skia/ext/platform_device_mac.h

// Copyright (c) 2011 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 SKIA_EXT_PLATFORM_DEVICE_MAC_H_
#define SKIA_EXT_PLATFORM_DEVICE_MAC_H_
#pragma once

#include "third_party/skia/include/core/SkDevice.h"

typedef struct CGContext* CGContextRef;
typedef struct CGRect CGRect;

class SkMatrix;
class SkPath;
class SkRegion;

namespace skia {

// Returns the CGContext that backing the SkDevice.  Forwards to the bound
// PlatformDevice.  Returns NULL if no PlatformDevice is bound.
SK_API CGContextRef GetBitmapContext(SkDevice* device);

// A device is basically a wrapper around SkBitmap that provides a surface for
// SkCanvas to draw into. Our device provides a surface CoreGraphics can also
// write to. It also provides functionality to play well with CG drawing
// functions.
// This class is abstract and must be subclassed. It provides the basic
// interface to implement it either with or without a bitmap backend.
class PlatformDevice : public SkDevice {
 public:
  typedef CGContextRef PlatformSurface;

  // The CGContext that corresponds to the bitmap, used for CoreGraphics
  // operations drawing into the bitmap. This is possibly heavyweight, so it
  // should exist only during one pass of rendering.
  virtual CGContextRef GetBitmapContext() = 0;

  // Draws to the given graphics context. If the bitmap context doesn't exist,
  // this will temporarily create it. However, if you have created the bitmap
  // context, it will be more efficient if you don't free it until after this
  // call so it doesn't have to be created twice.  If src_rect is null, then
  // the entirety of the source device will be copied.
  virtual void DrawToNativeContext(CGContextRef context, int x, int y,
                                   const CGRect* src_rect) = 0;

  // Sets the opacity of each pixel in the specified region to be opaque.
  virtual void MakeOpaque(int x, int y, int width, int height) { }

  // Returns if native platform APIs are allowed to render text to this device.
  virtual bool IsNativeFontRenderingAllowed();

  virtual PlatformSurface BeginPlatformPaint();
  virtual void EndPlatformPaint();

  // Initializes the default settings and colors in a device context.
  static void InitializeCGContext(CGContextRef context);

  // Loads a SkPath into the CG context. The path can there after be used for
  // clipping or as a stroke.
  static void LoadPathToCGContext(CGContextRef context, const SkPath& path);

  // Loads a SkRegion into the CG context.
  static void LoadClippingRegionToCGContext(CGContextRef context,
                                            const SkRegion& region,
                                            const SkMatrix& transformation);

 protected:
  // Forwards |bitmap| to SkDevice's constructor.
  PlatformDevice(const SkBitmap& bitmap);

  // Loads the specified Skia transform into the device context
  static void LoadTransformToCGContext(CGContextRef context,
                                       const SkMatrix& matrix);
};

}  // namespace skia

#endif  // SKIA_EXT_PLATFORM_DEVICE_MAC_H_