MacViews: Clip contents for non-rectangular windows.

ui/views/cocoa/bridged_native_widget.mm

Index: ui/views/cocoa/bridged_native_widget.mm
diff --git a/ui/views/cocoa/bridged_native_widget.mm b/ui/views/cocoa/bridged_native_widget.mm
index 6f5dec0f96864ede56c8a7cf940de5ebf964aa92..c61991ee8f82148df257121fc8e402e961354069 100644
--- a/ui/views/cocoa/bridged_native_widget.mm
+++ b/ui/views/cocoa/bridged_native_widget.mm
@@ -4,6 +4,8 @@
 
 #import "ui/views/cocoa/bridged_native_widget.h"
 
+#import <Quartz/Quartz.h>

[tapted, 2016/02/24 05:05:03]

this can be grouped with the other <> includes, since they are all "operating
system headers" rather than STL/standard-library headers

[karandeepb, 2016/02/25 03:31:06]

Done. Aren't stdint.h and stddef.h standard library headers?

[tapted, 2016/02/25 08:07:21]

I guess it's a bit arbitrary, but I generally see it applied as "group stuff
with a '.' in the header, and group stuff like <vector><string>,etc."

+
 #import <objc/runtime.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -22,6 +24,7 @@
 #include "ui/gfx/geometry/dip_util.h"
 #import "ui/gfx/mac/coordinate_conversion.h"
 #import "ui/gfx/mac/nswindow_frame_controls.h"
+#import "ui/gfx/path_mac.h"
 #include "ui/gfx/screen.h"
 #import "ui/views/cocoa/bridged_content_view.h"
 #import "ui/views/cocoa/cocoa_mouse_capture.h"
@@ -683,13 +686,10 @@ void BridgedNativeWidget::OnSizeChanged() {
       MaybeWaitForFrame(new_size);
   }
 
-  // 10.9 is unable to generate a window shadow from the composited CALayer, so
-  // use Quartz.
-  // We don't update the window mask during a live resize, instead it is done
-  // after the resize is completed in viewDidEndLiveResize: in
-  // BridgedContentView.
-  if (base::mac::IsOSMavericksOrEarlier() && ![window_ inLiveResize])
-    [bridged_view_ updateWindowMask];
+  [bridged_view_ onSizeChanged];

[tapted, 2016/02/24 05:05:03]

Yeah, I'd call the method updateWindowMask and invoke it from UpdateMaskPath()
instead of here

[karandeepb, 2016/02/25 03:31:06]

Done.

+
+  // Update mask path to match the bridged view's new window mask.
+  UpdateMaskPath();
 }
 
 void BridgedNativeWidget::OnVisibilityChanged() {
@@ -1244,4 +1244,29 @@ void BridgedNativeWidget::SetDraggable(bool draggable) {
   [window_ setMovableByWindowBackground:YES];
 }
 
+void BridgedNativeWidget::UpdateMaskPath() {
+  // We only set the mask layer for windows with non-rectangular masks.
+  if (![bridged_view_ windowMask])

[tapted, 2016/02/24 05:05:03]

perhaps after this, do

{
  // Removing a mask after adding one isn't currently supported.
  DCHECK(![[compositor_superview_ layer] mask]);
  return;
}

[karandeepb, 2016/02/25 03:31:06]

Done.

+    return;
+
+  CAShapeLayer* mask_layer = base::mac::ObjCCastStrict<CAShapeLayer>(
+      [[compositor_superview_ layer] mask]);
+  if (mask_layer) {
+    [mask_layer
+        setPath:gfx::CreateCGPathFromNSBezierPath([bridged_view_ windowMask])];
+    return;
+  }
+
+  // If mask layer does not exist yet, create one and set it as the background

[karandeepb, 2016/02/24 04:27:18]

Another place to initialize the mask layer could be through
NativeWidgetMac::OnWidgetInitDone since by then the non client frame view would
have been attached to the widget.

[tapted, 2016/02/24 05:05:03]

I think this here is OK. E.g. it's feasible that we may want to support removing
the mask later on if the client frame view changes its mind about things after
it gets shown.

[karandeepb, 2016/02/25 03:31:06]

Done.

+  // layer's mask. Clipping will be done based on the alpha channel of the mask
+  // layer.
+  base::scoped_nsobject<CAShapeLayer> mask([[CAShapeLayer alloc] init]);
+  [mask setPath:gfx::CreateCGPathFromNSBezierPath([bridged_view_ windowMask])];
+  [mask setBackgroundColor:[[NSColor clearColor] CGColor]];

[tapted, 2016/02/24 05:05:03]

There's a CGColor constant for this (also I think this is default? So might not
need to be specified)

[karandeepb, 2016/02/25 03:31:06]

Done.

+
+  CALayer* background_layer = [compositor_superview_ layer];
+  [background_layer setMask:mask];
+  [background_layer setMasksToBounds:YES];
+}
+
 }  // namespace views