electron/lib/browser/desktop-capturer.ts

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import { EventEmitter } from 'events'
const { createDesktopCapturer } = process.electronBinding('desktop_capturer')
const deepEqual = (a: ElectronInternal.GetSourcesOptions, b: ElectronInternal.GetSourcesOptions) => JSON.stringify(a) === JSON.stringify(b)
let currentlyRunning: {
options: ElectronInternal.GetSourcesOptions;
getSources: Promise<ElectronInternal.GetSourcesResult[]>;
}[] = []
export const getSources = (event: Electron.IpcMainEvent, options: ElectronInternal.GetSourcesOptions) => {
for (const running of currentlyRunning) {
if (deepEqual(running.options, options)) {
// If a request is currently running for the same options
// return that promise
return running.getSources
}
}
const getSources = new Promise<ElectronInternal.GetSourcesResult[]>((resolve, reject) => {
const stopRunning = () => {
// Remove from currentlyRunning once we resolve or reject
currentlyRunning = currentlyRunning.filter(running => running.options !== options)
}
const emitter = new EventEmitter()
emitter.once('error', (event, error: string) => {
stopRunning()
reject(error)
})
emitter.once('finished', (event, sources: Electron.DesktopCapturerSource[], fetchWindowIcons: boolean) => {
stopRunning()
resolve(sources.map(source => ({
id: source.id,
name: source.name,
thumbnail: source.thumbnail.toDataURL(),
display_id: source.display_id,
appIcon: (fetchWindowIcons && source.appIcon) ? source.appIcon.toDataURL() : null
})))
})
let capturer: ElectronInternal.DesktopCapturer | null = createDesktopCapturer()
capturer.emit = emitter.emit.bind(emitter)
capturer.startHandling(options.captureWindow, options.captureScreen, options.thumbnailSize, options.fetchWindowIcons)
// If the WebContents is destroyed before receiving result, just remove the
// reference to emit and the capturer itself so that it never dispatches
// back to the renderer
event.sender.once('destroyed', () => {
capturer!.emit = null
capturer = null
stopRunning()
})
})
currentlyRunning.push({
options,
getSources
})
return getSources
}