Maximize main window if monitor removed/changed resolution (#2486)

* Maximize main window if monitor removed/changed resolution

* Fix unit tests

* Add better handlers to support active screen changes

src/main/app/initialize.test.js

@@ -51,6 +51,9 @@ jest.mock('electron', () => ({
         handle: jest.fn(),
         emit: jest.fn(),
     },
+    screen: {
+        on: jest.fn(),
+    },
     session: {
         defaultSession: {
             setSpellCheckerDictionaryDownloadURL: jest.fn(),

src/main/app/initialize.ts

@@ -3,7 +3,7 @@
 
 import path from 'path';
 
-import {app, ipcMain, session} from 'electron';
+import {app, ipcMain, screen, session} from 'electron';
 import installExtension, {REACT_DEVELOPER_TOOLS} from 'electron-devtools-installer';
 import isDev from 'electron-is-dev';
 import log from 'electron-log';
@@ -119,6 +119,8 @@ export async function initialize() {
         app.whenReady(),
     ]);
 
+    initializeScreenEventListeners();
+
     // no need to continue initializing if app is quitting
     if (global.willAppQuit) {
         return;
@@ -188,6 +190,11 @@ function initializeAppEventListeners() {
     app.on('will-finish-launching', handleAppWillFinishLaunching);
 }
 
+function initializeScreenEventListeners() {
+    screen.on('display-removed', WindowManager.displayRemoved);
+    screen.on('display-metrics-changed', WindowManager.displayMetricsChanged);
+}
+
 function initializeBeforeAppReady() {
     if (!Config.data) {
         log.error('No config loaded');

src/main/windows/windowManager.ts

@@ -4,7 +4,7 @@
 /* eslint-disable max-lines */
 import path from 'path';
 
-import {app, BrowserWindow, nativeImage, systemPreferences, ipcMain, IpcMainEvent, IpcMainInvokeEvent, desktopCapturer} from 'electron';
+import {app, BrowserWindow, nativeImage, systemPreferences, ipcMain, IpcMainEvent, IpcMainInvokeEvent, desktopCapturer, Display, screen} from 'electron';
 import log from 'electron-log';
 
 import {
@@ -255,6 +255,42 @@ export class WindowManager {
         this.sendToRenderer(MAXIMIZE_CHANGE, false);
     }
 
+    maximizeMainWindow = () => {
+        if (!(this.viewManager && this.mainWindow)) {
+            return;
+        }
+        this.mainWindow.maximize?.();
+    }
+
+    displayRemoved = (event: Event, oldDisplay: Display) => {
+        log.debug('WindowManager.displayRemoved', {oldDisplay});
+
+        if (!oldDisplay) {
+            return;
+        }
+
+        if (this.isActiveScreen(oldDisplay.id)) {
+            this.maximizeMainWindow();
+        }
+    }
+
+    displayMetricsChanged = (event: Event, display: Display, changedMetrics: string[]) => {
+        log.debug('WindowManager.displayMetricsChanged', {display, changedMetrics});
+
+        this.maximizeMainWindow();
+    }
+
+    isActiveScreen = (id: Display['id']): boolean => {
+        if (!(this.viewManager && this.mainWindow)) {
+            return false;
+        }
+
+        const mainWindowBounds = this.mainWindow.getBounds();
+        const currentDisplay = screen.getDisplayNearestPoint({x: mainWindowBounds.x, y: mainWindowBounds.y});
+        log.debug('WindowManager.isActiveScreen', {id, currentDisplay});
+        return currentDisplay.id === id;
+    }
+
     isResizing = false;
 
     handleWillResizeMainWindow = (event: Event, newBounds: Electron.Rectangle) => {