SGH / COMPONENTS

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@license
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This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
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<link rel="import" href="../polymer/polymer.html">
<link rel="import" href="../paper-material/paper-material.html">
<link rel="import" href="../iron-flex-layout/iron-flex-layout.html">

<!--
Material design: [Cards](https://www.google.com/design/spec/components/cards.html)

`paper-card` is a container with a drop shadow.

Example:

    <paper-card heading="Card Title">
      <div class="card-content">Some content</div>
      <div class="card-actions">
        <paper-button>Some action</paper-button>
      </div>
    </paper-card>

Example - top card image:

    <paper-card heading="Card Title" image="/path/to/image.png">
      ...
    </paper-card>

### Accessibility

By default, the `aria-label` will be set to the value of the `heading` attribute.

### Styling

The following custom properties and mixins are available for styling:

Custom property | Description | Default
----------------|-------------|----------
`--paper-card-header-color` | The color of the header text | `#000`
`--paper-card-header` | Mixin applied to the card header section | `{}`
`--paper-card-header-text` | Mixin applied to the title in the card header section | `{}`
`--paper-card-header-image` | Mixin applied to the image in the card header section | `{}`
`--paper-card-header-image-text` | Mixin applied to the text overlapping the image in the card header section | `{}`
`--paper-card-content` | Mixin applied to the card content section| `{}`
`--paper-card-actions` | Mixin applied to the card action section | `{}`
`--paper-card` | Mixin applied to the card | `{}`

@group Paper Elements
@element paper-card
@demo demo/index.html
-->

<dom-module id="paper-card">
  <template>
    <style include="paper-material">
      :host {
        display: inline-block;
        position: relative;
        box-sizing: border-box;

        background: #fff;
        border-radius: 2px;
        @apply(--paper-card);
      }

      /* IE 10 support for HTML5 hidden attr */
      [hidden] {
        display: none !important;
      }

      .header {
        position: relative;
        border-top-left-radius: inherit;
        border-top-right-radius: inherit;
        overflow: hidden;
        @apply(--paper-card-header);
      }

      .header img {
        width: 100%;
        pointer-events: none;
        @apply(--paper-card-header-image);
      }

      .header .title-text {
        padding: 16px;
        font-size: 24px;
        font-weight: bold;
        color: var(--paper-card-header-color, #000);
        @apply(--paper-card-header-text);
      }

      .header .title-text.over-image {
        position: absolute;
        bottom: 0px;
        @apply(--paper-card-header-image-text);
      }

      :host ::content .card-content {
        padding: 16px;
        position:relative;
        @apply(--paper-card-content);
      }

      :host ::content .card-actions {
        border-top: 1px solid #e8e8e8;
        padding: 5px 16px;
        position:relative;
        @apply(--paper-card-actions);
      }
    </style>

    <div class="header">
      <img hidden$="[[!image]]" src="[[image]]">
      <div hidden$="[[!heading]]" class$="[[_computeHeadingClass(image)]]">[[heading]]</div>
    </div>

    <content></content>
  </template>

</dom-module>

<script>

  Polymer({

    is: 'paper-card',

    properties: {

      /**
       * The title of the card.
       */
      heading: {
        type: String,
        value: '',
        observer: '_headingChanged'
      },

      /**
       * The url of the title image of the card.
       */
      image: {
        type: String,
        value: ''
      },

      /**
       * The z-depth of the card, from 0-5.
       */
      elevation: {
        type: Number,
        value: 1,
        reflectToAttribute: true
      },

      /**
       * Set this to true to animate the card shadow when setting a new
       * `z` value.
       */
      animatedShadow: {
        type: Boolean,
        value: false
      },

      /**
       * Read-only property used to pass down the `animatedShadow` value to
       * the underlying paper-material style (since they have different names).
       */
      animated: {
        type: Boolean,
        reflectToAttribute: true,
        readOnly: true,
        computed: '_computeAnimated(animatedShadow)'
      }
    },

    _headingChanged: function(heading) {
      var label = this.getAttribute('aria-label');
      this.setAttribute('aria-label', heading);
    },

    _computeHeadingClass: function(image) {
      var cls = 'title-text';
      if (image)
        cls += ' over-image';
      return cls;
    },

    _computeAnimated: function(animatedShadow) {
      return animatedShadow;
    }
  });
</script>