evas: Fix support for image_data_get on snapshot

evas_object_image_data_get() is a legacy API that I made work
with snapshot objects (evas_object_image_snapshot_set()). Some
changes in the engine broke the behaviour and this patch fixes
it.

When getting the pixels from an FBO, in read-only mode, we need
to create a temporary image (pixels surface) that contains the
copy of the pixels we get from glReadPixels. This image needs
to be deleted afterwards. It is thus stored by the image object
and freed upon _image_data_set() (good) or object deletion (bad).

FBO + read-write is not supported by this API (it is supported
through buffer_map as the filters had to use that).

Fixes T5754

src/lib/evas/canvas/evas_image_legacy.c

@@ -14,6 +14,14 @@
    EVAS_IMAGE_API(_o, __VA_ARGS__); \
    } while (0)
 
+typedef struct _Evas_Image_Legacy_Pixels_Entry Evas_Image_Legacy_Pixels_Entry;
+
+struct _Evas_Image_Legacy_Pixels_Entry
+{
+   Eo    *object;
+   void  *image;
+};
+
 EAPI Evas_Object *
 evas_object_image_add(Evas *eo_e)
 {
@@ -552,7 +560,7 @@ evas_object_image_data_set(Eo *eo_obj, void *data)
 
    Evas_Object_Protected_Data *obj = efl_data_scope_get(eo_obj, EFL_CANVAS_OBJECT_CLASS);
    Evas_Image_Data *o = efl_data_scope_get(eo_obj, EFL_CANVAS_IMAGE_INTERNAL_CLASS);
-   void *p_data;
+   void *p_data, *pixels;
    Eina_Bool resize_call = EINA_FALSE;
 
 
@@ -563,6 +571,13 @@ evas_object_image_data_set(Eo *eo_obj, void *data)
    p_data = o->engine_data;
    if (data)
      {
+        // r/o FBO data_get: only free the image, don't update pixels
+        if ((pixels = eina_hash_find(o->pixels->images_to_free, data)) != NULL)
+          {
+             eina_hash_del(o->pixels->images_to_free, data, pixels);
+             return;
+          }
+
         if (o->engine_data)
           {
              o->engine_data = ENFN->image_data_put(ENDT, o->engine_data, data);
@@ -640,14 +655,28 @@ evas_object_image_data_set(Eo *eo_obj, void *data)
    if (resize_call) evas_object_inform_call_image_resize(eo_obj);
 }
 
+static void
+_image_to_free_del_cb(void *data)
+{
+   Evas_Image_Legacy_Pixels_Entry *px_entry = data;
+   Evas_Object_Protected_Data *obj;
+
+   obj = efl_data_scope_safe_get(px_entry->object, EFL_CANVAS_OBJECT_CLASS);
+   EINA_SAFETY_ON_NULL_RETURN(obj);
+   ENFN->image_free(ENDT, px_entry->image);
+   free(px_entry);
+}
+
 EAPI void*
 evas_object_image_data_get(const Eo *eo_obj, Eina_Bool for_writing)
 {
    EVAS_IMAGE_API(eo_obj, NULL);
 
    Evas_Image_Data *o = efl_data_scope_get(eo_obj, EFL_CANVAS_IMAGE_INTERNAL_CLASS);
+   Evas_Image_Legacy_Pixels_Entry *px_entry = NULL;
+   Eina_Bool tofree = 0;
+   void *pixels = NULL;
    int stride = 0;
-   void *pixels;
    DATA32 *data;
 
    if (!o->engine_data) return NULL;
@@ -662,25 +691,48 @@ evas_object_image_data_get(const Eo *eo_obj, Eina_Bool for_writing)
      ENFN->image_scale_hint_set(ENDT, o->engine_data, o->scale_hint);
    if (ENFN->image_content_hint_set)
      ENFN->image_content_hint_set(ENDT, o->engine_data, o->content_hint);
-   pixels = ENFN->image_data_get(ENDT, o->engine_data, for_writing, &data, &o->load_error, NULL);
+   pixels = ENFN->image_data_get(ENDT, o->engine_data, for_writing, &data, &o->load_error, &tofree);
 
    /* if we fail to get engine_data, we have to return NULL */
    if (!pixels) return NULL;
 
-   o->engine_data = pixels;
-   if (ENFN->image_stride_get)
-     ENFN->image_stride_get(ENDT, o->engine_data, &stride);
-   else
-     stride = o->cur->image.w * 4;
-
-   if (o->cur->image.stride != stride)
+   if (!tofree)
      {
-        EINA_COW_IMAGE_STATE_WRITE_BEGIN(o, state_write)
-          state_write->image.stride = stride;
-        EINA_COW_IMAGE_STATE_WRITE_END(o, state_write);
+        o->engine_data = pixels;
+        if (ENFN->image_stride_get)
+          ENFN->image_stride_get(ENDT, o->engine_data, &stride);
+        else
+           stride = o->cur->image.w * 4;
+
+        if (o->cur->image.stride != stride)
+          {
+             EINA_COW_IMAGE_STATE_WRITE_BEGIN(o, state_write)
+                   state_write->image.stride = stride;
+             EINA_COW_IMAGE_STATE_WRITE_END(o, state_write);
+          }
+
+        o->pixels_checked_out++;
+     }
+   else
+     {
+        Eina_Hash *hash = o->pixels->images_to_free;
+
+        if (!hash)
+          {
+             hash = eina_hash_pointer_new(_image_to_free_del_cb);
+             if (!hash) goto error;
+             EINA_COW_PIXEL_WRITE_BEGIN(o, pixi_write)
+               pixi_write->images_to_free = hash;
+             EINA_COW_PIXEL_WRITE_END(o, pixi_write);
+          }
+
+        px_entry = calloc(1, sizeof(*px_entry));
+        px_entry->object = (Eo *) eo_obj;
+        px_entry->image = pixels;
+        if (!eina_hash_add(hash, data, px_entry))
+          goto error;
      }
 
-   o->pixels_checked_out++;
    if (for_writing)
      {
         o->written = EINA_TRUE;
@@ -688,6 +740,12 @@ evas_object_image_data_get(const Eo *eo_obj, Eina_Bool for_writing)
      }
 
    return data;
+
+error:
+   free(px_entry);
+   if (tofree && pixels)
+     ENFN->image_free(ENDT, pixels);
+   return NULL;
 }
 
 EAPI void

src/lib/evas/canvas/evas_image_private.h

@@ -61,6 +61,7 @@ struct _Evas_Object_Image_Pixels
       Evas_Object_Image_Pixels_Get_Cb  get_pixels;
       void                            *get_pixels_data;
    } func;
+   Eina_Hash       *images_to_free; /* pixel void* -> Evas_Image_Legacy_Pixels_Entry */
 
    Evas_Video_Surface video;
    unsigned int video_caps;

src/lib/evas/canvas/evas_object_image.c

@@ -1511,6 +1511,13 @@ evas_object_image_free(Evas_Object *eo_obj, Evas_Object_Protected_Data *obj)
         efl_del(o->file_obj);
         o->file_obj = NULL;
      }
+   if (o->pixels->images_to_free)
+     {
+        eina_hash_free(o->pixels->images_to_free);
+        EINA_COW_PIXEL_WRITE_BEGIN(o, pixi_write)
+          pixi_write->images_to_free = NULL;
+        EINA_COW_PIXEL_WRITE_END(o, pixi_write);
+     }
    if (o->pixels->pixel_updates)
      {
        EINA_COW_PIXEL_WRITE_BEGIN(o, pixi_write)