skia/ext/bitmap_platform_device_mac.h

   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_MAC_H_
   6 #define SKIA_EXT_BITMAP_PLATFORM_DEVICE_MAC_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 CoreGraphics can also
  17 // write to. BitmapPlatformDevice creates a bitmap using
  18 // CGCreateBitmapContext() in a format that Skia supports and can then use this
  19 // to draw text into, etc. This pixel data is provided to the bitmap that the
  20 // device contains so that it 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 SkBitmapDevice, public PlatformDevice {
  30  public:
  31   // Creates a BitmapPlatformDevice instance. |is_opaque| should be set if the
  32   // caller knows the bitmap will be completely opaque and allows some
  33   // optimizations.
  34   // |context| may be NULL. If |context| is NULL, then the bitmap backing store
  35   // is not initialized.
  36   static BitmapPlatformDevice* Create(CGContextRef context,
  37                                       int width, int height,
  38                                       bool is_opaque);
  39
  40   // Creates a BitmapPlatformDevice instance.  If |is_opaque| is false,
  41   // then the bitmap is initialzed to 0.
  42   static BitmapPlatformDevice* CreateAndClear(int width, int height,
  43                                               bool is_opaque);
  44
  45   // Creates a context for |data| and calls Create.
  46   // If |data| is NULL, then the bitmap backing store is not initialized.
  47   static BitmapPlatformDevice* CreateWithData(uint8_t* data,
  48                                               int width, int height,
  49                                               bool is_opaque);
  50
  51   virtual ~BitmapPlatformDevice();
  52
  53   // PlatformDevice overrides
  54   virtual CGContextRef GetBitmapContext() OVERRIDE;
  55   virtual void DrawToNativeContext(CGContextRef context, int x, int y,
  56                                    const CGRect* src_rect) OVERRIDE;
  57
  58   // SkBaseDevice overrides
  59   virtual void setMatrixClip(const SkMatrix& transform, const SkRegion& region,
  60                              const SkClipStack&) OVERRIDE;
  61
  62  protected:
  63   // Reference counted data that can be shared between multiple devices. This
  64   // allows copy constructors and operator= for devices to work properly. The
  65   // bitmaps used by the base device class are already refcounted and copyable.
  66   class BitmapPlatformDeviceData;
  67
  68   BitmapPlatformDevice(const skia::RefPtr<BitmapPlatformDeviceData>& data,
  69                        const SkBitmap& bitmap);
  70
  71   virtual SkBaseDevice* onCreateCompatibleDevice(SkBitmap::Config, int width,
  72                                                  int height, bool isOpaque,
  73                                                  Usage usage) OVERRIDE;
  74
  75   // Data associated with this device, guaranteed non-null.
  76   skia::RefPtr<BitmapPlatformDeviceData> data_;
  77
  78   DISALLOW_COPY_AND_ASSIGN(BitmapPlatformDevice);
  79 };
  80
  81 }  // namespace skia
  82
  83 #endif  // SKIA_EXT_BITMAP_PLATFORM_DEVICE_MAC_H_