polymer-selector.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
 */
/**
 * polymer-selector is used to manage a list of elements that can be selected.
 * The attribute "selected" indicates which item element is being selected.
 * The attribute "multi" indicates if multiple items can be selected at once.
 * Tapping on the item element would fire "polymer-activate" event. Use
 * "polymer-select" event to listen for selection changes.
 *
 * Example:
 *
 *     <polymer-selector selected="0">
 *       <div>Item 1</div>
 *       <div>Item 2</div>
 *       <div>Item 3</div>
 *     </polymer-selector>
 *
 * polymer-selector is not styled.  So one needs to use "polymer-selected" CSS
 * class to style the selected element.
 * 
 *     <style>
 *       .item.polymer-selected {
 *         background: #eee;
 *       }
 *     </style>
 *     ...
 *     <polymer-selector>
 *       <div class="item">Item 1</div>
 *       <div class="item">Item 2</div>
 *       <div class="item">Item 3</div>
 *     </polymer-selector>
 *
 * @class polymer-selector
 * @status stable
 */
/**
 * 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
 */
/**
 * Fired when an item element is tapped.
 * 
 * @event polymer-activate
 * @param {Object} detail
 *   @param {Object} detail.item the item element
 */
-->
<link rel="import" href="../polymer/polymer.html">
<link rel="import" href="../polymer-selection/polymer-selection.html">

<polymer-element name="polymer-selector"
    attributes="selected multi valueattr selectedClass selectedProperty selectedAttribute selectedItem selectedModel selectedIndex notap target itemsSelector activateEvent">
  <template>
    <polymer-selection id="selection" multi="{{multi}}" on-polymer-select="{{selectionSelect}}"></polymer-selection>
    <content id="items" select="*"></content>
  </template>
  <script>
    Polymer('polymer-selector', {
      /**
       * Gets or sets the selected element.  Default to use the index
       * of the item element.
       *
       * If you want a specific attribute value of the element to be
       * used instead of index, set "valueattr" to that attribute name.
       *
       * Example:
       *
       *     <polymer-selector valueattr="label" selected="foo">
       *       <div label="foo"></div>
       *       <div label="bar"></div>
       *       <div label="zot"></div>
       *     </polymer-selector>
       *
       * In multi-selection this should be an array of values.
       *
       * Example:
       *
       *     <polymer-selector id="selector" valueattr="label" multi>
       *       <div label="foo"></div>
       *       <div label="bar"></div>
       *       <div label="zot"></div>
       *     </polymer-selector>
       *
       *     this.$.selector.selected = ['foo', 'zot'];
       *
       * @attribute selected
       * @type Object
       * @default null
       */
      selected: null,
      /**
       * If true, multiple selections are allowed.
       *
       * @attribute multi
       * @type boolean
       * @default false
       */
      multi: false,
      /**
       * Specifies the attribute to be used for "selected" attribute.
       *
       * @attribute valueattr
       * @type string
       * @default 'name'
       */
      valueattr: 'name',
      /**
       * Specifies the CSS class to be used to add to the selected element.
       * 
       * @attribute selectedClass
       * @type string
       * @default 'polymer-selected'
       */
      selectedClass: 'polymer-selected',
      /**
       * Specifies the property to be used to set on the selected element
       * to indicate its active state.
       *
       * @attribute selectedProperty
       * @type string
       * @default ''
       */
      selectedProperty: '',
      /**
       * Specifies the property to be used to set on the selected element
       * to indicate its active state.
       *
       * @attribute selectedProperty
       * @type string
       * @default 'active'
       */
      selectedAttribute: 'active',
      /**
       * Returns the currently selected element. In multi-selection this returns
       * an array of selected elements.
       * 
       * @attribute selectedItem
       * @type Object
       * @default null
       */
      selectedItem: null,
      /**
       * In single selection, this returns the model associated with the
       * selected element.
       * 
       * @attribute selectedModel
       * @type Object
       * @default null
       */
      selectedModel: null,
      /**
       * In single selection, this returns the selected index.
       *
       * @attribute selectedIndex
       * @type number
       * @default -1
       */
      selectedIndex: -1,
      /**
       * The target element that contains items.  If this is not set 
       * polymer-selector is the container.
       * 
       * @attribute target
       * @type Object
       * @default null
       */
      target: null,
      /**
       * This can be used to query nodes from the target node to be used for 
       * selection items.  Note this only works if the 'target' property is set.
       *
       * Example:
       *
       *     <polymer-selector target="{{$.myForm}}" itemsSelector="input[type=radio]"></polymer-selector>
       *     <form id="myForm">
       *       <label><input type="radio" name="color" value="red"> Red</label> <br>
       *       <label><input type="radio" name="color" value="green"> Green</label> <br>
       *       <label><input type="radio" name="color" value="blue"> Blue</label> <br>
       *       <p>color = {{color}}</p>
       *     </form>
       * 
       * @attribute itemSelector
       * @type string
       * @default ''
       */
      itemsSelector: '',
      /**
       * The event that would be fired from the item element to indicate
       * it is being selected.
       *
       * @attribute activateEvent
       * @type string
       * @default 'tap'
       */
      activateEvent: 'tap',
      notap: false,
      ready: function() {
        this.activateListener = this.activateHandler.bind(this);
        this.observer = new MutationObserver(this.updateSelected.bind(this));
        if (!this.target) {
          this.target = this;
        }
      },
      get items() {
        var nodes = this.target !== this ? (this.itemsSelector ? 
            this.target.querySelectorAll(this.itemsSelector) : 
                this.target.children) : this.$.items.getDistributedNodes();
        return Array.prototype.filter.call(nodes || [], function(n) {
          return n && n.localName !== 'template';
        });
      },
      targetChanged: function(old) {
        if (old) {
          this.removeListener(old);
          this.observer.disconnect();
        }
        if (this.target) {
          this.addListener(this.target);
          this.observer.observe(this.target, {childList: true});
        }
      },
      addListener: function(node) {
        node.addEventListener(this.activateEvent, this.activateListener);
      },
      removeListener: function(node) {
        node.removeEventListener(this.activateEvent, this.activateListener);
      },
      get selection() {
        return this.$.selection.getSelection();
      },
      selectedChanged: function() {
        this.updateSelected();
      },
      updateSelected: function() {
        this.validateSelected();
        if (this.multi) {
          this.clearSelection();
          this.selected && this.selected.forEach(function(s) {
            this.valueToSelection(s);
          }, this);
        } else {
          this.valueToSelection(this.selected);
        }
      },
      validateSelected: function() {
        // convert to an array for multi-selection
        if (this.multi && !Array.isArray(this.selected) && 
            this.selected !== null && this.selected !== undefined) {
          this.selected = [this.selected];
        }
      },
      clearSelection: function() {
        if (this.multi) {
          this.selection.slice().forEach(function(s) {
            this.$.selection.setItemSelected(s, false);
          }, this);
        } else {
          this.$.selection.setItemSelected(this.selection, false);
        }
        this.selectedItem = null;
        this.$.selection.clear();
      },
      valueToSelection: function(value) {
        var item = (value === null || value === undefined) ? 
            null : this.items[this.valueToIndex(value)];
        this.$.selection.select(item);
      },
      updateSelectedItem: function() {
        this.selectedItem = this.selection;
      },
      selectedItemChanged: function() {
        if (this.selectedItem) {
          var t = this.selectedItem.templateInstance;
          this.selectedModel = t ? t.model : undefined;
        } else {
          this.selectedModel = null;
        }
        this.selectedIndex = this.selectedItem ? 
            parseInt(this.valueToIndex(this.selected)) : -1;
      },
      valueToIndex: function(value) {
        // find an item with value == value and return it's index
        for (var i=0, items=this.items, c; (c=items[i]); i++) {
          if (this.valueForNode(c) == value) {
            return i;
          }
        }
        // if no item found, the value itself is probably the index
        return value;
      },
      valueForNode: function(node) {
        return node[this.valueattr] || node.getAttribute(this.valueattr);
      },
      // events fired from <polymer-selection> object
      selectionSelect: function(e, detail) {
        this.updateSelectedItem();
        if (detail.item) {
          this.applySelection(detail.item, detail.isSelected);
        }
      },
      applySelection: function(item, isSelected) {
        if (this.selectedClass) {
          item.classList.toggle(this.selectedClass, isSelected);
        }
        if (this.selectedProperty) {
          item[this.selectedProperty] = isSelected;
        }
        if (this.selectedAttribute && item.setAttribute) {
          if (isSelected) {
            item.setAttribute(this.selectedAttribute, '');
          } else {
            item.removeAttribute(this.selectedAttribute);
          }
        }
      },
      // event fired from host
      activateHandler: function(e) {
        if (!this.notap) {
          var i = this.findDistributedTarget(e.target, this.items);
          if (i >= 0) {
            var item = this.items[i];
            var s = this.valueForNode(item) || i;
            if (this.multi) {
              if (this.selected) {
                this.addRemoveSelected(s);
              } else {
                this.selected = [s];
              }
            } else {
              this.selected = s;
            }
            this.asyncFire('polymer-activate', {item: item});
          }
        }
      },
      addRemoveSelected: function(value) {
        var i = this.selected.indexOf(value);
        if (i >= 0) {
          this.selected.splice(i, 1);
        } else {
          this.selected.push(value);
        }
        this.valueToSelection(value);
      },
      findDistributedTarget: function(target, nodes) {
        // find first ancestor of target (including itself) that
        // is in nodes, if any
        while (target && target != this) {
          var i = Array.prototype.indexOf.call(nodes, target);
          if (i >= 0) {
            return i;
          }
          target = target.parentNode;
        }
      }
    });
  </script>
</polymer-element>