OLD | NEW |
| (Empty) |
1 // Copyright 2013 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_CAIRO_H_ | |
6 #define SKIA_EXT_BITMAP_PLATFORM_DEVICE_CAIRO_H_ | |
7 | |
8 #include <stdint.h> | |
9 | |
10 #include "base/compiler_specific.h" | |
11 #include "base/macros.h" | |
12 #include "base/memory/ref_counted.h" | |
13 #include "skia/ext/platform_device.h" | |
14 | |
15 typedef struct _cairo_surface cairo_surface_t; | |
16 | |
17 // ----------------------------------------------------------------------------- | |
18 // Image byte ordering on Linux: | |
19 // | |
20 // Pixels are packed into 32-bit words these days. Even for 24-bit images, | |
21 // often 8-bits will be left unused for alignment reasons. Thus, when you see | |
22 // ARGB as the byte order you have to wonder if that's in memory order or | |
23 // little-endian order. Here I'll write A.R.G.B to specifiy the memory order. | |
24 // | |
25 // GdkPixbuf's provide a nice backing store and defaults to R.G.B.A order. | |
26 // They'll do the needed byte swapping to match the X server when drawn. | |
27 // | |
28 // Skia can be controled in skia/include/corecg/SkUserConfig.h (see bits about | |
29 // SK_R32_SHIFT). For Linux we define it to be ARGB in registers. For little | |
30 // endian machines that means B.G.R.A in memory. | |
31 // | |
32 // The image loaders are controlled in | |
33 // webkit/port/platform/image-decoders/ImageDecoder.h (see setRGBA). These are | |
34 // also configured for ARGB in registers. | |
35 // | |
36 // Cairo's only 32-bit mode is ARGB in registers. | |
37 // | |
38 // X servers commonly have a 32-bit visual with xRGB in registers (since they | |
39 // typically don't do alpha blending of drawables at the user level. Composite | |
40 // extensions aside.) | |
41 // | |
42 // We don't use GdkPixbuf because its byte order differs from the rest. Most | |
43 // importantly, it differs from Cairo which, being a system library, is | |
44 // something that we can't easily change. | |
45 // ----------------------------------------------------------------------------- | |
46 | |
47 namespace skia { | |
48 | |
49 // ----------------------------------------------------------------------------- | |
50 // This is the Linux bitmap backing for Skia. We create a Cairo image surface | |
51 // to store the backing buffer. This buffer is BGRA in memory (on little-endian | |
52 // machines). | |
53 // | |
54 // For now we are also using Cairo to paint to the Drawables so we provide an | |
55 // accessor for getting the surface. | |
56 // | |
57 // This is all quite ok for test_shell. In the future we will want to use | |
58 // shared memory between the renderer and the main process at least. In this | |
59 // case we'll probably create the buffer from a precreated region of memory. | |
60 // ----------------------------------------------------------------------------- | |
61 class BitmapPlatformDevice : public SkBitmapDevice, public PlatformDevice { | |
62 public: | |
63 // Create a BitmapPlatformDeviceLinux from an already constructed bitmap; | |
64 // you should probably be using Create(). This may become private later if | |
65 // we ever have to share state between some native drawing UI and Skia, like | |
66 // the Windows and Mac versions of this class do. | |
67 // | |
68 // This object takes ownership of @cairo. | |
69 BitmapPlatformDevice(const SkBitmap& other, cairo_t* cairo); | |
70 ~BitmapPlatformDevice() override; | |
71 | |
72 // Constructs a device with size |width| * |height| with contents initialized | |
73 // to zero. |is_opaque| should be set if the caller knows the bitmap will be | |
74 // completely opaque and allows some optimizations. | |
75 static BitmapPlatformDevice* Create(int width, int height, bool is_opaque); | |
76 | |
77 // This doesn't take ownership of |data|. If |data| is NULL, the contents | |
78 // of the device are initialized to 0. | |
79 static BitmapPlatformDevice* Create(int width, int height, bool is_opaque, | |
80 uint8_t* data); | |
81 | |
82 protected: | |
83 SkBaseDevice* onCreateDevice(const CreateInfo&, const SkPaint*) override; | |
84 | |
85 private: | |
86 // Overridden from PlatformDevice: | |
87 cairo_t* BeginPlatformPaint(const SkMatrix& transform, | |
88 const SkIRect& clip_bounds) override; | |
89 | |
90 static BitmapPlatformDevice* Create(int width, int height, bool is_opaque, | |
91 cairo_surface_t* surface); | |
92 | |
93 // Loads the current transform and clip into the context. | |
94 void LoadConfig(const SkMatrix& transform, const SkIRect& clip_bounds); | |
95 | |
96 // Graphics context used to draw into the surface. | |
97 cairo_t* cairo_; | |
98 | |
99 DISALLOW_COPY_AND_ASSIGN(BitmapPlatformDevice); | |
100 }; | |
101 | |
102 } // namespace skia | |
103 | |
104 #endif // SKIA_EXT_BITMAP_PLATFORM_DEVICE_CAIRO_H_ | |
OLD | NEW |