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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef SKIA_EXT_BITMAP_PLATFORM_DEVICE_WIN_H_
      6 #define SKIA_EXT_BITMAP_PLATFORM_DEVICE_WIN_H_
      7 
      8 #include "base/basictypes.h"
      9 #include "base/compiler_specific.h"
     10 #include "skia/ext/platform_device.h"
     11 #include "skia/ext/refptr.h"
     12 
     13 namespace skia {
     14 
     15 // A device is basically a wrapper around SkBitmap that provides a surface for
     16 // SkCanvas to draw into. Our device provides a surface Windows can also write
     17 // to. BitmapPlatformDevice creates a bitmap using CreateDIBSection() in a
     18 // format that Skia supports and can then use this to draw ClearType into, etc.
     19 // This pixel data is provided to the bitmap that the device contains so that it
     20 // can be shared.
     21 //
     22 // The device owns the pixel data, when the device goes away, the pixel data
     23 // also becomes invalid. THIS IS DIFFERENT THAN NORMAL SKIA which uses
     24 // reference counting for the pixel data. In normal Skia, you could assign
     25 // another bitmap to this device's bitmap and everything will work properly.
     26 // For us, that other bitmap will become invalid as soon as the device becomes
     27 // invalid, which may lead to subtle bugs. Therefore, DO NOT ASSIGN THE
     28 // DEVICE'S PIXEL DATA TO ANOTHER BITMAP, make sure you copy instead.
     29 class SK_API BitmapPlatformDevice : public SkDevice, public PlatformDevice {
     30  public:
     31   // Factory function. is_opaque should be set if the caller knows the bitmap
     32   // will be completely opaque and allows some optimizations.
     33   //
     34   // The |shared_section| parameter is optional (pass NULL for default
     35   // behavior). If |shared_section| is non-null, then it must be a handle to a
     36   // file-mapping object returned by CreateFileMapping.  See CreateDIBSection
     37   // for details. If |shared_section| is null, the bitmap backing store is not
     38   // initialized.
     39   static BitmapPlatformDevice* Create(int width, int height,
     40                                       bool is_opaque, HANDLE shared_section);
     41 
     42   // Create a BitmapPlatformDevice with no shared section. The bitmap is not
     43   // initialized to 0.
     44   static BitmapPlatformDevice* Create(int width, int height, bool is_opaque);
     45 
     46   // Creates a BitmapPlatformDevice instance respecting the parameters as above.
     47   // If |is_opaque| is false, then the bitmap is initialzed to 0.
     48   static BitmapPlatformDevice* CreateAndClear(int width, int height,
     49                                               bool is_opaque);
     50 
     51   virtual ~BitmapPlatformDevice();
     52 
     53   // PlatformDevice overrides
     54   // Retrieves the bitmap DC, which is the memory DC for our bitmap data. The
     55   // bitmap DC is lazy created.
     56   virtual PlatformSurface BeginPlatformPaint() OVERRIDE;
     57   virtual void EndPlatformPaint() OVERRIDE;
     58 
     59   virtual void DrawToNativeContext(HDC dc, int x, int y,
     60                                    const RECT* src_rect) OVERRIDE;
     61 
     62   // Loads the given transform and clipping region into the HDC. This is
     63   // overridden from SkDevice.
     64   virtual void setMatrixClip(const SkMatrix& transform, const SkRegion& region,
     65                              const SkClipStack&) OVERRIDE;
     66 
     67  protected:
     68   // Flushes the Windows device context so that the pixel data can be accessed
     69   // directly by Skia. Overridden from SkDevice, this is called when Skia
     70   // starts accessing pixel data.
     71   virtual const SkBitmap& onAccessBitmap(SkBitmap* bitmap) OVERRIDE;
     72 
     73   virtual SkDevice* onCreateCompatibleDevice(SkBitmap::Config, int width,
     74                                              int height, bool isOpaque,
     75                                              Usage usage) OVERRIDE;
     76 
     77  private:
     78   // Reference counted data that can be shared between multiple devices. This
     79   // allows copy constructors and operator= for devices to work properly. The
     80   // bitmaps used by the base device class are already refcounted and copyable.
     81   class BitmapPlatformDeviceData;
     82 
     83   // Private constructor.
     84   BitmapPlatformDevice(const skia::RefPtr<BitmapPlatformDeviceData>& data,
     85                        const SkBitmap& bitmap);
     86 
     87   // Data associated with this device, guaranteed non-null.
     88   skia::RefPtr<BitmapPlatformDeviceData> data_;
     89 
     90 #ifdef SK_DEBUG
     91   int begin_paint_count_;
     92 #endif
     93 
     94   DISALLOW_COPY_AND_ASSIGN(BitmapPlatformDevice);
     95 };
     96 
     97 }  // namespace skia
     98 
     99 #endif  // SKIA_EXT_BITMAP_PLATFORM_DEVICE_WIN_H_
    100