Bug fix #34943

With extreme narrow scaled editors, the slider/mask code in View3d could deliver
zero sized or invalid window matrices.

Needs confirmation from Sergey if it works :)

1 files changed, 17 insertions, 12 deletions

diff --git a/source/blender/editors/interface/view2d.c b/source/blender/editors/interface/view2d.c
index a66169d54ae..a7061ca0fed 100644
--- a/source/blender/editors/interface/view2d.c
+++ b/source/blender/editors/interface/view2d.c
@@ -997,19 +997,24 @@ static void view2d_map_cur_using_mask(View2D *v2d, rctf *curmasked)
 	*curmasked = v2d->cur;
 	
 	if (view2d_scroll_mapped(v2d->scroll)) {
-		float dx = BLI_rctf_size_x(&v2d->cur) / ((float)(BLI_rcti_size_x(&v2d->mask) + 1));
-		float dy = BLI_rctf_size_y(&v2d->cur) / ((float)(BLI_rcti_size_y(&v2d->mask) + 1));
-		
-		if (v2d->mask.xmin != 0)
-			curmasked->xmin -= dx * (float)v2d->mask.xmin;
-		if (v2d->mask.xmax + 1 != v2d->winx)
-			curmasked->xmax += dx * (float)(v2d->winx - v2d->mask.xmax - 1);
-		
-		if (v2d->mask.ymin != 0)
-			curmasked->ymin -= dy * (float)v2d->mask.ymin;
-		if (v2d->mask.ymax + 1 != v2d->winy)
-			curmasked->ymax += dy * (float)(v2d->winy - v2d->mask.ymax - 1);
+		float sizex = BLI_rcti_size_x(&v2d->mask);
+		float sizey = BLI_rcti_size_y(&v2d->mask);
 		
+		/* prevent tiny or narrow regions to get invalid coordinates - mask can get negative even... */
+		if (sizex > 0.0f && sizey > 0.0f) {
+			float dx = BLI_rctf_size_x(&v2d->cur) / (sizex + 1);
+			float dy = BLI_rctf_size_y(&v2d->cur) / (sizey + 1);
+			
+			if (v2d->mask.xmin != 0)
+				curmasked->xmin -= dx * (float)v2d->mask.xmin;
+			if (v2d->mask.xmax + 1 != v2d->winx)
+				curmasked->xmax += dx * (float)(v2d->winx - v2d->mask.xmax - 1);
+			
+			if (v2d->mask.ymin != 0)
+				curmasked->ymin -= dy * (float)v2d->mask.ymin;
+			if (v2d->mask.ymax + 1 != v2d->winy)
+				curmasked->ymax += dy * (float)(v2d->winy - v2d->mask.ymax - 1);
+		}
 	}
 }