Screen Sharing

CometChat Calls SDK v5 — Screen Sharing

Overview

The Web Calls SDK can initiate and receive screen shares. When a user starts screen sharing, the browser's native screen picker dialog appears. The call layout automatically adjusts to display shared content.

Key Imports

import { CometChatCalls } from '@cometchat/calls-sdk-javascript';

Implementation

Start / Stop Screen Sharing

CometChatCalls.startScreenSharing();  // opens browser screen picker
CometChatCalls.stopScreenSharing();   // stops sharing

Listen for Screen Share Events (Local)

CometChatCalls.addEventListener('onScreenShareStarted', () => {
  // Local user started screen sharing
  // Update UI to show "sharing" indicator
});

CometChatCalls.addEventListener('onScreenShareStopped', () => {
  // Local user stopped screen sharing
});

Listen for Participant Screen Share Events

CometChatCalls.addEventListener('onParticipantStartedScreenShare', (participant) => {
  console.log(`${participant.name} started screen sharing`);
  // Layout auto-adjusts to show shared screen
});

CometChatCalls.addEventListener('onParticipantStoppedScreenShare', (participant) => {
  console.log(`${participant.name} stopped screen sharing`);
  // Layout returns to normal
});

Configure Screen Share Button Visibility

const sessionSettings: SessionSettings = {
  hideScreenSharingButton: false,  // show screen share button (default)
};

Handle Button Click Event

CometChatCalls.addEventListener('onScreenShareButtonClicked', () => {
  // Fires when user clicks the built-in screen share button
});

Gotchas

• Screen sharing requires HTTPS (or localhost) — browsers block getDisplayMedia() on HTTP
• The browser shows its own screen picker dialog — the SDK cannot bypass this
• Only one user can screen share at a time in a session
• If the user cancels the browser picker, no event fires
• The user can also stop sharing via the browser's native "Stop sharing" button — onScreenShareStopped fires in both cases
• Screen sharing may pause the local video (depending on browser/device) — the SDK handles this automatically
• Android/iOS mobile clients can receive screen shares from web but cannot initiate them