[polymer] interop with polymer-element and polymer.js

samples/third_party/todomvc/web/lib-elements/polymer-selection.html

+<!--
+Copyright 2013 The Polymer Authors. All rights reserved.
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file.
+-->
+<!--
+/**
+ * @module Polymer Elements
+ */
+-->
+<!--
+/**
+ * The polymer-selection element is used to manage selection state. It has no
+ * visual appearance and is typically used in conjuneciton with another element.
+ * For example, <a href="polymer-selector.html">polymer-selector</a>
+ * use a polymer-selection to manage selection.
+ *
+ * To mark an item as selected, call the select(item) method on
+ * polymer-selection. Notice that the item itself is an argument to this method.
+ * The polymer-selection element manages selection state for any given set of
+ * items. When an item is selected, the `polymer-select` event is fired.
+ * The attribute "multi" indicates if multiple items can be selected at once.
+ *
+ * Example:
+ *
+ *     <polymer-element name="selection-example">
+ *        <template>
+ *          <style>
+ *            ::-webkit-distributed(> .selected) {
+ *              font-weight: bold;
+ *              font-style: italic;
+ *            }
+ *          </style>
+ *          <ul on-tap="{{itemTapAction}}">
+ *            <content></content>
+ *          </ul>
+ *          <polymer-selection id="selection" multi on-polymer-select="{{selectAction}}"></polymer-selection>
+ *        </template>
+ *        <script>
+ *          Polymer('selection-example', {
+ *            itemTapAction: function(e) {
+ *              this.$.selection.select(e.target);
+ *            },
+ *            selectAction: function(e, detail) {
+ *              detail.item.classList.toggle('selected', detail.isSelected);
+ *            }
+ *          });
+ *        </script>
+ *     </polymer-element>
+ *
+ *     <selection-example>
+ *       <li>Red</li>
+ *       <li>Green</li>
+ *       <li>Blue</li>
+ *     </selection-example>
+ *
+ * @class polymer-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 polymer-select
+ * @param {Object} detail
+ *   @param {boolean} detail.isSelected true for selection and false for deselection
+ *   @param {Object} detail.item the item element
+ */
+-->
+<polymer-element name="polymer-selection" attributes="multi">
+  <template>
+    <style>
+      :host {
+        display: none !important;
+      }
+    </style>
+  </template>
+  <script>
+    Polymer('polymer-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("polymer-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>