[Bf-blender-cvs] [e3faef686d3] master: Fix/Refactor RNA ID preview getter creating preview data.

[Bastien Montagne]

Commit: e3faef686d3850f2e87d1a92506ba487a3594242
Author: Bastien Montagne
Date:   Tue May 25 10:38:23 2021 +0200
Branches: master
https://developer.blender.org/rBe3faef686d3850f2e87d1a92506ba487a3594242

Fix/Refactor RNA ID preview getter creating preview data.

Same as with forcefields, accessors should never generate data.

===================================================================

M	release/scripts/modules/bl_previews_utils/bl_previews_render.py
M	source/blender/makesrna/intern/rna_ID.c

===================================================================

diff --git a/release/scripts/modules/bl_previews_utils/bl_previews_render.py b/release/scripts/modules/bl_previews_utils/bl_previews_render.py
index 979b47f7a14..51ea53c0eba 100644
--- a/release/scripts/modules/bl_previews_utils/bl_previews_render.py
+++ b/release/scripts/modules/bl_previews_utils/bl_previews_render.py
@@ -37,6 +37,9 @@ OBJECT_TYPES_RENDER = {'MESH', 'CURVE', 'SURFACE', 'META', 'FONT'}
 def ids_nolib(bids):
     return (bid for bid in bids if not bid.library)
 
+def ids_nolib_with_preview(bids):
+    return (bid for bid in bids if (not bid.library and bid.preview))
+
 
 def rna_backup_gen(data, include_props=None, exclude_props=None, root=()):
     # only writable properties...
@@ -313,8 +316,9 @@ def do_previews(do_objects, do_collections, do_scenes, do_data_intern):
         image = bpy.data.images[render_context.image, None]
         item = getattr(bpy.data, item_container)[item_name, None]
         image.reload()
-        item.preview.image_size = (RENDER_PREVIEW_SIZE, RENDER_PREVIEW_SIZE)
-        item.preview.image_pixels_float[:] = image.pixels
+        preview = item.preview_ensure()
+        preview.image_size = (RENDER_PREVIEW_SIZE, RENDER_PREVIEW_SIZE)
+        preview.image_pixels_float[:] = image.pixels
 
     # And now, main code!
     do_save = True
@@ -451,15 +455,15 @@ def do_clear_previews(do_objects, do_collections, do_scenes, do_data_intern):
         bpy.ops.wm.previews_clear(id_type={'SHADING'})
 
     if do_objects:
-        for ob in ids_nolib(bpy.data.objects):
+        for ob in ids_nolib_with_preview(bpy.data.objects):
             ob.preview.image_size = (0, 0)
 
     if do_collections:
-        for grp in ids_nolib(bpy.data.collections):
+        for grp in ids_nolib_with_preview(bpy.data.collections):
             grp.preview.image_size = (0, 0)
 
     if do_scenes:
-        for scene in ids_nolib(bpy.data.scenes):
+        for scene in ids_nolib_with_preview(bpy.data.scenes):
             scene.preview.image_size = (0, 0)
 
     print("Saving %s..." % bpy.data.filepath)
diff --git a/source/blender/makesrna/intern/rna_ID.c b/source/blender/makesrna/intern/rna_ID.c
index 5c0691f0320..2818f251085 100644
--- a/source/blender/makesrna/intern/rna_ID.c
+++ b/source/blender/makesrna/intern/rna_ID.c
@@ -1137,7 +1137,7 @@ static void rna_ImagePreview_icon_reload(PreviewImage *prv)
 static PointerRNA rna_IDPreview_get(PointerRNA *ptr)
 {
   ID *id = (ID *)ptr->data;
-  PreviewImage *prv_img = BKE_previewimg_id_ensure(id);
+  PreviewImage *prv_img = BKE_previewimg_id_get(id);
 
   return rna_pointer_inherit_refine(ptr, &RNA_ImagePreview, prv_img);
 }
@@ -1707,12 +1707,12 @@ static void rna_def_ID(BlenderRNA *brna)
       srna, "override_library", "IDOverrideLibrary", "Library Override", "Library override data");
   RNA_def_property_clear_flag(prop, PROP_EDITABLE);
 
-  prop = RNA_def_pointer(
-      srna,
-      "preview",
-      "ImagePreview",
-      "Preview",
-      "Preview image and icon of this data-block (None if not supported for this type of data)");
+  prop = RNA_def_pointer(srna,
+                         "preview",
+                         "ImagePreview",
+                         "Preview",
+                         "Preview image and icon of this data-block (always None if not supported "
+                         "for this type of data)");
   RNA_def_property_clear_flag(prop, PROP_EDITABLE);
   RNA_def_property_override_flag(prop, PROPOVERRIDE_NO_COMPARISON);
   RNA_def_property_pointer_funcs(prop, "rna_IDPreview_get", NULL, NULL, NULL);
@@ -1826,6 +1826,13 @@ static void rna_def_ID(BlenderRNA *brna)
                                   "e.g. when calling :class:`bpy.types.Scene.update`");
   RNA_def_enum_flag(func, "refresh", update_flag_items, 0, "", "Type of updates to perform");
 
+  func = RNA_def_function(srna, "preview_ensure", "BKE_previewimg_id_ensure");
+  RNA_def_function_ui_description(func,
+                                  "Ensure that this ID has preview data (if ID type supports it)");
+  parm = RNA_def_pointer(
+      func, "preview_image", "ImagePreview", "", "The existing or created preview");
+  RNA_def_function_return(func, parm);
+
 #  ifdef WITH_PYTHON
   RNA_def_struct_register_funcs(srna, NULL, NULL, "rna_ID_instance");
 #  endif