startScreenCapture method

@override void startScreenCapture(int? viewId, TRTCVideoStreamType streamType, TRTCVideoEncParam encParam)

Start screen sharing

This API can capture the content of the entire screen or a specified application and share it with other users in the same room. (iOS platform calls this interface to support only sharing within the application. System-level sharing requires the use of startScreenCaptureByReplaykit)

Parameters:

• encParam(TRTCVideoEncParam):
  • Image encoding parameters used for screen sharing, which can be set to empty, indicating to let the SDK choose the optimal encoding parameters (such as resolution and bitrate).
• streamType(TRTCVideoStreamType):
  • Channel used for screen sharing, which can be the primary stream (TRTCVideoStreamType.big) or substream (TRTCVideoStreamType.sub).
• viewId(int):
  • Parent control of the rendering control, which can be set to 0, indicating not to display the preview of the shared screen. (Currently only Android can do local preview)

Note:

1. A user can publish at most one primary stream (TRTCVideoStreamType.big) and one substream (TRTCVideoStreamType.sub) at the same time.
2. By default, screen sharing uses the substream image. If you want to use the primary stream for screen sharing, you need to stop camera capturing (through stopLocalPreview) in advance to avoid conflicts.
3. Only one user can use the substream for screen sharing in the same room at any time; that is, only one user is allowed to enable the substream in the same room at any time.
4. When there is already a user in the room using the substream for screen sharing, calling this API will return the TRTCCloudListener.onError (ERR_SERVER_CENTER_ANOTHER_USER_PUSH_SUB_VIDEO) callback.

Implementation

@override
void startScreenCapture(int? viewId, TRTCVideoStreamType streamType, TRTCVideoEncParam encParam) async {
  TRTCLog(_tag, "startScreenCapture: viewId:$viewId, streamType:$streamType, encParam:$encParam");
  if (TRTCPlatform.isIOS) {
    TRTCMethodChannel().startScreenCapture(viewId, streamType, encParam);
    return;
  }
  int? effectiveViewId = viewId;
  if (effectiveViewId != null && effectiveViewId != 0 && !TRTCCloudVideoView.containsViewId(effectiveViewId)) {
    TRTCLog(
      _tag,
      "startScreenCapture WARNING: viewId=$effectiveViewId is invalid (not registered in TRTCCloudVideoView). "
      "Fallback to no local preview. Ensure the TRTCCloudVideoView is created and onViewCreated has fired before calling startScreenCapture.",
      level: 3, // warning
    );
    effectiveViewId = null;
  }
  TRTCCloudNative.instance.startScreenCapture(_isNativeTexturePlatform ? null : effectiveViewId, streamType, encParam);
  if (_isNativeTexturePlatform) {
    if (effectiveViewId == null || effectiveViewId == 0) {
      await TRTCMethodChannel().unsetLocalTextureRender(streamType);
      if (_screenCaptureStreamType == streamType) {
        _screenCaptureStreamType = null;
      }
    } else {
      _screenCaptureStreamType = streamType;
      await TRTCMethodChannel().setLocalTextureRender(effectiveViewId, streamType);
    }
  }
}