1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
|
// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef SKIA_EXT_BITMAP_PLATFORM_DEVICE_LINUX_H_
#define SKIA_EXT_BITMAP_PLATFORM_DEVICE_LINUX_H_
#pragma once
#include "base/ref_counted.h"
#include "skia/ext/platform_device_linux.h"
typedef struct _cairo_surface cairo_surface_t;
// -----------------------------------------------------------------------------
// Image byte ordering on Linux:
//
// Pixels are packed into 32-bit words these days. Even for 24-bit images,
// often 8-bits will be left unused for alignment reasons. Thus, when you see
// ARGB as the byte order you have to wonder if that's in memory order or
// little-endian order. Here I'll write A.R.G.B to specifiy the memory order.
//
// GdkPixbuf's provide a nice backing store and defaults to R.G.B.A order.
// They'll do the needed byte swapping to match the X server when drawn.
//
// Skia can be controled in skia/include/corecg/SkUserConfig.h (see bits about
// SK_R32_SHIFT). For Linux we define it to be ARGB in registers. For little
// endian machines that means B.G.R.A in memory.
//
// The image loaders are controlled in
// webkit/port/platform/image-decoders/ImageDecoder.h (see setRGBA). These are
// also configured for ARGB in registers.
//
// Cairo's only 32-bit mode is ARGB in registers.
//
// X servers commonly have a 32-bit visual with xRGB in registers (since they
// typically don't do alpha blending of drawables at the user level. Composite
// extensions aside.)
//
// We don't use GdkPixbuf because its byte order differs from the rest. Most
// importantly, it differs from Cairo which, being a system library, is
// something that we can't easily change.
// -----------------------------------------------------------------------------
namespace skia {
// -----------------------------------------------------------------------------
// This is the Linux bitmap backing for Skia. We create a Cairo image surface
// to store the backing buffer. This buffer is BGRA in memory (on little-endian
// machines).
//
// For now we are also using Cairo to paint to the Drawables so we provide an
// accessor for getting the surface.
//
// This is all quite ok for test_shell. In the future we will want to use
// shared memory between the renderer and the main process at least. In this
// case we'll probably create the buffer from a precreated region of memory.
// -----------------------------------------------------------------------------
class BitmapPlatformDevice : public PlatformDevice {
// A reference counted cairo surface
class BitmapPlatformDeviceData;
public:
static BitmapPlatformDevice* Create(int width, int height, bool is_opaque);
// This doesn't take ownership of |data|
static BitmapPlatformDevice* Create(int width, int height,
bool is_opaque, uint8_t* data);
// Create a BitmapPlatformDeviceLinux from an already constructed bitmap;
// you should probably be using Create(). This may become private later if
// we ever have to share state between some native drawing UI and Skia, like
// the Windows and Mac versions of this class do.
//
// This object takes ownership of @data.
BitmapPlatformDevice(const SkBitmap& other, BitmapPlatformDeviceData* data);
virtual ~BitmapPlatformDevice();
BitmapPlatformDevice& operator=(const BitmapPlatformDevice& other);
// A stub copy constructor. Needs to be properly implemented.
BitmapPlatformDevice(const BitmapPlatformDevice& other);
// Bitmaps aren't vector graphics.
virtual bool IsVectorial() { return false; }
// If someone wants to paint on a Cairo surface version of our
// buffer, then give them the surface we're already using.
virtual cairo_t* beginPlatformPaint();
// Loads the given transform and clipping region into the HDC. This is
// overridden from SkDevice.
virtual void setMatrixClip(const SkMatrix& transform, const SkRegion& region);
private:
static BitmapPlatformDevice* Create(int width, int height, bool is_opaque,
cairo_surface_t* surface);
scoped_refptr<BitmapPlatformDeviceData> data_;
};
} // namespace skia
#endif // SKIA_EXT_BITMAP_PLATFORM_DEVICE_LINUX_H_
|
