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   BitmapPlatformDevice(CGContextRef context,
  64                        const SkBitmap& bitmap);
  65
  66   virtual SkBaseDevice* onCreateDevice(const SkImageInfo& info,
  67                                        Usage usage) OVERRIDE;
  68
  69  private:
  70   void ReleaseBitmapContext();
  71
  72   // Sets the transform and clip operations. This will not update the CGContext,
  73   // but will mark the config as dirty. The next call of LoadConfig will
  74   // pick up these changes.
  75   void SetMatrixClip(const SkMatrix& transform, const SkRegion& region);
  76
  77   // Loads the current transform and clip into the context. Can be called even
  78   // when |bitmap_context_| is NULL (will be a NOP).
  79   void LoadConfig();
  80
  81   // Lazily-created graphics context used to draw into the bitmap.
  82   CGContextRef bitmap_context_;
  83
  84   // True when there is a transform or clip that has not been set to the
  85   // context.  The context is retrieved for every text operation, and the
  86   // transform and clip do not change as much. We can save time by not loading
  87   // the clip and transform for every one.
  88   bool config_dirty_;
  89
  90   // Translation assigned to the context: we need to keep track of this
  91   // separately so it can be updated even if the context isn't created yet.
  92   SkMatrix transform_;
  93
  94   // The current clipping
  95   SkRegion clip_region_;
  96   DISALLOW_COPY_AND_ASSIGN(BitmapPlatformDevice);
  97 };
  98
  99 }  // namespace skia
 100
 101 #endif  // SKIA_EXT_BITMAP_PLATFORM_DEVICE_MAC_H_