Polymer elements added to third_party/polymer.

third_party/polymer/components/core-selection/core-selection.html

+<!--
+Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
+This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
+The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
+The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
+Code distributed by Google as part of the polymer project is also
+subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
+-->
+<!--
+@group Polymer Core Elements
+
+The `<core-selection>` element is used to manage selection state. It has no
+visual appearance and is typically used in conjunction with another element.
+For example, [core-selector](#core-selector)
+use a `<core-selection>` to manage selection.
+
+To mark an item as selected, call the `select(item)` method on 
+`<core-selection>`. The item itself is an argument to this method.
+
+The `<core-selection>`element manages selection state for any given set of
+items. When an item is selected, the `core-select` event is fired.
+
+The attribute `multi` indicates if multiple items can be selected at once.
+  
+Example:
+ 
+    <polymer-element name="selection-example">
+       <template>
+         <style>
+           polyfill-next-selector { content: ':host > .selected'; }
+           ::content > .selected {
+             font-weight: bold;
+             font-style: italic;
+           }
+         </style>
+         <ul on-tap="{{itemTapAction}}">
+           <content></content>
+         </ul>
+         <core-selection id="selection" multi
+                         on-core-select="{{selectAction}}"></core-selection>
+       </template>
+       <script>
+         Polymer('selection-example', {
+           itemTapAction: function(e, detail, sender) {
+             this.$.selection.select(e.target);
+           },
+           selectAction: function(e, detail, sender) {
+             detail.item.classList.toggle('selected', detail.isSelected);
+           }
+         });
+       </script>
+    </polymer-element>
+
+    <selection-example>
+      <li>Red</li>
+      <li>Green</li>
+      <li>Blue</li>
+    </selection-example>
+ 
+@element core-selection
+-->
+
+<!--
+Fired when an item's selection state is changed. This event is fired both
+when an item is selected or deselected. The `isSelected` detail property
+contains the selection state.
+
+@event core-select
+@param {Object} detail
+  @param {boolean} detail.isSelected true for selection and false for de-selection
+  @param {Object} detail.item the item element
+-->
+<link rel="import" href="../polymer/polymer.html">
+
+<polymer-element name="core-selection" attributes="multi" hidden>
+  <script>
+    Polymer('core-selection', {
+      /**
+       * If true, multiple selections are allowed.
+       *
+       * @attribute multi
+       * @type boolean
+       * @default false
+       */
+      multi: false,
+      ready: function() {
+        this.clear();
+      },
+      clear: function() {
+        this.selection = [];
+      },
+      /**
+       * Retrieves the selected item(s).
+       * @method getSelection
+       * @returns Returns the selected item(s). If the multi property is true,
+       * getSelection will return an array, otherwise it will return 
+       * the selected item or undefined if there is no selection.
+      */
+      getSelection: function() {
+        return this.multi ? this.selection : this.selection[0];
+      },
+      /**
+       * Indicates if a given item is selected.
+       * @method isSelected
+       * @param {any} item The item whose selection state should be checked.
+       * @returns Returns true if `item` is selected.
+      */
+      isSelected: function(item) {
+        return this.selection.indexOf(item) >= 0;
+      },
+      setItemSelected: function(item, isSelected) {
+        if (item !== undefined && item !== null) {
+          if (isSelected) {
+            this.selection.push(item);
+          } else {
+            var i = this.selection.indexOf(item);
+            if (i >= 0) {
+              this.selection.splice(i, 1);
+            }
+          }
+          this.fire("core-select", {isSelected: isSelected, item: item});
+        }
+      },
+      /**
+       * Set the selection state for a given `item`. If the multi property
+       * is true, then the selected state of `item` will be toggled; otherwise
+       * the `item` will be selected.
+       * @method select
+       * @param {any} item: The item to select.
+      */
+      select: function(item) {
+        if (this.multi) {
+          this.toggle(item);
+        } else if (this.getSelection() !== item) {
+          this.setItemSelected(this.getSelection(), false);
+          this.setItemSelected(item, true);
+        }
+      },
+      /**
+       * Toggles the selection state for `item`.
+       * @method toggle
+       * @param {any} item: The item to toggle.
+      */
+      toggle: function(item) {
+        this.setItemSelected(item, !this.isSelected(item));
+      }
+    });
+  </script>
+</polymer-element>