1 /*
2  *  Copyright 2018 The WebRTC project authors. All Rights Reserved.
3  *
4  *  Use of this source code is governed by a BSD-style license
5  *  that can be found in the LICENSE file in the root of the source
6  *  tree. An additional intellectual property rights grant can be found
7  *  in the file PATENTS.  All contributing project authors may
8  *  be found in the AUTHORS file in the root of the source tree.
9  */
10 
11 #ifndef MODULES_DESKTOP_CAPTURE_LINUX_SCREEN_CAPTURER_X11_H_
12 #define MODULES_DESKTOP_CAPTURE_LINUX_SCREEN_CAPTURER_X11_H_
13 
14 #include <X11/X.h>
15 #include <X11/Xlib.h>
16 #include <X11/extensions/Xdamage.h>
17 #include <X11/extensions/Xfixes.h>
18 #include <X11/extensions/Xrandr.h>
19 
20 #include <memory>
21 
22 #include "modules/desktop_capture/desktop_capture_options.h"
23 #include "modules/desktop_capture/desktop_capturer.h"
24 #include "modules/desktop_capture/desktop_frame.h"
25 #include "modules/desktop_capture/desktop_region.h"
26 #include "modules/desktop_capture/linux/shared_x_display.h"
27 #include "modules/desktop_capture/linux/x_atom_cache.h"
28 #include "modules/desktop_capture/linux/x_server_pixel_buffer.h"
29 #include "modules/desktop_capture/screen_capture_frame_queue.h"
30 #include "modules/desktop_capture/screen_capturer_helper.h"
31 #include "modules/desktop_capture/shared_desktop_frame.h"
32 #include "rtc_base/constructor_magic.h"
33 
34 namespace webrtc {
35 
36 // A class to perform video frame capturing for Linux on X11.
37 //
38 // If XDamage is used, this class sets DesktopFrame::updated_region() according
39 // to the areas reported by XDamage. Otherwise this class does not detect
40 // DesktopFrame::updated_region(), the field is always set to the entire frame
41 // rectangle. ScreenCapturerDifferWrapper should be used if that functionality
42 // is necessary.
43 class ScreenCapturerX11 : public DesktopCapturer,
44                           public SharedXDisplay::XEventHandler {
45  public:
46   ScreenCapturerX11();
47   ~ScreenCapturerX11() override;
48 
49   static std::unique_ptr<DesktopCapturer> CreateRawScreenCapturer(
50       const DesktopCaptureOptions& options);
51 
52   // TODO(ajwong): Do we really want this to be synchronous?
53   bool Init(const DesktopCaptureOptions& options);
54 
55   // DesktopCapturer interface.
56   void Start(Callback* delegate) override;
57   void CaptureFrame() override;
58   bool GetSourceList(SourceList* sources) override;
59   bool SelectSource(SourceId id) override;
60 
61  private:
display()62   Display* display() { return options_.x_display()->display(); }
63 
64   // SharedXDisplay::XEventHandler interface.
65   bool HandleXEvent(const XEvent& event) override;
66 
67   void InitXDamage();
68   void InitXrandr();
69   void UpdateMonitors();
70 
71   // Capture screen pixels to the current buffer in the queue. In the DAMAGE
72   // case, the ScreenCapturerHelper already holds the list of invalid rectangles
73   // from HandleXEvent(). In the non-DAMAGE case, this captures the
74   // whole screen, then calculates some invalid rectangles that include any
75   // differences between this and the previous capture.
76   std::unique_ptr<DesktopFrame> CaptureScreen();
77 
78   // Called when the screen configuration is changed.
79   void ScreenConfigurationChanged();
80 
81   // Synchronize the current buffer with |last_buffer_|, by copying pixels from
82   // the area of |last_invalid_rects|.
83   // Note this only works on the assumption that kNumBuffers == 2, as
84   // |last_invalid_rects| holds the differences from the previous buffer and
85   // the one prior to that (which will then be the current buffer).
86   void SynchronizeFrame();
87 
88   void DeinitXlib();
89 
90   DesktopCaptureOptions options_;
91 
92   Callback* callback_ = nullptr;
93 
94   // X11 graphics context.
95   GC gc_ = nullptr;
96   Window root_window_ = BadValue;
97 
98   // XRandR 1.5 monitors.
99   bool use_randr_ = false;
100   int randr_event_base_ = 0;
101   XRRMonitorInfo* monitors_ = nullptr;
102   int num_monitors_ = 0;
103   DesktopRect selected_monitor_rect_;
104   // selected_monitor_name_ will be changed to kFullDesktopScreenId
105   // by a call to SelectSource() at the end of Init() because
106   // selected_monitor_rect_ should be updated as well.
107   // Setting it to kFullDesktopScreenId here might be misleading.
108   Atom selected_monitor_name_ = 0;
109   typedef XRRMonitorInfo* (*get_monitors_func)(Display*, Window, Bool, int*);
110   typedef void (*free_monitors_func)(XRRMonitorInfo*);
111   get_monitors_func get_monitors_ = nullptr;
112   free_monitors_func free_monitors_ = nullptr;
113 
114   // XFixes.
115   bool has_xfixes_ = false;
116   int xfixes_event_base_ = -1;
117   int xfixes_error_base_ = -1;
118 
119   // XDamage information.
120   bool use_damage_ = false;
121   Damage damage_handle_ = 0;
122   int damage_event_base_ = -1;
123   int damage_error_base_ = -1;
124   XserverRegion damage_region_ = 0;
125 
126   // Access to the X Server's pixel buffer.
127   XServerPixelBuffer x_server_pixel_buffer_;
128 
129   // A thread-safe list of invalid rectangles, and the size of the most
130   // recently captured screen.
131   ScreenCapturerHelper helper_;
132 
133   // Queue of the frames buffers.
134   ScreenCaptureFrameQueue<SharedDesktopFrame> queue_;
135 
136   // Invalid region from the previous capture. This is used to synchronize the
137   // current with the last buffer used.
138   DesktopRegion last_invalid_region_;
139 
140   std::unique_ptr<XAtomCache> atom_cache_;
141 
142   RTC_DISALLOW_COPY_AND_ASSIGN(ScreenCapturerX11);
143 };
144 
145 }  // namespace webrtc
146 
147 #endif  // MODULES_DESKTOP_CAPTURE_LINUX_SCREEN_CAPTURER_X11_H_
148