screen-sharing

name	screen-sharing
description	Start and stop screen sharing during calls. Web clients can initiate screen sharing. Use when implementing screen share, listening for screen share events, or checking presenter status. Triggers on "screen sharing", "screen share", "share screen", "startScreenSharing".
inclusion	manual

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