chrome.tabCapture

Description
Use the chrome.tabCapture API to interact with tab media streams.
Permissions
tabCapture

Summary

Types
CaptureInfo
CaptureOptions
GetMediaStreamOptions
MediaStreamConstraint
TabCaptureState
Methods
capture
tabCapture.capture(options: CaptureOptions, callback: function)
captureOffscreenTab
tabCapture.captureOffscreenTab(startUrl: string, options: CaptureOptions, callback: function)
getCapturedTabs
tabCapture.getCapturedTabs(callback: function)
getMediaStreamId
tabCapture.getMediaStreamId(options?: GetMediaStreamOptions, callback: function)
Events
onStatusChanged

Types

CaptureInfo

Properties

fullscreen
boolean
Whether an element in the tab being captured is in fullscreen mode.
status
TabCaptureState
The new capture status of the tab.
tabId
number
The id of the tab whose status changed.

CaptureOptions

Properties

audio
boolean optional
audioConstraints
MediaStreamConstraint optional
video
boolean optional
videoConstraints
MediaStreamConstraint optional

GetMediaStreamOptions

Since Chrome 71.

Properties

consumerTabId
number optional
Optional tab id of the tab which will later invoke getUserMedia() to consume the stream. If not specified then the resulting stream can be used only by the calling extension. The stream can only be used by frames in the given tab whose security origin matches the consumber tab's origin. The tab's origin must be a secure origin, e.g. HTTPS.
targetTabId
number optional
Optional tab id of the tab which will be captured. If not specified then the current active tab will be selected. Only tabs for which the extension has been granted the activeTab permission can be used as the target tab.

MediaStreamConstraint

Properties

mandatory
object
optional
object optional

TabCaptureState

Enum

"pending", "active", "stopped", or "error"

Methods

capture

tabCapture.capture(options: CaptureOptions, callback: function)

Captures the visible area of the currently active tab. Capture can only be started on the currently active tab after the extension has been invoked, similar to the way that activeTab works. Capture is maintained across page navigations within the tab, and stops when the tab is closed, or the media stream is closed by the extension.

Parameters

options
CaptureOptions
Configures the returned media stream.
callback
function
Callback with either the tab capture MediaStream or null. null indicates an error has occurred and the client may query runtime.lastError to access the error details.
The callback parameter should be a function that looks like this:
(stream: LocalMediaStream) => {...}
- stream
  LocalMediaStream

captureOffscreenTab

tabCapture.captureOffscreenTab(startUrl: string, options: CaptureOptions, callback: function)

Since Chrome 47.

Creates an off-screen tab and navigates it to the given startUrl. Then, capture is started and a MediaStream is returned via callback.

Off-screen tabs are isolated from the user's normal browser experience. They do not show up in the browser window or tab strip, nor are they visible to extensions (e.g., via the chrome.tabs.* APIs).

An off-screen tab remains alive until one of three events occurs: 1. All MediaStreams providing its captured content are closed; 2. the page self-closes (e.g., via window.close()); 3. the extension that called captureOffscreenTab() is unloaded.

Sandboxing: The off-screen tab does not have any access whatsoever to the local user profile (including cookies, HTTP auth, etc.). Instead, it is provided its own sandboxed profile. Also, it cannot access any interactive resources such as keyboard/mouse input, media recording devices (e.g., web cams), copy/paste to/from the system clipboard, etc.

Note: This is a new API, currently only available in Canary/Dev channel, and may change without notice.

Parameters

startUrl
string
options
CaptureOptions
Constraints for the capture and returned MediaStream.
callback
function
Callback with either the tab capture MediaStream or null. null indicates an error has occurred and the client may query runtime.lastError to access the error details.
The callback parameter should be a function that looks like this:
(stream: LocalMediaStream) => {...}
- stream
  LocalMediaStream

getCapturedTabs

tabCapture.getCapturedTabs(callback: function)

Returns a list of tabs that have requested capture or are being captured, i.e. status != stopped and status != error. This allows extensions to inform the user that there is an existing tab capture that would prevent a new tab capture from succeeding (or to prevent redundant requests for the same tab).

Parameters

callback
function
Callback invoked with CaptureInfo[] for captured tabs.
The callback parameter should be a function that looks like this:
(result: CaptureInfo[]) => {...}
- result
  CaptureInfo[]

getMediaStreamId

tabCapture.getMediaStreamId(options?: GetMediaStreamOptions, callback: function)

Since Chrome 71.

Creates a stream ID to capture the target tab. Similar to chrome.tabCapture.capture() method, but returns a media stream ID, instead of a media stream, to the consumer tab.

Parameters

options
GetMediaStreamOptions optional
callback
function
Callback to invoke with the result. If successful, the result is an opaque string that can be passed to the getUserMedia() API to generate a media stream that corresponds to the target tab. The created streamId can only be used once and expires after a few seconds if it is not used.
The callback parameter should be a function that looks like this:
(streamId: string) => {...}
- streamId
  string

Events

onStatusChanged

tabCapture.onStatusChanged.addListener(listener: function)

Event fired when the capture status of a tab changes. This allows extension authors to keep track of the capture status of tabs to keep UI elements like page actions in sync.

Event

listener
function
The listener parameter should be a function that looks like this:
(info: CaptureInfo) => {...}
- info
  CaptureInfo
  CaptureInfo with new capture status for the tab.