SGH / COMPONENTS

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<link rel="import" href="../polymer/polymer.html">
<link rel="import" href="../iron-media-query/iron-media-query.html">
<link rel="import" href="../iron-selector/iron-selector.html">
<link rel="import" href="../iron-resizable-behavior/iron-resizable-behavior.html">

<!--
Material design: [Navigation drawer](https://www.google.com/design/spec/patterns/navigation-drawer.html)

`paper-drawer-panel` contains a drawer panel and a main panel.  The drawer
and the main panel are side-by-side with drawer on the left.  When the browser
window size is smaller than the `responsiveWidth`, `paper-drawer-panel`
changes to narrow layout.  In narrow layout, the drawer will be stacked on top
of the main panel.  The drawer will slide in/out to hide/reveal the main
panel.

Use the attribute `drawer` to indicate that the element is the drawer panel and
`main` to indicate that the element is the main panel.

Example:

    <paper-drawer-panel>
      <div drawer> Drawer panel... </div>
      <div main> Main panel... </div>
    </paper-drawer-panel>

The drawer and the main panels are not scrollable.  You can set CSS overflow
property on the elements to make them scrollable or use `paper-header-panel`.

Example:

    <paper-drawer-panel>
      <paper-header-panel drawer>
        <paper-toolbar></paper-toolbar>
        <div> Drawer content... </div>
      </paper-header-panel>
      <paper-header-panel main>
        <paper-toolbar></paper-toolbar>
        <div> Main content... </div>
      </paper-header-panel>
    </paper-drawer-panel>

An element that should toggle the drawer will automatically do so if it's
given the `paper-drawer-toggle` attribute.  Also this element will automatically
be hidden in wide layout.

Example:

    <paper-drawer-panel>
      <paper-header-panel drawer>
        <paper-toolbar>
          <div>Application</div>
        </paper-toolbar>
        <div> Drawer content... </div>
      </paper-header-panel>
      <paper-header-panel main>
        <paper-toolbar>
          <paper-icon-button icon="menu" paper-drawer-toggle></paper-icon-button>
          <div>Title</div>
        </paper-toolbar>
        <div> Main content... </div>
      </paper-header-panel>
    </paper-drawer-panel>

To position the drawer to the right, add `right-drawer` attribute.

    <paper-drawer-panel right-drawer>
      <div drawer> Drawer panel... </div>
      <div main> Main panel... </div>
    </paper-drawer-panel>

### Styling

To change the main container:

    paper-drawer-panel {
      --paper-drawer-panel-main-container: {
        background-color: gray;
      };
    }

To change the drawer container when it's in the left side:

    paper-drawer-panel {
      --paper-drawer-panel-left-drawer-container: {
        background-color: white;
      };
    }

To change the drawer container when it's in the right side:

    paper-drawer-panel {
      --paper-drawer-panel-right-drawer-container: {
        background-color: white;
      };
    }

To customize the scrim:

    paper-drawer-panel {
      --paper-drawer-panel-scrim: {
        background-color: red;
      };
    }

The following custom properties and mixins are available for styling:

Custom property | Description | Default
----------------|-------------|----------
`--paper-drawer-panel-scrim-opacity` | Scrim opacity | 1
`--paper-drawer-panel-drawer-container` | Mixin applied to drawer container | {}
`--paper-drawer-panel-left-drawer-container` | Mixin applied to container when it's in the left side | {}
`--paper-drawer-panel-main-container` | Mixin applied to main container | {}
`--paper-drawer-panel-right-drawer-container` | Mixin applied to container when it's in the right side | {}
`--paper-drawer-panel-scrim` | Mixin applied to scrim | {}

@group Paper elements
@element paper-drawer-panel
@demo demo/index.html
@hero hero.svg
-->

<dom-module id="paper-drawer-panel">
  <template>
    <style>
      :host {
        display: block;
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        overflow: hidden;
      }

      iron-selector > #drawer {
        position: absolute;
        top: 0;
        left: 0;
        height: 100%;
        background-color: white;

        -moz-box-sizing: border-box;
        box-sizing: border-box;

        @apply(--paper-drawer-panel-drawer-container);
      }

      .transition > #drawer {
        transition: -webkit-transform ease-in-out 0.3s, width ease-in-out 0.3s, visibility 0.3s;
        transition: transform ease-in-out 0.3s, width ease-in-out 0.3s, visibility 0.3s;
      }

      .left-drawer > #drawer {
        @apply(--paper-drawer-panel-left-drawer-container);
      }

      .right-drawer > #drawer {
        left: auto;
        right: 0;

        @apply(--paper-drawer-panel-right-drawer-container);
      }

      iron-selector > #main {
        position: absolute;
        top: 0;
        right: 0;
        bottom: 0;

        @apply(--paper-drawer-panel-main-container);
      }

      .transition > #main {
        transition: left ease-in-out 0.3s, padding ease-in-out 0.3s;
      }

      .right-drawer > #main {
        left: 0;
      }

      .right-drawer.transition > #main {
        transition: right ease-in-out 0.3s, padding ease-in-out 0.3s;
      }

      #main > ::content > [main] {
        height: 100%;
      }

      #drawer > ::content > [drawer] {
        height: 100%;
      }

      #scrim {
        position: absolute;
        top: 0;
        right: 0;
        bottom: 0;
        left: 0;
        visibility: hidden;
        opacity: 0;
        transition: opacity ease-in-out 0.38s, visibility ease-in-out 0.38s;
        background-color: rgba(0, 0, 0, 0.3);

        @apply(--paper-drawer-panel-scrim);
      }

      .narrow-layout > #drawer {
        will-change: transform;
      }

      .narrow-layout > #drawer.iron-selected {
        box-shadow: 2px 2px 4px rgba(0, 0, 0, 0.15);
      }

      .right-drawer.narrow-layout > #drawer.iron-selected {
        box-shadow: -2px 2px 4px rgba(0, 0, 0, 0.15);
      }

      .narrow-layout > #drawer > ::content > [drawer] {
        border: 0;
      }

      .left-drawer.narrow-layout > #drawer:not(.iron-selected) {
        -webkit-transform: translateX(-100%);
        transform: translateX(-100%);
      }

      .right-drawer.narrow-layout > #drawer:not(.iron-selected) {
        left: auto;
        visibility: hidden;

        -webkit-transform: translateX(100%);
        transform: translateX(100%);
      }

      .right-drawer.narrow-layout.dragging > #drawer:not(.iron-selected),
      .right-drawer.narrow-layout.peeking > #drawer:not(.iron-selected) {
        visibility: visible;
      }

      .narrow-layout > #main {
        padding: 0;
      }

      .right-drawer.narrow-layout > #main {
        left: 0;
        right: 0;
      }

      .narrow-layout > #main:not(.iron-selected) > #scrim,
      .dragging > #main > #scrim {
        visibility: visible;
        opacity: var(--paper-drawer-panel-scrim-opacity, 1);
      }

      .narrow-layout > #main > * {
        margin: 0;
        min-height: 100%;
        left: 0;
        right: 0;

        -moz-box-sizing: border-box;
        box-sizing: border-box;
      }

      iron-selector:not(.narrow-layout) #main ::content [paper-drawer-toggle] {
        display: none;
      }
    </style>

    <iron-media-query
        id="mq"
        on-query-matches-changed="_onQueryMatchesChanged"
        query="[[_computeMediaQuery(forceNarrow, responsiveWidth)]]">
    </iron-media-query>

    <iron-selector
        attr-for-selected="id"
        class$="[[_computeIronSelectorClass(narrow, _transition, dragging, rightDrawer, peeking)]]"
        activate-event=""
        selected="[[selected]]">

      <div id="main" style$="[[_computeMainStyle(narrow, rightDrawer, drawerWidth)]]" on-transitionend="_onMainTransitionEnd">
        <content select="[main]"></content>
        <div id="scrim" on-tap="closeDrawer"></div>
      </div>

      <div id="drawer" style$="[[_computeDrawerStyle(drawerWidth)]]">
        <content select="[drawer]"></content>
      </div>

    </iron-selector>
  </template>

  <script>
    (function() {
      'use strict';

      // this would be the only `paper-drawer-panel` in
      // the whole app that can be in `dragging` state
      var sharedPanel = null;

      function classNames(obj) {
        var classes = [];
        for (var key in obj) {
          if (obj.hasOwnProperty(key) && obj[key]) {
            classes.push(key);
          }
        }

        return classes.join(' ');
      }

      Polymer({

        is: 'paper-drawer-panel',

        behaviors: [Polymer.IronResizableBehavior],

        /**
         * Fired when the narrow layout changes.
         *
         * @event paper-responsive-change {{narrow: boolean}} detail -
         *     narrow: true if the panel is in narrow layout.
         */

        /**
         * Fired when the a panel is selected.
         *
         * Listening for this event is an alternative to observing changes in the `selected` attribute.
         * This event is fired both when a panel is selected.
         *
         * @event iron-select {{item: Object}} detail -
         *     item: The panel that the event refers to.
         */

        /**
         * Fired when a panel is deselected.
         *
         * Listening for this event is an alternative to observing changes in the `selected` attribute.
         * This event is fired both when a panel is deselected.
         *
         * @event iron-deselect {{item: Object}} detail -
         *     item: The panel that the event refers to.
         */
        properties: {

          /**
           * The panel to be selected when `paper-drawer-panel` changes to narrow
           * layout.
           */
          defaultSelected: {
            type: String,
            value: 'main'
          },

          /**
           * If true, swipe from the edge is disabled.
           */
          disableEdgeSwipe: {
            type: Boolean,
            value: false
          },

          /**
           * If true, swipe to open/close the drawer is disabled.
           */
          disableSwipe: {
            type: Boolean,
            value: false
          },

          /**
           * Whether the user is dragging the drawer interactively.
           */
          dragging: {
            type: Boolean,
            value: false,
            readOnly: true,
            notify: true
          },

          /**
           * Width of the drawer panel.
           */
          drawerWidth: {
            type: String,
            value: '256px'
          },

          /**
           * How many pixels on the side of the screen are sensitive to edge
           * swipes and peek.
           */
          edgeSwipeSensitivity: {
            type: Number,
            value: 30
          },

          /**
           * If true, ignore `responsiveWidth` setting and force the narrow layout.
           */
          forceNarrow: {
            type: Boolean,
            value: false
          },

          /**
           * Whether the browser has support for the transform CSS property.
           */
          hasTransform: {
            type: Boolean,
            value: function() {
              return 'transform' in this.style;
            }
          },

          /**
           * Whether the browser has support for the will-change CSS property.
           */
          hasWillChange: {
            type: Boolean,
            value: function() {
              return 'willChange' in this.style;
            }
          },

          /**
           * Returns true if the panel is in narrow layout.  This is useful if you
           * need to show/hide elements based on the layout.
           */
          narrow: {
            reflectToAttribute: true,
            type: Boolean,
            value: false,
            readOnly: true,
            notify: true
          },

          /**
           * Whether the drawer is peeking out from the edge.
           */
          peeking: {
            type: Boolean,
            value: false,
            readOnly: true,
            notify: true
          },

          /**
           * Max-width when the panel changes to narrow layout.
           */
          responsiveWidth: {
            type: String,
            value: '600px'
          },

          /**
           * If true, position the drawer to the right.
           */
          rightDrawer: {
            type: Boolean,
            value: false
          },

          /**
           * The panel that is being selected. `drawer` for the drawer panel and
           * `main` for the main panel.
           */
          selected: {
            reflectToAttribute: true,
            notify: true,
            type: String,
            value: null
          },

          /**
           * The attribute on elements that should toggle the drawer on tap, also elements will
           * automatically be hidden in wide layout.
           */
          drawerToggleAttribute: {
            type: String,
            value: 'paper-drawer-toggle'
          },

          /**
           * Whether the transition is enabled.
           */
          _transition: {
            type: Boolean,
            value: false
          },

        },

        listeners: {
          tap: '_onTap',
          track: '_onTrack',
          down: '_downHandler',
          up: '_upHandler'
        },

        observers: [
          '_forceNarrowChanged(forceNarrow, defaultSelected)'
        ],

        /**
         * Toggles the panel open and closed.
         *
         * @method togglePanel
         */
        togglePanel: function() {
          if (this._isMainSelected()) {
            this.openDrawer();
          } else {
            this.closeDrawer();
          }
        },

        /**
         * Opens the drawer.
         *
         * @method openDrawer
         */
        openDrawer: function() {
          this.selected = 'drawer';
        },

        /**
         * Closes the drawer.
         *
         * @method closeDrawer
         */
        closeDrawer: function() {
          this.selected = 'main';
        },

        ready: function() {
          // Avoid transition at the beginning e.g. page loads and enable
          // transitions only after the element is rendered and ready.
          this._transition = true;
        },

        _onMainTransitionEnd: function (e) {
          if (e.currentTarget === this.$.main && (e.propertyName === 'left' || e.propertyName === 'right')) {
            this.notifyResize();
          }
        },

        _computeIronSelectorClass: function(narrow, transition, dragging, rightDrawer, peeking) {
          return classNames({
            dragging: dragging,
            'narrow-layout': narrow,
            'right-drawer': rightDrawer,
            'left-drawer': !rightDrawer,
            transition: transition,
            peeking: peeking
          });
        },

        _computeDrawerStyle: function(drawerWidth) {
          return 'width:' + drawerWidth + ';';
        },

        _computeMainStyle: function(narrow, rightDrawer, drawerWidth) {
          var style = '';

          style += 'left:' + ((narrow || rightDrawer) ? '0' : drawerWidth) + ';';

          if (rightDrawer) {
            style += 'right:' + (narrow ? '' : drawerWidth) + ';';
          }

          return style;
        },

        _computeMediaQuery: function(forceNarrow, responsiveWidth) {
          return forceNarrow ? '' : '(max-width: ' + responsiveWidth + ')';
        },

        _computeSwipeOverlayHidden: function(narrow, disableEdgeSwipe) {
          return !narrow || disableEdgeSwipe;
        },

        _onTrack: function(event) {
          if (sharedPanel && this !== sharedPanel) {
            return;
          }
          switch (event.detail.state) {
            case 'start':
              this._trackStart(event);
              break;
            case 'track':
              this._trackX(event);
              break;
            case 'end':
              this._trackEnd(event);
              break;
          }

        },

        _responsiveChange: function(narrow) {
          this._setNarrow(narrow);

          if (this.narrow) {
            this.selected = this.defaultSelected;
          }

          this.setScrollDirection(this._swipeAllowed() ? 'y' : 'all');
          this.fire('paper-responsive-change', {narrow: this.narrow});
        },

        _onQueryMatchesChanged: function(event) {
          this._responsiveChange(event.detail.value);
        },

        _forceNarrowChanged: function() {
          // set the narrow mode only if we reached the `responsiveWidth`
          this._responsiveChange(this.forceNarrow || this.$.mq.queryMatches);
        },

        _swipeAllowed: function() {
          return this.narrow && !this.disableSwipe;
        },

        _isMainSelected: function() {
          return this.selected === 'main';
        },

        _startEdgePeek: function() {
          this.width = this.$.drawer.offsetWidth;
          this._moveDrawer(this._translateXForDeltaX(this.rightDrawer ?
              -this.edgeSwipeSensitivity : this.edgeSwipeSensitivity));
          this._setPeeking(true);
        },

        _stopEdgePeek: function() {
          if (this.peeking) {
            this._setPeeking(false);
            this._moveDrawer(null);
          }
        },

        _downHandler: function(event) {
          if (!this.dragging && this._isMainSelected() && this._isEdgeTouch(event) && !sharedPanel) {
            this._startEdgePeek();
            // cancel selection
            event.preventDefault();
            // grab this panel
            sharedPanel = this;
          }
        },

        _upHandler: function() {
          this._stopEdgePeek();
          // release the panel
          sharedPanel = null;
        },

        _onTap: function(event) {
          var targetElement = Polymer.dom(event).localTarget;
          var isTargetToggleElement = targetElement &&
            this.drawerToggleAttribute &&
            targetElement.hasAttribute(this.drawerToggleAttribute);

          if (isTargetToggleElement) {
            this.togglePanel();
          }
        },

        _isEdgeTouch: function(event) {
          var x = event.detail.x;

          return !this.disableEdgeSwipe && this._swipeAllowed() &&
            (this.rightDrawer ?
              x >= this.offsetWidth - this.edgeSwipeSensitivity :
              x <= this.edgeSwipeSensitivity);
        },

        _trackStart: function(event) {
          if (this._swipeAllowed()) {
            sharedPanel = this;
            this._setDragging(true);

            if (this._isMainSelected()) {
              this._setDragging(this.peeking || this._isEdgeTouch(event));
            }

            if (this.dragging) {
              this.width = this.$.drawer.offsetWidth;
              this._transition = false;
            }
          }
        },

        _translateXForDeltaX: function(deltaX) {
          var isMain = this._isMainSelected();

          if (this.rightDrawer) {
            return Math.max(0, isMain ? this.width + deltaX : deltaX);
          } else {
            return Math.min(0, isMain ? deltaX - this.width : deltaX);
          }
        },

        _trackX: function(event) {
          if (this.dragging) {
            var dx = event.detail.dx;

            if (this.peeking) {
              if (Math.abs(dx) <= this.edgeSwipeSensitivity) {
                // Ignore trackx until we move past the edge peek.
                return;
              }
              this._setPeeking(false);
            }

            this._moveDrawer(this._translateXForDeltaX(dx));
          }
        },

        _trackEnd: function(event) {
          if (this.dragging) {
            var xDirection = event.detail.dx > 0;

            this._setDragging(false);
            this._transition = true;
            sharedPanel = null;
            this._moveDrawer(null);

            if (this.rightDrawer) {
              this[xDirection ? 'closeDrawer' : 'openDrawer']();
            } else {
              this[xDirection ? 'openDrawer' : 'closeDrawer']();
            }
          }
        },

        _transformForTranslateX: function(translateX) {
          if (translateX === null) {
            return '';
          }

          return this.hasWillChange ? 'translateX(' + translateX + 'px)' :
              'translate3d(' + translateX + 'px, 0, 0)';
        },

        _moveDrawer: function(translateX) {
          this.transform(this._transformForTranslateX(translateX), this.$.drawer);
        }

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