1 /*
2  *  Copyright (c) 2016 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_SCREEN_DRAWER_H_
12 #define MODULES_DESKTOP_CAPTURE_SCREEN_DRAWER_H_
13 
14 #include "modules/desktop_capture/desktop_capture_types.h"
15 #include "modules/desktop_capture/desktop_geometry.h"
16 #include "modules/desktop_capture/rgba_color.h"
17 
18 namespace webrtc {
19 
20 // A cross-process lock to ensure only one ScreenDrawer can be used at a certain
21 // time.
22 class ScreenDrawerLock {
23  public:
24   virtual ~ScreenDrawerLock();
25 
26   static std::unique_ptr<ScreenDrawerLock> Create();
27 
28  protected:
29   ScreenDrawerLock();
30 };
31 
32 // A set of basic platform dependent functions to draw various shapes on the
33 // screen.
34 class ScreenDrawer {
35  public:
36   // Creates a ScreenDrawer for the current platform, returns nullptr if no
37   // ScreenDrawer implementation available.
38   // If the implementation cannot guarantee two ScreenDrawer instances won't
39   // impact each other, this function may block current thread until another
40   // ScreenDrawer has been destroyed.
41   static std::unique_ptr<ScreenDrawer> Create();
42 
43   ScreenDrawer();
44   virtual ~ScreenDrawer();
45 
46   // Returns the region inside which DrawRectangle() function are expected to
47   // work, in capturer coordinates (assuming ScreenCapturer::SelectScreen has
48   // not been called). This region may exclude regions of the screen reserved by
49   // the OS for things like menu bars or app launchers. The DesktopRect is in
50   // system coordinate, i.e. the primary monitor always starts from (0, 0).
51   virtual DesktopRect DrawableRegion() = 0;
52 
53   // Draws a rectangle to cover |rect| with |color|. Note, rect.bottom() and
54   // rect.right() two lines are not included. The part of |rect| which is out of
55   // DrawableRegion() will be ignored.
56   virtual void DrawRectangle(DesktopRect rect, RgbaColor color) = 0;
57 
58   // Clears all content on the screen by filling the area with black.
59   virtual void Clear() = 0;
60 
61   // Blocks current thread until OS finishes previous DrawRectangle() actions.
62   // ScreenCapturer should be able to capture the changes after this function
63   // finish.
64   virtual void WaitForPendingDraws() = 0;
65 
66   // Returns true if incomplete shapes previous actions required may be drawn on
67   // the screen after a WaitForPendingDraws() call. i.e. Though the complete
68   // shapes will eventually be drawn on the screen, due to some OS limitations,
69   // these shapes may be partially appeared sometimes.
70   virtual bool MayDrawIncompleteShapes() = 0;
71 
72   // Returns the id of the drawer window. This function returns kNullWindowId if
73   // the implementation does not draw on a window of the system.
74   virtual WindowId window_id() const = 0;
75 };
76 
77 }  // namespace webrtc
78 
79 #endif  // MODULES_DESKTOP_CAPTURE_SCREEN_DRAWER_H_
80