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// 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__)
// 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_
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