electron/lib/browser/api/web-contents.js

'use strict'

const { EventEmitter } = require('events')
const electron = require('electron')
const path = require('path')
const url = require('url')
const { app, ipcMain, session, NavigationController, deprecate } = electron

const errorUtils = require('@electron/internal/common/error-utils')

// session is not used here, the purpose is to make sure session is initalized
// before the webContents module.
// eslint-disable-next-line
session

let nextId = 0
const getNextId = function () {
  return ++nextId
}

// Stock page sizes
const PDFPageSizes = {
  A5: {
    custom_display_name: 'A5',
    height_microns: 210000,
    name: 'ISO_A5',
    width_microns: 148000
  },
  A4: {
    custom_display_name: 'A4',
    height_microns: 297000,
    name: 'ISO_A4',
    is_default: 'true',
    width_microns: 210000
  },
  A3: {
    custom_display_name: 'A3',
    height_microns: 420000,
    name: 'ISO_A3',
    width_microns: 297000
  },
  Legal: {
    custom_display_name: 'Legal',
    height_microns: 355600,
    name: 'NA_LEGAL',
    width_microns: 215900
  },
  Letter: {
    custom_display_name: 'Letter',
    height_microns: 279400,
    name: 'NA_LETTER',
    width_microns: 215900
  },
  Tabloid: {
    height_microns: 431800,
    name: 'NA_LEDGER',
    width_microns: 279400,
    custom_display_name: 'Tabloid'
  }
}

// Default printing setting
const defaultPrintingSetting = {
  pageRage: [],
  mediaSize: {},
  landscape: false,
  color: 2,
  headerFooterEnabled: false,
  marginsType: 0,
  isFirstRequest: false,
  requestID: getNextId(),
  previewModifiable: true,
  printToPDF: true,
  printWithCloudPrint: false,
  printWithPrivet: false,
  printWithExtension: false,
  deviceName: 'Save as PDF',
  generateDraftData: true,
  fitToPageEnabled: false,
  scaleFactor: 1,
  dpiHorizontal: 72,
  dpiVertical: 72,
  rasterizePDF: false,
  duplex: 0,
  copies: 1,
  collate: true,
  shouldPrintBackgrounds: false,
  shouldPrintSelectionOnly: false
}

// JavaScript implementations of WebContents.
const binding = process.atomBinding('web_contents')
const { WebContents } = binding

Object.setPrototypeOf(NavigationController.prototype, EventEmitter.prototype)
Object.setPrototypeOf(WebContents.prototype, NavigationController.prototype)

// WebContents::send(channel, args..)
// WebContents::sendToAll(channel, args..)
WebContents.prototype.send = function (channel, ...args) {
  if (channel == null) throw new Error('Missing required channel argument')
  return this._send(false, channel, args)
}
WebContents.prototype.sendToAll = function (channel, ...args) {
  if (channel == null) throw new Error('Missing required channel argument')
  return this._send(true, channel, args)
}

// Following methods are mapped to webFrame.
const webFrameMethods = [
  'insertCSS',
  'insertText',
  'setLayoutZoomLevelLimits',
  'setVisualZoomLevelLimits'
]

const asyncWebFrameMethods = function (requestId, method, callback, ...args) {
  return new Promise((resolve, reject) => {
    this.send('ELECTRON_INTERNAL_RENDERER_ASYNC_WEB_FRAME_METHOD', requestId, method, args)
    ipcMain.once(`ELECTRON_INTERNAL_BROWSER_ASYNC_WEB_FRAME_RESPONSE_${requestId}`, function (event, error, result) {
      if (error == null) {
        if (typeof callback === 'function') callback(result)
        resolve(result)
      } else {
        reject(errorUtils.deserialize(error))
      }
    })
  })
}

for (const method of webFrameMethods) {
  WebContents.prototype[method] = function (...args) {
    this.send('ELECTRON_INTERNAL_RENDERER_WEB_FRAME_METHOD', method, args)
  }
}

// Make sure WebContents::executeJavaScript would run the code only when the
// WebContents has been loaded.
WebContents.prototype.executeJavaScript = function (code, hasUserGesture, callback) {
  const requestId = getNextId()

  if (typeof hasUserGesture === 'function') {
    // Shift.
    callback = hasUserGesture
    hasUserGesture = null
  }

  if (hasUserGesture == null) {
    hasUserGesture = false
  }

  if (this.getURL() && !this.isLoadingMainFrame()) {
    return asyncWebFrameMethods.call(this, requestId, 'executeJavaScript', callback, code, hasUserGesture)
  } else {
    return new Promise((resolve, reject) => {
      this.once('did-stop-loading', () => {
        asyncWebFrameMethods.call(this, requestId, 'executeJavaScript', callback, code, hasUserGesture).then(resolve).catch(reject)
      })
    })
  }
}

WebContents.prototype.takeHeapSnapshot = function (filePath) {
  return new Promise((resolve, reject) => {
    const channel = `ELECTRON_TAKE_HEAP_SNAPSHOT_RESULT_${getNextId()}`
    ipcMain.once(channel, (event, success) => {
      if (success) {
        resolve()
      } else {
        reject(new Error('takeHeapSnapshot failed'))
      }
    })
    if (!this._takeHeapSnapshot(filePath, channel)) {
      ipcMain.emit(channel, false)
    }
  })
}

// Translate the options of printToPDF.
WebContents.prototype.printToPDF = function (options, callback) {
  const printingSetting = Object.assign({}, defaultPrintingSetting)
  if (options.landscape) {
    printingSetting.landscape = options.landscape
  }
  if (options.marginsType) {
    printingSetting.marginsType = options.marginsType
  }
  if (options.printSelectionOnly) {
    printingSetting.shouldPrintSelectionOnly = options.printSelectionOnly
  }
  if (options.printBackground) {
    printingSetting.shouldPrintBackgrounds = options.printBackground
  }

  if (options.pageSize) {
    const pageSize = options.pageSize
    if (typeof pageSize === 'object') {
      if (!pageSize.height || !pageSize.width) {
        return callback(new Error('Must define height and width for pageSize'))
      }
      // Dimensions in Microns
      // 1 meter = 10^6 microns
      printingSetting.mediaSize = {
        name: 'CUSTOM',
        custom_display_name: 'Custom',
        height_microns: Math.ceil(pageSize.height),
        width_microns: Math.ceil(pageSize.width)
      }
    } else if (PDFPageSizes[pageSize]) {
      printingSetting.mediaSize = PDFPageSizes[pageSize]
    } else {
      return callback(new Error(`Does not support pageSize with ${pageSize}`))
    }
  } else {
    printingSetting.mediaSize = PDFPageSizes['A4']
  }

  this._printToPDF(printingSetting, callback)
}

WebContents.prototype.getZoomLevel = function (callback) {
  if (typeof callback !== 'function') {
    throw new Error('Must pass function as an argument')
  }
  process.nextTick(() => {
    const zoomLevel = this._getZoomLevel()
    callback(zoomLevel)
  })
}

WebContents.prototype.loadFile = function (filePath, options = {}) {
  if (typeof filePath !== 'string') {
    throw new Error('Must pass filePath as a string')
  }
  const { query, search, hash } = options

  return this.loadURL(url.format({
    protocol: 'file',
    slashes: true,
    pathname: path.resolve(app.getAppPath(), filePath),
    query,
    search,
    hash
  }))
}

WebContents.prototype.getZoomFactor = function (callback) {
  if (typeof callback !== 'function') {
    throw new Error('Must pass function as an argument')
  }
  process.nextTick(() => {
    const zoomFactor = this._getZoomFactor()
    callback(zoomFactor)
  })
}

// Add JavaScript wrappers for WebContents class.
WebContents.prototype._init = function () {
  // The navigation controller.
  NavigationController.call(this, this)

  // Every remote callback from renderer process would add a listenter to the
  // render-view-deleted event, so ignore the listenters warning.
  this.setMaxListeners(0)

  // Dispatch IPC messages to the ipc module.
  this.on('ipc-message', function (event, [channel, ...args]) {
    ipcMain.emit(channel, event, ...args)
  })
  this.on('ipc-message-sync', function (event, [channel, ...args]) {
    Object.defineProperty(event, 'returnValue', {
      set: function (value) {
        return event.sendReply([value])
      },
      get: function () {}
    })
    ipcMain.emit(channel, event, ...args)
  })

  // Handle context menu action request from pepper plugin.
  this.on('pepper-context-menu', function (event, params, callback) {
    // Access Menu via electron.Menu to prevent circular require.
    const menu = electron.Menu.buildFromTemplate(params.menu)
    menu.popup({
      window: event.sender.getOwnerBrowserWindow(),
      x: params.x,
      y: params.y,
      callback
    })
  })

  deprecate.event(this, 'did-get-response-details', '-did-get-response-details')
  deprecate.event(this, 'did-get-redirect-request', '-did-get-redirect-request')

  // The devtools requests the webContents to reload.
  this.on('devtools-reload-page', function () {
    this.reload()
  })

  app.emit('web-contents-created', {}, this)
}

// JavaScript wrapper of Debugger.
const { Debugger } = process.atomBinding('debugger')

Object.setPrototypeOf(Debugger.prototype, EventEmitter.prototype)

// Public APIs.
module.exports = {
  create (options = {}) {
    return binding.create(options)
  },

  fromId (id) {
    return binding.fromId(id)
  },

  getFocusedWebContents () {
    let focused = null
    for (const contents of binding.getAllWebContents()) {
      if (!contents.isFocused()) continue
      if (focused == null) focused = contents
      // Return webview web contents which may be embedded inside another
      // web contents that is also reporting as focused
      if (contents.getType() === 'webview') return contents
    }
    return focused
  },

  getAllWebContents () {
    return binding.getAllWebContents()
  }
}