// Copyright (c) 2006-2008 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_CANVAS_H_
#define SKIA_EXT_PLATFORM_CANVAS_H_

// The platform-specific device will include the necessary platform headers
// to get the surface type.
#include "skia/ext/platform_device.h"
#include "third_party/skia/include/core/SkCanvas.h"

namespace skia {

// This class is a specialization of the regular SkCanvas that is designed to
// work with a PlatformDevice to manage platform-specific drawing. It allows
// using both Skia operations and platform-specific operations.
class PlatformCanvas : public SkCanvas {
 public:
  // Set is_opaque if you are going to erase the bitmap and not use
  // transparency: this will enable some optimizations.
  // If you use the version with no arguments, you MUST call initialize()
  PlatformCanvas();
  PlatformCanvas(int width, int height, bool is_opaque);
  virtual ~PlatformCanvas();

#if defined(WIN32)
  // Windows ------------------------------------------------------------------

  // The shared_section parameter is passed to gfx::PlatformDevice::create.
  // See it for details.
  PlatformCanvas(int width, int height, bool is_opaque, HANDLE shared_section);

  // For two-part init, call if you use the no-argument constructor above. Note
  // that we want this to optionally match the Linux initialize if you only
  // pass 3 arguments, hence the evil default argument.
  bool initialize(int width, int height, bool is_opaque,
                  HANDLE shared_section = NULL);

#elif defined(__APPLE__)
  // Mac -----------------------------------------------------------------------

  PlatformCanvas(int width, int height, bool is_opaque,
                 CGContextRef context);
  PlatformCanvas(int width, int height, bool is_opaque, uint8_t* context);

  // For two-part init, call if you use the no-argument constructor above
  bool initialize(int width, int height, bool is_opaque, uint8_t* data = NULL);

#elif defined(__linux__) || defined(__FreeBSD__)
  // Linux ---------------------------------------------------------------------

  // Construct a canvas from the given memory region. The memory is not cleared
  // first. @data must be, at least, @height * StrideForWidth(@width) bytes.
  PlatformCanvas(int width, int height, bool is_opaque, uint8_t* data);

  // For two-part init, call if you use the no-argument constructor above
  bool initialize(int width, int height, bool is_opaque, uint8_t* data = NULL);

#endif
  // Shared --------------------------------------------------------------------

  // These calls should surround calls to platform drawing routines, the
  // surface returned here can be used with the native platform routines
  //
  // Call endPlatformPaint when you are done and want to use Skia operations
  // after calling the platform-specific beginPlatformPaint; this will
  // synchronize the bitmap to OS if necessary.
  PlatformDevice::PlatformSurface beginPlatformPaint();
  void endPlatformPaint();

  // Returns the platform device pointer of the topmost rect with a non-empty
  // clip. In practice, this is usually either the top layer or nothing, since
  // we usually set the clip to new layers when we make them.
  //
  // If there is no layer that is not all clipped out, this will return a
  // dummy device so callers do not have to check. If you are concerned about
  // performance, check the clip before doing any painting.
  //
  // This is different than SkCanvas' getDevice, because that returns the
  // bottommost device.
  //
  // Danger: the resulting device should not be saved. It will be invalidated
  // by the next call to save() or restore().
  PlatformDevice& getTopPlatformDevice() const;

  // Return the stride (length of a line in bytes) for the given width. Because
  // we use 32-bits per pixel, this will be roughly 4*width. However, for
  // alignment reasons we may wish to increase that.
  static size_t StrideForWidth(unsigned width);

  // Allow callers to see the non-virtual function even though we have an
  // override of a virtual one.
  // FIXME(brettw) is this necessary?
  using SkCanvas::clipRect;

 protected:
  // Creates a device store for use by the canvas. We override this so that
  // the device is always our own so we know that we can use platform
  // operations on it.
  virtual SkDevice* createDevice(SkBitmap::Config,
                                 int width,
                                 int height,
                                 bool is_opaque,
                                 bool isForLayer);

 private:
  // Unimplemented. This is to try to prevent people from calling this function
  // on SkCanvas. SkCanvas' version is not virtual, so we can't prevent this
  // 100%, but hopefully this will make people notice and not use the function.
  // Calling SkCanvas' version will create a new device which is not compatible
  // with us and we will crash if somebody tries to draw into it with
  // CoreGraphics.
  virtual SkDevice* setBitmapDevice(const SkBitmap& bitmap);

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

}  // namespace skia

#endif  // SKIA_EXT_PLATFORM_CANVAS_H_