Alpha-over images on a black background when in RGB display mode

This is actually a bit arbitrary decision and mainly it preserves
compatibility with how images were displaying in previous releases.

In fact, we actually would need to think about configurable backdrop
color and blending mode to be used for display in RGB mode.

3 files changed, 22 insertions, 6 deletions

diff --git a/source/blender/editors/space_image/image_draw.c b/source/blender/editors/space_image/image_draw.c
index 0534b9f4ffd..7b4814d1ab2 100644
--- a/source/blender/editors/space_image/image_draw.c
+++ b/source/blender/editors/space_image/image_draw.c
@@ -514,11 +514,15 @@ static void draw_image_buffer(const bContext *C, SpaceImage *sima, ARegion *ar,
 		unsigned char *display_buffer;
 		void *cache_handle;
 
+		glEnable(GL_BLEND);
+		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
 		if (sima->flag & SI_USE_ALPHA) {
 			fdrawcheckerboard(x, y, x + ibuf->x * zoomx, y + ibuf->y * zoomy);
-
-			glEnable(GL_BLEND);
-			glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+		}
+		else {
+			glColor4f(0.0f, 0.0f, 0.0f, 1.0f);
+			glRecti(x, y, x + ibuf->x * zoomx, y + ibuf->y * zoomy);
 		}
 
 		display_buffer = IMB_display_buffer_acquire_ctx(C, ibuf, &cache_handle);
@@ -532,8 +536,7 @@ static void draw_image_buffer(const bContext *C, SpaceImage *sima, ARegion *ar,
 
 		IMB_display_buffer_release(cache_handle);
 
-		if (sima->flag & SI_USE_ALPHA)
-			glDisable(GL_BLEND);
+		glDisable(GL_BLEND);
 	}
 
 	/* reset zoom */
diff --git a/source/blender/editors/space_node/drawnode.c b/source/blender/editors/space_node/drawnode.c
index ef69358c24f..981a1775b51 100644
--- a/source/blender/editors/space_node/drawnode.c
+++ b/source/blender/editors/space_node/drawnode.c
@@ -3271,10 +3271,18 @@ void draw_nodespace_back_pix(const bContext *C, ARegion *ar, SpaceNode *snode)
 				}
 				else {
 					glPixelZoom(snode->zoom, snode->zoom);
-					
+
+					glEnable(GL_BLEND);
+					glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+					glColor4f(0.0f, 0.0f, 0.0f, 1.0f);
+					glRecti(x, y, x + ibuf->x * snode->zoom, y + ibuf->y * snode->zoom);
+
 					glaDrawPixelsSafe(x, y, ibuf->x, ibuf->y, ibuf->x, GL_RGBA, GL_UNSIGNED_BYTE, display_buffer);
 					
 					glPixelZoom(1.0f, 1.0f);
+
+					glDisable(GL_BLEND);
 				}
 			}
 
diff --git a/source/blender/editors/space_sequencer/sequencer_draw.c b/source/blender/editors/space_sequencer/sequencer_draw.c
index 9e55d95637d..9477b3197fa 100644
--- a/source/blender/editors/space_sequencer/sequencer_draw.c
+++ b/source/blender/editors/space_sequencer/sequencer_draw.c
@@ -1058,6 +1058,10 @@ void draw_image_seq(const bContext *C, Scene *scene, ARegion *ar, SpaceSeq *sseq
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 
 	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, ibuf->x, ibuf->y, 0, GL_RGBA, GL_UNSIGNED_BYTE, display_buffer);
+
+	glEnable(GL_BLEND);
+	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
 	glBegin(GL_QUADS);
 
 	if (draw_overlay) {
@@ -1089,6 +1093,7 @@ void draw_image_seq(const bContext *C, Scene *scene, ARegion *ar, SpaceSeq *sseq
 	glEnd();
 	glBindTexture(GL_TEXTURE_2D, last_texid);
 	glDisable(GL_TEXTURE_2D);
+	glDisable(GL_BLEND);
 	glDeleteTextures(1, &texid);
 
 	if (sseq->mainb == SEQ_DRAW_IMG_IMBUF) {