extensions/renderer/resources/guest_view/guest_view_attributes.js

   1 // Copyright 2015 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 // This module implements the base attributes of the GuestView tags.
   6
   7 // -----------------------------------------------------------------------------
   8 // Attribute object.
   9
  10 // Default implementation of a GuestView attribute.
  11 function Attribute(name, view) {
  12   this.dirty = false;
  13   this.ignoreMutation = false;
  14   this.name = name;
  15   this.view = view;
  16
  17   this.defineProperty();
  18 }
  19
  20 // Retrieves and returns the attribute's value.
  21 Attribute.prototype.getValue = function() {
  22   return this.view.element.getAttribute(this.name) || '';
  23 };
  24
  25 // Retrieves and returns the attribute's value if it has been dirtied since
  26 // the last time this method was called. Returns null otherwise.
  27 Attribute.prototype.getValueIfDirty = function() {
  28   if (!this.dirty)
  29     return null;
  30   this.dirty = false;
  31   return this.getValue();
  32 };
  33
  34 // Sets the attribute's value.
  35 Attribute.prototype.setValue = function(value) {
  36   this.view.element.setAttribute(this.name, value || '');
  37 };
  38
  39 // Changes the attribute's value without triggering its mutation handler.
  40 Attribute.prototype.setValueIgnoreMutation = function(value) {
  41   this.ignoreMutation = true;
  42   this.setValue(value);
  43   this.ignoreMutation = false;
  44 };
  45
  46 // Defines this attribute as a property on the view's element.
  47 Attribute.prototype.defineProperty = function() {
  48   $Object.defineProperty(this.view.element, this.name, {
  49     get: function() {
  50       return this.getValue();
  51     }.bind(this),
  52     set: function(value) {
  53       this.setValue(value);
  54     }.bind(this),
  55     enumerable: true
  56   });
  57 };
  58
  59 // Called when the attribute's value changes.
  60 Attribute.prototype.maybeHandleMutation = function(oldValue, newValue) {
  61   if (this.ignoreMutation)
  62     return;
  63
  64   this.dirty = true;
  65   this.handleMutation(oldValue, newValue);
  66 };
  67
  68 // Called when a change that isn't ignored occurs to the attribute's value.
  69 Attribute.prototype.handleMutation = function(oldValue, newValue) {};
  70
  71 // Called when the view's element is attached to the DOM tree.
  72 Attribute.prototype.attach = function() {};
  73
  74 // Called when the view's element is detached from the DOM tree.
  75 Attribute.prototype.detach = function() {};
  76
  77 // -----------------------------------------------------------------------------
  78 // BooleanAttribute object.
  79
  80 // An attribute that is treated as a Boolean.
  81 function BooleanAttribute(name, view) {
  82   Attribute.call(this, name, view);
  83 }
  84
  85 BooleanAttribute.prototype.__proto__ = Attribute.prototype;
  86
  87 BooleanAttribute.prototype.getValue = function() {
  88   return this.view.element.hasAttribute(this.name);
  89 };
  90
  91 BooleanAttribute.prototype.setValue = function(value) {
  92   if (!value) {
  93     this.view.element.removeAttribute(this.name);
  94   } else {
  95     this.view.element.setAttribute(this.name, '');
  96   }
  97 };
  98
  99 // -----------------------------------------------------------------------------
 100 // IntegerAttribute object.
 101
 102 // An attribute that is treated as an integer.
 103 function IntegerAttribute(name, view) {
 104   Attribute.call(this, name, view);
 105 }
 106
 107 IntegerAttribute.prototype.__proto__ = Attribute.prototype;
 108
 109 IntegerAttribute.prototype.getValue = function() {
 110   return parseInt(this.view.element.getAttribute(this.name)) || 0;
 111 };
 112
 113 IntegerAttribute.prototype.setValue = function(value) {
 114   this.view.element.setAttribute(this.name, parseInt(value) || 0);
 115 };
 116
 117 // -----------------------------------------------------------------------------
 118 // ReadOnlyAttribute object.
 119
 120 // An attribute that cannot be changed (externally). The only way to set it
 121 // internally is via |setValueIgnoreMutation|.
 122 function ReadOnlyAttribute(name, view) {
 123   Attribute.call(this, name, view);
 124 }
 125
 126 ReadOnlyAttribute.prototype.__proto__ = Attribute.prototype;
 127
 128 ReadOnlyAttribute.prototype.handleMutation = function(oldValue, newValue) {
 129   this.setValueIgnoreMutation(oldValue);
 130 }
 131
 132 // -----------------------------------------------------------------------------
 133
 134 var GuestViewAttributes = {
 135   Attribute: Attribute,
 136   BooleanAttribute: BooleanAttribute,
 137   IntegerAttribute: IntegerAttribute,
 138   ReadOnlyAttribute: ReadOnlyAttribute
 139 };
 140
 141 // Exports.
 142 exports.GuestViewAttributes = GuestViewAttributes;