Convert frame region handling to cairo regions

It's useful to get frame shapes and manipulate them within Mutter, for
example so that the compositor can use them to clip drawing.
For this, we'll need the regions as cairo regions not X regions, so
convert frame shaping code to work in terms of cairo_region_t.

https://bugzilla.gnome.org/show_bug.cgi?id=635268

Author: owtaylor

src/ui/frames.c

@@ -780,6 +780,39 @@ meta_frames_unflicker_bg (MetaFrames *frames,
   set_background_none (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()), frame->xwindow);
 }
 
+#ifdef HAVE_SHAPE
+static void
+apply_cairo_region_to_window (Display        *display,
+                              Window          xwindow,
+                              cairo_region_t *region,
+                              int             op)
+{
+  int n_rects, i;
+  XRectangle *rects;
+
+  n_rects = cairo_region_num_rectangles (region);
+  rects = g_new (XRectangle, n_rects);
+
+  for (i = 0; i < n_rects; i++)
+    {
+      cairo_rectangle_int_t rect;
+
+      cairo_region_get_rectangle (region, i, &rect);
+
+      rects[i].x = rect.x;
+      rects[i].y = rect.y;
+      rects[i].width = rect.width;
+      rects[i].height = rect.height;
+    }
+
+  XShapeCombineRectangles (display, xwindow,
+                           ShapeBounding, 0, 0, rects, n_rects,
+                           ShapeSet, YXBanded);
+
+  g_free (rects);
+}
+#endif
+
 void
 meta_frames_apply_shapes (MetaFrames *frames,
                           Window      xwindow,
@@ -794,6 +827,9 @@ meta_frames_apply_shapes (MetaFrames *frames,
   XRectangle xrect;
   Region corners_xregion;
   Region window_xregion;
+  cairo_rectangle_int_t rect;
+  cairo_region_t *corners_region;
+  cairo_region_t *window_region;
   gint scale;
 
   frame = meta_frames_lookup_window (frames, xwindow);
@@ -827,7 +863,7 @@ meta_frames_apply_shapes (MetaFrames *frames,
       return; /* nothing to do */
     }
 
-  corners_xregion = XCreateRegion ();
+  corners_region = cairo_region_create ();
   scale = gdk_window_get_scale_factor (frame->window);
 
   if (fgeom.top_left_corner_rounded_radius != 0)
@@ -839,12 +875,12 @@ meta_frames_apply_shapes (MetaFrames *frames,
       for (i=0; i<corner; i++)
         {
           const int width = floor(0.5 + radius - sqrt(radius*radius - (radius-(i+0.5))*(radius-(i+0.5))));
-          xrect.x = 0;
-          xrect.y = i;
-          xrect.width = width;
-          xrect.height = 1;
+          rect.x = 0;
+          rect.y = i;
+          rect.width = width;
+          rect.height = 1;
 
-          XUnionRectWithRegion (&xrect, corners_xregion, corners_xregion);
+          cairo_region_union_rectangle (corners_region, &rect);
         }
     }
 
@@ -857,12 +893,12 @@ meta_frames_apply_shapes (MetaFrames *frames,
       for (i=0; i<corner; i++)
         {
           const int width = floor(0.5 + radius - sqrt(radius*radius - (radius-(i+0.5))*(radius-(i+0.5))));
-          xrect.x = new_window_width - width;
-          xrect.y = i;
-          xrect.width = width;
-          xrect.height = 1;
+          rect.x = new_window_width - width;
+          rect.y = i;
+          rect.width = width;
+          rect.height = 1;
 
-          XUnionRectWithRegion (&xrect, corners_xregion, corners_xregion);
+          cairo_region_union_rectangle (corners_region, &rect);
         }
     }
 
@@ -875,12 +911,12 @@ meta_frames_apply_shapes (MetaFrames *frames,
       for (i=0; i<corner; i++)
         {
           const int width = floor(0.5 + radius - sqrt(radius*radius - (radius-(i+0.5))*(radius-(i+0.5))));
-          xrect.x = 0;
-          xrect.y = new_window_height - i - 1;
-          xrect.width = width;
-          xrect.height = 1;
+          rect.x = 0;
+          rect.y = new_window_height - i - 1;
+          rect.width = width;
+          rect.height = 1;
 
-          XUnionRectWithRegion (&xrect, corners_xregion, corners_xregion);
+          cairo_region_union_rectangle (corners_region, &rect);
         }
     }
 
@@ -893,27 +929,27 @@ meta_frames_apply_shapes (MetaFrames *frames,
       for (i=0; i<corner; i++)
         {
           const int width = floor(0.5 + radius - sqrt(radius*radius - (radius-(i+0.5))*(radius-(i+0.5))));
-          xrect.x = new_window_width - width;
-          xrect.y = new_window_height - i - 1;
-          xrect.width = width;
-          xrect.height = 1;
+          rect.x = new_window_width - width;
+          rect.y = new_window_height - i - 1;
+          rect.width = width;
+          rect.height = 1;
 
-          XUnionRectWithRegion (&xrect, corners_xregion, corners_xregion);
+          cairo_region_union_rectangle (corners_region, &rect);
         }
     }
 
-  window_xregion = XCreateRegion ();
+  window_region = cairo_region_create ();
 
-  xrect.x = 0;
-  xrect.y = 0;
-  xrect.width = new_window_width;
-  xrect.height = new_window_height;
+  rect.x = 0;
+  rect.y = 0;
+  rect.width = new_window_width;
+  rect.height = new_window_height;
 
-  XUnionRectWithRegion (&xrect, window_xregion, window_xregion);
+  cairo_region_union_rectangle (window_region, &rect);
 
-  XSubtractRegion (window_xregion, corners_xregion, window_xregion);
+  cairo_region_subtract (window_region, corners_region);
 
-  XDestroyRegion (corners_xregion);
+  cairo_region_destroy (corners_region);
 
   if (window_has_shape)
     {
@@ -926,7 +962,7 @@ meta_frames_apply_shapes (MetaFrames *frames,
       XSetWindowAttributes attrs;
       Window shape_window;
       Window client_window;
-      Region client_xregion;
+      cairo_region_t *client_region;
       GdkScreen *screen;
       int screen_number;
 
@@ -966,21 +1002,21 @@ meta_frames_apply_shapes (MetaFrames *frames,
       /* Punch the client area out of the normal frame shape,
        * then union it with the shape_window's existing shape
        */
-      client_xregion = XCreateRegion ();
+      client_region = cairo_region_create ();
 
-      xrect.x = fgeom.left_width;
-      xrect.y = fgeom.top_height;
-      xrect.width = new_window_width - fgeom.right_width - xrect.x;
-      xrect.height = new_window_height - fgeom.bottom_height - xrect.y;
+      rect.x = fgeom.left_width;
+      rect.y = fgeom.top_height;
+      rect.width = new_window_width - fgeom.right_width - rect.x;
+      rect.height = new_window_height - fgeom.bottom_height - rect.y;
 
-      XUnionRectWithRegion (&xrect, client_xregion, client_xregion);
+      cairo_region_union_rectangle (client_region, &rect);
 
-      XSubtractRegion (window_xregion, client_xregion, window_xregion);
+      cairo_region_subtract (window_region, client_region);
 
-      XDestroyRegion (client_xregion);
+      cairo_region_destroy (client_region);
 
-      XShapeCombineRegion (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()), shape_window,
-                           ShapeBounding, 0, 0, window_xregion, ShapeUnion);
+      apply_cairo_region_to_window (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()), shape_window,
+                                    window_region, ShapeUnion);
 
       /* Now copy shape_window shape to the real frame */
       XShapeCombineShape (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()), frame->xwindow, ShapeBounding,
@@ -999,13 +1035,13 @@ meta_frames_apply_shapes (MetaFrames *frames,
                   "Frame 0x%lx has shaped corners\n",
                   frame->xwindow);
 
-      XShapeCombineRegion (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()), frame->xwindow,
-                           ShapeBounding, 0, 0, window_xregion, ShapeSet);
+      apply_cairo_region_to_window (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()), frame->xwindow,
+                                    window_region, ShapeSet);
     }
 
   frame->shape_applied = TRUE;
 
-  XDestroyRegion (window_xregion);
+  cairo_region_destroy (window_region);
 #endif /* HAVE_SHAPE */
 }