Implement screen sharing on Windows

1. Configure encoding parameters

To customize the encoding parameters for the screen sharing stream, call the setScreenShareEncoderConfiguration API to configure properties such as resolution, frame rate, bitrate, GOP, and video orientation.

The following table describes the parameters.

/* 
  'config' is a user-defined configuration struct. 
*/

AliEngineScreenShareEncoderConfiguration encoderConfig;

encoderConfig.dimensions = AliEngineVideoDimensions(config.dimensions.width, config.dimensions.height);
encoderConfig.frameRate = (AliEngineFrameRate)config.frameRate;
encoderConfig.bitrate = (int)config.bitrate;
encoderConfig.rotationMode = (AliEngineRotationMode)config.rotationMode;
encoderConfig.keyFrameInterval = (int)config.keyFrameInterval;
encoderConfig.forceStrictKeyFrameInterval = config.forceStrictKeyFrameInterval;
   
mpEngine->SetScreenShareEncoderConfiguration(encoderConfig);

2. Configure the preview

To preview the screen sharing content, call SetLocalViewConfig to configure the display view for the screen sharing stream (AliEngineVideoTrackScreen).

AliEngineVideoCanvas canvas;
canvas.renderMode = AliEngineRenderModeFill;
/* Configure the window handle for display. */
canvas.displayView = (void*)hWnd;
canvas.scaleMode = AliEngineVideoScale_16_9;

mpEngine->SetLocalViewConfig(canvas, AliEngineVideoTrackScreen);

3. View a remote screen share

To view a remote user's screen share, call SetRemoteViewConfig to configure the display view for the screen sharing stream in the OnRemoteTrackAvailableNotify callback.

void ARTCEventListernerImpl::OnRemoteTrackAvailableNotify(const char *uid,
	AliEngineAudioTrack audioTrack,
	AliEngineVideoTrack videoTrack) {

	char logBuffer[MAX_LOG_STRING_SIZE];
	snprintf(logBuffer, USE_LOG_STRING_SIZE, "user %s push video=%d audio=%d", uid, videoTrack, audioTrack);
	SendMessageA(this->mLogHandle, LB_ADDSTRING, WPARAM(), (LPARAM)logBuffer);

	mDlg->HandleTrackChangeEvent(uid, audioTrack, videoTrack);

}

void CARTCExampleDlg::HandleTrackChangeEvent(const char *uid,
	AliEngineAudioTrack audioTrack,
	AliEngineVideoTrack videoTrack) {

	if ((videoTrack & AliEngineVideoTrackScreen) > 0) {

		if ((videoTrack & AliEngineVideoTrackCamera) == 0) {

			AliEngineVideoCanvas canvas;
			canvas.displayView = nullptr;

			mEngine->SetRemoteViewConfig(canvas, uid, AliEngineVideoTrackCamera);
		}


		{
			AliEngineVideoCanvas canvas;
			canvas.displayView = mRemoteView.GetSafeHwnd();

			mEngine->SetRemoteViewConfig(canvas, uid, AliEngineVideoTrackScreen);
		}

		return;
	}

	if ( (videoTrack & AliEngineVideoTrackCamera) > 0) {

		AliEngineVideoCanvas canvas;
		canvas.displayView = mRemoteView.GetSafeHwnd();

		mEngine->SetRemoteViewConfig(canvas, uid, AliEngineVideoTrackCamera );
	}
}

4. Start screen sharing

Call StartScreenShareByScreenRegion to start screen sharing.

/*
* Share a region of the screen.
*/
  RECT rc;
  ::GetWindowRect(::GetDesktopWindow(), &rc);

  AliEngineScreenShareRegion screenRegion;
  screenRegion.originX = (float)rc.left;
  screenRegion.originY = (float)rc.top;
  screenRegion.width = (float)(rc.right - rc.left);
  screenRegion.height = (float)(rc.bottom - rc.top);

  AliEngineScreenShareConfig mScreenConfig;
  mScreenConfig.isShareByRegion = false;
  mScreenConfig.shareRegion = screenRegion;
  /* 
    If you only want to preview the stream without publishing it, set this to FALSE.
    If you want to preview and publish simultaneously, set this to TRUE. This allows you to skip Step 5 (Update configuration) and start publishing directly.
  */        
  mScreenConfig.isPushStream = FALSE ; 
  
  mpEngine->StartScreenShareByScreenRegion(screenRegion, mScreenConfig);

5. (Optional) Update the configuration

To update the screen sharing configuration, call UpdateScreenShareConfig.

/* Set to publish the screen sharing stream. */
mScreenConfig.isPushStream = TRUE ;

/* To share a region: */
mScreenConfig.isShareByRegion = true ;

screenRegion.originX = (float)rc.left;
screenRegion.originY = (float)rc.top;
screenRegion.width = (float)(rc.right - rc.left);
screenRegion.height = (float)(rc.bottom - rc.top);

mScreenConfig.isShareByRegion = true;
mScreenConfig.shareRegion = screenRegion;
      
mpEngine->UpdateScreenShareConfig(mScreenConfig);

6. Stop screen sharing

mpEngine->StopScreenShare();

1. Enumerate all shareable windows or desktops

Call GetScreenShareSourceInfo to get a list of shareable windows and desktops.

/*
  1. Set the enumeration type as needed.
*/
mScreenShareType = AliEngineScreenShareDesktop ; 
mScreenShareType = AliEngineScreenShareWindow ; 

/*
 2. The following code populates a combo box list.
*/
CComboBox *listBox = (CComboBox *)GetDlgItem(IDC_COMBO_SCREEN_SOURCE_LIST);
listBox->ResetContent();

AliEngineScreenSourceList* mCurrentSourceList = mEngine->GetScreenShareSourceInfo(mScreenShareType);

  if (nullptr != mCurrentSourceList)
  {
      for (size_t i = 0; i < mCurrentSourceList->GetCount(); i++) {
      
        AliEngineScreenSourcInfo info = mCurrentSourceList->GetSourceInfo(i);

        /*
        * To exclude the application's own window from being shared, you can use `sourceIsSelf` to filter it out.
        */
        if ( info.sourceIsSelf ) {
           continue ;
        }
        
        CString s = AliStringToCString(info.sourceName);
        listBox->AddString(s)
      }    
      
  }

  /*
  3. After an item is selected, record its ID and title.
  */
  int idx = listBox->GetCurSel();
  
  if (mCurrentSourceList && idx < mCurrentSourceList->GetCount())
  {
    AliEngineScreenSourcInfo info = mCurrentSourceList->GetSourceInfo(idx);
    mSourceId = info.sourceId;
    mSourceTitle = info.sourceName;
  }

2. Share the selected window or desktop

Call either StartScreenShareByWindowId or StartScreenShareByDesktopId to share the selected window or desktop.

// msSourceId is the ID of the desktop to share, which can be obtained through the enumeration API described above.
// screenShareSource is the configuration object.

AliEngineScreenShareRegion  shareRegion ;
shareRegion.originX = 0.f;
shareRegion.originY = 0.f;
shareRegion.width = 640.f;
shareRegion.height = 480.f;
            
screenShareSource.isShareByRegion = true ;
screenShareSource.shareRegion =  shareRegion;

  /*
  * To preview without publishing the stream, set isPushStream=FALSE as described in the screen sharing section.
  */


/*
* Based on your product requirements, call the appropriate API to share a desktop or a window.
* Share a desktop:
*/
mpEngine->StartScreenShareByDesktopId(atol(msSourceId.c_str()), screenShareSource);

/*
* Or, share a window:
*/
mpEngine->StartScreenShareByWindowId(atol(msSourceId.c_str()), screenShareSource);

/*
* You can retrieve and display the region and title of the shared window.
*/
AliEngineScreenShareRegion region;
		mEngine->GetDesktopRegion(mSourceId, mSourceTitle, region);
		CString resolutionMsg;
		resolutionMsg.Format(_T("Resolution: %d x %d"), region.width, region.height);
		((CStatic*)GetDlgItem(IDC_STATIC_SCREEN_SOURCE_RESOLUTION))->SetWindowTextW(resolutionMsg);
		((CEdit*)GetDlgItem(IDC_EDIT_SHARE_REGION_X))->SetWindowTextW(std::to_wstring(mScreenShareSource.shareRegion.originX).c_str());
		((CEdit*)GetDlgItem(IDC_EDIT_SHARE_REGION_Y))->SetWindowTextW(std::to_wstring(mScreenShareSource.shareRegion.originY).c_str());
		((CEdit*)GetDlgItem(IDC_EDIT_SHARE_REGION_X2))->SetWindowTextW(std::to_wstring(mScreenShareSource.shareRegion.width).c_str());
		((CEdit*)GetDlgItem(IDC_EDIT_SHARE_REGION_Y2))->SetWindowTextW(std::to_wstring(mScreenShareSource.shareRegion.height).c_str());
	}
  

3. Stop sharing the window or desktop

mpEngine->StopScreenShare();