SGH / 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-styles/color.html">
<link rel="import" href="../paper-behaviors/paper-checked-element-behavior.html">

<!--
Material design: [Checkbox](https://www.google.com/design/spec/components/selection-controls.html#selection-controls-checkbox)

`paper-checkbox` is a button that can be either checked or unchecked.  User
can tap the checkbox to check or uncheck it.  Usually you use checkboxes
to allow user to select multiple options from a set.  If you have a single
ON/OFF option, avoid using a single checkbox and use `paper-toggle-button`
instead.

Example:

    <paper-checkbox>label</paper-checkbox>

    <paper-checkbox checked> label</paper-checkbox>

### Styling

The following custom properties and mixins are available for styling:

Custom property | Description | Default
----------------|-------------|----------
`--paper-checkbox-unchecked-background-color` | Checkbox background color when the input is not checked | `transparent`
`--paper-checkbox-unchecked-color` | Checkbox border color when the input is not checked | `--primary-text-color`
`--paper-checkbox-unchecked-ink-color` | Selected/focus ripple color when the input is not checked | `--primary-text-color`
`--paper-checkbox-checked-color` | Checkbox color when the input is checked | `--default-primary-color`
`--paper-checkbox-checked-ink-color` | Selected/focus ripple color when the input is checked | `--default-primary-color`
`--paper-checkbox-checkmark-color` | Checkmark color | `white`
`--paper-checkbox-label-color` | Label color | `--primary-text-color`
`--paper-checkbox-label-spacing` | Spacing between the label and the checkbox | `8px`
`--paper-checkbox-error-color` | Checkbox color when invalid | `--google-red-500`

@demo demo/index.html
-->

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

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

      .hidden {
        display: none;
      }

      #checkboxContainer {
        display: inline-block;
        position: relative;
        width: 18px;
        height: 18px;
        cursor: pointer;
        -webkit-transform: translateZ(0);
        transform: translateZ(0);
        vertical-align: middle;
        background-color: var(--paper-checkbox-unchecked-background-color, transparent);
      }

      #ink {
        position: absolute;
        top: -15px;
        left: -15px;
        width: 48px;
        height: 48px;
        color: var(--paper-checkbox-unchecked-ink-color, --primary-text-color);
        opacity: 0.6;
        pointer-events: none;
      }

      :host-context([dir="rtl"]) #ink {
        right: -15px;
        left: auto;
      }

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

      #checkbox {
        position: relative;
        box-sizing: border-box;
        height: 100%;
        border: solid 2px;
        border-color: var(--paper-checkbox-unchecked-color, --primary-text-color);
        border-radius: 2px;
        pointer-events: none;
        -webkit-transition: background-color 140ms, border-color 140ms;
        transition: background-color 140ms, border-color 140ms;
      }

      /* checkbox checked animations */
      #checkbox.checked #checkmark {
        -webkit-animation: checkmark-expand 140ms ease-out forwards;
        animation: checkmark-expand 140ms ease-out forwards;
      }

      @-webkit-keyframes checkmark-expand {
        0% {
          top: 9px;
          left: 6px;
          width: 0px;
          height: 0px;
        }
        100% {
          top: -1px;
          left: 4px;
          width: 5px;
          height: 10px;
        }
      }

      @keyframes checkmark-expand {
        0% {
          top: 9px;
          left: 6px;
          width: 0px;
          height: 0px;
        }
        100% {
          top: -1px;
          left: 4px;
          width: 5px;
          height: 10px;
        }
      }

      #checkbox.checked {
        background-color: var(--paper-checkbox-checked-color, --default-primary-color);
        border-color: var(--paper-checkbox-checked-color, --default-primary-color);
      }

      #checkmark {
        -webkit-transform: rotate(45deg);
        transform: rotate(45deg);
        position: absolute;
        top: -1px;
        left: 4px;
        width: 5px;
        height: 10px;
        border-style: solid;
        border-top: none;
        border-left: none;
        border-right-width: 2px;
        border-bottom-width: 2px;
        border-color: var(--paper-checkbox-checkmark-color, white);
      }

      /* label */
      #checkboxLabel {
        position: relative;
        display: inline-block;
        vertical-align: middle;
        padding-left: var(--paper-checkbox-label-spacing, 8px);
        white-space: normal;
        pointer-events: none;
        color: var(--paper-checkbox-label-color, --primary-text-color);
      }

      :host-context([dir="rtl"]) #checkboxLabel {
        padding-right: var(--paper-checkbox-label-spacing, 8px);
        padding-left: 0;
      }

      #checkboxLabel[hidden] {
        display: none;
      }

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

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

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

      :host([disabled]) #checkboxLabel  {
        opacity: 0.65;
      }

      /* invalid state */
      #checkbox.invalid:not(.checked) {
        border-color: var(--paper-checkbox-error-color, --google-red-500);
      }
    </style>

    <div id="checkboxContainer">
      <div id="checkbox" class$="[[_computeCheckboxClass(checked, invalid)]]">
        <div id="checkmark" class$="[[_computeCheckmarkClass(checked)]]"></div>
      </div>
    </div>

    <div id="checkboxLabel"><content></content></div>
  </template>

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

      behaviors: [
        Polymer.PaperCheckedElementBehavior
      ],

      hostAttributes: {
        role: 'checkbox',
        '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: {
          type: String,
          value: 'aria-checked'
        }
      },

      _computeCheckboxClass: function(checked, invalid) {
        var className = '';
        if (checked) {
          className += 'checked ';
        }
        if (invalid) {
          className += 'invalid';
        }
        return className;
      },

      _computeCheckmarkClass: function(checked) {
        return checked ? '' : 'hidden';
      },

      // create ripple inside the checkboxContainer
      _createRipple: function() {
        this._rippleContainer = this.$.checkboxContainer;
        return Polymer.PaperInkyFocusBehaviorImpl._createRipple.call(this);
      }

    });
  </script>
</dom-module>