Screen Sharing
Feature Overview
Screen sharing refers to sharing screen content as video with other viewers during video calls or interactive live streaming to enhance interactive experience and improve communication efficiency.
Only Linux systems with a graphical interface are supported, including Uniontech UOS and Kylin OS. Linux systems without a graphical interface do not support this feature.
Screen sharing is widely used in the following scenarios:
- In video conferencing scenarios, screen sharing can share the speaker's local files, data, web pages, PPTs, and other content with other participants;
- In online classroom scenarios, screen sharing can display the teacher's courseware, notes, lecture content, and other materials for students to view.
Download Example Source Code
Please refer to Download Example Source Code to get the source code.
For related source code, please check files in the "/ZegoExpressExample/Example/Others/ScreenSharing/" directory.
others
...
├── ScreenSharing
│ ├── ScreenCaptureSourceDialog.cpp // Display thumbnails of shareable windows
│ ├── ScreenCaptureSourceDialog.h
│ ├── ScreenCaptureSourceDialog.ui
│ ├── ScreenSharing.cpp // Main screen sharing workflow
│ ├── ScreenSharing.h
│ └── ScreenSharing.ui
...Prerequisites
To implement screen sharing on Linux, please contact ZEGOCLOUD Technical Support.
Implementation Flow
During screen capture, only iOS and Android platforms support simultaneous video and audio capture; other platforms only support video capture. For audio capture, developers need to implement the related logic themselves.
Create Screen Sharing Source
-
The SDK can get information about all currently shareable windows through getScreenCaptureSources.
IZegoExpressEngine *engine = ZegoExpressSDK::getEngine(); std::vector<ZegoScreenCaptureSourceInfo> infoList = engine->getScreenCaptureSources(400, 400, 100, 100); -
Using the window ID and window type from the above window information, call the createScreenCaptureSource interface to create a screen sharing source object.
if (infoList.size() > 0) { ZegoScreenCaptureSourceInfo info = infoList[0]; IZegoScreenCaptureSource *source = engine->createScreenCaptureSource(info.sourceID, info.sourceType); }
Set Capture Source to Screen Sharing Source
The default video source for SDK stream publishing is camera. If you need to publish a screen sharing source, you need to switch to screen sharing through setVideoSource.
engine->setVideoSource(ZEGO_VIDEO_SOURCE_SCREEN_CAPTURE, source->getIndex(), ZEGO_PUBLISH_CHANNEL_MAIN);Start Sharing
Call the startCapture interface to share the window content.
source->startCapture();(Optional) Additional Operations
-
Update Sharing Source Call the updateCaptureSource interface to update the shared window content.
ZegoScreenCaptureSourceInfo info = infoList[1]; source->updateCaptureSource(info.sourceID, info.sourceType); -
Update Sharing Source Region Call the updateCaptureRegion interface to dynamically update the shared window region. Setting it to (0, 0, 0, 0) restores sharing the entire window.
source->updateCaptureRegion(10, 10, 400, 400); -
Activate Window If the window to be captured is blocked by other windows, you can call the enableWindowActivate interface to bring the window to be captured to the front to activate the currently shared window.
source->enableWindowActivate(true); -
Show/Hide Cursor Call the enableCursorVisible interface to show or hide the mouse cursor.
source->enableCursorVisible(true);
Set Event Handler
Call the setEventHandler interface to set the sharing source event handler.
std::shared_ptr<ScreenCaptureSourceEventHandler> handler = std::make_shared<ScreenCaptureSourceEventHandler>(this);
source->setEventHandler(handler);
···
// Capture data callback, can be used for local recording.
void onAvailableFrame(IZegoScreenCaptureSource * /*source*/, const void * /*data*/,unsigned int /*dataLength*/, ZegoVideoFrameParam /*param*/) override;
// Capture exception callback, when an exception callback occurs, capture will be interrupted.
void onExceptionOccurred(IZegoScreenCaptureSource * /*source*/,ZegoScreenCaptureSourceExceptionType /*exceptionType*/) override;
// Window capture state callback, when window region position changes, this callback will notify; when the window is not in the current screen region, capture will stop.
void onWindowStateChanged(IZegoScreenCaptureSource * /*source*/,ZegoScreenCaptureWindowState /*windowState*/,ZegoRect /*windowRect*/) override;Login Room and Start Publishing Stream
Call the loginRoom interface, pass in the Room ID parameter "roomID" and user parameter "user", to login the room.
Call the startPublishingStream interface, pass in the Stream ID parameter "streamID", to send the local audio and video stream to remote users.
// Start logging in the room
ZegoUser user(m_currentUserId, m_currentUserId);
engine->loginRoom(m_currentRoomId, user);
// Start publishing stream
engine->startPublishingStream(m_currentPublishStreamId, ZEGO_PUBLISH_CHANNEL_MAIN);At this point, we have completed the operation of capturing screen data and sharing it to remote users through ZEGO Express SDK.
Watch Remote Screen Sharing
After completing the above steps, other users can use the startPlayingStream interface to play the screen sharing stream.
ZegoCanvas canvas(ZegoUtilHelper::GetView(ui->frame_Play));
canvas.viewMode = ZEGO_VIEW_MODE_ASPECT_FIT;
engine->startPlayingStream(m_currentPlayStreamId, &canvas);Stop Sharing
Users can call the stopCapture interface to stop sharing.
source->stopCapture();Destroy Screen Capture Source Object
When the screen capture feature is no longer needed, you can call the destroyScreenCaptureSource interface to destroy the screen capture source object.
engine->destroyScreenCaptureSource(source);