157 lines
4.9 KiB
Markdown
157 lines
4.9 KiB
Markdown
# Quick start
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## Introduction
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Generally, atom-shell enables you to create desktop applications with pure
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JavaScript by providing a runtime with rich native APIs. You could see it as
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a variant of the io.js runtime which is focused on desktop applications
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instead of web servers.
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It doesn't mean atom-shell is a JavaScript binding to GUI libraries. Instead,
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atom-shell uses web pages as its GUI, so you could also see it as a minimal
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Chromium browser, controlled by JavaScript.
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### The main process
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In atom-shell the process that runs `package.json`'s `main` script is called
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__the main process__. The script runs in the main process can display GUI by
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creating web pages.
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### The renderer process
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Since atom-shell uses Chromium for displaying web pages, Chromium's
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multi-processes architecture is also used. Each web page in atom-shell runs in
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its own process, which is called __the renderer process__.
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In normal browsers web pages usually run in a sandboxed environment and are not
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allowed access to native resources. In atom-shell users have the power to use
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io.js APIs in web pages and it is therefore possible to interact with low level
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operating system features.
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### Differences between main process and renderer process
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The main process creates web pages by creating `BrowserWindow` instances, and
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each `BrowserWindow` instance runs the web page in its own renderer process,
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when a `BrowserWindow` instance is destroyed, the corresponding renderer process
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would also be terminated.
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So the main process manages all web pages and their corresponding renderer
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processes, and each renderer process is separated from each other and only care
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about the web page running in it.
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In web pages, it is not allowed to call native GUI related APIs because managing
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native GUI resources in web pages is very dangerous and easy to leak resources.
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If you want to do GUI operations in web pages, you have to communicate with
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the main process to do it there.
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In atom-shell, we have provided the [ipc](../api/ipc-renderer.md) module for
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communication between main process and renderer process. And there is also a
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[remote](../api/remote.md) module for RPC style communication.
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## Write your first atom-shell app
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Generally, an atom-shell app would be structured like this (see the
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[hello-atom](https://github.com/dougnukem/hello-atom) repo for reference):
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```text
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your-app/
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├── package.json
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├── main.js
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└── index.html
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```
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The format of `package.json` is exactly the same as that of Node's modules, and
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the script specified by the `main` field is the startup script of your app,
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which will run on the main process. An example of your `package.json` might look
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like this:
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```json
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{
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"name" : "your-app",
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"version" : "0.1.0",
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"main" : "main.js"
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}
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```
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The `main.js` should create windows and handle system events, a typical
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example being:
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```javascript
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var app = require('app'); // Module to control application life.
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var BrowserWindow = require('browser-window'); // Module to create native browser window.
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// Report crashes to our server.
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require('crash-reporter').start();
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// Keep a global reference of the window object, if you don't, the window will
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// be closed automatically when the javascript object is GCed.
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var mainWindow = null;
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// Quit when all windows are closed.
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app.on('window-all-closed', function() {
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if (process.platform != 'darwin')
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app.quit();
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});
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// This method will be called when atom-shell has done everything
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// initialization and ready for creating browser windows.
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app.on('ready', function() {
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// Create the browser window.
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mainWindow = new BrowserWindow({width: 800, height: 600});
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// and load the index.html of the app.
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mainWindow.loadUrl('file://' + __dirname + '/index.html');
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// Emitted when the window is closed.
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mainWindow.on('closed', function() {
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// Dereference the window object, usually you would store windows
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// in an array if your app supports multi windows, this is the time
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// when you should delete the corresponding element.
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mainWindow = null;
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});
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});
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```
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Finally the `index.html` is the web page you want to show:
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```html
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<!DOCTYPE html>
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<html>
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<head>
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<title>Hello World!</title>
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</head>
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<body>
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<h1>Hello World!</h1>
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We are using node.js <script>document.write(process.version)</script>
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and atom-shell <script>document.write(process.versions['electron'])</script>.
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</body>
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</html>
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```
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## Run your app
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After you're done writing your app, you can create a distribution by
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following the [Application distribution](./application-distribution.md) guide
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and then execute the packaged app. You can also just use the downloaded
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atom-shell binary to execute your app directly.
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On Windows:
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```cmd
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$ .\atom-shell\atom.exe your-app\
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```
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On Linux:
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```bash
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$ ./atom-shell/atom your-app/
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```
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On OS X:
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```bash
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$ ./Electron.app/Contents/MacOS/Atom your-app/
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```
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`Electron.app` here is part of the atom-shell's release package, you can download
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it from [here](https://github.com/atom/electron/releases).
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