Disable scope updates in texture and image paint modes.

Scope update is very slow for high resolutions, and currently blocks
the UI thread(!). This is especially terrible in paint modes, where
each stroke causes a scope update and unacceptable freezing.

The scopes update method tries to avoid this somewhat by skipping if the
toolbar is disabled, but this doesn't help when painting where brush
tools etc. are frequently needed. It's also a bad-level poll, with the
core system accessing a UI element.

Eventually scope updates should become a low-priority background job,
as well as becoming threaded. Until then this polling provides a usable
workaround to the most outrageous cases.

2 files changed, 17 insertions, 2 deletions

diff --git a/source/blender/editors/space_image/image_edit.c b/source/blender/editors/space_image/image_edit.c
index 757059ebc29..8e2c6b97a5b 100644
--- a/source/blender/editors/space_image/image_edit.c
+++ b/source/blender/editors/space_image/image_edit.c
@@ -35,6 +35,7 @@
 
 #include "BLI_rect.h"
 
+#include "BKE_colortools.h"
 #include "BKE_context.h"
 #include "BKE_global.h"
 #include "BKE_image.h"
@@ -290,6 +291,20 @@ void ED_image_point_pos__reverse(SpaceImage *sima, ARegion *ar, const float co[2
 	r_co[1] = (co[1] * height * zoomy) + (float)sy;
 }
 
+void ED_space_image_scopes_update(const struct bContext *C, struct SpaceImage *sima, struct ImBuf *ibuf, bool use_view_settings)
+{
+	Scene *scene = CTX_data_scene(C);
+	Object *ob = CTX_data_active_object(C);
+	
+	/* scope update can be expensive, don't update during paint modes */
+	if (sima->mode == SI_MODE_PAINT)
+		return;
+	if (ob && ((ob->mode & OB_MODE_TEXTURE_PAINT) != 0))
+		return;
+	
+	scopes_update(&sima->scopes, ibuf, use_view_settings ? &scene->view_settings : NULL, &scene->display_settings);
+}
+
 bool ED_space_image_show_render(SpaceImage *sima)
 {
 	return (sima->image && ELEM(sima->image->type, IMA_TYPE_R_RESULT, IMA_TYPE_COMPOSITE));
diff --git a/source/blender/editors/space_image/space_image.c b/source/blender/editors/space_image/space_image.c
index 6cf53533618..af1502509f5 100644
--- a/source/blender/editors/space_image/space_image.c
+++ b/source/blender/editors/space_image/space_image.c
@@ -899,9 +899,9 @@ static void image_tools_area_draw(const bContext *C, ARegion *ar)
 				BKE_histogram_update_sample_line(&sima->sample_line_hist, ibuf, &scene->view_settings, &scene->display_settings);
 			}
 			if (sima->image->flag & IMA_VIEW_AS_RENDER)
-				scopes_update(&sima->scopes, ibuf, &scene->view_settings, &scene->display_settings);
+				ED_space_image_scopes_update(C, sima, ibuf, true);
 			else
-				scopes_update(&sima->scopes, ibuf, NULL, &scene->display_settings);
+				ED_space_image_scopes_update(C, sima, ibuf, false);
 		}
 	}
 	ED_space_image_release_buffer(sima, ibuf, lock);