paper-dropdown-menu.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
-->

<!--

`paper-dropdown-menu` works together with `paper-dropdown` and `core-menu` to
implement a drop-down menu. The currently selected item is displayed in the
control. If no item is selected, the `label` is displayed instead.

The child element with the class `dropdown` will be used as the drop-down
menu. It should be a `paper-dropdown` or other overlay element. You should
also provide a `core-selector` or other selector element, such as `core-menu`,
in the drop-down. You should apply the class `menu` to the selector element.

Example:

    <paper-dropdown-menu label="Your favorite pastry">
        <paper-dropdown class="dropdown">
            <core-menu class="menu">
                <paper-item>Croissant</paper-item>
                <paper-item>Donut</paper-item>
                <paper-item>Financier</paper-item>
                <paper-item>Madeleine</paper-item>
            </core-menu>
        </paper-dropdown>
    </paper-dropdown-menu>

This example renders a drop-down menu with 4 options.

@group Paper Elements
@element paper-dropdown-menu
@extends core-dropdown-base
@mixins Polymer.CoreFocusable https://github.com/polymer/core-focusable
@status unstable
@homepage github.io
-->

<!--
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 deselection
  @param {Object} detail.item the item element
-->
<link href="../polymer/polymer.html" rel="import">

<link href="../core-a11y-keys/core-a11y-keys.html" rel="import">
<link href="../core-dropdown/core-dropdown-base.html" rel="import">
<link href="../core-focusable/core-focusable.html" rel="import">
<link href="../core-icon/core-icon.html" rel="import">
<link href="../core-icons/core-icons.html" rel="import">
<link href="../paper-shadow/paper-shadow.html" rel="import">

<style shim-shadowdom>
  html /deep/ #paper-dropdown-menu-dropdown {
    margin: 12px;
    overflow: visible;
  }

  html /deep/ #paper-dropdown-menu-dropdown #menu {
    padding: 8px 0;
    margin: 0;
  }

  html /deep/ #paper-dropdown-menu-dropdown .menu-container {
    overflow: auto;
    max-height: 100%;
    max-width: 100%;
  }
</style>

<polymer-element name="paper-dropdown-menu" extends="core-dropdown-base" relative layout inline horizontal center tabindex="0">
<template>

  <style>
    :host {
      -moz-user-select: none;
      -ms-user-select: none;
      -webkit-user-select: none;
      user-select: none;
      cursor: pointer;
      padding: 0.5em 0 0.25em;
      margin: 1.1em 0;
      border-bottom: 1px solid #757575;
      outline: none;
    }

    #label:not(.selectedItem), #arrow {
      color: #757575;
    }

    #label {
      overflow: hidden;
      white-space: nowrap;
      text-overflow: ellipsis;
    }
  </style>

  <core-a11y-keys target="{{}}" keys="enter space" on-keys-pressed="{{toggleOverlay}}"></core-a11y-keys>

  <div flex auto id="label">{{selectedItemLabel || label}}</div>
  <core-icon id="arrow" icon="{{opened ? openedIcon : closedIcon}}"></core-icon>

  <content></content>

</template>
<script>

(function() {

  var p = {

    publish: {

      /**
       * A label for the control. The label is displayed if no item is selected.
       *
       * @attribute label
       * @type string
       * @default 'Select an item'
       */
      label: 'Select an item',

      /**
       * The icon to display when the drop-down is opened.
       *
       * @attribute openedIcon
       * @type string
       * @default 'arrow-drop-up'
       */
      openedIcon: 'arrow-drop-up',

      /**
       * The icon to display when the drop-down is closed.
       *
       * @attribute closedIcon
       * @type string
       * @default 'arrow-drop-down'
       */
      closedIcon: 'arrow-drop-down'

    },

    selectedItemLabel: '',

    overlayListeners: {
      'core-overlay-open': 'openAction',
      'core-activate': 'activateAction',
      'core-select': 'selectAction'
    },

    activateAction: function(e) {
      this.opened = false;
    },

    selectAction: function(e) {
      var detail = e.detail;
      if (detail.isSelected) {
        this.$.label.classList.add('selectedItem');
        this.selectedItemLabel = detail.item.label || detail.item.textContent;
      } else {
        this.$.label.classList.remove('selectedItem');
        this.selectedItemLabel = '';
      }
    }

  };

  Polymer.mixin2(p, Polymer.CoreFocusable);
  Polymer(p);

})();

</script>
</polymer-element>