paper-dialog-scrollable.html 4.01 KB
<!--
@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="../iron-flex-layout/iron-flex-layout.html">
<link rel="import" href="../paper-styles/default-theme.html">

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

`paper-dialog-scrollable` implements a scrolling area used in a Material Design dialog. It shows
a divider at the top and/or bottom indicating more content, depending on scroll position. Use this
together with elements implementing `Polymer.PaperDialogBehavior`.

    <paper-dialog-impl>
      <h2>Header</h2>
      <paper-dialog-scrollable>
        Lorem ipsum...
      </paper-dialog-scrollable>
      <div class="buttons">
        <paper-button>OK</paper-button>
      </div>
    </paper-dialog-impl>

It shows a top divider after scrolling if it is not the first child in its parent container,
indicating there is more content above. It shows a bottom divider if it is scrollable and it is not
the last child in its parent container, indicating there is more content below. The bottom divider
is hidden if it is scrolled to the bottom.

@group Paper Elements
@element paper-dialog-scrollable
@demo demo/index.html
@hero hero.svg
-->

<dom-module id="paper-dialog-scrollable">

  <style>

    :host {
      display: block;
      position: relative;
    }

    :host(.is-scrolled:not(:first-child))::before {
      content: '';
      position: absolute;
      top: 0;
      left: 0;
      right: 0;
      height: 1px;
      background: var(--divider-color);
    }

    :host(.can-scroll:not(.scrolled-to-bottom):not(:last-child))::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      height: 1px;
      background: var(--divider-color);
    }

    .scrollable {
      padding: 0 24px;

      @apply(--layout-scroll);
      @apply(--paper-dialog-scrollable);
    }

    .fit {
      @apply(--layout-fit);
    }
  </style>

  <template>
    <div id="scrollable" class="scrollable">
      <content></content>
    </div>
  </template>

</dom-module>

<script>

(function() {

  Polymer({

    is: 'paper-dialog-scrollable',

    properties: {

      /**
       * The dialog element that implements `Polymer.PaperDialogBehavior` containing this element.
       * @type {?Node}
       */
      dialogElement: {
        type: Object,
        value: function() {
          return this.parentNode;
        }
      }

    },

    listeners: {
      'scrollable.scroll': '_onScroll',
      'iron-resize': '_onIronResize'
    },

    /**
     * Returns the scrolling element.
     */
    get scrollTarget() {
      return this.$.scrollable;
    },

    attached: function() {
      this.classList.add('no-padding');
      // Set itself to the overlay sizing target
      this.dialogElement.sizingTarget = this.scrollTarget;
      // If the host is sized, fit the scrollable area to the container. Otherwise let it be
      // its natural size.
      requestAnimationFrame(function() {
        if (this.offsetHeight > 0) {
          this.$.scrollable.classList.add('fit');
        }
        this._scroll();
      }.bind(this));
    },

    _scroll: function() {
      this.toggleClass('is-scrolled', this.scrollTarget.scrollTop > 0);
      this.toggleClass('can-scroll', this.scrollTarget.offsetHeight < this.scrollTarget.scrollHeight);
      this.toggleClass('scrolled-to-bottom',
        this.scrollTarget.scrollTop + this.scrollTarget.offsetHeight >= this.scrollTarget.scrollHeight);
    },

    _onScroll: function() {
      this._scroll();
    }

  })

})();

</script>