WebCompDev / COMPONENTS

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<link rel="import" href="../polymer/polymer.html">
<link rel="import" href="../paper-ripple/paper-ripple.html">
<link rel="import" href="../paper-styles/default-theme.html">
<link rel="import" href="../paper-behaviors/paper-inky-focus-behavior.html">
<link rel="import" href="../iron-checked-element-behavior/iron-checked-element-behavior.html">

<!--
`paper-radio-button` is a button that can be either checked or unchecked.
User can tap the radio button to check or uncheck it.

Use a `<paper-radio-group>` to group a set of radio buttons.  When radio buttons
are inside a radio group, exactly one radio button in the group can be checked
at any time.

Example:

    <paper-radio-button></paper-radio-button>
    <paper-radio-button>Item label</paper-radio-button>

### Styling

The following custom properties and mixins are available for styling:

Custom property | Description | Default
----------------|-------------|----------
`--paper-radio-button-unchecked-background-color` | Radio button background color when the input is not checked | `transparent`
`--paper-radio-button-unchecked-color` | Radio button color when the input is not checked | `--primary-text-color`
`--paper-radio-button-unchecked-ink-color` | Selected/focus ripple color when the input is not checked | `--primary-text-color`
`--paper-radio-button-checked-color` | Radio button color when the input is checked | `--default-primary-color`
`--paper-radio-button-checked-ink-color` | Selected/focus ripple color when the input is checked | `--default-primary-color`
`--paper-radio-button-label-color` | Label color | `--primary-text-color`

@group Paper Elements
@element paper-radio-button
@hero hero.svg
@demo demo/index.html
-->

<dom-module id="paper-radio-button">
  <template>
    <style>
      :host {
        display: inline-block;
        white-space: nowrap;
      }

      :host(:focus) {
        outline: none;
      }

      #radioContainer {
        display: inline-block;
        position: relative;
        width: 16px;
        height: 16px;
        cursor: pointer;
        vertical-align: middle;
      }

      :host #ink {
        position: absolute;
        top: -16px;
        left: -16px;
        width: 48px;
        height: 48px;
        color: var(--paper-radio-button-unchecked-ink-color, --primary-text-color);
        opacity: 0.6;
        pointer-events: none;
      }

      :host #ink[checked] {
        color: var(--paper-radio-button-checked-ink-color, --default-primary-color);
      }

      :host #offRadio {
        position: absolute;
        box-sizing: content-box;
        top: 0px;
        left: 0px;
        width: 12px;
        height: 12px;
        border-radius: 50%;
        border: solid 2px;
        background-color: var(--paper-radio-button-unchecked-background-color, transparent);
        border-color: var(--paper-radio-button-unchecked-color, --primary-text-color);
        transition: border-color 0.28s;
      }

      :host #onRadio {
        position: absolute;
        box-sizing: content-box;
        top: 4px;
        left: 4px;
        width: 8px;
        height: 8px;
        border-radius: 50%;
        background-color: var(--paper-radio-button-checked-color, --default-primary-color);
        -webkit-transform: scale(0);
        transform: scale(0);
        transition: -webkit-transform ease 0.28s;
        transition: transform ease 0.28s;
      }

      :host([checked]) #offRadio {
        border-color: var(--paper-radio-button-checked-color, --default-primary-color);
      }

      :host([checked]) #onRadio {
        -webkit-transform: scale(1);
        transform: scale(1);
      }

      #radioLabel {
        position: relative;
        display: inline-block;
        vertical-align: middle;
        margin-left: 10px;
        white-space: normal;
        pointer-events: none;
        color: var(--paper-radio-button-label-color, --primary-text-color);
      }

      #radioLabel[hidden] {
        display: none;
      }

      /* disabled state */
      :host([disabled]) {
        pointer-events: none;
      }

      :host([disabled]) #offRadio {
        border-color: var(--paper-radio-button-unchecked-color, --primary-text-color);
        opacity: 0.5;
      }

      :host([disabled][checked]) #onRadio {
        background-color: var(--paper-radio-button-unchecked-color, --primary-text-color);
        opacity: 0.5;
      }

      :host([disabled]) #radioLabel {
        /* slightly darker than the button, so that it's readable */
        opacity: 0.65;
      }
    </style>

    <div id="radioContainer">
      <div id="offRadio"></div>
      <div id="onRadio"></div>
      <paper-ripple id="ink" class="circle" center checked$="[[checked]]"></paper-ripple>
    </div>

    <div id="radioLabel"><content></content></div>

  </template>

  <script>
    Polymer({
      is: 'paper-radio-button',

      behaviors: [
        Polymer.PaperInkyFocusBehavior,
        Polymer.IronCheckedElementBehavior
      ],

      hostAttributes: {
        role: 'radio',
        'aria-checked': false,
        tabindex: 0
      },

      properties: {
        /**
         * Fired when the checked state changes due to user interaction.
         *
         * @event change
         */

        /**
         * Fired when the checked state changes.
         *
         * @event iron-change
         */

         ariaActiveAttribute: {
           value: 'aria-checked'
         }
      },

      attached: function() {
        this._isReady = true;

        // Don't stomp over a user-set aria-label.
        if (!this.getAttribute('aria-label')) {
          this.updateAriaLabel();
        }
      },

      /**
       * Update the checkbox aria-label. This is a temporary workaround not
       * being able to observe changes in <content>
       * (see: https://github.com/Polymer/polymer/issues/1773)
       *
       * Call this if you manually change the contents of the checkbox
       * and want the aria-label to match the new contents.
       */
      updateAriaLabel: function() {
        this.setAttribute('aria-label', Polymer.dom(this).textContent.trim());
      },

      _buttonStateChanged: function() {
        if (this.disabled) {
          return;
        }
        if (this._isReady) {
          this.checked = this.active;
        }
      }
    })
  </script>

</dom-module>