Electron使用指南——特性和技巧

╰+攻爆jí腚メ 2022-12-02 00:43 291阅读 0赞

## 共享API (Shared API) ##

本节重点讲解 `process`、`screen`、`shell`、`nativeImage`、`clipboard` 几个部分内容。

## 1、process (进程) ##

### 1.1 index.html ###

<!DOCTYPE html>
    <html>
      <head>
        <meta charset="UTF-8">
        <meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline'">
        <title>Hello World!</title>
      </head>
      <body>
        <h1>Hello World!</h1>
    
        
        We are using Node.js <strong><script>document.write( process.versions.node)</script></strong>,
        and Electron <strong><script>document.write( process.versions.electron )</script></strong>.
    
        <br><button type="button" onclick="process.hang()">Hang Renderer</button>
        <br><button type="button" onclick="process.crash()">Crash Renderer</button>
    
        <script>
          // let i = 1
          // setInterval(() => {
          //   console.log(i)
          //   i++
          // }, 500)
    
        </script>
      </body>
    </html>

### 1.2 main.js ###

// Modules
    const {app, BrowserWindow} = require('electron')
    
    // Keep a global reference of the window object, if you don't, the window will
    // be closed automatically when the JavaScript object is garbage collected.
    let mainWindow
    
    // Create a new BrowserWindow when `app` is ready
    function createWindow () {
    
      mainWindow = new BrowserWindow({
        width: 1000, height: 800,
        webPreferences: { nodeIntegration: true }
      })
    
      // Load index.html into the new BrowserWindow
      mainWindow.loadFile('index.html')
    
      // Open DevTools - Remove for PRODUCTION!
      mainWindow.webContents.openDevTools();
    
      mainWindow.webContents.on( 'crashed', mainWindow.reload )
    
      // Listen for window being closed
      mainWindow.on('closed',  () => {
        mainWindow = null
      })
    }
    
    // Electron `app` is ready
    app.on('ready', createWindow)
    
    // Quit when all windows are closed - (Not macOS - Darwin)
    app.on('window-all-closed', () => {
      if (process.platform !== 'darwin') app.quit()
    })
    
    // When app icon is clicked and app is running, (macOS) recreate the BrowserWindow
    app.on('activate', () => {
      if (mainWindow === null) createWindow()
    })

## 2、screen (屏幕) ##

### 1.1 main.js ###

// Modules
    const electron = require('electron')
    const {app, BrowserWindow} = electron
    
    // Keep a global reference of the window object, if you don't, the window will
    // be closed automatically when the JavaScript object is garbage collected.
    let mainWindow
    
    // Create a new BrowserWindow when `app` is ready
    function createWindow () {
    
      let primaryDisplay = electron.screen.getPrimaryDisplay()
    
      mainWindow = new BrowserWindow({
        x: primaryDisplay.bounds.x, y: primaryDisplay.bounds.y,
        width: primaryDisplay.size.width/2, height: primaryDisplay.size.height,
        webPreferences: { nodeIntegration: true }
      })
    
      // Load index.html into the new BrowserWindow
      mainWindow.loadFile('index.html')
    
      // Open DevTools - Remove for PRODUCTION!
      mainWindow.webContents.openDevTools();
    
      // Listen for window being closed
      mainWindow.on('closed',  () => {
        mainWindow = null
      })
    }
    
    // Electron `app` is ready
    app.on('ready', createWindow)
    
    // Quit when all windows are closed - (Not macOS - Darwin)
    app.on('window-all-closed', () => {
      if (process.platform !== 'darwin') app.quit()
    })
    
    // When app icon is clicked and app is running, (macOS) recreate the BrowserWindow
    app.on('activate', () => {
      if (mainWindow === null) createWindow()
    })

### 1.2 renderer.js ###

const electron = require('electron')
    
    const displays = electron.screen.getAllDisplays()
    
    console.log( `${displays[0].size.width} x ${displays[0].size.height}` )
    console.log( `${displays[0].bounds.x}, ${displays[0].bounds.y}` )
    console.log( `${displays[1].size.width} x ${displays[1].size.height}` )
    console.log( `${displays[1].bounds.x}, ${displays[1].bounds.y}` )
    
    
    electron.screen.on( 'display-metrics-changed', (e, display, metricsChanged) => {
      console.log( metricsChanged )
    })
    
    document.getElementsByTagName('body')[0].addEventListener( 'click', e => {
      console.log( electron.screen.getCursorScreenPoint() )
    })

## 3、shell ##

<!DOCTYPE html>
    <html>
      <head>
        <meta charset="UTF-8">
        <meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline'">
        <title>Hello World!</title>
      </head>
      <body>
        <h1>Hello World!</h1>
    
        <button onclick="showSite()">Launch Electron.js Site</button><br>
        <button onclick="openSplash()">Open Splash.png</button><br>
        <button onclick="showSplashFile()">Show Splash.png</button><br>
        <button onclick="deleteSplashFile()">Delete Splash.png</button><br>
    
        <script>
    
          const { shell } = require('electron')
    
          const showSite = e => {
            shell.openExternal('https://electronjs.org')
          }
    
    
          const splashPath = `${__dirname}/splash.png`
    
          const openSplash = e => {
            shell.openItem(splashPath)
          }
          const showSplashFile = e => {
            shell.showItemInFolder(splashPath)
          }
          const deleteSplashFile = e => {
            shell.moveItemToTrash(splashPath)
          }
    
        </script>
      </body>
    </html>

## 4、nativeImage (本地图片) ##

<!DOCTYPE html>
    <html>
      <head>
        <meta charset="UTF-8">
        <meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline'">
        <title>Hello World!</title>
      </head>
      <body>
        <h1>Convert splash.png:</h1>
    
        <button onclick="toPng()">PNG</button>
        <button onclick="toJpg()">JPG</button>
        <button onclick="toTag()">Show</button>
        <br><img src="" id="preview">
    
    
        <script>
    
          const fs = require('fs')
          const { nativeImage, remote } = require('electron')
    
          const splash = nativeImage.createFromPath(`${__dirname}/splash.png`)
    
          const saveToDesktop = (data, ext) => {
    
            let desktopPath = remote.app.getPath('desktop')
            fs.writeFile( `${desktopPath}/splash.${ext}`, data, console.log )
          }
    
          const toTag = e => {
    
            let size = splash.getSize()
    
            let splashURL = splash.resize({ width: size.width/4, height: size.height/4 }).toDataURL()
            document.getElementById('preview').src = splashURL
          }
          const toPng = e => {
            let pngSplash = splash.toPNG()
            saveToDesktop( pngSplash, 'png' )
          }
          const toJpg = e => {
            let jpgSplash = splash.toJPEG(100)
            saveToDesktop( jpgSplash, 'jpg' )
          }
    
        </script>
      </body>
    </html>

## 5、clipboard（剪贴板） ##

### 5.1 index.html ###

<!DOCTYPE html>
    <html>
      <head>
        <meta charset="UTF-8">
        <meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline'">
        <title>Hello World!</title>
      </head>
      <body>
        <h1>Hello World!</h1>
    
        
        We are using Node.js <strong><script>document.write( process.versions.node)</script></strong>,
        and Electron <strong><script>document.write( process.versions.electron )</script></strong>.
    
        <br><button onclick="makeUpper()">Make clipboard uppercase</button>
        <br><button onclick="showImage()">Show clipboard image</button>
    
        <br><img src="" id="cbImage">
    
        <script>
    
          const { clipboard } = require('electron')
    
          console.log( clipboard.readText() )
    
          const showImage = e => {
            let image = clipboard.readImage()
            document.getElementById('cbImage').src = image.toDataURL()
          }
    
          const makeUpper = e => {
            let cbText = clipboard.readText()
            clipboard.writeText( cbText.toUpperCase() )
          }
    
        </script>
      </body>
    </html>

### 5.2 main.js ###

// Modules
    const {app, BrowserWindow, clipboard} = require('electron')
    
    // Keep a global reference of the window object, if you don't, the window will
    // be closed automatically when the JavaScript object is garbage collected.
    let mainWindow
    
    // Create a new BrowserWindow when `app` is ready
    function createWindow () {
    
      clipboard.writeText('Hello from the main process!')
    
      mainWindow = new BrowserWindow({
        width: 1000, height: 800,
        webPreferences: { nodeIntegration: true }
      })
    
      // Load index.html into the new BrowserWindow
      mainWindow.loadFile('index.html')
    
      // Open DevTools - Remove for PRODUCTION!
      mainWindow.webContents.openDevTools();
    
      // Listen for window being closed
      mainWindow.on('closed',  () => {
        mainWindow = null
      })
    }
    
    // Electron `app` is ready
    app.on('ready', createWindow)
    
    // Quit when all windows are closed - (Not macOS - Darwin)
    app.on('window-all-closed', () => {
      if (process.platform !== 'darwin') app.quit()
    })
    
    // When app icon is clicked and app is running, (macOS) recreate the BrowserWindow
    app.on('activate', () => {
      if (mainWindow === null) createWindow()
    })