src/third_party/webrtc/modules/desktop_capture/win/screen_capturer_win_magnifier.h

   1 /*
   2  *  Copyright (c) 2014 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 WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_SCREEN_CAPTURER_WIN_MAGNIFIER_H_
  12 #define WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_SCREEN_CAPTURER_WIN_MAGNIFIER_H_
  13
  14 #include <windows.h>
  15 #include <magnification.h>
  16 #include <wincodec.h>
  17
  18 #include "webrtc/base/constructormagic.h"
  19 #include "webrtc/modules/desktop_capture/screen_capture_frame_queue.h"
  20 #include "webrtc/modules/desktop_capture/screen_capturer.h"
  21 #include "webrtc/modules/desktop_capture/screen_capturer_helper.h"
  22 #include "webrtc/modules/desktop_capture/win/scoped_thread_desktop.h"
  23 #include "webrtc/system_wrappers/interface/atomic32.h"
  24 #include "webrtc/system_wrappers/interface/scoped_ptr.h"
  25
  26 namespace webrtc {
  27
  28 class DesktopFrame;
  29 class DesktopRect;
  30 class Differ;
  31
  32 // Captures the screen using the Magnification API to support window exclusion.
  33 // Each capturer must run on a dedicated thread because it uses thread local
  34 // storage for redirecting the library callback. Also the thread must have a UI
  35 // message loop to handle the window messages for the magnifier window.
  36 class ScreenCapturerWinMagnifier : public ScreenCapturer {
  37  public:
  38   // |fallback_capturer| will be used to capture the screen if a non-primary
  39   // screen is being captured, or the OS does not support Magnification API, or
  40   // the magnifier capturer fails (e.g. in Windows8 Metro mode).
  41   explicit ScreenCapturerWinMagnifier(
  42       scoped_ptr<ScreenCapturer> fallback_capturer);
  43   virtual ~ScreenCapturerWinMagnifier();
  44
  45   // Overridden from ScreenCapturer:
  46   virtual void Start(Callback* callback) OVERRIDE;
  47   virtual void Capture(const DesktopRegion& region) OVERRIDE;
  48   virtual bool GetScreenList(ScreenList* screens) OVERRIDE;
  49   virtual bool SelectScreen(ScreenId id) OVERRIDE;
  50   virtual void SetExcludedWindow(WindowId window) OVERRIDE;
  51
  52  private:
  53   typedef BOOL(WINAPI* MagImageScalingCallback)(HWND hwnd,
  54                                                 void* srcdata,
  55                                                 MAGIMAGEHEADER srcheader,
  56                                                 void* destdata,
  57                                                 MAGIMAGEHEADER destheader,
  58                                                 RECT unclipped,
  59                                                 RECT clipped,
  60                                                 HRGN dirty);
  61   typedef BOOL(WINAPI* MagInitializeFunc)(void);
  62   typedef BOOL(WINAPI* MagUninitializeFunc)(void);
  63   typedef BOOL(WINAPI* MagSetWindowSourceFunc)(HWND hwnd, RECT rect);
  64   typedef BOOL(WINAPI* MagSetWindowFilterListFunc)(HWND hwnd,
  65                                                    DWORD dwFilterMode,
  66                                                    int count,
  67                                                    HWND* pHWND);
  68   typedef BOOL(WINAPI* MagSetImageScalingCallbackFunc)(
  69       HWND hwnd,
  70       MagImageScalingCallback callback);
  71
  72   static BOOL WINAPI OnMagImageScalingCallback(HWND hwnd,
  73                                                void* srcdata,
  74                                                MAGIMAGEHEADER srcheader,
  75                                                void* destdata,
  76                                                MAGIMAGEHEADER destheader,
  77                                                RECT unclipped,
  78                                                RECT clipped,
  79                                                HRGN dirty);
  80
  81   // Captures the screen within |rect| in the desktop coordinates. Returns true
  82   // if succeeded.
  83   // It can only capture the primary screen for now. The magnification library
  84   // crashes under some screen configurations (e.g. secondary screen on top of
  85   // primary screen) if it tries to capture a non-primary screen. The caller
  86   // must make sure not calling it on non-primary screens.
  87   bool CaptureImage(const DesktopRect& rect);
  88
  89   // Helper method for setting up the magnifier control. Returns true if
  90   // succeeded.
  91   bool InitializeMagnifier();
  92
  93   // Called by OnMagImageScalingCallback to output captured data.
  94   void OnCaptured(void* data, const MAGIMAGEHEADER& header);
  95
  96   // Makes sure the current frame exists and matches |size|.
  97   void CreateCurrentFrameIfNecessary(const DesktopSize& size);
  98
  99   // Returns true if we are capturing the primary screen only.
 100   bool IsCapturingPrimaryScreenOnly() const;
 101
 102   // Start the fallback capturer and select the screen.
 103   void StartFallbackCapturer();
 104
 105   static Atomic32 tls_index_;
 106
 107   scoped_ptr<ScreenCapturer> fallback_capturer_;
 108   bool fallback_capturer_started_;
 109   Callback* callback_;
 110   ScreenId current_screen_id_;
 111   std::wstring current_device_key_;
 112   HWND excluded_window_;
 113
 114   // A thread-safe list of invalid rectangles, and the size of the most
 115   // recently captured screen.
 116   ScreenCapturerHelper helper_;
 117
 118   // Queue of the frames buffers.
 119   ScreenCaptureFrameQueue queue_;
 120
 121   // Class to calculate the difference between two screen bitmaps.
 122   scoped_ptr<Differ> differ_;
 123
 124   // Used to suppress duplicate logging of SetThreadExecutionState errors.
 125   bool set_thread_execution_state_failed_;
 126
 127   ScopedThreadDesktop desktop_;
 128
 129   // Used for getting the screen dpi.
 130   HDC desktop_dc_;
 131
 132   HMODULE mag_lib_handle_;
 133   MagInitializeFunc mag_initialize_func_;
 134   MagUninitializeFunc mag_uninitialize_func_;
 135   MagSetWindowSourceFunc set_window_source_func_;
 136   MagSetWindowFilterListFunc set_window_filter_list_func_;
 137   MagSetImageScalingCallbackFunc set_image_scaling_callback_func_;
 138
 139   // The hidden window hosting the magnifier control.
 140   HWND host_window_;
 141   // The magnifier control that captures the screen.
 142   HWND magnifier_window_;
 143
 144   // True if the magnifier control has been successfully initialized.
 145   bool magnifier_initialized_;
 146
 147   // True if the last OnMagImageScalingCallback was called and handled
 148   // successfully. Reset at the beginning of each CaptureImage call.
 149   bool magnifier_capture_succeeded_;
 150
 151   DISALLOW_COPY_AND_ASSIGN(ScreenCapturerWinMagnifier);
 152 };
 153
 154 }  // namespace webrtc
 155
 156 #endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_SCREEN_CAPTURER_WIN_MAGNIFIER_H_