remoting/webapp/clipboard.js

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * @fileoverview
   7  * A class for moving clipboard items between the plugin and the OS.
   8  */
   9
  10 'use strict';
  11
  12 /** @suppress {duplicate} */
  13 var remoting = remoting || {};
  14
  15 /**
  16  * @constructor
  17  */
  18 remoting.Clipboard = function() {
  19 };
  20
  21 /**
  22  * @private
  23  * @enum {string}
  24  */
  25 remoting.Clipboard.prototype.ItemTypes = {
  26   TEXT_TYPE: 'text/plain',
  27   TEXT_UTF8_TYPE: 'text/plain; charset=UTF-8'
  28 };
  29
  30 /**
  31  * @private
  32  * @type {string}
  33  */
  34 remoting.Clipboard.prototype.itemToHostText = "";
  35
  36 /**
  37  * @private
  38  * @type {string}
  39  */
  40 remoting.Clipboard.prototype.itemFromHostText = "";
  41
  42 /**
  43  * @private
  44  * @type {boolean}
  45  */
  46 remoting.Clipboard.prototype.itemFromHostTextPending = false;
  47
  48 /**
  49  * @private
  50  * @type {boolean}
  51  */
  52 remoting.Clipboard.prototype.blockOneClipboardSend_ = false;
  53
  54 /**
  55  * Notifies this object that a session has started.
  56  *
  57  * @return {void} Nothing.
  58  */
  59 remoting.Clipboard.prototype.startSession = function() {
  60   // Clear the store of items sent and received. Those items now relate to a
  61   // previous session.
  62   this.itemToHostText = "";
  63   this.itemFromHostText = "";
  64   this.itemFromHostTextPending = false;
  65
  66   // Do a paste operation, but make sure the resulting clipboard data isn't sent
  67   // to the host. This stops the host seeing items that were placed on the
  68   // clipboard before the session began. The user may not have intended such
  69   // items to be sent to the host.
  70   this.blockOneClipboardSend_ = true;
  71   this.initiateToHost();
  72 };
  73
  74 /**
  75  * Accepts a clipboard from the OS, and sends any changed clipboard items to
  76  * the host.
  77  *
  78  * Currently only text items are supported.
  79  *
  80  * @param {remoting.ClipboardData} clipboardData
  81  * @return {void} Nothing.
  82  */
  83 remoting.Clipboard.prototype.toHost = function(clipboardData) {
  84   if (!clipboardData || !clipboardData.types || !clipboardData.getData) {
  85     return;
  86   }
  87   if (!remoting.clientSession || !remoting.clientSession.plugin) {
  88     return;
  89   }
  90   var plugin = remoting.clientSession.plugin;
  91   for (var i = 0; i < clipboardData.types.length; i++) {
  92     var type = clipboardData.types[i];
  93     // The browser presents text clipboard items as 'text/plain'.
  94     if (type == this.ItemTypes.TEXT_TYPE) {
  95       var item = clipboardData.getData(type);
  96       if (!item) {
  97         item = "";
  98       }
  99       // Don't send an item that's already been sent to the host.
 100       // And don't send an item that we received from the host: if we do, we
 101       // may send the same item to and fro indefinitely.
 102       if ((item != this.itemToHostText) && (item != this.itemFromHostText)) {
 103         if (!this.blockOneClipboardSend_) {
 104           // The plugin's JSON reader emits UTF-8.
 105           plugin.sendClipboardItem(this.ItemTypes.TEXT_UTF8_TYPE, item);
 106         }
 107         this.itemToHostText = item;
 108       }
 109     }
 110   }
 111   this.blockOneClipboardSend_ = false;
 112 };
 113
 114 /**
 115  * Accepts a clipboard item from the host, and stores it so that toOs() will
 116  * subsequently send it to the OS clipboard.
 117  *
 118  * @param {string} mimeType The MIME type of the clipboard item.
 119  * @param {string} item The clipboard item.
 120  * @return {void} Nothing.
 121  */
 122 remoting.Clipboard.prototype.fromHost = function(mimeType, item) {
 123   // The plugin's JSON layer will correctly convert only UTF-8 data sent from
 124   // the host.
 125   if (mimeType != this.ItemTypes.TEXT_UTF8_TYPE) {
 126     return;
 127   }
 128   if (item == this.itemToHostText) {
 129     return;
 130   }
 131   this.itemFromHostText = item;
 132   this.itemFromHostTextPending = true;
 133   this.initiateToOs();
 134 };
 135
 136 /**
 137  * Moves any pending clipboard items to a ClipboardData object.
 138  *
 139  * @param {remoting.ClipboardData} clipboardData
 140  * @return {boolean} Whether any clipboard items were moved to the ClipboardData
 141  *     object.
 142  */
 143 remoting.Clipboard.prototype.toOs = function(clipboardData) {
 144   if (!this.itemFromHostTextPending) {
 145     return false;
 146   }
 147   // The JSON layer between the plugin and this webapp converts UTF-8 to the
 148   // JS string encoding. The browser will convert JS strings to the correct
 149   // encoding, per OS and locale conventions, provided the data type is
 150   // 'text/plain'.
 151   clipboardData.setData(this.ItemTypes.TEXT_TYPE, this.itemFromHostText);
 152   this.itemFromHostTextPending = false;
 153   return true;
 154 };
 155
 156 /**
 157  * Initiates the process of sending any fresh items on the OS clipboard, to the
 158  * host.
 159  *
 160  * This method makes the browser fire a paste event, which provides access to
 161  * the OS clipboard. That event will be caught by a handler in the document,
 162  * which will call toHost().
 163  */
 164 remoting.Clipboard.prototype.initiateToHost = function() {
 165   // It would be cleaner to send a paste command to the plugin element,
 166   // but that's not supported.
 167   document.execCommand("paste");
 168 };
 169
 170 /**
 171  * Initiates the process of sending any items freshly received from the host,
 172  * to the OS clipboard.
 173  *
 174  * This method makes the browser fire a copy event, which provides access to
 175  * the OS clipboard. That event will be caught by a handler in the document,
 176  * which will call toOs().
 177  */
 178 remoting.Clipboard.prototype.initiateToOs = function() {
 179   // It would be cleaner to send a paste command to the plugin element,
 180   // but that's not supported.
 181   document.execCommand("copy");
 182 };
 183
 184 /** @type {remoting.Clipboard} */
 185 remoting.clipboard = null;