From 6de3db148294ce06fdb3888eb7d0090c3b46c738 Mon Sep 17 00:00:00 2001
From: VincentWei <vincent@minigui.org>
Date: Tue, 18 Sep 2018 13:36:33 +0800
Subject: [PATCH] TUNE

---
 src/newgdi/bitmap.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/newgdi/bitmap.c b/src/newgdi/bitmap.c
index 1db517c7..25a2858d 100644
--- a/src/newgdi/bitmap.c
+++ b/src/newgdi/bitmap.c
@@ -1032,7 +1032,9 @@ BOOL GUIAPI FillBoxWithBitmapPart (HDC hdc, int x, int y, int w, int h,
         if (xo != 0 || yo != 0) {
             part.bmBits += part.bmPitch * yo + 
                     xo * GAL_BytesPerPixel (pdc->surface);
-            part.bmAlphaMask += yo * part.bmAlphaPitch + xo;
+            if (part.bmType & BMP_TYPE_ALPHA_MASK) {
+                part.bmAlphaMask += yo * part.bmAlphaPitch + xo;
+            }
         }
         _dc_fillbox_bmp_clip (pdc, &rect, &part);
     }