Fl_Xlib_Graphics_Driver::scale_clip: restrict the computed X11 region to the 16-bit coordinate space.

This member function transforms the current clip region from FLTK units to pixel units
multiplying FLTK units by the current value of the scale factor to get pixel units.
The current clip region has been, by construction, restricted to the 16-bit coordinate space.
But these data can evade this space after multiplication by the scale factor.
Thus, it's necessary to enforce the 16-bit space here which is done with Fl_Xlib_Graphics_Driver::XRectangleRegion.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@12727 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

1 files changed, 7 insertions, 6 deletions

diff --git a/src/drivers/Xlib/Fl_Xlib_Graphics_Driver.cxx b/src/drivers/Xlib/Fl_Xlib_Graphics_Driver.cxx
index dfae0c006..568143811 100644
--- a/src/drivers/Xlib/Fl_Xlib_Graphics_Driver.cxx
+++ b/src/drivers/Xlib/Fl_Xlib_Graphics_Driver.cxx
@@ -249,15 +249,16 @@ Region Fl_Xlib_Graphics_Driver::scale_clip(float f) {
   if (r == 0 || (f == 1 && offset_x_ == 0 && offset_y_ == 0) ) return 0;
   int deltaf = f/2;
   Region r2 = XCreateRegion();
-  XRectangle R;
   for (int i = 0; i < r->numRects; i++) {
     int x = (r->rects[i].x1 + offset_x_)*f;
     int y = (r->rects[i].y1 + offset_y_)*f;
-    R.x = x - deltaf + line_delta_;
-    R.y = y - deltaf + line_delta_;
-    R.width = int((r->rects[i].x2 + offset_x_) * f) - x;
-    R.height = int((r->rects[i].y2 + offset_y_) * f) - y;
-    XUnionRectWithRegion(&R, r2, r2);
+    int w = int((r->rects[i].x2 + offset_x_) * f) - x;
+    int h = int((r->rects[i].y2 + offset_y_) * f) - y;
+    x += line_delta_ - deltaf;
+    y += line_delta_ - deltaf;
+    Region R = XRectangleRegion(x, y, w, h);
+    XUnionRegion(R, r2, r2);
+    ::XDestroyRegion(R);
   }
   rstack[rstackptr] = r2;
   return r;