feat: make desktopCapturer main-process-only (#30720)

* feat: make desktopCapturer main-process-only

* remove --enable-api-filtering-logging

* remove test

* merge lib/browser/api/desktop-capturer.ts with lib/browser/desktop-capturer.ts

* remove desktop-capturer-get-sources event

* fix specs

* getSources needs to be async

Co-authored-by: Milan Burda <milan.burda@gmail.com>

docs/api/app.md

@@ -500,16 +500,6 @@ gets emitted.
 **Note:** Extra command line arguments might be added by Chromium,
 such as `--original-process-start-time`.
 
-### Event: 'desktop-capturer-get-sources'
-
-Returns:
-
-* `event` Event
-* `webContents` [WebContents](web-contents.md)
-
-Emitted when `desktopCapturer.getSources()` is called in the renderer process of `webContents`.
-Calling `event.preventDefault()` will make it return empty sources.
-
 ## Methods
 
 The `app` object has the following methods:

docs/api/command-line-switches.md

@@ -61,12 +61,6 @@ throttling in one window, you can take the hack of
 
 Forces the maximum disk space to be used by the disk cache, in bytes.
 
-### --enable-api-filtering-logging
-
-Enables caller stack logging for the following APIs (filtering events):
-
-* `desktopCapturer.getSources()` / `desktop-capturer-get-sources`
-
 ### --enable-logging[=file]
 
 Prints Chromium's logging to stderr (or a log file).

docs/api/desktop-capturer.md

@@ -3,40 +3,49 @@
 > Access information about media sources that can be used to capture audio and
 > video from the desktop using the [`navigator.mediaDevices.getUserMedia`] API.
 
-Process: [Main](../glossary.md#main-process), [Renderer](../glossary.md#renderer-process)
+Process: [Main](../glossary.md#main-process)
 
 The following example shows how to capture video from a desktop window whose
 title is `Electron`:
 
 ```javascript
-// In the renderer process.
+// In the main process.
 const { desktopCapturer } = require('electron')
 
 desktopCapturer.getSources({ types: ['window', 'screen'] }).then(async sources => {
   for (const source of sources) {
     if (source.name === 'Electron') {
-      try {
-        const stream = await navigator.mediaDevices.getUserMedia({
-          audio: false,
-          video: {
-            mandatory: {
-              chromeMediaSource: 'desktop',
-              chromeMediaSourceId: source.id,
-              minWidth: 1280,
-              maxWidth: 1280,
-              minHeight: 720,
-              maxHeight: 720
-            }
-          }
-        })
-        handleStream(stream)
-      } catch (e) {
-        handleError(e)
-      }
+      mainWindow.webContents.send('SET_SOURCE', source.id)
       return
     }
   }
 })
+```
+
+```javascript
+// In the preload script.
+const { ipcRenderer } = require('electron')
+
+ipcRenderer.on('SET_SOURCE', async (event, sourceId) => {
+  try {
+    const stream = await navigator.mediaDevices.getUserMedia({
+      audio: false,
+      video: {
+        mandatory: {
+          chromeMediaSource: 'desktop',
+          chromeMediaSourceId: sourceId,
+          minWidth: 1280,
+          maxWidth: 1280,
+          minHeight: 720,
+          maxHeight: 720
+        }
+      }
+    })
+    handleStream(stream)
+  } catch (e) {
+    handleError(e)
+  }
+})
 
 function handleStream (stream) {
   const video = document.querySelector('video')

docs/api/web-contents.md

@@ -856,15 +856,6 @@ Returns:
 
 Emitted when the renderer process sends a synchronous message via `ipcRenderer.sendSync()`.
 
-#### Event: 'desktop-capturer-get-sources'
-
-Returns:
-
-* `event` Event
-
-Emitted when `desktopCapturer.getSources()` is called in the renderer process.
-Calling `event.preventDefault()` will make it return empty sources.
-
 #### Event: 'preferred-size-changed'
 
 Returns:

filenames.auto.gni

@@ -142,7 +142,6 @@ auto_filenames = {
     "lib/common/web-view-methods.ts",
     "lib/renderer/api/context-bridge.ts",
     "lib/renderer/api/crash-reporter.ts",
-    "lib/renderer/api/desktop-capturer.ts",
     "lib/renderer/api/ipc-renderer.ts",
     "lib/renderer/api/web-frame.ts",
     "lib/renderer/inspector.ts",
@@ -224,7 +223,6 @@ auto_filenames = {
     "lib/browser/api/web-contents.ts",
     "lib/browser/api/web-frame-main.ts",
     "lib/browser/default-menu.ts",
-    "lib/browser/desktop-capturer.ts",
     "lib/browser/devtools.ts",
     "lib/browser/guest-view-manager.ts",
     "lib/browser/guest-window-manager.ts",
@@ -271,7 +269,6 @@ auto_filenames = {
     "lib/common/webpack-provider.ts",
     "lib/renderer/api/context-bridge.ts",
     "lib/renderer/api/crash-reporter.ts",
-    "lib/renderer/api/desktop-capturer.ts",
     "lib/renderer/api/exports/electron.ts",
     "lib/renderer/api/ipc-renderer.ts",
     "lib/renderer/api/module-list.ts",
@@ -309,7 +306,6 @@ auto_filenames = {
     "lib/common/webpack-provider.ts",
     "lib/renderer/api/context-bridge.ts",
     "lib/renderer/api/crash-reporter.ts",
-    "lib/renderer/api/desktop-capturer.ts",
     "lib/renderer/api/exports/electron.ts",
     "lib/renderer/api/ipc-renderer.ts",
     "lib/renderer/api/module-list.ts",

lib/browser/api/desktop-capturer.ts

@@ -1,5 +1,72 @@
-import { getSourcesImpl } from '@electron/internal/browser/desktop-capturer';
+const { createDesktopCapturer } = process._linkedBinding('electron_browser_desktop_capturer');
 
-export async function getSources (options: Electron.SourcesOptions) {
-  return getSourcesImpl(null, options);
+const deepEqual = (a: ElectronInternal.GetSourcesOptions, b: ElectronInternal.GetSourcesOptions) => JSON.stringify(a) === JSON.stringify(b);
+
+let currentlyRunning: {
+  options: ElectronInternal.GetSourcesOptions;
+  getSources: Promise<ElectronInternal.GetSourcesResult[]>;
+}[] = [];
+
+// |options.types| can't be empty and must be an array
+function isValid (options: Electron.SourcesOptions) {
+  const types = options ? options.types : undefined;
+  return Array.isArray(types);
+}
+
+export async function getSources (args: Electron.SourcesOptions) {
+  if (!isValid(args)) throw new Error('Invalid options');
+
+  const captureWindow = args.types.includes('window');
+  const captureScreen = args.types.includes('screen');
+
+  const { thumbnailSize = { width: 150, height: 150 } } = args;
+  const { fetchWindowIcons = false } = args;
+
+  const options = {
+    captureWindow,
+    captureScreen,
+    thumbnailSize,
+    fetchWindowIcons
+  };
+
+  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) => {
+    let capturer: ElectronInternal.DesktopCapturer | null = createDesktopCapturer();
+
+    const stopRunning = () => {
+      if (capturer) {
+        delete capturer._onerror;
+        delete capturer._onfinished;
+        capturer = null;
+      }
+      // Remove from currentlyRunning once we resolve or reject
+      currentlyRunning = currentlyRunning.filter(running => running.options !== options);
+    };
+
+    capturer._onerror = (error: string) => {
+      stopRunning();
+      reject(error);
+    };
+
+    capturer._onfinished = (sources: Electron.DesktopCapturerSource[]) => {
+      stopRunning();
+      resolve(sources);
+    };
+
+    capturer.startHandling(captureWindow, captureScreen, thumbnailSize, fetchWindowIcons);
+  });
+
+  currentlyRunning.push({
+    options,
+    getSources
+  });
+
+  return getSources;
 }

lib/browser/rpc-server.ts

@@ -1,30 +1,9 @@
-import { app } from 'electron/main';
-import type { WebContents } from 'electron/main';
 import { clipboard } from 'electron/common';
 import * as fs from 'fs';
 import { ipcMainInternal } from '@electron/internal/browser/ipc-main-internal';
 import * as ipcMainUtils from '@electron/internal/browser/ipc-main-internal-utils';
 import { IPC_MESSAGES } from '@electron/internal/common/ipc-messages';
 
-import type * as desktopCapturerModule from '@electron/internal/browser/desktop-capturer';
-
-const eventBinding = process._linkedBinding('electron_browser_event');
-
-const emitCustomEvent = function (contents: WebContents, eventName: string, ...args: any[]) {
-  const event = eventBinding.createWithSender(contents);
-
-  app.emit(eventName, event, contents, ...args);
-  contents.emit(eventName, event, ...args);
-
-  return event;
-};
-
-const logStack = function (contents: WebContents, code: string, stack: string) {
-  if (stack) {
-    console.warn(`WebContents (${contents.id}): ${code}`, stack);
-  }
-};
-
 // Implements window.close()
 ipcMainInternal.on(IPC_MESSAGES.BROWSER_WINDOW_CLOSE, function (event) {
   const window = event.sender.getOwnerBrowserWindow();
@@ -58,22 +37,6 @@ ipcMainUtils.handleSync(IPC_MESSAGES.BROWSER_CLIPBOARD_SYNC, function (event, me
   return (clipboard as any)[method](...args);
 });
 
-if (BUILDFLAG(ENABLE_DESKTOP_CAPTURER)) {
-  const desktopCapturer = require('@electron/internal/browser/desktop-capturer') as typeof desktopCapturerModule;
-
-  ipcMainInternal.handle(IPC_MESSAGES.DESKTOP_CAPTURER_GET_SOURCES, async function (event, options: Electron.SourcesOptions, stack: string) {
-    logStack(event.sender, 'desktopCapturer.getSources()', stack);
-    const customEvent = emitCustomEvent(event.sender, 'desktop-capturer-get-sources');
-
-    if (customEvent.defaultPrevented) {
-      console.error('Blocked desktopCapturer.getSources()');
-      return [];
-    }
-
-    return await desktopCapturer.getSourcesImpl(event.sender, options);
-  });
-}
-
 const getPreloadScript = async function (preloadPath: string) {
   let preloadSrc = null;
   let preloadError = null;

lib/common/ipc-messages.ts

@@ -28,6 +28,4 @@ export const enum IPC_MESSAGES {
   INSPECTOR_CONFIRM = 'INSPECTOR_CONFIRM',
   INSPECTOR_CONTEXT_MENU = 'INSPECTOR_CONTEXT_MENU',
   INSPECTOR_SELECT_FILE = 'INSPECTOR_SELECT_FILE',
-
-  DESKTOP_CAPTURER_GET_SOURCES = 'DESKTOP_CAPTURER_GET_SOURCES',
 }