Fix T38245: render slot getting lost when switching slots while compositing.

2 files changed, 12 insertions, 7 deletions

diff --git a/source/blender/blenkernel/BKE_image.h b/source/blender/blenkernel/BKE_image.h
index ea63161e008..ff0b5a1d4bf 100644
--- a/source/blender/blenkernel/BKE_image.h
+++ b/source/blender/blenkernel/BKE_image.h
@@ -221,7 +221,7 @@ void BKE_image_release_renderresult(struct Scene *scene, struct Image *ima);
 bool BKE_image_is_openexr(struct Image *ima);
 
 /* for multiple slot render, call this before render */
-void BKE_image_backup_render(struct Scene *scene, struct Image *ima);
+void BKE_image_backup_render(struct Scene *scene, struct Image *ima, bool free_current_slot);
 
 /* for singlelayer openexr saving */
 bool BKE_image_save_openexr_multiview(struct Image *ima, struct ImBuf *ibuf, const char *filepath, const int flags);
diff --git a/source/blender/blenkernel/intern/image.c b/source/blender/blenkernel/intern/image.c
index f4fce5c0019..6ff30134210 100644
--- a/source/blender/blenkernel/intern/image.c
+++ b/source/blender/blenkernel/intern/image.c
@@ -2923,7 +2923,7 @@ bool BKE_image_is_openexr(struct Image *ima)
 	return false;
 }
 
-void BKE_image_backup_render(Scene *scene, Image *ima)
+void BKE_image_backup_render(Scene *scene, Image *ima, bool free_current_slot)
 {
 	/* called right before rendering, ima->renders contains render
 	 * result pointers for everything but the current render */
@@ -2931,13 +2931,18 @@ void BKE_image_backup_render(Scene *scene, Image *ima)
 	int slot = ima->render_slot, last = ima->last_render_slot;
 
 	if (slot != last) {
-		if (ima->renders[slot]) {
-			RE_FreeRenderResult(ima->renders[slot]);
-			ima->renders[slot] = NULL;
-		}
-
 		ima->renders[last] = NULL;
 		RE_SwapResult(re, &ima->renders[last]);
+
+		if (ima->renders[slot]) {
+			if (free_current_slot) {
+				RE_FreeRenderResult(ima->renders[slot]);
+				ima->renders[slot] = NULL;
+			}
+			else {
+				RE_SwapResult(re, &ima->renders[slot]);
+			}
+		}
 	}
 
 	ima->last_render_slot = slot;