ui/gfx/canvas_paint_mac.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_PAINT_MAC_H_
#define UI_GFX_CANVAS_PAINT_MAC_H_

#include "skia/ext/platform_canvas.h"
#include "ui/gfx/canvas.h"

#import <Cocoa/Cocoa.h>

namespace gfx {

// A class designed to translate skia painting into a region to the current
// graphics context.  On construction, it will set up a context for painting
// into, and on destruction, it will commit it to the current context.
// Note: The created context is always inialized to (0, 0, 0, 0).
class GFX_EXPORT CanvasSkiaPaint : public Canvas {
 public:
  // This constructor assumes the result is opaque.
  explicit CanvasSkiaPaint(NSRect dirtyRect);
  CanvasSkiaPaint(NSRect dirtyRect, bool opaque);
  virtual ~CanvasSkiaPaint();

  // If true, the data painted into the CanvasSkiaPaint is blended onto the
  // current context, else it is copied.
  void set_composite_alpha(bool composite_alpha) {
    composite_alpha_ = composite_alpha;
  }

  // Returns true if the invalid region is empty. The caller should call this
  // function to determine if anything needs painting.
  bool is_empty() const {
    return NSIsEmptyRect(rectangle_);
  }

  const NSRect& rectangle() const {
    return rectangle_;
  }

 private:
  void Init(bool opaque);

  CGContext* context_;
  NSRect rectangle_;
  // See description above setter.
  bool composite_alpha_;

  // Disallow copy and assign.
  CanvasSkiaPaint(const CanvasSkiaPaint&);
  CanvasSkiaPaint& operator=(const CanvasSkiaPaint&);
};

}  // namespace gfx


#endif  // UI_GFX_CANVAS_PAINT_MAC_H_