:
 - Use `lv_obj_move_foreground(obj)` to explicitly tell the library to bring an object to the foreground. Similarly, use `lv_obj_move_background(obj)` to move to the background.
-- Use `lv_obj_move_up(obj)` moves the object one position up in the hierarchy, Similarly, use `lv_obj_move_down(obj)` moves the object one position down in the hierarchy. 
+- Use `lv_obj_move_to_index(obj, index)` to set the index of the object in its parent. 
 - Use `lv_obj_swap(obj1, obj2)` to swap the relative position of two objects.
 - When `lv_obj_set_parent(obj, new_parent)` is used, `obj` will be on the foreground on the `new_parent`.
 

docs/widgets/obj.md

@@ -65,11 +65,11 @@ for(i = 0; i < lv_obj_get_child_cnt(parent); i++) {
 }
 ```
 
-`lv_obj_get_child_id(obj)` returns the index of the object. That is how many younger children its parent has.
+`lv_obj_get_index(obj)` returns the index of the object. That is how many younger children its parent has.
 
 You can bring an object to the foreground or send it to the background with `lv_obj_move_foreground(obj)` and `lv_obj_move_background(obj)`.
 
-You can move an object one position up or down in the hierargy with `lv_obj_move_up(obj)` and `lv_obj_move_down(obj)`. 
+You can change the index of an object in its parent using  `lv_obj_move_to_index(obj, index)`. 
 
 You can swap the position of two objects with `lv_obj_swap(obj1, obj2)`.
 

examples/widgets/list/lv_example_list_2.c

@@ -1,4 +1,5 @@
-#include <stdio.h>
+#include <stdlib.h>
+
 
 #include "../../lv_examples.h"
 #if LV_USE_LIST && LV_BUILD_EXAMPLES
@@ -58,25 +59,45 @@ static void event_handler_up(lv_event_t* e)
     if ((code == LV_EVENT_CLICKED) || (code == LV_EVENT_LONG_PRESSED_REPEAT))
     {
         if (currentButton == NULL) return;
-        lv_obj_move_up(currentButton);
+        uint32_t index = lv_obj_get_index(currentButton);
+        if (index <= 0) return;
+        lv_obj_move_to_index(currentButton, index - 1);
+        lv_obj_scroll_to_view(currentButton, LV_ANIM_ON);
+    }
+}
+
+static void event_handler_center(lv_event_t* e)
+{
+    const lv_event_code_t code = lv_event_get_code(e);
+    if ((code == LV_EVENT_CLICKED) || (code == LV_EVENT_LONG_PRESSED_REPEAT))
+    {
+        if (currentButton == NULL) return;
+
+        lv_obj_t* parent = lv_obj_get_parent(currentButton);
+        const uint32_t pos = lv_obj_get_child_cnt(parent) / 2;
+
+        lv_obj_move_to_index(currentButton, pos);
+
         lv_obj_scroll_to_view(currentButton, LV_ANIM_ON);
     }
 }
 
 static void event_handler_dn(lv_event_t* e)
 {
-    lv_event_code_t code = lv_event_get_code(e);
+    const lv_event_code_t code = lv_event_get_code(e);
     if ((code == LV_EVENT_CLICKED) || (code == LV_EVENT_LONG_PRESSED_REPEAT))
     {
         if (currentButton == NULL) return;
-        lv_obj_move_down(currentButton);
+        const uint32_t index = lv_obj_get_index(currentButton);
+
+        lv_obj_move_to_index(currentButton, index + 1);
         lv_obj_scroll_to_view(currentButton, LV_ANIM_ON);
     }
 }
 
 static void event_handler_bottom(lv_event_t* e)
 {
-    lv_event_code_t code = lv_event_get_code(e);
+    const lv_event_code_t code = lv_event_get_code(e);
     if (code == LV_EVENT_CLICKED)
     {
         if (currentButton == NULL) return;
@@ -87,28 +108,21 @@ static void event_handler_bottom(lv_event_t* e)
 
 static void event_handler_swap(lv_event_t* e)
 {
-    lv_event_code_t code = lv_event_get_code(e);
+    const lv_event_code_t code = lv_event_get_code(e);
     // lv_obj_t* obj = lv_event_get_target(e);
     if ((code == LV_EVENT_CLICKED) || (code == LV_EVENT_LONG_PRESSED_REPEAT))
     {
-        uint32_t first = 0;
+        uint32_t cnt = lv_obj_get_child_cnt(list1);
-        uint32_t last = lv_obj_get_child_cnt(list1);
+        for (int i = 0; i < 100; i++)
-        if (last > 1)
+            if (cnt > 1)
-        {
-            last--;
-            while (first < last)
             {
-                lv_obj_t* obj1 = lv_obj_get_child(list1, first);
+                lv_obj_t* obj = lv_obj_get_child(list1, rand() % cnt);
-                lv_obj_t* obj2 = lv_obj_get_child(list1, last);
+                lv_obj_move_to_index(obj, rand() % cnt);
-                lv_obj_swap(obj1, obj2);
+                if (currentButton != NULL)
-                first++;
+                {
-                last--;
+                    lv_obj_scroll_to_view(currentButton, LV_ANIM_ON);
+                }
             }
-            if (currentButton != NULL)
-            {
-                lv_obj_scroll_to_view(currentButton, LV_ANIM_ON);
-            }
-        }
     }
 }
 
@@ -122,7 +136,7 @@ void lv_example_list_2(void)
     /*Add buttons to the list*/
     lv_obj_t* btn;
     int i;
-    for (i = 0; i < 30; i++) {
+    for (i = 0; i < 15; i++) {
         btn = lv_btn_create(list1);
         lv_obj_set_width(btn, lv_pct(50));
         lv_obj_add_event_cb(btn, event_handler, LV_EVENT_CLICKED, NULL);
@@ -149,6 +163,10 @@ void lv_example_list_2(void)
     lv_obj_add_event_cb(btn, event_handler_up, LV_EVENT_ALL, NULL);
     lv_group_remove_obj(btn);
 
+    btn = lv_list_add_btn(list2, LV_SYMBOL_LEFT, "Center");
+    lv_obj_add_event_cb(btn, event_handler_center, LV_EVENT_ALL, NULL);
+    lv_group_remove_obj(btn);
+
     btn = lv_list_add_btn(list2, LV_SYMBOL_DOWN, "Down");
     lv_obj_add_event_cb(btn, event_handler_dn, LV_EVENT_ALL, NULL);
     lv_group_remove_obj(btn);

examples/widgets/win/lv_example_win_1.c

@@ -5,7 +5,7 @@
 static void event_handler(lv_event_t * e)
 {
     lv_obj_t * obj = lv_event_get_target(e);
-    LV_LOG_USER("Button %d clicked", lv_obj_get_child_id(obj));
+    LV_LOG_USER("Button %d clicked", lv_obj_get_index(obj));
 }
 
 void lv_example_win_1(void)

src/core/lv_obj_tree.c

@@ -6,6 +6,8 @@
 /*********************
  *      INCLUDES
  *********************/
+#include <stdlib.h>
+
 #include "lv_obj.h"
 #include "lv_indev.h"
 #include "../misc/lv_anim.h"
@@ -28,9 +30,9 @@
 /**********************
  *  STATIC PROTOTYPES
  **********************/
-static void lv_obj_del_async_cb(void * obj);
+static void lv_obj_del_async_cb(void* obj);
 static void obj_del_core(lv_obj_t * obj);
-static lv_obj_tree_walk_res_t walk_core(lv_obj_t * obj, lv_obj_tree_walk_cb_t cb, void * user_data);
+static lv_obj_tree_walk_res_t walk_core(lv_obj_t * obj, lv_obj_tree_walk_cb_t cb, void* user_data);
 
 /**********************
  *  STATIC VARIABLES
@@ -73,7 +75,7 @@ void lv_obj_del(lv_obj_t * obj)
     }
 
     /*Handle if the active screen was deleted*/
-    if(act_scr_del)  {
+    if(act_scr_del) {
         LV_LOG_WARN("the active screen was deleted")
         disp->act_scr = NULL;
     }
@@ -159,8 +161,8 @@ void lv_obj_set_parent(lv_obj_t * obj, lv_obj_t * parent)
 
     /*Remove the object from the old parent's child list*/
     int32_t i;
-    for(i = lv_obj_get_child_id(obj); i <= (int32_t)lv_obj_get_child_cnt(old_parent) - 2; i++) {
+    for(i = lv_obj_get_index(obj); i <= (int32_t)lv_obj_get_child_cnt(old_parent) - 2; i++) {
-        old_parent->spec_attr->children[i] = old_parent->spec_attr->children[i+1];
+        old_parent->spec_attr->children[i] = old_parent->spec_attr->children[i + 1];
     }
     old_parent->spec_attr->child_cnt--;
     if(old_parent->spec_attr->child_cnt) {
@@ -195,39 +197,39 @@ void lv_obj_set_parent(lv_obj_t * obj, lv_obj_t * parent)
     lv_obj_invalidate(obj);
 }
 
-void lv_obj_move_foreground(lv_obj_t * obj)
+void lv_obj_move_to_index(lv_obj_t * obj, int32_t index)
 {
     LV_ASSERT_OBJ(obj, MY_CLASS);
 
-    lv_obj_t * parent = lv_obj_get_parent(obj);
+    const int32_t old_index = lv_obj_get_index(obj);
-
-    uint32_t i;
-    for(i = lv_obj_get_child_id(obj); i < lv_obj_get_child_cnt(parent) - 1; i++) {
-        parent->spec_attr->children[i] = parent->spec_attr->children[i + 1];
-    }
-    parent->spec_attr->children[lv_obj_get_child_cnt(parent) - 1] = obj;
-
-    /*Notify the new parent about the child*/
-    lv_event_send(parent, LV_EVENT_CHILD_CHANGED, obj);
-
-    lv_obj_invalidate(parent);
-}
-
-void lv_obj_move_background(lv_obj_t * obj)
-{
-    LV_ASSERT_OBJ(obj, MY_CLASS);
 
     lv_obj_t * parent = lv_obj_get_parent(obj);
 
-    int32_t i;
+    if(index < 0) return;
-    for(i = lv_obj_get_child_id(obj); i > 0; i--) {
+    if(index >= (int32_t) lv_obj_get_child_cnt(parent)) return;
-        parent->spec_attr->children[i] = parent->spec_attr->children[i-1];
+    if(index == old_index) return;
+
+    int32_t i = old_index;
+    if(index < old_index)
+    {
+        while (i > index)
+        {
+            parent->spec_attr->children[i] = parent->spec_attr->children[i - 1];
+            lv_event_send(parent, LV_EVENT_CHILD_CHANGED, parent->spec_attr->children[i]);
+            i--;
+        }
     }
-    parent->spec_attr->children[0] = obj;
+    else
-
+    {
-    /*Notify the new parent about the child*/
+        while (i < index)
+        {
+            parent->spec_attr->children[i] = parent->spec_attr->children[i + 1];
+            lv_event_send(parent, LV_EVENT_CHILD_CHANGED, parent->spec_attr->children[i]);
+            i++;
+        }
+    }
+    parent->spec_attr->children[index] = obj;
     lv_event_send(parent, LV_EVENT_CHILD_CHANGED, obj);
-
     lv_obj_invalidate(parent);
 }
 
@@ -236,11 +238,11 @@ void lv_obj_swap(lv_obj_t * obj1, lv_obj_t * obj2)
     LV_ASSERT_OBJ(obj1, MY_CLASS);
     LV_ASSERT_OBJ(obj2, MY_CLASS);
 
-    lv_obj_t* parent = lv_obj_get_parent(obj1);
+    lv_obj_t * parent = lv_obj_get_parent(obj1);
-    lv_obj_t* parent2 = lv_obj_get_parent(obj2);
+    lv_obj_t * parent2 = lv_obj_get_parent(obj2);
 
-    uint_fast32_t index1 = lv_obj_get_child_id(obj1);
+    uint_fast32_t index1 = lv_obj_get_index(obj1);
-    uint_fast32_t index2 = lv_obj_get_child_id(obj2);
+    uint_fast32_t index2 = lv_obj_get_index(obj2);
 
     parent->spec_attr->children[index1] = obj2;
     parent2->spec_attr->children[index2] = obj1;
@@ -249,57 +251,14 @@ void lv_obj_swap(lv_obj_t * obj1, lv_obj_t * obj2)
     lv_event_send(parent2, LV_EVENT_CHILD_CHANGED, obj1);
 
     lv_obj_invalidate(parent);
-    if( parent != parent2) {
+
+    if(parent != parent2)
+    {
         lv_obj_invalidate(parent2);
     }
-
     lv_group_swap_obj(obj1, obj2);
 }
 
-void lv_obj_move_up(lv_obj_t * obj)
-{
-    LV_ASSERT_OBJ(obj, MY_CLASS);
-
-    lv_obj_t* parent = lv_obj_get_parent(obj);
-
-    uint_fast32_t index = lv_obj_get_child_id(obj);
-    if (index > 0)
-    {
-        lv_obj_t* obj2 = parent->spec_attr->children[index - 1];
-        parent->spec_attr->children[index - 1] = obj;
-        parent->spec_attr->children[index] = obj2;
-
-        lv_event_send(parent, LV_EVENT_CHILD_CHANGED, obj);
-        lv_event_send(parent, LV_EVENT_CHILD_CHANGED, obj2);
-
-        lv_obj_invalidate(parent);
-
-        lv_group_swap_obj(obj, obj2);
-    }
-}
-
-void lv_obj_move_down(lv_obj_t* obj)
-{
-    LV_ASSERT_OBJ(obj, MY_CLASS);
-
-    lv_obj_t* parent = lv_obj_get_parent(obj);
-
-    uint_fast32_t index = lv_obj_get_child_id(obj);
-    if (index < lv_obj_get_child_cnt(parent) - 1)
-    {
-        lv_obj_t* obj2 = parent->spec_attr->children[index + 1];
-        parent->spec_attr->children[index + 1] = obj;
-        parent->spec_attr->children[index] = obj2;
-
-        lv_event_send(parent, LV_EVENT_CHILD_CHANGED, obj);
-        lv_event_send(parent, LV_EVENT_CHILD_CHANGED, obj2);
-
-        lv_obj_invalidate(parent);
-
-        lv_group_swap_obj(obj, obj2);
-    }
-}
-
 lv_obj_t * lv_obj_get_screen(const lv_obj_t * obj)
 {
     LV_ASSERT_OBJ(obj, MY_CLASS);
@@ -309,10 +268,10 @@ lv_obj_t * lv_obj_get_screen(const lv_obj_t * obj)
 
     do {
         act_par = par;
-        par   = lv_obj_get_parent(act_par);
+        par = lv_obj_get_parent(act_par);
     } while(par != NULL);
 
-    return (lv_obj_t*)act_par;
+    return (lv_obj_t *)act_par;
 }
 
 lv_disp_t * lv_obj_get_disp(const lv_obj_t * obj)
@@ -370,7 +329,7 @@ uint32_t lv_obj_get_child_cnt(const lv_obj_t * obj)
     return obj->spec_attr->child_cnt;
 }
 
-uint32_t lv_obj_get_child_id(const lv_obj_t * obj)
+uint32_t lv_obj_get_index(const lv_obj_t * obj)
 {
     LV_ASSERT_OBJ(obj, MY_CLASS);
 
@@ -385,8 +344,7 @@ uint32_t lv_obj_get_child_id(const lv_obj_t * obj)
     return 0xFFFFFFFF; /*Shouldn't happen*/
 }
 
-
+void lv_obj_tree_walk(lv_obj_t * start_obj, lv_obj_tree_walk_cb_t cb, void* user_data)
-void lv_obj_tree_walk(lv_obj_t * start_obj, lv_obj_tree_walk_cb_t cb, void * user_data)
 {
     walk_core(start_obj, cb, user_data);
 }
@@ -395,7 +353,7 @@ void lv_obj_tree_walk(lv_obj_t * start_obj, lv_obj_tree_walk_cb_t cb, void * use
  *   STATIC FUNCTIONS
  **********************/
 
-static void lv_obj_del_async_cb(void * obj)
+static void lv_obj_del_async_cb(void* obj)
 {
     LV_ASSERT_OBJ(obj, MY_CLASS);
 
@@ -415,10 +373,10 @@ static void obj_del_core(lv_obj_t * obj)
         child = lv_obj_get_child(obj, 0);
     }
 
-    lv_group_t * group = lv_obj_get_group(obj);
+    lv_group_t* group = lv_obj_get_group(obj);
 
     /*Reset all input devices if the object to delete is used*/
-    lv_indev_t * indev = lv_indev_get_next(NULL);
+    lv_indev_t* indev = lv_indev_get_next(NULL);
     while(indev) {
         if(indev->proc.types.pointer.act_obj == obj || indev->proc.types.pointer.last_obj == obj) {
             lv_indev_reset(indev, obj);
@@ -454,7 +412,7 @@ static void obj_del_core(lv_obj_t * obj)
     }
     /*Remove the object from the child list of its parent*/
     else {
-        uint32_t id = lv_obj_get_child_id(obj);
+        uint32_t id = lv_obj_get_index(obj);
         uint32_t i;
         for(i = id; i < obj->parent->spec_attr->child_cnt - 1; i++) {
             obj->parent->spec_attr->children[i] = obj->parent->spec_attr->children[i + 1];
@@ -468,7 +426,7 @@ static void obj_del_core(lv_obj_t * obj)
 }
 
 
-static lv_obj_tree_walk_res_t walk_core(lv_obj_t * obj, lv_obj_tree_walk_cb_t cb, void * user_data)
+static lv_obj_tree_walk_res_t walk_core(lv_obj_t * obj, lv_obj_tree_walk_cb_t cb, void* user_data)
 {
     lv_obj_tree_walk_res_t res = LV_OBJ_TREE_WALK_NEXT;
 

src/core/lv_obj_tree.h

@@ -85,22 +85,6 @@ void lv_obj_del_async(struct _lv_obj_t * obj);
  */
 void lv_obj_set_parent(struct _lv_obj_t * obj, struct _lv_obj_t * parent);
 
-/**
- * Move the object to the foreground.
- * It will look like if it was created as the last child of its parent.
- * It also means it can cover any of the siblings.
- * @param obj       pointer to an object
- */
-void lv_obj_move_foreground(struct _lv_obj_t * obj);
-
-/**
- * Move the object to the background.
- * It will look like if it was created as the first child of its parent.
- * It also means any of the siblings can cover the object.
- * @param obj       pointer to an object
- */
-void lv_obj_move_background(struct _lv_obj_t * obj);
-
 /**
  * Swap the positions of two objects.
  * When used in listboxes, it can be used to sort the listbox items.
@@ -110,18 +94,14 @@ void lv_obj_move_background(struct _lv_obj_t * obj);
 void lv_obj_swap(struct _lv_obj_t* obj1, struct _lv_obj_t* obj2);
 
 /**
- * moves the object one position up in the hierarchy.
+ * moves the object to the given index in its parent.
  * When used in listboxes, it can be used to sort the listbox items.
- * @param obj  pointer to the object to be moved upwards.
+ * @param obj  pointer to the object to be moved.
+ * @param index  new index in parent.
+ * @note to move to the foreground: lv_obj_move_to_index(obj, 0)
+ * @note to move forward (up): lv_obj_move_to_index(obj, lv_obj_get_index(obj) - 1) 
  */
-void lv_obj_move_up(struct _lv_obj_t* obj);
+void lv_obj_move_to_index(struct _lv_obj_t* obj, int32_t index);
-
-/**
- * moves the object one position down in the hierarchy.
- * When used in listboxes, it can be used to sort the listbox items.
- * @param obj  pointer to the object to be moved downwards.
- */
-void lv_obj_move_down(struct _lv_obj_t* obj);
 
 /**
  * Get the screen of an object
@@ -166,11 +146,11 @@ uint32_t lv_obj_get_child_cnt(const struct _lv_obj_t * obj);
 
 /**
  * Get the index of a child.
- * @param obj       pointer to an obejct
+ * @param obj       pointer to an object
  * @return          the child index of the object.
  *                  E.g. 0: the oldest (firstly created child)
  */
-uint32_t lv_obj_get_child_id(const struct _lv_obj_t * obj);
+uint32_t lv_obj_get_index(const struct _lv_obj_t* obj);
 
 /**
  * Iterate through all children of any object.

src/extra/themes/basic/lv_theme_basic.c

@@ -201,12 +201,12 @@ static void theme_apply(lv_theme_t * th, lv_obj_t * obj)
 
 #if LV_USE_WIN
         /*Header*/
-        if(lv_obj_get_child_id(obj) == 0 && lv_obj_check_type(lv_obj_get_parent(obj), &lv_win_class)) {
+        if(lv_obj_get_index(obj) == 0 && lv_obj_check_type(lv_obj_get_parent(obj), &lv_win_class)) {
             lv_obj_add_style(obj, &styles->light, 0);
             return;
         }
         /*Content*/
-        else if(lv_obj_get_child_id(obj) == 1 && lv_obj_check_type(lv_obj_get_parent(obj), &lv_win_class)) {
+        else if(lv_obj_get_index(obj) == 1 && lv_obj_check_type(lv_obj_get_parent(obj), &lv_win_class)) {
             lv_obj_add_style(obj, &styles->light, 0);
             lv_obj_add_style(obj, &styles->scrollbar, LV_PART_SCROLLBAR);
             return;

src/extra/themes/default/lv_theme_default.c

@@ -630,13 +630,13 @@ static void theme_apply(lv_theme_t * th, lv_obj_t * obj)
 
 #if LV_USE_WIN
         /*Header*/
-        if(lv_obj_get_child_id(obj) == 0 && lv_obj_check_type(lv_obj_get_parent(obj), &lv_win_class)) {
+        if(lv_obj_get_index(obj) == 0 && lv_obj_check_type(lv_obj_get_parent(obj), &lv_win_class)) {
             lv_obj_add_style(obj, &styles->bg_color_grey, 0);
             lv_obj_add_style(obj, &styles->pad_tiny, 0);
             return;
         }
         /*Content*/
-        else if(lv_obj_get_child_id(obj) == 1 && lv_obj_check_type(lv_obj_get_parent(obj), &lv_win_class)) {
+        else if(lv_obj_get_index(obj) == 1 && lv_obj_check_type(lv_obj_get_parent(obj), &lv_win_class)) {
             lv_obj_add_style(obj, &styles->scr, 0);
             lv_obj_add_style(obj, &styles->pad_normal, 0);
             lv_obj_add_style(obj, &styles->scrollbar, LV_PART_SCROLLBAR);

src/extra/themes/mono/lv_theme_mono.c

@@ -219,13 +219,13 @@ static void theme_apply(lv_theme_t * th, lv_obj_t * obj)
 
 #if LV_USE_WIN
         /*Header*/
-        if(lv_obj_get_child_id(obj) == 0 && lv_obj_check_type(lv_obj_get_parent(obj), &lv_win_class)) {
+        if(lv_obj_get_index(obj) == 0 && lv_obj_check_type(lv_obj_get_parent(obj), &lv_win_class)) {
             lv_obj_add_style(obj, &styles->card, 0);
             lv_obj_add_style(obj, &styles->no_radius, 0);
             return;
         }
         /*Content*/
-        else if(lv_obj_get_child_id(obj) == 1 && lv_obj_check_type(lv_obj_get_parent(obj), &lv_win_class)) {
+        else if(lv_obj_get_index(obj) == 1 && lv_obj_check_type(lv_obj_get_parent(obj), &lv_win_class)) {
             lv_obj_add_style(obj, &styles->card, 0);
             lv_obj_add_style(obj, &styles->no_radius, 0);
             lv_obj_add_style(obj, &styles->scrollbar, LV_PART_SCROLLBAR);

src/lv_api_map.h

@@ -41,6 +41,46 @@ static inline LV_ATTRIBUTE_TIMER_HANDLER uint32_t lv_task_handler(void)
  *      MACROS
  **********************/
 
+
+/**********************
+ * INLINE FUNCTIONS
+ **********************/
+
+/**
+ * Move the object to the foreground.
+ * It will look like if it was created as the last child of its parent.
+ * It also means it can cover any of the siblings.
+ * @param obj       pointer to an object
+ */
+static inline void lv_obj_move_foreground(lv_obj_t* obj)
+{
+    lv_obj_t* parent = lv_obj_get_parent(obj);
+    lv_obj_move_to_index(obj, lv_obj_get_child_cnt(parent) - 1);
+}
+
+/**
+ * Move the object to the background.
+ * It will look like if it was created as the first child of its parent.
+ * It also means any of the siblings can cover the object.
+ * @param obj       pointer to an object
+ */
+static inline void lv_obj_move_background(lv_obj_t* obj)
+{
+    lv_obj_move_to_index(obj, 0);
+}
+
+
+
+/**********************
+ * DEPRECATED FUNCTIONS
+ **********************/
+
+static inline uint32_t lv_obj_get_child_id(const struct _lv_obj_t* obj)
+{
+    LV_LOG_WARN("lv_obj_get_child_id(obj) is deprecated, please use lv_obj_get_index(obj).");
+    return lv_obj_get_index(obj);
+}
+
 #ifdef __cplusplus
 } /*extern "C"*/
 #endif