paper-tooltip.html

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Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
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Code distributed by Google as part of the polymer project is also
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-->


<link rel="import" href="../polymer/polymer.html">
<!--

`<paper-tooltip>` is a label that appears on hover and focus when the user
hovers over an element with the cursor or with the keyboard. It will be centered
to an anchor element specified in the `for` attribute, or, if that doesn't exist,
centered to the parent node containing it.

Example:

    <div style="display:inline-block">
      <button>Click me!</button>
      <paper-tooltip>Tooltip text</paper-tooltip>
    </div>

    <div>
      <button id="btn">Click me!</button>
      <paper-tooltip for="btn">Tooltip text</paper-tooltip>
    </div>

### Styling

The following custom properties and mixins are available for styling:

Custom property | Description | Default
----------------|-------------|----------
`--paper-tooltip-background` | The background color of the tooltip | `#616161`
`--paper-tooltip-opacity` | The opacity of the tooltip | `0.9`
`--paper-tooltip-text-color` | The text color of the tooltip | `white`
`--paper-tooltip` | Mixin applied to the tooltip | `{}`

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

<dom-module id="paper-tooltip">
  <style>
    :host {
      display: block;
      position: absolute;
      outline: none;
    }

    #tooltip {
      outline: none;
      @apply(--paper-font-common-base);
      font-size: 10px;

      background-color: var(--paper-tooltip-background, #616161);
      color: var(--paper-tooltip-text-color, white);
      padding: 8px;
      border-radius: 2px;
      max-width: var(--paper-tooltip-max-width, 300px);

      @apply(--paper-tooltip);
    }

    :host[_showing] {
      opacity: 0.9;
      transition: opacity 0.5s ease-in-out 0.25s;
      z-index: 1002;
    }

    :host:not([_showing]) {
      opacity: 0;
      pointer-events:none;
      position:absolute;
    }

    #arrow {
      border: solid transparent;
      height: 0;
      width: 0;
      position: absolute;
      pointer-events: none;
      border-width: 5px;
    }

    :host[position='left'] #arrow {
      left: 100%;
      border-left-color: var(--paper-tooltip-background, #616161);
    }

    :host[position='right'] #arrow {
      right: 100%;
      border-right-color: var(--paper-tooltip-background, #616161);
    }

    :host[position='bottom'] #arrow {
      bottom: 100%;
      border-bottom-color: var(--paper-tooltip-background, #616161);
    }

    :host[position='top'] #arrow {
      top: 100%;
      border-top-color: var(--paper-tooltip-background, #616161);
    }
  </style>

  <template>
    <div id="tooltip">
      <content></content>
      <div id="arrow"></div>
    </div>
  </template>

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

      hostAttributes: {
        role: 'tooltip',
        tabindex: -1
      },

      properties: {
        /**
         * The cardinal position of the tooltip relative to its element. Options are 
         * 'top', 'left', 'right', 'bottom', and can be blank.
         */
        position: String,

        /**
         * The id of the element that the tooltip is anchored to. This element
         * must be a sibling of the tooltip.
         */
        for: {
          type: String
        },

        /**
         * The spacing between the edge of the tooltip and the element it is
         * anchored to.
         */
        margin: {
          type: Number,
          value: 14
        },

        _showing: {
          type: Boolean,
          value: false,
          reflectToAttribute: true
        }
      },

      _targetRect: Object,

      /**
       * Returns the target element that this tooltip is anchored to. It is
       * either the element given by the `for` attribute, or the immediate parent
       * of the tooltip.
       */
      get target () {
        var ownerRoot = Polymer.dom(this).getOwnerRoot();
        var parentNode = Polymer.dom(this).parentNode;
        var target;

        if (this.for) {
          target = parentNode.querySelector('#' + this.for);
        } else if (parentNode.nodeType == 11) { // DOCUMENT_FRAGMENT_NODE
          target = ownerRoot.host;
        } else {
          target = parentNode;
        }

        return target;
      },

      attached: function() {
        this._target = this.target;

        this.listen(this._target, 'mouseenter', 'show');
        this.listen(this._target, 'focus', 'show');
        this.listen(this._target, 'mouseleave', 'hide');
        this.listen(this._target, 'blur', 'hide');
      },

      detached: function() {
        if (this._target) {
          this.unlisten(this._target, 'mouseenter', 'show');
          this.unlisten(this._target, 'focus', 'show');
          this.unlisten(this._target, 'mouseleave', 'hide');
          this.unlisten(this._target, 'blur', 'hide');
        }
      },

      show: function() {
        this._setPosition();

        this._showing = true;
      },

      hide: function() {
        this._showing = false;
      },

      _setPosition: function() {
        if (!this._target) {
          return;
        }

        var targetRect = this._target.getBoundingClientRect();
        if (this._targetRect.top === targetRect.top && 
            this._targetRect.left === targetRect.left &&
            this._targetRect.height === targetRect.height &&
            this._targetRect.width === targetRect.width) {
          return;
        } 
        this._targetRect = targetRect;

        var parentRect = this.offsetParent.getBoundingClientRect();
        var thisRect = this.getBoundingClientRect();
        var centerHorizontalOffset = (targetRect.width - thisRect.width)/2;
        var centerVerticalOffset = (targetRect.height - thisRect.height)/2;
        var leftSide = targetRect.left - parentRect.left;
        var topSide = targetRect.top - parentRect.top;

        var arrowSideLength = 5*Math.sqrt(2);

        switch (this.position) {
          case 'top':
            this.style.left = leftSide + centerHorizontalOffset + 'px';
            this.style.width = thisRect.width + 'px';
            this.style.top = topSide - thisRect.height - this.margin + 'px'; 
            this.$.arrow.style.left = (thisRect.width - arrowSideLength)/2 + 'px';
            break;
          case 'left':
            this.style.left = leftSide - thisRect.width - this.margin + 'px';
            this.style.width = thisRect.width + 'px';
            this.style.top = topSide + centerVerticalOffset + 'px';
            this.$.arrow.style.top = (thisRect.height - arrowSideLength)/2 + 'px';
            break;
          case 'right':
            this.style.left = leftSide + targetRect.width + this.margin + 'px';
            this.style.width = thisRect.width + 'px';
            this.style.top = topSide + centerVerticalOffset + 'px';
            this.$.arrow.style.top = (thisRect.height - arrowSideLength)/2 + 'px';
            break;
          case 'bottom':
          default:
            this.style.left = leftSide + centerHorizontalOffset + 'px';
            this.style.width = thisRect.width + 'px';
            this.style.top = topSide + targetRect.height + this.margin + 'px';
            this.$.arrow.style.left = (thisRect.width - arrowSideLength)/2 + 'px';
            break;
        }
      },
    })
  </script>
</dom-module>