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, bool do_clear = false);
  39
  40   // Creates a context for |data| and calls Create.
  41   // If |data| is NULL, then the bitmap backing store is not initialized.
  42   static BitmapPlatformDevice* CreateWithData(uint8_t* data,
  43                                               int width, int height,
  44                                               bool is_opaque);
  45
  46   ~BitmapPlatformDevice() override;
  47
  48   // PlatformDevice overrides
  49   CGContextRef GetBitmapContext() override;
  50
  51   // SkBaseDevice overrides
  52   void setMatrixClip(const SkMatrix& transform,
  53                      const SkRegion& region,
  54                      const SkClipStack&) override;
  55
  56  protected:
  57   BitmapPlatformDevice(CGContextRef context,
  58                        const SkBitmap& bitmap);
  59
  60   SkBaseDevice* onCreateCompatibleDevice(const CreateInfo& info) override;
  61
  62  private:
  63   void ReleaseBitmapContext();
  64
  65   // Sets the transform and clip operations. This will not update the CGContext,
  66   // but will mark the config as dirty. The next call of LoadConfig will
  67   // pick up these changes.
  68   void SetMatrixClip(const SkMatrix& transform, const SkRegion& region);
  69
  70   // Loads the current transform and clip into the context. Can be called even
  71   // when |bitmap_context_| is NULL (will be a NOP).
  72   void LoadConfig();
  73
  74   // Lazily-created graphics context used to draw into the bitmap.
  75   CGContextRef bitmap_context_;
  76
  77   // True when there is a transform or clip that has not been set to the
  78   // context.  The context is retrieved for every text operation, and the
  79   // transform and clip do not change as much. We can save time by not loading
  80   // the clip and transform for every one.
  81   bool config_dirty_;
  82
  83   // Translation assigned to the context: we need to keep track of this
  84   // separately so it can be updated even if the context isn't created yet.
  85   SkMatrix transform_;
  86
  87   // The current clipping
  88   SkRegion clip_region_;
  89   DISALLOW_COPY_AND_ASSIGN(BitmapPlatformDevice);
  90 };
  91
  92 }  // namespace skia
  93
  94 #endif  // SKIA_EXT_BITMAP_PLATFORM_DEVICE_MAC_H_