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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 REMOTING_HOST_CAPTURER_H_ | |
6 #define REMOTING_HOST_CAPTURER_H_ | |
7 | |
8 #include "base/basictypes.h" | |
9 #include "base/callback.h" | |
10 #include "media/base/video_frame.h" | |
11 #include "third_party/skia/include/core/SkRegion.h" | |
12 | |
13 namespace remoting { | |
14 | |
15 namespace protocol { | |
16 class CursorShapeInfo; | |
17 } | |
18 | |
19 class CaptureData; | |
20 | |
21 // A class to perform the task of capturing the image of a window. | |
22 // The capture action is asynchronous to allow maximum throughput. | |
23 // | |
24 // The full capture process is as follows: | |
25 // | |
26 // (1) Start | |
27 // This is when pre-capture steps are executed, such as flagging the | |
28 // display to prevent it from sleeping during a session. | |
29 // | |
30 // (2) InvalidateRects | |
31 // This is an optional step where regions of the screen are marked as | |
32 // invalid. Some platforms (Windows, for now) won't use this and will | |
33 // instead calculate the diff-regions later (in step (2). Other | |
34 // platforms (Mac) will use this to mark all the changed regions of the | |
35 // screen. Some limited rect-merging (e.g., to eliminate exact | |
36 // duplicates) may be done here. | |
37 // | |
38 // (3) CaptureInvalidRects | |
39 // This is where the bits for the invalid rects are packaged up and sent | |
40 // to the encoder. | |
41 // A screen capture is performed if needed. For example, Windows requires | |
42 // a capture to calculate the diff from the previous screen, whereas the | |
43 // Mac version does not. | |
44 // | |
45 // (4) Stop | |
46 // This is when post-capture steps are executed, such as releasing the | |
47 // assertion that prevents the display from sleeping. | |
48 // | |
49 // Implementation has to ensure the following guarantees: | |
50 // 1. Double buffering | |
51 // Since data can be read while another capture action is happening. | |
52 class Capturer { | |
53 public: | |
54 // CaptureCompletedCallback is called when the capturer has completed. | |
55 typedef base::Callback<void(scoped_refptr<CaptureData>)> | |
56 CaptureCompletedCallback; | |
57 | |
58 // CursorShapeChangedCallback is called when the cursor shape has changed. | |
59 typedef base::Callback<void(scoped_ptr<protocol::CursorShapeInfo>)> | |
60 CursorShapeChangedCallback; | |
61 | |
62 virtual ~Capturer() {} | |
63 | |
64 // Create platform-specific capturer. | |
65 static Capturer* Create(); | |
66 | |
67 #if defined(OS_LINUX) | |
68 // Set whether the Capturer should try to use X DAMAGE support if it is | |
69 // available. This needs to be called before the Capturer is created. | |
70 // This is used by the Virtual Me2Me host, since the XDamage extension is | |
71 // known to work reliably in this case. | |
72 | |
73 // TODO(lambroslambrou): This currently sets a global flag, referenced during | |
74 // Capturer::Create(). This is a temporary solution, until the | |
75 // DesktopEnvironment class is refactored to allow applications to control | |
76 // the creation of various stubs (including the Capturer) - see | |
77 // http://crbug.com/104544 | |
78 static void EnableXDamage(bool enable); | |
79 #endif // defined(OS_LINUX) | |
80 | |
81 // Called at the beginning of a capturing session. | |
82 virtual void Start( | |
83 const CursorShapeChangedCallback& callback) = 0; | |
84 | |
85 // Called at the end of a capturing session. | |
86 virtual void Stop() = 0; | |
87 | |
88 // Called when the screen configuration is changed. | |
89 virtual void ScreenConfigurationChanged() = 0; | |
90 | |
91 // Return the pixel format of the screen. | |
92 virtual media::VideoFrame::Format pixel_format() const = 0; | |
93 | |
94 // Clear out the invalid region. | |
95 virtual void ClearInvalidRegion() = 0; | |
96 | |
97 // Invalidate the specified region. | |
98 virtual void InvalidateRegion(const SkRegion& invalid_region) = 0; | |
99 | |
100 // Invalidate the entire screen, of a given size. | |
101 virtual void InvalidateScreen(const SkISize& size) = 0; | |
102 | |
103 // Invalidate the entire screen, using the size of the most recently | |
104 // captured screen. | |
105 virtual void InvalidateFullScreen() = 0; | |
106 | |
107 // Capture the screen data associated with each of the accumulated | |
108 // dirty region. | |
109 // When the capture is complete, |callback| is called even if the dirty region | |
110 // is empty. | |
111 // | |
112 // It is OK to call this method while another thread is reading | |
113 // data of the previous capture. | |
114 // There can be at most one concurrent read going on when this | |
115 // method is called. | |
116 virtual void CaptureInvalidRegion( | |
117 const CaptureCompletedCallback& callback) = 0; | |
118 | |
119 // Get the size of the most recently captured screen. | |
120 virtual const SkISize& size_most_recent() const = 0; | |
121 }; | |
122 | |
123 } // namespace remoting | |
124 | |
125 #endif // REMOTING_HOST_CAPTURER_H_ | |
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