- [fe->image drawInRect:NSMakeRect(0, 0, bl->w, bl->h)
- fromRect:NSMakeRect(x, fe->h - y - bl->h, bl->w, bl->h)
- operation:NSCompositeCopy fraction:1.0];
+
+ /*
+ * Find the intersection of the source and destination rectangles,
+ * so as to avoid trying to copy from outside the source image,
+ * which GNUstep dislikes.
+ *
+ * Lower-case x,y coordinates are bottom left box corners;
+ * upper-case X,Y are the top right.
+ */
+ sx = x; sy = fe->h - y - bl->h;
+ sX = sx + bl->w; sY = sy + bl->h;
+ dx = dy = 0;
+ dX = bl->w; dY = bl->h;
+ if (sx < 0) {
+ dx += -sx;
+ sx = 0;
+ }
+ if (sy < 0) {
+ dy += -sy;
+ sy = 0;
+ }
+ if (sX > fe->w) {
+ dX -= (sX - fe->w);
+ sX = fe->w;
+ }
+ if (sY > fe->h) {
+ dY -= (sY - fe->h);
+ sY = fe->h;
+ }
+
+ [fe->image drawInRect:NSMakeRect(dx, dy, dX-dx, dY-dy)
+ fromRect:NSMakeRect(sx, sy, sX-sx, sY-sy)
+ operation:NSCompositeCopy fraction:1.0];