MacViews: draw combobox arrow backgrounds

ui/gfx/canvas.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_CANVAS_H_
 #define UI_GFX_CANVAS_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 56 matching lines @@
     // Specifies if words can be split by new lines.
     // This only works with MULTI_LINE.
     CHARACTER_BREAK = 1 << 8,
 
     // Instructs DrawStringRect() to not use subpixel rendering.  This is useful
     // when rendering text onto a fully- or partially-transparent background
     // that will later be blended with another image.
     NO_SUBPIXEL_RENDERING = 1 << 9,
   };
 
+  // This class represents a scoped state of a Canvas. When a ScopedState is

[tapted, 2016/03/21 07:09:04]

ui/gfx/scoped_canvas.h?

[Elly Fong-Jones, 2016/03/21 18:53:56]

Ach! The idiom I'm used to is having these Scoped* classes as inner classes of
the thing they're scoping, instead of separate classes. Oops :) Deleted this.

+  // constructed, it saves the state of the supplied Canvas; when a ScopedState
+  // is destroyed, it restores the state it saved earlier.
+  class ScopedState {
+   public:
+    ScopedState(Canvas* canvas) : canvas_(canvas) {
+      canvas_->Save();
+    }
+    ~ScopedState() {
+      canvas_->Restore();
+    }
+   private:
+    Canvas* canvas_;
+  };
+
   // Creates an empty canvas with image_scale of 1x.
   Canvas();
 
   // Creates canvas with provided DIP |size| and |image_scale|.
   // If this canvas is not opaque, it's explicitly cleared to transparent before
   // being returned.
   Canvas(const Size& size, float image_scale, bool is_opaque);
 
   // Constructs a canvas with the size and the image_scale of the provided
   // |image_rep|, and draws the |image_rep| into it.
@@ skipping 363 matching lines @@
   float image_scale_;
 
   skia::RefPtr<SkCanvas> canvas_;
 
   DISALLOW_COPY_AND_ASSIGN(Canvas);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_CANVAS_H_