Fix asset preview not showing up for current file data-blocks

For data-blocks from the current file, the image-buffer for dragging
wasn't set at all. This wasn't intentional, dragging things in the Asset
Browser should just always show the preview.

4 files changed, 24 insertions, 4 deletions

diff --git a/source/blender/editors/include/UI_interface.h b/source/blender/editors/include/UI_interface.h
index 725c9921d13..065b0a2d057 100644
--- a/source/blender/editors/include/UI_interface.h
+++ b/source/blender/editors/include/UI_interface.h
@@ -773,6 +773,7 @@ void UI_block_translate(uiBlock *block, int x, int y);
 int UI_but_return_value_get(uiBut *but);
 
 void UI_but_drag_set_id(uiBut *but, struct ID *id);
+void UI_but_drag_attach_image(uiBut *but, struct ImBuf *imb, const float scale);
 void UI_but_drag_set_asset(uiBut *but,
                            const struct AssetHandle *asset,
                            const char *path,
diff --git a/source/blender/editors/interface/interface.c b/source/blender/editors/interface/interface.c
index 9f9324505ad..6ad0ef9de18 100644
--- a/source/blender/editors/interface/interface.c
+++ b/source/blender/editors/interface/interface.c
@@ -6239,6 +6239,16 @@ void UI_but_drag_set_id(uiBut *but, ID *id)
 }
 
 /**
+ * Set an image to display while dragging. This works for any drag type (`WM_DRAG_XXX`).
+ * Not to be confused with #UI_but_drag_set_image(), which sets up dragging of an image.
+ */
+void UI_but_drag_attach_image(uiBut *but, struct ImBuf *imb, const float scale)
+{
+  but->imb = imb;
+  but->imb_scale = scale;
+}
+
+/**
  * \param asset: May be passed from a temporary variable, drag data only stores a copy of this.
  */
 void UI_but_drag_set_asset(uiBut *but,
@@ -6266,8 +6276,7 @@ void UI_but_drag_set_asset(uiBut *but,
   }
   but->dragpoin = asset_drag;
   but->dragflag |= UI_BUT_DRAGPOIN_FREE;
-  but->imb = imb;
-  but->imb_scale = scale;
+  UI_but_drag_attach_image(but, imb, scale);
 }
 
 void UI_but_drag_set_rna(uiBut *but, PointerRNA *ptr)
@@ -6322,8 +6331,7 @@ void UI_but_drag_set_image(
   if (use_free) {
     but->dragflag |= UI_BUT_DRAGPOIN_FREE;
   }
-  but->imb = imb;
-  but->imb_scale = scale;
+  UI_but_drag_attach_image(but, imb, scale);
 }
 
 PointerRNA *UI_but_operator_ptr_get(uiBut *but)
diff --git a/source/blender/editors/space_file/file_draw.c b/source/blender/editors/space_file/file_draw.c
index 66aabe39e44..e393cc41a86 100644
--- a/source/blender/editors/space_file/file_draw.c
+++ b/source/blender/editors/space_file/file_draw.c
@@ -178,6 +178,10 @@ static void file_draw_icon(const SpaceFile *sfile,
 
     if ((id = filelist_file_get_id(file))) {
       UI_but_drag_set_id(but, id);
+      ImBuf *preview_image = filelist_file_getimage(file);
+      if (preview_image) {
+        UI_but_drag_attach_image(but, preview_image, UI_DPI_FAC);
+      }
     }
     else if (sfile->browse_mode == FILE_BROWSE_MODE_ASSETS &&
              (file->typeflag & FILE_TYPE_ASSET) != 0) {
@@ -504,6 +508,7 @@ static void file_draw_preview(const SpaceFile *sfile,
 
     if ((id = filelist_file_get_id(file))) {
       UI_but_drag_set_id(but, id);
+      UI_but_drag_attach_image(but, imb, scale);
     }
     /* path is no more static, cannot give it directly to but... */
     else if (sfile->browse_mode == FILE_BROWSE_MODE_ASSETS &&
diff --git a/source/blender/windowmanager/intern/wm_dragdrop.c b/source/blender/windowmanager/intern/wm_dragdrop.c
index 64aa55c058c..49b84abf9a2 100644
--- a/source/blender/windowmanager/intern/wm_dragdrop.c
+++ b/source/blender/windowmanager/intern/wm_dragdrop.c
@@ -767,6 +767,12 @@ static void wm_drag_draw_icon(bContext *UNUSED(C),
                               const int xy[2])
 {
   int x, y;
+
+  /* This could also get the preview image of an ID when dragging one. But the big preview icon may
+   * actually not always be wanted, for example when dragging objects in the Outliner it gets in
+   * the way). So make the drag user set an image buffer explicitly (e.g. through
+   * #UI_but_drag_attach_image()). */
+
   if (drag->imb) {
     x = xy[0] - drag->sx / 2;
     y = xy[1] - drag->sy / 2;