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Electron Desktop App Development · Lezione

Architetture multi-finestra

Progetti e implementi applicazioni Electron complesse con più finestre, gestendo efficacemente la comunicazione tra finestre e lo stato.

Architetture multi-finestra è una lezione Electron Desktop App Development gratuita su CoddyKit. Questa è la lezione 1 di 4. Puoi leggere la lezione completa qui gratuitamente — poi esercitati direttamente nel browser con un editor di codice integrato e un tutor IA disponibile 24/7. Fa parte del percorso di apprendimento Electron Desktop App Development, e i tuoi progressi si sincronizzano tra il web e l'app CoddyKit. Il corso Electron Desktop App Development include 4 lezioni in totale.

Parti di questa lezione non sono ancora state tradotte e vengono mostrate in inglese.

Why Multiple Windows?

Electron applications often benefit from using multiple windows. Think of a chat application: you might have a main contact list and separate windows for each active conversation.

  • Separate Workflows: Isolate tasks into dedicated windows.
  • User Preferences: A settings window distinct from the main application.
  • Auxiliary Tools: Dedicated viewers, inspectors, or side panels.
  • Enhanced User Experience: Provides flexibility and organization for complex apps.

Spawning a New Window

Creating additional windows in Electron is similar to creating your initial main window. You simply instantiate another BrowserWindow in your main process.

Here's how you can create a second window that loads a different HTML file.

const { app, BrowserWindow } = require('electron');
const path = require('path');

let mainWindow;
let secondWindow;

function createMainWindow() {
  mainWindow = new BrowserWindow({
    width: 800,
    height: 600,
    webPreferences: {
      nodeIntegration: false,
      contextIsolation: true,
      preload: path.join(__dirname, 'preload.js')
    }
  });
  mainWindow.loadFile('index.html');
}

function createSecondWindow() {
  secondWindow = new BrowserWindow({
    width: 400,
    height: 300,
    parent: mainWindow, // Optional: make it a child window
    modal: false, // Optional: for modal behavior
    show: false, // Don't show immediately
    webPreferences: {
      nodeIntegration: false,
      contextIsolation: true,
      preload: path.join(__dirname, 'preload_second.js')
    }
  });
  secondWindow.loadFile('second.html');
  secondWindow.once('ready-to-show', () => {
    secondWindow.show();
  });
}

app.whenReady().then(() => {
  createMainWindow();
  createSecondWindow();

  app.on('activate', () => {
    if (BrowserWindow.getAllWindows().length === 0) {
      createMainWindow();
    }
  });
});

app.on('window-all-closed', () => {
  if (process.platform !== 'darwin') {
    app.quit();
  }
});

Content for Multiple Windows

Each BrowserWindow instance loads its own content, typically an HTML file. This allows you to design completely independent user interfaces for different parts of your application.

For the previous example, you would need:

  • index.html: The main window's interface.
  • second.html: The second window's distinct interface.
  • Corresponding renderer and preload scripts for each, if needed.

Managing Window References

When working with multiple windows, it's crucial to keep track of their references. You can store them in an array or a map, allowing you to interact with specific windows later.

This helps in sending targeted messages, closing specific windows, or managing their states.

const { app, BrowserWindow } = require('electron');
const path = require('path');

let allWindows = []; // Array to hold references to all windows

function createNewWindow(htmlFile, width, height) {
  let newWindow = new BrowserWindow({
    width: width,
    height: height,
    webPreferences: {
      nodeIntegration: false,
      contextIsolation: true,
      preload: path.join(__dirname, 'preload.js') // Can be different per window
    }
  });
  newWindow.loadFile(htmlFile);
  allWindows.push(newWindow); // Add to our list

  // Remove from list when closed
  newWindow.on('closed', () => {
    allWindows = allWindows.filter(win => win !== newWindow);
  });

  return newWindow;
}

app.whenReady().then(() => {
  createNewWindow('index.html', 800, 600); // Create main window
  createNewWindow('second.html', 400, 300); // Create a second window

  // Example: Accessing windows later
  // allWindows[0].setTitle('Main App');
});

app.on('window-all-closed', () => {
  if (process.platform !== 'darwin') {
    app.quit();
  }
});

Main to Specific Renderer IPC

The main process can send messages to a specific renderer process using the webContents.send() method of that window instance.

This is essential for updating UI elements, pushing data, or triggering actions in a particular window.

const { app, BrowserWindow, ipcMain } = require('electron');
const path = require('path');

let mainWindow;
let settingsWindow;

function createWindows() {
  mainWindow = new BrowserWindow({
    width: 800, height: 600,
    webPreferences: { preload: path.join(__dirname, 'preload.js'), contextIsolation: true }
  });
  mainWindow.loadFile('index.html');

  settingsWindow = new BrowserWindow({
    width: 400, height: 300, show: false,
    webPreferences: { preload: path.join(__dirname, 'preload_settings.js'), contextIsolation: true }
  });
  settingsWindow.loadFile('settings.html');
}

app.whenReady().then(createWindows);

// Main process sends message to settings window
ipcMain.on('open-settings', () => {
  if (settingsWindow) {
    settingsWindow.show();
    settingsWindow.webContents.send('settings-opened', 'Welcome to settings!');
  }
});

// --- Renderer (preload_settings.js) for settings.html ---
// const { ipcRenderer, contextBridge } = require('electron');
// contextBridge.exposeInMainWorld('electronAPI', {
//   onSettingsOpened: (callback) => ipcRenderer.on('settings-opened', (event, message) => callback(message))
// });

// --- Renderer (settings.html script) ---
// window.electronAPI.onSettingsOpened((msg) => {
//   document.getElementById('message').innerText = msg;
// });

Renderer to Main (Identifying Sender)

When a renderer process sends a message to the main process via ipcRenderer.send(), the main process receives an event object.

This event object contains information about the sender, including event.senderFrame or event.sender (which is the WebContents object of the sending window). This allows the main process to identify which window sent the message.

const { app, BrowserWindow, ipcMain } = require('electron');
const path = require('path');

let windows = {}; // Store windows by an ID or name

function createWindows() {
  const mainWin = new BrowserWindow({
    width: 800, height: 600, title: 'Main',
    webPreferences: { preload: path.join(__dirname, 'preload_main.js'), contextIsolation: true }
  });
  mainWin.loadFile('main.html');
  windows['main'] = mainWin;

  const toolWin = new BrowserWindow({
    width: 400, height: 300, title: 'Tool',
    webPreferences: { preload: path.join(__dirname, 'preload_tool.js'), contextIsolation: true }
  });
  toolWin.loadFile('tool.html');
  windows['tool'] = toolWin;
}

app.whenReady().then(createWindows);

ipcMain.on('renderer-message', (event, data) => {
  const senderWindow = BrowserWindow.fromWebContents(event.sender);
  const senderId = Object.keys(windows).find(key => windows[key] === senderWindow);
  console.log(`Message from ${senderId || 'Unknown'}: ${data}`);
  senderWindow.webContents.send('main-reply', `Received from ${senderId}!`);
});

// --- preload_main.js / preload_tool.js (simplified) ---
// const { ipcRenderer, contextBridge } = require('electron');
// contextBridge.exposeInMainWorld('electronAPI', {
//   sendMessage: (data) => ipcRenderer.send('renderer-message', data),
//   onMainReply: (callback) => ipcRenderer.on('main-reply', (event, msg) => callback(msg))
// });

// --- main.html / tool.html script ---
// window.electronAPI.sendMessage('Hello from my window!');

Renderer to Renderer Communication

Renderer processes cannot directly communicate with each other. All inter-process communication (IPC) must be mediated by the main process.

This means a message from one renderer will go to the main process, which then relays it to the target renderer process. This centralizes communication and enhances security.

const { app, BrowserWindow, ipcMain } = require('electron');
const path = require('path');

let windowA, windowB;

function createWindows() {
  windowA = new BrowserWindow({
    width: 600, height: 400, title: 'Window A',
    webPreferences: { preload: path.join(__dirname, 'preload_a.js'), contextIsolation: true }
  });
  windowA.loadFile('window_a.html');

  windowB = new BrowserWindow({
    width: 600, height: 400, title: 'Window B',
    webPreferences: { preload: path.join(__dirname, 'preload_b.js'), contextIsolation: true }
  });
  windowB.loadFile('window_b.html');
}

app.whenReady().then(createWindows);

// Renderer A sends to Main, Main relays to Renderer B
ipcMain.on('message-from-a', (event, message) => {
  console.log('Main received from A:', message);
  if (windowB) {
    windowB.webContents.send('message-to-b', `Relayed from A: ${message}`);
  }
});

// Renderer B sends to Main, Main relays to Renderer A
ipcMain.on('message-from-b', (event, message) => {
  console.log('Main received from B:', message);
  if (windowA) {
    windowA.webContents.send('message-to-a', `Relayed from B: ${message}`);
  }
});

// --- preload_a.js (example) ---
// const { ipcRenderer, contextBridge } = require('electron');
// contextBridge.exposeInMainWorld('electronAPI', {
//   sendToB: (msg) => ipcRenderer.send('message-from-a', msg),
//   onMessageFromB: (callback) => ipcRenderer.on('message-to-a', (event, msg) => callback(msg))
// });

// --- window_a.html script ---
// window.electronAPI.sendToB('Hello from Window A!');

Managing Shared State

When you have multiple windows, they often need to access or share the same data. Here are common strategies:

  • Main Process as Source of Truth: Store shared data in the main process and use IPC to request/update it from renderers.
  • Electron Store: A simple, cross-platform solution for persisting user settings and application state.
  • IPC for Data Sync: Renderers notify the main process of changes, and the main process broadcasts updates to other affected renderers.
  • Global Object (Careful!): In some simple cases, a global JavaScript object in the main process can hold shared state, but this can get messy in complex apps.

Multi-Window Best Practices

Designing multi-window applications requires thoughtful consideration:

  • Memory Usage: Each BrowserWindow is a separate Chromium instance, consuming memory. Minimize unnecessary windows.
  • Lifecycle Management: Decide if closing a child window should affect its parent or the main application.
  • User Experience: Provide clear navigation between windows. Consider window positioning and remember user preferences.
  • Error Handling: Implement robust error handling for IPC and window events to prevent crashes.
  • Context Isolation: Always enable contextIsolation and use preload scripts for secure API exposure, especially with multiple windows.

Multi-Window IPC Check

You have two renderer processes, Renderer A and Renderer B. Renderer A needs to send a message to Renderer B. How should this communication be structured in Electron?

Recap: Multi-Window Architectures

Congratulations! You've learned how to design and implement multi-window Electron applications.

We covered creating multiple BrowserWindow instances, managing their references, and implementing secure inter-window communication via the main process. You also explored strategies for shared state and best practices for building complex, multi-window desktop experiences.

Domande Frequenti

La lezione «Architetture multi-finestra» è gratuita?

Sì — il testo completo di «Architetture multi-finestra» è gratuito qui sul web. Per esercitarvi in modo interattivo (un editor di codice integrato e un tutor IA 24/7) e sbloccare il resto del corso Electron Desktop App Development, passa a CoddyKit PRO. Il corso Electron Desktop App Development include 4 lezioni in totale.

Cosa imparerò in «Architetture multi-finestra»?

Progetti e implementi applicazioni Electron complesse con più finestre, gestendo efficacemente la comunicazione tra finestre e lo stato. Eserciti Electron Desktop App Development con codice pratico che esegui direttamente nel browser, e un tutor IA 24/7 risponde alle tue domande mentre lavori sulla lezione.

Ho bisogno di esperienza per iniziare Electron Desktop App Development?

Non è richiesta alcuna esperienza precedente. Electron Desktop App Development su CoddyKit è strutturato per principianti e studenti avanzati, quindi puoi iniziare da qui o dall'inizio e procedere al tuo ritmo. Questa è la lezione 1 di 4.

Quanto tempo richiede la lezione «Architetture multi-finestra»?

La maggior parte delle lezioni CoddyKit richiede circa 5–10 minuti. Ogni lezione è breve e interattiva, quindi fai progressi costanti e riprendi esattamente da dove hai lasciato su web e app.

Posso scrivere ed eseguire codice in questa lezione Electron Desktop App Development?

Sì. Ogni lezione Electron Desktop App Development include un editor di codice integrato, quindi scrivi ed esegui codice reale direttamente nel tuo browser e ricevi feedback istantaneo dall'IA — nessuna configurazione locale necessaria.

Tutte le lezioni di questo corso

  1. Architetture multi-finestra
  2. Processi e worker in background
  3. Integrazione con i servizi cloud
  4. Aggiornare automaticamente la vostra app Electron
← Torna a Electron Desktop App Development