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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.
#include "skia/ext/platform_device_win.h"
namespace skia {
// A device is basically a wrapper around SkBitmap that provides a surface for
// SkCanvas to draw into. Our device provides a surface Windows can also write
// to. BitmapPlatformDeviceWin creates a bitmap using CreateDIBSection() in a
// format that Skia supports and can then use this to draw ClearType into, etc.
// This pixel data is provided to the bitmap that the device contains so that it
// can be shared.
// The device owns the pixel data, when the device goes away, the pixel data
// also becomes invalid. THIS IS DIFFERENT THAN NORMAL SKIA which uses
// reference counting for the pixel data. In normal Skia, you could assign
// another bitmap to this device's bitmap and everything will work properly.
// For us, that other bitmap will become invalid as soon as the device becomes
// invalid, which may lead to subtle bugs. Therefore, DO NOT ASSIGN THE
// DEVICE'S PIXEL DATA TO ANOTHER BITMAP, make sure you copy instead.
class BitmapPlatformDeviceWin : public PlatformDeviceWin {
// Factory function. The screen DC is used to create the bitmap, and will not
// be stored beyond this function. is_opaque should be set if the caller
// knows the bitmap will be completely opaque and allows some optimizations.
// The shared_section parameter is optional (pass NULL for default behavior).
// If shared_section is non-null, then it must be a handle to a file-mapping
// object returned by CreateFileMapping. See CreateDIBSection for details.
static BitmapPlatformDeviceWin* create(HDC screen_dc,
int width,
int height,
bool is_opaque,
HANDLE shared_section);
// Copy constructor. When copied, devices duplicate their internal data, so
// stay linked. This is because their implementation is very heavyweight
// (lots of memory and some GDI objects). If a device has been copied, both
// clip rects and other state will stay in sync.
// This means it will NOT work to duplicate a device and assign it to a
// canvas, because the two canvases will each set their own clip rects, and
// the resulting GDI clip rect will be random.
// Copy constucting and "=" is designed for saving the device or passing it
// around to another routine willing to deal with the bitmap data directly.
BitmapPlatformDeviceWin(const BitmapPlatformDeviceWin& other);
virtual ~BitmapPlatformDeviceWin();
// See warning for copy constructor above.
BitmapPlatformDeviceWin& operator=(const BitmapPlatformDeviceWin& other);
// Retrieves the bitmap DC, which is the memory DC for our bitmap data. The
// bitmap DC is lazy created.
virtual HDC getBitmapDC();
virtual void setMatrixClip(const SkMatrix& transform, const SkRegion& region);
virtual void drawToHDC(HDC dc, int x, int y, const RECT* src_rect);
virtual void prepareForGDI(int x, int y, int width, int height);
virtual void postProcessGDI(int x, int y, int width, int height);
virtual void makeOpaque(int x, int y, int width, int height);
virtual void fixupAlphaBeforeCompositing();
virtual bool IsVectorial() { return false; }
// Returns the color value at the specified location. This does not
// consider any transforms that may be set on the device.
SkColor getColorAt(int x, int y);
// Flushes the Windows device context so that the pixel data can be accessed
// directly by Skia. Overridden from SkDevice, this is called when Skia
// starts accessing pixel data.
virtual void onAccessBitmap(SkBitmap* bitmap);
// Function pointer used by the processPixels method for setting the alpha
// value of a particular pixel.
typedef void (*adjustAlpha)(uint32_t* pixel);
// Reference counted data that can be shared between multiple devices. This
// allows copy constructors and operator= for devices to work properly. The
// bitmaps used by the base device class are already refcounted and copyable.
class BitmapPlatformDeviceWinData;
// Private constructor. The data should already be ref'ed for us.
BitmapPlatformDeviceWin(BitmapPlatformDeviceWinData* data,
const SkBitmap& bitmap);
// Loops through each of the pixels in the specified range, invoking
// adjustor for the alpha value of each pixel. If |width| or |height| are -1,
// the available width/height is used.
template<adjustAlpha adjustor>
void processPixels(int x,
int y,
int width,
int height);
// Data associated with this device, guaranteed non-null. We hold a reference
// to this object.
BitmapPlatformDeviceWinData* data_;
} // namespace skia