feat(obj): add obj_id, class names, and dump support (#4536)

Signed-off-by: Xu Xingliang <xuxingliang@xiaomi.com>

Kconfig

@@ -61,6 +61,15 @@ menu "LVGL configuration"
 			default 0x00FF00
 			help
 				See misc/lv_color.h for some color values examples.
+
+		config LV_USE_OBJ_ID
+			bool "Add id field to obj."
+			default n
+
+		config LV_USE_OBJ_ID_BUILTIN
+			bool "Use builtin method to deal with obj ID"
+			default n
+
 	endmenu
 
 	menu "Memory settings"

demos/stress/lv_demo_stress.c

@@ -34,6 +34,8 @@ static lv_obj_t * main_page;
 static lv_obj_t * ta;
 static const char * mbox_buttons[] = {"Ok", "Cancel", ""};
 static uint32_t mem_free_start = 0;
+static int16_t g_state = -1;
+
 /**********************
  *      MACROS
  **********************/
@@ -45,7 +47,13 @@ static uint32_t mem_free_start = 0;
 void lv_demo_stress(void)
 {
     LV_LOG_USER("Starting stress test. (< 100 bytes permanent memory leak is normal due to fragmentation)");
-    lv_timer_create(obj_test_task_cb, LV_DEMO_STRESS_TIME_STEP, NULL);
+    lv_timer_t * t = lv_timer_create(obj_test_task_cb, LV_DEMO_STRESS_TIME_STEP, NULL);
+    lv_timer_ready(t); /*Prepare the test right now in first state change.*/
+}
+
+bool lv_demo_stress_finished(void)
+{
+    return g_state == -1;
 }
 
 /**********************
@@ -55,12 +63,11 @@ void lv_demo_stress(void)
 static void obj_test_task_cb(lv_timer_t * tmr)
 {
     (void) tmr;    /*Unused*/
-    static int16_t state = -1;
 
     lv_anim_t a;
     lv_obj_t * obj;
 
-    switch(state) {
+    switch(g_state) {
         case -1: {
                 lv_result_t res = lv_mem_test();
                 if(res != LV_RESULT_OK) {
@@ -404,13 +411,13 @@ static void obj_test_task_cb(lv_timer_t * tmr)
         case 31:
             lv_obj_clean(lv_scr_act());
             main_page = NULL;
-            state = -2;
+            g_state = -2;
             break;
         default:
             break;
     }
 
-    state++;
+    g_state++;
 }
 
 static void auto_del(lv_obj_t * obj, uint32_t delay)

demos/stress/lv_demo_stress.h

@@ -30,6 +30,11 @@ extern "C" {
  **********************/
 void lv_demo_stress(void);
 
+/**
+ * Check if stress demo has finished one round.
+ */
+bool lv_demo_stress_finished(void);
+
 /**********************
  *      MACROS
  **********************/

docs/others/index.rst

@@ -13,3 +13,4 @@ Others
     msg
     imgfont
     ime_pinyin
+    obj_id

docs/others/obj_id.rst

@@ -0,0 +1,52 @@
+======
+OBJ ID
+======
+
+LVGL provides an optional field in `lv_obj_t` to store the object ID.
+Object ID can be used in many cases, for example, to identify the object.
+Or we can store a program backtrace to where the object is created.
+
+Usage
+-----
+
+Enable this feature by setting ``LV_USE_OBJ_ID`` to 1 in `lv_conf.h`.
+Use the builtin obj ID generator by setting ``LV_USE_OBJ_ID_BUILTIN`` to 1.
+Otherwise provide your own custom implementation.
+
+The ID is automatically generated and assigned to `obj->id` during obj's
+construction by calling API `lv_obj_assign_id(obj)` from ``lv_obj_constructor``.
+
+You can directly access the ID by `obj->id` or use API ``lv_obj_stringify_id(obj, buf, len)``
+to get a string representation of the ID.
+
+Use custom ID generator
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Set `LV_USE_OBJ_ID_BUILTIN` to 0 in `lv_conf.h`. Below APIs needed to be impemented and
+linked to lvgl.
+
+.. code:: c
+
+    void lv_obj_assign_id(const lv_obj_class_t * class_p, lv_obj_t * obj);
+    void lv_obj_free_id(lv_obj_t * obj);
+    const char * lv_obj_stringify_id(lv_obj_t * obj, char * buf, uint32_t len);
+
+
+:c:func:``lv_obj_assign_id`` is called when an object is created. The object final class is passed from
+parameter ``class_p``. Note it may be different than ``obj->class_p`` which is the class
+currently being constructed.
+
+:c:func:``lv_obj_free_id`` is called when object is deconstructed. Free any resource alloced in ``lv_obj_assign_id``.
+
+:c:func:``lv_obj_stringify_id`` converts id to a string representation. The string is stored in ``buf``.
+
+Dump obj tree
+~~~~~~~~~~~~~
+
+Use API ``lv_obj_dump_tree(lv_obj_t * obj, int depth)`` to dump the object tree.
+It will walk through all children and print the object ID together with object address.
+
+This is useful to debug UI crash. From log we can rebuilt UI the moment before crash.
+For example, if the obj is stored to a timer->user_data, but obj is deleted when timer expired.
+Timer callback will crash because of accessing wild pointer.
+From the dump log we can clearly see that the obj does not exist.

lv_conf_template.h

@@ -264,7 +264,13 @@
 
 
 /* Add 2 x 32 bit variables to each lv_obj_t to speed up getting style properties */
-#define  LV_OBJ_STYLE_CACHE 1
+#define LV_OBJ_STYLE_CACHE 0
+
+/* Add `id` field to `lv_obj_t` */
+#define LV_USE_OBJ_ID 0
+
+/* Use lvgl builtin method for obj ID */
+#define LV_USE_OBJ_ID_BUILTIN 0
 
 /*=====================
  *  COMPILER SETTINGS

src/core/lv_global.h

@@ -187,6 +187,11 @@ typedef struct _lv_global_t {
 #if LV_USE_IME_PINYIN != 0
     size_t ime_cand_len;
 #endif
+
+#if LV_USE_OBJ_ID_BUILTIN
+    void * objid_array;
+    uint32_t objid_count;
+#endif
 } lv_global_t;
 
 

src/core/lv_obj.c

@@ -49,6 +49,7 @@ static void lv_obj_set_state(lv_obj_t * obj, lv_state_t new_state);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_obj_class = {
     .constructor_cb = lv_obj_constructor,
     .destructor_cb = lv_obj_destructor,
@@ -59,6 +60,7 @@ const lv_obj_class_t lv_obj_class = {
     .group_def = LV_OBJ_CLASS_GROUP_DEF_FALSE,
     .instance_size = (sizeof(lv_obj_t)),
     .base_class = NULL,
+    .name = "obj",
 };
 
 /**********************
@@ -306,6 +308,10 @@ static void lv_obj_constructor(const lv_obj_class_t * class_p, lv_obj_t * obj)
     obj->flags |= LV_OBJ_FLAG_SCROLL_WITH_ARROW;
     if(parent) obj->flags |= LV_OBJ_FLAG_GESTURE_BUBBLE;
 
+#if LV_USE_OBJ_ID
+    lv_obj_assign_id(class_p, obj);
+#endif
+
     LV_TRACE_OBJ_CREATE("finished");
 }
 
@@ -341,6 +347,10 @@ static void lv_obj_destructor(const lv_obj_class_t * class_p, lv_obj_t * obj)
         lv_free(obj->spec_attr);
         obj->spec_attr = NULL;
     }
+
+#if LV_USE_OBJ_ID
+    lv_obj_free_id(obj);
+#endif
 }
 
 static void lv_obj_draw(lv_event_t * e)

src/core/lv_obj.h

@@ -185,6 +185,9 @@ typedef struct _lv_obj_t {
     uint32_t style_other_prop_is_set;
 #endif
     void * user_data;
+#if LV_USE_OBJ_ID
+    void * id;
+#endif
     lv_area_t coords;
     lv_obj_flag_t flags;
     lv_state_t state;
@@ -347,6 +350,42 @@ const lv_obj_class_t * lv_obj_get_class(const lv_obj_t * obj);
  */
 bool lv_obj_is_valid(const lv_obj_t * obj);
 
+#if LV_USE_OBJ_ID
+
+/**
+ * Assign an id to an object if not previously assigned
+ * Set `LV_USE_OBJ_ID_BUILTIN` to 1 to use builtin method to generate object ID.
+ * Otherwise, these functions including `lv_obj_[assign|free|stringify]_id` should be implemented externally.
+ *
+ * @param class_p   the class this obj belongs to. Note obj->class_p is the class currently being constructed.
+ * @param obj   pointer to an object
+ */
+void lv_obj_assign_id(const lv_obj_class_t * class_p, lv_obj_t * obj);
+
+/**
+ * Free resources allocated by `lv_obj_assign_id`
+ * @param obj   pointer to an object
+ */
+void lv_obj_free_id(lv_obj_t * obj);
+
+/**
+ * Format an object's id into a string.
+ * @param obj   pointer to an object
+ * @param buf   buffer to write the string into
+ * @param len   length of the buffer
+ */
+const char * lv_obj_stringify_id(lv_obj_t * obj, char * buf, uint32_t len);
+
+#if LV_USE_OBJ_ID_BUILTIN
+/**
+ * Free resources used by builtin ID generator.
+ */
+void lv_objid_builtin_destroy(void);
+
+#endif
+
+#endif /*LV_USE_OBJ_ID*/
+
 /**********************
  *      MACROS
  **********************/

src/core/lv_obj_class.h

@@ -62,6 +62,7 @@ typedef struct _lv_obj_class_t {
     void (*event_cb)(const struct _lv_obj_class_t * class_p,
                      struct _lv_event_t * e);  /**< Widget type specific event function*/
     void * user_data;
+    const char * name;
     lv_coord_t width_def;
     lv_coord_t height_def;
     uint32_t editable : 2;             /**< Value from ::lv_obj_class_editable_t*/

src/core/lv_obj_id_builtin.c

@@ -0,0 +1,108 @@
+/**
+ * @file lv_obj_id.c
+ *
+ */
+
+/*********************
+ *      INCLUDES
+ *********************/
+#include "lv_obj.h"
+#include "lv_global.h"
+#include "../osal/lv_os.h"
+#include "../stdlib/lv_sprintf.h"
+
+/*********************
+ *      DEFINES
+ *********************/
+
+/**********************
+ *      TYPEDEFS
+ **********************/
+
+/**********************
+ *  STATIC PROTOTYPES
+ **********************/
+
+typedef struct _class_info_t {
+    const lv_obj_class_t * class_p;
+    uint32_t obj_count;
+} class_info_t;
+
+/**********************
+ *  STATIC VARIABLES
+ **********************/
+
+/**********************
+ *      MACROS
+ **********************/
+
+/**********************
+ *   GLOBAL FUNCTIONS
+ **********************/
+
+#if LV_USE_OBJ_ID_BUILTIN
+
+void lv_obj_assign_id(const lv_obj_class_t * class_p, lv_obj_t * obj)
+{
+    LV_ASSERT(obj && class_p);
+
+    uint32_t i;
+    uint32_t id = 0;
+    lv_global_t * global = LV_GLOBAL_DEFAULT();
+    class_info_t * info = NULL;
+
+    if(obj == NULL || class_p == NULL) return;
+    if(global == NULL) return;
+
+    obj->id = NULL;
+
+    for(i = 0; i < global->objid_count; i ++) {
+        info = ((class_info_t *)global->objid_array) + i;
+        if(class_p == info->class_p) break;
+    }
+
+    /*Resize array*/
+    if(i == global->objid_count) {
+        void * array = lv_realloc(global->objid_array, sizeof(class_info_t) * (global->objid_count + 1));
+        LV_ASSERT_MALLOC(array);
+        if(array == NULL) return;
+        global->objid_array = array;
+        global->objid_count ++;
+        info = ((class_info_t *)global->objid_array) + i;
+        info->obj_count = 0;
+        info->class_p = class_p;
+    }
+
+    id = ++info->obj_count;
+
+    obj->id = (void *)(lv_uintptr_t)id;
+}
+
+void lv_obj_free_id(lv_obj_t * obj)
+{
+    LV_UNUSED(obj);
+}
+
+const char * lv_obj_stringify_id(lv_obj_t * obj, char * buf, uint32_t len)
+{
+    const char * name;
+    if(obj == NULL || obj->class_p == NULL) return NULL;
+    if(buf == NULL) return NULL;
+
+    name = obj->class_p->name;
+    if(name == NULL) name = "nameless";
+
+    lv_snprintf(buf, len, "%s%" LV_PRId32 "", name, (uint32_t)(lv_uintptr_t)obj->id);
+    return buf;
+}
+
+void lv_objid_builtin_destroy(void)
+{
+    lv_global_t * global = LV_GLOBAL_DEFAULT();
+    if(global == NULL) return;
+
+    lv_free(global->objid_array);
+    global->objid_count = 0;
+}
+
+#endif /*LV_USE_OBJ_ID_BUILTIN*/

src/core/lv_obj_tree.c

@@ -23,6 +23,8 @@
 #define MY_CLASS &lv_obj_class
 #define disp_ll_p &(LV_GLOBAL_DEFAULT()->disp_ll)
 
+#define OBJ_DUMP_STRING_LEN 128
+
 /**********************
  *      TYPEDEFS
  **********************/
@@ -33,6 +35,7 @@
 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 dump_tree_core(lv_obj_t * obj, lv_coord_t depth);
 
 /**********************
  *  STATIC VARIABLES
@@ -359,6 +362,23 @@ void lv_obj_tree_walk(lv_obj_t * start_obj, lv_obj_tree_walk_cb_t cb, void * use
     walk_core(start_obj, cb, user_data);
 }
 
+void lv_obj_dump_tree(lv_obj_t * start_obj)
+{
+    if(start_obj == NULL) {
+        lv_display_t * disp = lv_display_get_next(NULL);
+        while(disp) {
+            uint32_t i;
+            for(i = 0; i < disp->screen_cnt; i++) {
+                dump_tree_core(disp->screens[i], 0);
+            }
+            disp = lv_display_get_next(disp);
+        }
+    }
+    else {
+        dump_tree_core(start_obj, 0);
+    }
+}
+
 /**********************
  *   STATIC FUNCTIONS
  **********************/
@@ -486,3 +506,32 @@ static lv_obj_tree_walk_res_t walk_core(lv_obj_t * obj, lv_obj_tree_walk_cb_t cb
     }
     return LV_OBJ_TREE_WALK_NEXT;
 }
+
+static lv_obj_tree_walk_res_t dump_tree_core(lv_obj_t * obj, lv_coord_t depth)
+{
+    lv_obj_tree_walk_res_t res;
+    const char * id;
+
+#if LV_USE_OBJ_ID
+    char buf[OBJ_DUMP_STRING_LEN];
+    id = lv_obj_stringify_id(obj, buf, sizeof(buf));
+    if(id == NULL) id = "obj0";
+#else
+    id = "obj0";
+#endif
+
+    /*id of `obj0` is an invalid id for builtin id*/
+    LV_LOG_USER("parent:%p, obj:%p, id:%s;", (void *)(obj ? obj->parent : NULL), (void *)obj, id);
+
+    if(obj && obj->spec_attr && obj->spec_attr->child_cnt) {
+        for(uint32_t i = 0; i < obj->spec_attr->child_cnt; i++) {
+            res = dump_tree_core(lv_obj_get_child(obj, i), depth + 1);
+            if(res == LV_OBJ_TREE_WALK_END)
+                break;
+        }
+        return LV_OBJ_TREE_WALK_NEXT;
+    }
+    else {
+        return LV_OBJ_TREE_WALK_END;
+    }
+}

src/core/lv_obj_tree.h

@@ -164,6 +164,12 @@ uint32_t lv_obj_get_index(const struct _lv_obj_t * obj);
  */
 void lv_obj_tree_walk(struct _lv_obj_t * start_obj, lv_obj_tree_walk_cb_t cb, void * user_data);
 
+/**
+ * Iterate through all children of any object and print their ID.
+ * @param start_obj     start integrating from this object
+ */
+void lv_obj_dump_tree(struct _lv_obj_t * start_ob);
+
 /**********************
  *      MACROS
  **********************/

src/libs/barcode/lv_barcode.c

@@ -36,7 +36,8 @@ const lv_obj_class_t lv_barcode_class = {
     .destructor_cb = lv_barcode_destructor,
     .width_def = LV_SIZE_CONTENT,
     .instance_size = sizeof(lv_barcode_t),
-    .base_class = &lv_canvas_class
+    .base_class = &lv_canvas_class,
+    .name = "barcode",
 };
 
 /**********************

src/libs/ffmpeg/lv_ffmpeg.c

@@ -88,11 +88,13 @@ static void lv_ffmpeg_player_destructor(const lv_obj_class_t * class_p, lv_obj_t
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_ffmpeg_player_class = {
     .constructor_cb = lv_ffmpeg_player_constructor,
     .destructor_cb = lv_ffmpeg_player_destructor,
     .instance_size = sizeof(lv_ffmpeg_player_t),
-    .base_class = &lv_image_class
+    .base_class = &lv_image_class,
+    .name = "ffmpeg-player",
 };
 
 /**********************

src/libs/gif/lv_gif.c

@@ -31,11 +31,13 @@ static void next_frame_task_cb(lv_timer_t * t);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_gif_class = {
     .constructor_cb = lv_gif_constructor,
     .destructor_cb = lv_gif_destructor,
     .instance_size = sizeof(lv_gif_t),
-    .base_class = &lv_image_class
+    .base_class = &lv_image_class,
+    .name = "gif",
 };
 
 /**********************

src/libs/qrcode/lv_qrcode.c

@@ -30,11 +30,13 @@ static void lv_qrcode_destructor(const lv_obj_class_t * class_p, lv_obj_t * obj)
  *  STATIC VARIABLES
  **********************/
 
+
 const lv_obj_class_t lv_qrcode_class = {
     .constructor_cb = lv_qrcode_constructor,
     .destructor_cb = lv_qrcode_destructor,
     .instance_size = sizeof(lv_qrcode_t),
-    .base_class = &lv_canvas_class
+    .base_class = &lv_canvas_class,
+    .name = "qrcode",
 };
 
 /**********************

src/libs/rlottie/lv_rlottie.c

@@ -32,11 +32,13 @@ static void next_frame_task_cb(lv_timer_t * t);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_rlottie_class = {
     .constructor_cb = lv_rlottie_constructor,
     .destructor_cb = lv_rlottie_destructor,
     .instance_size = sizeof(lv_rlottie_t),
-    .base_class = &lv_image_class
+    .base_class = &lv_image_class,
+    .name = "rlottie",
 };
 
 typedef struct {

src/lv_conf_internal.h

@@ -721,14 +721,28 @@
 
 /* Add 2 x 32 bit variables to each lv_obj_t to speed up getting style properties */
 #ifndef LV_OBJ_STYLE_CACHE
-    #ifdef _LV_KCONFIG_PRESENT
-        #ifdef CONFIG_LV_OBJ_STYLE_CACHE
-            #define LV_OBJ_STYLE_CACHE CONFIG_LV_OBJ_STYLE_CACHE
-        #else
-            #define LV_OBJ_STYLE_CACHE 0
-        #endif
+    #ifdef CONFIG_LV_OBJ_STYLE_CACHE
+        #define LV_OBJ_STYLE_CACHE CONFIG_LV_OBJ_STYLE_CACHE
     #else
-        #define  LV_OBJ_STYLE_CACHE 1
+        #define LV_OBJ_STYLE_CACHE 0
+    #endif
+#endif
+
+/* Add `id` field to `lv_obj_t` */
+#ifndef LV_USE_OBJ_ID
+    #ifdef CONFIG_LV_USE_OBJ_ID
+        #define LV_USE_OBJ_ID CONFIG_LV_USE_OBJ_ID
+    #else
+        #define LV_USE_OBJ_ID 0
+    #endif
+#endif
+
+/* Use lvgl builtin method for obj ID */
+#ifndef LV_USE_OBJ_ID_BUILTIN
+    #ifdef CONFIG_LV_USE_OBJ_ID_BUILTIN
+        #define LV_USE_OBJ_ID_BUILTIN CONFIG_LV_USE_OBJ_ID_BUILTIN
+    #else
+        #define LV_USE_OBJ_ID_BUILTIN 0
     #endif
 #endif
 

src/lv_init.c

@@ -310,6 +310,10 @@ void lv_deinit(void)
 #if LV_USE_LOG
     lv_log_register_print_cb(NULL);
 #endif
+
+#if LV_USE_OBJ_ID_BUILTIN
+    lv_objid_builtin_destroy();
+#endif
 }
 #endif
 

src/others/file_explorer/lv_file_explorer.c

@@ -53,7 +53,8 @@ const lv_obj_class_t lv_file_explorer_class = {
     .width_def      = LV_SIZE_CONTENT,
     .height_def     = LV_SIZE_CONTENT,
     .instance_size  = sizeof(lv_file_explorer_t),
-    .base_class     = &lv_obj_class
+    .base_class     = &lv_obj_class,
+    .name = "file-explorer",
 };
 
 /**********************

src/others/ime/lv_ime_pinyin.c

@@ -48,6 +48,7 @@ static void pinyin_ime_clear_data(lv_obj_t * obj);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_ime_pinyin_class = {
     .constructor_cb = lv_ime_pinyin_constructor,
     .destructor_cb  = lv_ime_pinyin_destructor,
@@ -55,7 +56,8 @@ const lv_obj_class_t lv_ime_pinyin_class = {
     .height_def     = LV_SIZE_CONTENT,
     .group_def      = LV_OBJ_CLASS_GROUP_DEF_TRUE,
     .instance_size  = sizeof(lv_ime_pinyin_t),
-    .base_class     = &lv_obj_class
+    .base_class     = &lv_obj_class,
+    .name = "ime-pinyin",
 };
 
 #if LV_IME_PINYIN_USE_K9_MODE

src/others/sysmon/lv_sysmon.c

@@ -57,6 +57,7 @@ static void sysmon_async_cb(void * user_data);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_sysmon_class = {
     .base_class = &lv_label_class,
     .constructor_cb = lv_sysmon_constructor,
@@ -64,6 +65,7 @@ const lv_obj_class_t lv_sysmon_class = {
     .height_def = LV_SIZE_CONTENT,
     .event_cb = lv_sysmon_event,
     .instance_size = sizeof(lv_sysmon_t),
+    .name = "sysmon",
 };
 
 /**********************

src/widgets/animimage/lv_animimage.c

@@ -42,10 +42,12 @@ static void lv_animimg_constructor(const lv_obj_class_t * class_p, lv_obj_t * ob
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_animimg_class = {
     .constructor_cb = lv_animimg_constructor,
     .instance_size = sizeof(lv_animimg_t),
-    .base_class = &lv_image_class
+    .base_class = &lv_image_class,
+    .name = "animimg",
 };
 
 /**********************

src/widgets/arc/lv_arc.c

@@ -49,7 +49,8 @@ const lv_obj_class_t lv_arc_class  = {
     .event_cb = lv_arc_event,
     .instance_size = sizeof(lv_arc_t),
     .editable = LV_OBJ_CLASS_EDITABLE_TRUE,
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "arc",
 };
 
 /**********************

src/widgets/bar/lv_bar.c

@@ -64,7 +64,8 @@ const lv_obj_class_t lv_bar_class = {
     .width_def = LV_DPI_DEF * 2,
     .height_def = LV_DPI_DEF / 10,
     .instance_size = sizeof(lv_bar_t),
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "bar",
 };
 
 /**********************

src/widgets/button/lv_button.c

@@ -33,7 +33,8 @@ const lv_obj_class_t lv_button_class  = {
     .height_def = LV_SIZE_CONTENT,
     .group_def = LV_OBJ_CLASS_GROUP_DEF_TRUE,
     .instance_size = sizeof(lv_button_t),
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "btn",
 };
 
 /**********************

src/widgets/buttonmatrix/lv_buttonmatrix.c

@@ -70,7 +70,8 @@ const lv_obj_class_t lv_buttonmatrix_class = {
     .instance_size = sizeof(lv_buttonmatrix_t),
     .editable = LV_OBJ_CLASS_EDITABLE_TRUE,
     .group_def = LV_OBJ_CLASS_GROUP_DEF_TRUE,
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "btnmatrix",
 };
 
 /**********************

src/widgets/calendar/lv_calendar.c

@@ -38,13 +38,15 @@ static void highlight_update(lv_obj_t * calendar);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_calendar_class = {
     .constructor_cb = lv_calendar_constructor,
     .width_def = (LV_DPI_DEF * 3) / 2,
     .height_def = (LV_DPI_DEF * 3) / 2,
     .group_def = LV_OBJ_CLASS_GROUP_DEF_TRUE,
     .instance_size = sizeof(lv_calendar_t),
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "calendar",
 };
 
 static const char * day_names_def[7] = LV_CALENDAR_DEFAULT_DAY_NAMES;

src/widgets/calendar/lv_calendar_header_arrow.c

@@ -32,11 +32,13 @@ static void value_changed_event_cb(lv_event_t * e);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_calendar_header_arrow_class = {
     .base_class = &lv_obj_class,
     .constructor_cb = my_constructor,
     .width_def = LV_PCT(100),
-    .height_def = LV_DPI_DEF / 3
+    .height_def = LV_DPI_DEF / 3,
+    .name = "calendar-header-arrow",
 };
 
 static const char * month_names_def[12] = LV_CALENDAR_DEFAULT_MONTH_NAMES;

src/widgets/calendar/lv_calendar_header_dropdown.c

@@ -32,11 +32,13 @@ static void value_changed_event_cb(lv_event_t * e);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_calendar_header_dropdown_class = {
     .base_class = &lv_obj_class,
     .width_def = LV_PCT(100),
     .height_def = LV_SIZE_CONTENT,
-    .constructor_cb = my_constructor
+    .constructor_cb = my_constructor,
+    .name = "calendar-header-dropdown",
 };
 
 static const char * month_list = "01\n02\n03\n04\n05\n06\n07\n08\n09\n10\n11\n12";

src/widgets/canvas/lv_canvas.c

@@ -34,11 +34,13 @@ static void lv_canvas_destructor(const lv_obj_class_t * class_p, lv_obj_t * obj)
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_canvas_class = {
     .constructor_cb = lv_canvas_constructor,
     .destructor_cb = lv_canvas_destructor,
     .instance_size = sizeof(lv_canvas_t),
-    .base_class = &lv_image_class
+    .base_class = &lv_image_class,
+    .name = "canvas",
 };
 
 /**********************

src/widgets/chart/lv_chart.c

@@ -46,6 +46,7 @@ lv_chart_tick_dsc_t * get_tick_gsc(lv_obj_t * obj, lv_chart_axis_t axis);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_chart_class = {
     .constructor_cb = lv_chart_constructor,
     .destructor_cb = lv_chart_destructor,
@@ -53,7 +54,8 @@ const lv_obj_class_t lv_chart_class = {
     .width_def = LV_PCT(100),
     .height_def = LV_DPI_DEF * 2,
     .instance_size = sizeof(lv_chart_t),
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "chart",
 };
 
 /**********************

src/widgets/checkbox/lv_checkbox.c

@@ -43,7 +43,8 @@ const lv_obj_class_t lv_checkbox_class = {
     .height_def = LV_SIZE_CONTENT,
     .group_def = LV_OBJ_CLASS_GROUP_DEF_TRUE,
     .instance_size = sizeof(lv_checkbox_t),
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "checkbox",
 };
 
 /**********************

src/widgets/dropdown/lv_dropdown.c

@@ -60,6 +60,7 @@ static lv_obj_t * get_label(const lv_obj_t * obj);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_dropdown_class = {
     .constructor_cb = lv_dropdown_constructor,
     .destructor_cb = lv_dropdown_destructor,
@@ -69,7 +70,8 @@ const lv_obj_class_t lv_dropdown_class = {
     .instance_size = sizeof(lv_dropdown_t),
     .editable = LV_OBJ_CLASS_EDITABLE_TRUE,
     .group_def = LV_OBJ_CLASS_GROUP_DEF_TRUE,
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "dropdown",
 };
 
 const lv_obj_class_t lv_dropdownlist_class = {
@@ -77,7 +79,8 @@ const lv_obj_class_t lv_dropdownlist_class = {
     .destructor_cb = lv_dropdownlist_destructor,
     .event_cb = lv_dropdown_list_event,
     .instance_size = sizeof(lv_dropdown_list_t),
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "dropdown-list",
 };
 
 

src/widgets/image/lv_image.c

@@ -38,7 +38,8 @@ const lv_obj_class_t lv_image_class = {
     .width_def = LV_SIZE_CONTENT,
     .height_def = LV_SIZE_CONTENT,
     .instance_size = sizeof(lv_image_t),
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "image",
 };
 
 /**********************

src/widgets/imgbtn/lv_imgbtn.c

@@ -36,11 +36,13 @@ static void update_src_info(lv_imgbtn_src_info_t * info, const void * src);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_imgbtn_class = {
     .base_class = &lv_obj_class,
     .instance_size = sizeof(lv_imgbtn_t),
     .constructor_cb = lv_imgbtn_constructor,
     .event_cb = lv_imgbtn_event,
+    .name = "imgbtn",
 };
 
 /**********************

src/widgets/keyboard/lv_keyboard.c

@@ -38,13 +38,15 @@ static void lv_keyboard_update_ctrl_map(lv_obj_t * obj);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_keyboard_class = {
     .constructor_cb = lv_keyboard_constructor,
     .width_def = LV_PCT(100),
     .height_def = LV_PCT(50),
     .instance_size = sizeof(lv_keyboard_t),
     .editable = 1,
-    .base_class = &lv_buttonmatrix_class
+    .base_class = &lv_buttonmatrix_class,
+    .name = "keyboard",
 };
 
 static const char * const default_kb_map_lc[] = {"1#", "q", "w", "e", "r", "t", "y", "u", "i", "o", "p", LV_SYMBOL_BACKSPACE, "\n",

src/widgets/label/lv_label.c

@@ -66,7 +66,8 @@ const lv_obj_class_t lv_label_class = {
     .width_def = LV_SIZE_CONTENT,
     .height_def = LV_SIZE_CONTENT,
     .instance_size = sizeof(lv_label_t),
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "label",
 };
 
 /**********************

src/widgets/led/lv_led.c

@@ -31,6 +31,7 @@ static void lv_led_event(const lv_obj_class_t * class_p, lv_event_t * e);
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_led_class  = {
     .base_class = &lv_obj_class,
     .constructor_cb = lv_led_constructor,
@@ -38,6 +39,7 @@ const lv_obj_class_t lv_led_class  = {
     .height_def = LV_DPI_DEF / 5,
     .event_cb = lv_led_event,
     .instance_size = sizeof(lv_led_t),
+    .name = "led",
 };
 
 /**********************

src/widgets/line/lv_line.c

@@ -40,7 +40,8 @@ const lv_obj_class_t lv_line_class = {
     .width_def = LV_SIZE_CONTENT,
     .height_def = LV_SIZE_CONTENT,
     .instance_size = sizeof(lv_line_t),
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "line",
 };
 
 /**********************

src/widgets/list/lv_list.c

@@ -27,19 +27,21 @@
 /**********************
  *  STATIC PROTOTYPES
  **********************/
-
 const lv_obj_class_t lv_list_class = {
     .base_class = &lv_obj_class,
     .width_def = (LV_DPI_DEF * 3) / 2,
-    .height_def = LV_DPI_DEF * 2
+    .height_def = LV_DPI_DEF * 2,
+    .name = "list",
 };
 
 const lv_obj_class_t lv_list_button_class = {
     .base_class = &lv_button_class,
+    .name = "list-btn",
 };
 
 const lv_obj_class_t lv_list_text_class = {
     .base_class = &lv_label_class,
+    .name = "list-text",
 };
 
 /**********************

src/widgets/menu/lv_menu.c

@@ -42,7 +42,8 @@ const lv_obj_class_t lv_menu_class = {
     .base_class = &lv_obj_class,
     .width_def = (LV_DPI_DEF * 3) / 2,
     .height_def = LV_DPI_DEF * 2,
-    .instance_size = sizeof(lv_menu_t)
+    .instance_size = sizeof(lv_menu_t),
+    .name = "menu",
 };
 const lv_obj_class_t lv_menu_page_class = {
     .constructor_cb = lv_menu_page_constructor,
@@ -50,43 +51,47 @@ const lv_obj_class_t lv_menu_page_class = {
     .base_class = &lv_obj_class,
     .width_def = LV_PCT(100),
     .height_def = LV_SIZE_CONTENT,
-    .instance_size = sizeof(lv_menu_page_t)
+    .instance_size = sizeof(lv_menu_page_t),
+    .name = "menu-page",
 };
 
 const lv_obj_class_t lv_menu_cont_class = {
     .constructor_cb = lv_menu_cont_constructor,
     .base_class = &lv_obj_class,
     .width_def = LV_PCT(100),
-    .height_def = LV_SIZE_CONTENT
+    .height_def = LV_SIZE_CONTENT,
+    .name = "menu-cont",
 };
 
 const lv_obj_class_t lv_menu_section_class = {
     .constructor_cb = lv_menu_section_constructor,
     .base_class = &lv_obj_class,
     .width_def = LV_PCT(100),
-    .height_def = LV_SIZE_CONTENT
+    .height_def = LV_SIZE_CONTENT,
+    .name = "menu-section",
 };
 
 const lv_obj_class_t lv_menu_separator_class = {
     .base_class = &lv_obj_class,
     .width_def = LV_SIZE_CONTENT,
-    .height_def = LV_SIZE_CONTENT
+    .height_def = LV_SIZE_CONTENT,
+    .name = "menu-separator",
 };
 
 const lv_obj_class_t lv_menu_sidebar_cont_class = {
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
 };
 
 const lv_obj_class_t lv_menu_main_cont_class = {
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
 };
 
 const lv_obj_class_t lv_menu_main_header_cont_class = {
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
 };
 
 const lv_obj_class_t lv_menu_sidebar_header_cont_class = {
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
 };
 
 static void lv_menu_refr(lv_obj_t * obj);

src/widgets/meter/lv_meter.c

@@ -37,12 +37,14 @@ static void inv_line(lv_obj_t * obj, lv_meter_indicator_t * indic, int32_t value
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_meter_class = {
     .constructor_cb = lv_meter_constructor,
     .destructor_cb = lv_meter_destructor,
     .event_cb = lv_meter_event,
     .instance_size = sizeof(lv_meter_t),
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "meter",
 };
 
 /**********************

src/widgets/msgbox/lv_msgbox.c

@@ -39,21 +39,24 @@ const lv_obj_class_t lv_msgbox_class = {
     .base_class = &lv_obj_class,
     .width_def = LV_DPI_DEF * 2,
     .height_def = LV_SIZE_CONTENT,
-    .instance_size = sizeof(lv_msgbox_t)
+    .instance_size = sizeof(lv_msgbox_t),
+    .name = "msgbox",
 };
 
 const lv_obj_class_t lv_msgbox_content_class = {
     .base_class = &lv_obj_class,
     .width_def = LV_PCT(100),
     .height_def = LV_SIZE_CONTENT,
-    .instance_size = sizeof(lv_obj_t)
+    .instance_size = sizeof(lv_obj_t),
+    .name = "msgbox-content",
 };
 
 const lv_obj_class_t lv_msgbox_backdrop_class = {
     .base_class = &lv_obj_class,
     .width_def = LV_PCT(100),
     .height_def = LV_PCT(100),
-    .instance_size = sizeof(lv_obj_t)
+    .instance_size = sizeof(lv_obj_t),
+    .name = "msgbox-backdrop",
 };
 
 /**********************

src/widgets/objx_templ/lv_objx_templ.c

@@ -47,7 +47,8 @@ const lv_obj_class_t lv_templ_class = {
     .instance_size = sizeof(lv_templ_t),
     .group_def = LV_OBJ_CLASS_GROUP_DEF_INHERIT,
     .editable = LV_OBJ_CLASS_EDITABLE_INHERIT,
-    .base_class = &lv_templ_class
+    .base_class = &lv_templ_class,
+    .name = "templ",
 };
 
 /**********************

src/widgets/roller/lv_roller.c

@@ -57,13 +57,15 @@ const lv_obj_class_t lv_roller_class = {
     .instance_size = sizeof(lv_roller_t),
     .editable = LV_OBJ_CLASS_EDITABLE_TRUE,
     .group_def = LV_OBJ_CLASS_GROUP_DEF_TRUE,
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "roller",
 };
 
 const lv_obj_class_t lv_roller_label_class  = {
     .event_cb = lv_roller_label_event,
     .instance_size = sizeof(lv_label_t),
-    .base_class = &lv_label_class
+    .base_class = &lv_label_class,
+    .name = "roller-label",
 };
 
 /**********************

src/widgets/scale/lv_scale.c

@@ -61,13 +61,15 @@ static void scale_build_custom_label_text(lv_obj_t * obj, lv_draw_label_dsc_t *
 /**********************
  *  STATIC VARIABLES
  **********************/
+
 const lv_obj_class_t lv_scale_class  = {
     .constructor_cb = lv_scale_constructor,
     .destructor_cb = lv_scale_destructor,
     .event_cb = lv_scale_event,
     .instance_size = sizeof(lv_scale_t),
     .editable = LV_OBJ_CLASS_EDITABLE_TRUE,
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "scale",
 };
 
 /**********************

src/widgets/slider/lv_slider.c

@@ -50,7 +50,8 @@ const lv_obj_class_t lv_slider_class = {
     .editable = LV_OBJ_CLASS_EDITABLE_TRUE,
     .group_def = LV_OBJ_CLASS_GROUP_DEF_TRUE,
     .instance_size = sizeof(lv_slider_t),
-    .base_class = &lv_bar_class
+    .base_class = &lv_bar_class,
+    .name = "slider",
 };
 
 /**********************

src/widgets/span/lv_span.c

@@ -77,6 +77,7 @@ const lv_obj_class_t lv_spangroup_class  = {
     .instance_size = sizeof(lv_spangroup_t),
     .width_def = LV_SIZE_CONTENT,
     .height_def = LV_SIZE_CONTENT,
+    .name = "span",
 };
 
 /**********************

src/widgets/spinbox/lv_spinbox.c

@@ -41,7 +41,8 @@ const lv_obj_class_t lv_spinbox_class = {
     .width_def = LV_DPI_DEF,
     .instance_size = sizeof(lv_spinbox_t),
     .editable = LV_OBJ_CLASS_EDITABLE_TRUE,
-    .base_class = &lv_textarea_class
+    .base_class = &lv_textarea_class,
+    .name = "spinbox",
 };
 /**********************
  *      MACROS

src/widgets/spinner/lv_spinner.c

@@ -31,7 +31,8 @@ static void arc_anim_end_angle(void * obj, int32_t v);
  **********************/
 const lv_obj_class_t lv_spinner_class = {
     .base_class = &lv_arc_class,
-    .constructor_cb = lv_spinner_constructor
+    .constructor_cb = lv_spinner_constructor,
+    .name = "spinner",
 };
 
 /**********************

src/widgets/switch/lv_switch.c

@@ -58,7 +58,8 @@ const lv_obj_class_t lv_switch_class = {
     .height_def = (4 * LV_DPI_DEF) / 17,
     .group_def = LV_OBJ_CLASS_GROUP_DEF_TRUE,
     .instance_size = sizeof(lv_switch_t),
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "switch",
 };
 
 /**********************

src/widgets/table/lv_table.c

@@ -63,6 +63,7 @@ const lv_obj_class_t lv_table_class  = {
     .editable = LV_OBJ_CLASS_EDITABLE_TRUE,
     .group_def = LV_OBJ_CLASS_GROUP_DEF_TRUE,
     .instance_size = sizeof(lv_table_t),
+    .name = "table",
 };
 /**********************
  *      MACROS

src/widgets/tabview/lv_tabview.c

@@ -40,7 +40,8 @@ const lv_obj_class_t lv_tabview_class = {
     .width_def = LV_PCT(100),
     .height_def = LV_PCT(100),
     .base_class = &lv_obj_class,
-    .instance_size = sizeof(lv_tabview_t)
+    .instance_size = sizeof(lv_tabview_t),
+    .name = "tabview",
 };
 
 typedef struct {

src/widgets/textarea/lv_textarea.c

@@ -73,7 +73,8 @@ const lv_obj_class_t lv_textarea_class = {
     .width_def = LV_DPI_DEF * 2,
     .height_def = LV_DPI_DEF,
     .instance_size = sizeof(lv_textarea_t),
-    .base_class = &lv_obj_class
+    .base_class = &lv_obj_class,
+    .name = "textarea",
 };
 
 static const char * ta_insert_replace;

src/widgets/tileview/lv_tileview.c

@@ -30,15 +30,19 @@ static void tileview_event_cb(lv_event_t * e);
  *  STATIC VARIABLES
  **********************/
 
-const lv_obj_class_t lv_tileview_class = {.constructor_cb = lv_tileview_constructor,
-                                          .base_class = &lv_obj_class,
-                                          .instance_size = sizeof(lv_tileview_t)
-                                         };
+const lv_obj_class_t lv_tileview_class = {
+    .constructor_cb = lv_tileview_constructor,
+    .base_class = &lv_obj_class,
+    .instance_size = sizeof(lv_tileview_t),
+    .name = "tileview",
+};
 
-const lv_obj_class_t lv_tileview_tile_class = {.constructor_cb = lv_tileview_tile_constructor,
-                                               .base_class = &lv_obj_class,
-                                               .instance_size = sizeof(lv_tileview_tile_t)
-                                              };
+const lv_obj_class_t lv_tileview_tile_class = {
+    .constructor_cb = lv_tileview_tile_constructor,
+    .base_class = &lv_obj_class,
+    .instance_size = sizeof(lv_tileview_tile_t),
+    .name = "tile",
+};
 
 /**********************
  *      MACROS

src/widgets/win/lv_win.c

@@ -31,7 +31,8 @@ const lv_obj_class_t lv_win_class = {
     .width_def = LV_PCT(100),
     .height_def = LV_PCT(100),
     .base_class = &lv_obj_class,
-    .instance_size = sizeof(lv_win_t)
+    .instance_size = sizeof(lv_win_t),
+    .name = "win",
 };
 /**********************
  *      MACROS

tests/src/lv_test_conf_full.h

@@ -85,4 +85,5 @@
 #define LV_USE_DEMO_MULTILANG   1
 #define LV_USE_DEMO_SCROLL      1
 
-
+#define LV_USE_OBJ_ID           1
+#define LV_USE_OBJ_ID_BUILTIN   1

tests/src/test_cases/test_demo_stress.c

@@ -10,7 +10,13 @@
 static void loop_through_stress_test(void)
 {
 #if LV_USE_DEMO_STRESS
-    lv_test_indev_wait(LV_DEMO_STRESS_TIME_STEP * 33); /* FIXME: remove magic number of states */
+    while(1) {
+        lv_timer_handler();
+        if(lv_demo_stress_finished()) {
+            break;
+        }
+        lv_tick_inc(1);
+    }
 #endif
 }
 void test_demo_stress(void)
@@ -21,7 +27,7 @@ void test_demo_stress(void)
     /* loop once to allow objects to be created */
     loop_through_stress_test();
     uint32_t mem_before = lv_test_get_free_mem();
-    /* loop 10 more times */
+    /* loop 5 more times */
     for(uint32_t i = 0; i < 5; i++) {
         loop_through_stress_test();
     }

tests/src/test_cases/test_objid.c

@@ -0,0 +1,29 @@
+#if LV_BUILD_TEST
+#include "../lvgl.h"
+
+#include "unity/unity.h"
+
+void test_obj_id_should_match_class_name(void)
+{
+    char buf[128];
+    lv_obj_t * obj = lv_obj_create(NULL);
+    lv_obj_stringify_id(obj, buf, sizeof(buf));
+
+    TEST_ASSERT_TRUE(strncmp("obj", buf, strlen("obj")) == 0);
+
+    lv_obj_t * img = lv_image_create(NULL);
+    lv_obj_stringify_id(img, buf, sizeof(buf));
+    TEST_ASSERT_TRUE(strncmp("image", buf, strlen("image")) == 0);
+}
+
+void test_obj_id_should_grow_by_one(void)
+{
+    uint32_t id1, id2;
+    lv_obj_t * obj1 = lv_label_create(NULL);
+    id1 = (lv_uintptr_t)obj1->id;
+    lv_obj_t * obj2 = lv_label_create(NULL);
+    id2 = (lv_uintptr_t)obj2->id;
+    TEST_ASSERT_EQUAL(id1 + 1, id2);
+}
+
+#endif