Bugreport in irc:

The Preview panel in UV window, for compositing, sets a 'crop' flag in the
scene when used. Somehow this flag can hang when you switch screens or
close windows. Or even worse, it crashed on renders.

This commit ensures that the compositor survives and gives error prints.
The real issue, hanging flags on closing windows, has to be solved still.

1 files changed, 34 insertions, 30 deletions

diff --git a/source/blender/blenkernel/intern/node_composite.c b/source/blender/blenkernel/intern/node_composite.c
index 7f957d4d943..49166a1a131 100644
--- a/source/blender/blenkernel/intern/node_composite.c
+++ b/source/blender/blenkernel/intern/node_composite.c
@@ -1000,36 +1000,40 @@ static void node_composit_exec_rlayers(void *data, bNode *node, bNodeStack **in,
 					stackbuf= alloc_compbuf(rr->rectx, rr->recty, CB_RGBA, 0);
 					stackbuf->rect= rl->rectf;
 				}
-				
-				stackbuf->xof= rr->xof;
-				stackbuf->yof= rr->yof;
-				
-				/* put on stack */	
-				out[RRES_OUT_IMAGE]->data= stackbuf;
-				
-				if(out[RRES_OUT_ALPHA]->hasoutput)
-					out[RRES_OUT_ALPHA]->data= valbuf_from_rgbabuf(stackbuf, CHAN_A);
-				if(out[RRES_OUT_Z]->hasoutput)
-					out[RRES_OUT_Z]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_Z);
-				if(out[RRES_OUT_VEC]->hasoutput)
-					out[RRES_OUT_VEC]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_VECTOR);
-				if(out[RRES_OUT_NOR]->hasoutput)
-					out[RRES_OUT_NOR]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_NORMAL);
-	/*			
-				if(out[RRES_OUT_COL]->hasoutput)
-					out[RRES_OUT_COL]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_RGBA);
-				if(out[RRES_OUT_DIFF]->hasoutput)
-					out[RRES_OUT_DIFF]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_DIFFUSE);
-				if(out[RRES_OUT_SPEC]->hasoutput)
-					out[RRES_OUT_SPEC]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_SPEC);
-				if(out[RRES_OUT_SHAD]->hasoutput)
-					out[RRES_OUT_SHAD]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_SHADOW);
-				if(out[RRES_OUT_AO]->hasoutput)
-					out[RRES_OUT_AO]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_AO);
-				if(out[RRES_OUT_RAY]->hasoutput)
-					out[RRES_OUT_RAY]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_RAY);
-	*/			
-				generate_preview(node, stackbuf);
+				if(stackbuf==NULL) {
+					printf("Error; Preview Panel in UV Window returns zero sized image\n");
+				}
+				else {
+					stackbuf->xof= rr->xof;
+					stackbuf->yof= rr->yof;
+					
+					/* put on stack */	
+					out[RRES_OUT_IMAGE]->data= stackbuf;
+					
+					if(out[RRES_OUT_ALPHA]->hasoutput)
+						out[RRES_OUT_ALPHA]->data= valbuf_from_rgbabuf(stackbuf, CHAN_A);
+					if(out[RRES_OUT_Z]->hasoutput)
+						out[RRES_OUT_Z]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_Z);
+					if(out[RRES_OUT_VEC]->hasoutput)
+						out[RRES_OUT_VEC]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_VECTOR);
+					if(out[RRES_OUT_NOR]->hasoutput)
+						out[RRES_OUT_NOR]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_NORMAL);
+		/*			
+					if(out[RRES_OUT_COL]->hasoutput)
+						out[RRES_OUT_COL]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_RGBA);
+					if(out[RRES_OUT_DIFF]->hasoutput)
+						out[RRES_OUT_DIFF]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_DIFFUSE);
+					if(out[RRES_OUT_SPEC]->hasoutput)
+						out[RRES_OUT_SPEC]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_SPEC);
+					if(out[RRES_OUT_SHAD]->hasoutput)
+						out[RRES_OUT_SHAD]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_SHADOW);
+					if(out[RRES_OUT_AO]->hasoutput)
+						out[RRES_OUT_AO]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_AO);
+					if(out[RRES_OUT_RAY]->hasoutput)
+						out[RRES_OUT_RAY]->data= compbuf_from_pass(rd, rl, rr->rectx, rr->recty, SCE_PASS_RAY);
+		*/			
+					generate_preview(node, stackbuf);
+				}
 			}
 		}
 	}