Ticket #8109: restorebg.diff

scummvm/scumm/gfx.cpp

@@ -1776 +1776 @@
 void Scumm::restoreBG(int left, int top, int right, int bottom)
 {
         VirtScreen *vs;
-        int topline, height, width, widthmod;
-        byte *backbuff, *bgbak, *mask;
+        int topline, height, width;
+        byte *backbuff, *bgbak;
 
         if (left == right || top == bottom)
                 return;
@@ -1812 +1812 @@
 
         backbuff = vs->screenPtr + height;
         bgbak = getResourceAddress(rtBuffer, vs->number + 5) + height;
-        mask = getResourceAddress(rtBuffer, 9) + top * gdi._numStrips + (left >> 3) + _screenStartStrip;
-        if (vs->number == 0) {
-                // FIXME: hardcoded value
-                mask += vs->topline * 216;
-        }
 
         height = bottom - top;
         width = right - left;
-        widthmod = (width >> 2) + 2;
 
         if (vs->alloctwobuffers && _currentRoom != 0 /*&& _vars[VAR_V5_DRAWFLAGS]&2 */ ) {
                 blit(backbuff, bgbak, width, height);
                 if (vs->number == 0 && charset._hasMask && height) {
+                        byte *mask;
+                        int mask_width = (width >> 3);
+
+                        if (width & 0x07)
+                                mask_width++;
+
+                        mask = getResourceAddress(rtBuffer, 9) + top * gdi._numStrips + (left >> 3) + _screenStartStrip;
+                        if (vs->number == 0)
+                                mask += vs->topline * gdi._numStrips;
+
                         do {
-                                memset(mask, 0, widthmod);
+                                memset(mask, 0, mask_width);
                                 mask += gdi._numStrips;
                         } while (--height);
                 }