paper-slider.html

<!--
@license
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
The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
Code distributed by Google as part of the polymer project is also
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<link rel="import" href="../polymer/polymer.html">
<link rel="import" href="../iron-a11y-keys-behavior/iron-a11y-keys-behavior.html">
<link rel="import" href="../iron-flex-layout/iron-flex-layout.html">
<link rel="import" href="../iron-form-element-behavior/iron-form-element-behavior.html">
<link rel="import" href="../iron-range-behavior/iron-range-behavior.html">
<link rel="import" href="../paper-behaviors/paper-inky-focus-behavior.html">
<link rel="import" href="../paper-input/paper-input.html">
<link rel="import" href="../paper-progress/paper-progress.html">
<link rel="import" href="../paper-styles/color.html">

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

`paper-slider` allows user to select a value from a range of values by
moving the slider thumb.  The interactive nature of the slider makes it a
great choice for settings that reflect intensity levels, such as volume,
brightness, or color saturation.

Example:

    <paper-slider></paper-slider>

Use `min` and `max` to specify the slider range.  Default is 0 to 100.

Example:

    <paper-slider min="10" max="200" value="110"></paper-slider>

### Styling

The following custom properties and mixins are available for styling:

Custom property | Description | Default
----------------|-------------|----------
`--paper-slider-container-color` | The background color of the bar | `--paper-grey-400`
`--paper-slider-bar-color` | The background color of the slider | `transparent`
`--paper-slider-active-color` | The progress bar color | `--google-blue-700`
`--paper-slider-secondary-color` | The secondary progress bar color | `--google-blue-300`
`--paper-slider-knob-color` | The knob color | `--google-blue-700`
`--paper-slider-disabled-knob-color` | The disabled knob color | `--paper-grey-400`
`--paper-slider-pin-color` | The pin color | `--google-blue-700`
`--paper-slider-font-color` | The pin's text color | `#fff`
`--paper-slider-markers-color` | The snaps markers color | `#000`
`--paper-slider-disabled-active-color` | The disabled progress bar color | `--paper-grey-400`
`--paper-slider-disabled-secondary-color` | The disabled secondary progress bar color | `--paper-grey-400`
`--paper-slider-knob-start-color` | The fill color of the knob at the far left | `transparent`
`--paper-slider-knob-start-border-color` | The border color of the knob at the far left | `--paper-grey-400`
`--paper-slider-pin-start-color` | The color of the pin at the far left | `--paper-grey-400`
`--paper-slider-height` | Height of the progress bar | `2px`
`--paper-slider-input` | Mixin applied to the input in editable mode | `{}`
`--paper-slider-input-container-input` | Mixin applied to the paper-input-container-input in editable mode | `{}`

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

<dom-module id="paper-slider">
  <template strip-whitespace>
    <style>
      :host {
        @apply --layout;
        @apply --layout-justified;
        @apply --layout-center;
        width: 200px;
        cursor: default;
        -webkit-user-select: none;
        -moz-user-select: none;
        -ms-user-select: none;
        user-select: none;
        -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
        --paper-progress-active-color: var(--paper-slider-active-color, var(--google-blue-700));
        --paper-progress-secondary-color: var(--paper-slider-secondary-color, var(--google-blue-300));
        --paper-progress-disabled-active-color: var(--paper-slider-disabled-active-color, var(--paper-grey-400));
        --paper-progress-disabled-secondary-color: var(--paper-slider-disabled-secondary-color, var(--paper-grey-400));
        --calculated-paper-slider-height: var(--paper-slider-height, 2px);
      }

      /* focus shows the ripple */
      :host(:focus) {
        outline: none;
      }

      /** 
       * NOTE(keanulee): Though :host-context is not universally supported, some pages
       * still rely on paper-slider being flipped when dir="rtl" is set on body. For full
       * compatability, dir="rtl" must be explicitly set on paper-slider.
       */
      :dir(rtl) #sliderContainer {
        -webkit-transform: scaleX(-1);
        transform: scaleX(-1);
      }

      /** 
       * NOTE(keanulee): This is separate from the rule above because :host-context may
       * not be recognized.
       */
      :host([dir="rtl"]) #sliderContainer {
        -webkit-transform: scaleX(-1);
        transform: scaleX(-1);
      }

      /** 
       * NOTE(keanulee): Needed to override the :host-context rule (where supported)
       * to support LTR sliders in RTL pages.
       */
      :host([dir="ltr"]) #sliderContainer {
        -webkit-transform: scaleX(1);
        transform: scaleX(1);
      }

      #sliderContainer {
        position: relative;
        width: 100%;
        height: calc(30px + var(--calculated-paper-slider-height));
        margin-left: calc(15px + var(--calculated-paper-slider-height)/2);
        margin-right: calc(15px + var(--calculated-paper-slider-height)/2);
      }

      #sliderContainer:focus {
        outline: 0;
      }

      #sliderContainer.editable {
        margin-top: 12px;
        margin-bottom: 12px;
      }

      .bar-container {
        position: absolute;
        top: 0;
        bottom: 0;
        left: 0;
        right: 0;
        overflow: hidden;
      }

      .ring > .bar-container {
        left: calc(5px + var(--calculated-paper-slider-height)/2);
        transition: left 0.18s ease;
      }

      .ring.expand.dragging > .bar-container {
        transition: none;
      }

      .ring.expand:not(.pin) > .bar-container {
        left: calc(8px + var(--calculated-paper-slider-height)/2);
      }

      #sliderBar {
        padding: 15px 0;
        width: 100%;
        background-color: var(--paper-slider-bar-color, transparent);
        --paper-progress-container-color: var(--paper-slider-container-color, var(--paper-grey-400));
        --paper-progress-height: var(--calculated-paper-slider-height);
      }

      .slider-markers {
        position: absolute;
        top: calc(14px + var(--paper-slider-height,2px)/2);
        height: var(--calculated-paper-slider-height);
        left: 0;
        right: -1px;
        box-sizing: border-box;
        pointer-events: none;
        @apply --layout-horizontal;
      }

      .slider-marker {
        @apply --layout-flex;
      }
      .slider-markers::after,
      .slider-marker::after {
        content: "";
        display: block;
        margin-left: -1px;
        width: 2px;
        height: var(--calculated-paper-slider-height);
        border-radius: 50%;
        background-color: var(--paper-slider-markers-color, #000);
      }

      .slider-knob {
        position: absolute;
        left: 0;
        top: 0;
        margin-left: calc(-15px - var(--calculated-paper-slider-height)/2);
        width: calc(30px + var(--calculated-paper-slider-height));
        height: calc(30px + var(--calculated-paper-slider-height));
      }

      .transiting > .slider-knob {
        transition: left 0.08s ease;
      }

      .slider-knob:focus {
        outline: none;
      }

      .slider-knob.dragging {
        transition: none;
      }

      .snaps > .slider-knob.dragging {
        transition: -webkit-transform 0.08s ease;
        transition: transform 0.08s ease;
      }

      .slider-knob-inner {
        margin: 10px;
        width: calc(100% - 20px);
        height: calc(100% - 20px);
        background-color: var(--paper-slider-knob-color, var(--google-blue-700));
        border: 2px solid var(--paper-slider-knob-color, var(--google-blue-700));
        border-radius: 50%;

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

        transition-property: -webkit-transform, background-color, border;
        transition-property: transform, background-color, border;
        transition-duration: 0.18s;
        transition-timing-function: ease;
      }

      .expand:not(.pin) > .slider-knob > .slider-knob-inner {
        -webkit-transform: scale(1.5);
        transform: scale(1.5);
      }

      .ring > .slider-knob > .slider-knob-inner {
        background-color: var(--paper-slider-knob-start-color, transparent);
        border: 2px solid var(--paper-slider-knob-start-border-color, var(--paper-grey-400));
      }

      .slider-knob-inner::before {
        background-color: var(--paper-slider-pin-color, var(--google-blue-700));
      }

      .pin > .slider-knob > .slider-knob-inner::before {
        content: "";
        position: absolute;
        top: 0;
        left: 50%;
        margin-left: -13px;
        width: 26px;
        height: 26px;
        border-radius: 50% 50% 50% 0;

        -webkit-transform: rotate(-45deg) scale(0) translate(0);
        transform: rotate(-45deg) scale(0) translate(0);
      }

      .slider-knob-inner::before,
      .slider-knob-inner::after {
        transition: -webkit-transform .18s ease, background-color .18s ease;
        transition: transform .18s ease, background-color .18s ease;
      }

      .pin.ring > .slider-knob > .slider-knob-inner::before {
        background-color: var(--paper-slider-pin-start-color, var(--paper-grey-400));
      }

      .pin.expand > .slider-knob > .slider-knob-inner::before {
        -webkit-transform: rotate(-45deg) scale(1) translate(17px, -17px);
        transform: rotate(-45deg) scale(1) translate(17px, -17px);
      }

      .pin > .slider-knob > .slider-knob-inner::after {
        content: attr(value);
        position: absolute;
        top: 0;
        left: 50%;
        margin-left: -16px;
        width: 32px;
        height: 26px;
        text-align: center;
        color: var(--paper-slider-font-color, #fff);
        font-size: 10px;

        -webkit-transform: scale(0) translate(0);
        transform: scale(0) translate(0);
      }

      .pin.expand > .slider-knob > .slider-knob-inner::after {
        -webkit-transform: scale(1) translate(0, -17px);
        transform: scale(1) translate(0, -17px);
      }

      /* paper-input */
      .slider-input {
        width: 50px;
        overflow: hidden;
        --paper-input-container-input: {
          text-align: center;
          @apply --paper-slider-input-container-input;
        };
        @apply --paper-slider-input;
      }

      /* disabled state */
      #sliderContainer.disabled {
        pointer-events: none;
      }

      .disabled > .slider-knob > .slider-knob-inner {
        background-color: var(--paper-slider-disabled-knob-color, var(--paper-grey-400));
        border: 2px solid var(--paper-slider-disabled-knob-color, var(--paper-grey-400));
        -webkit-transform: scale3d(0.75, 0.75, 1);
        transform: scale3d(0.75, 0.75, 1);
      }

      .disabled.ring > .slider-knob > .slider-knob-inner {
        background-color: var(--paper-slider-knob-start-color, transparent);
        border: 2px solid var(--paper-slider-knob-start-border-color, var(--paper-grey-400));
      }

      paper-ripple {
        color: var(--paper-slider-knob-color, var(--google-blue-700));
      }
    </style>

    <div id="sliderContainer"
      class$="[[_getClassNames(disabled, pin, snaps, immediateValue, min, expand, dragging, transiting, editable)]]">
      <div class="bar-container">
        <paper-progress
          disabled$="[[disabled]]"
          id="sliderBar"
          aria-hidden="true"
          min="[[min]]"
          max="[[max]]"
          step="[[step]]"
          value="[[immediateValue]]"
          secondary-progress="[[secondaryProgress]]"
          on-down="_bardown"
          on-up="_resetKnob"
          on-track="_onTrack">
        </paper-progress>
      </div>

      <template is="dom-if" if="[[snaps]]">
        <div class="slider-markers">
          <template is="dom-repeat" items="[[markers]]">
            <div class="slider-marker"></div>
          </template>
        </div>
      </template>

      <div id="sliderKnob"
        class="slider-knob"
        on-down="_knobdown"
        on-up="_resetKnob"
        on-track="_onTrack"
        on-transitionend="_knobTransitionEnd">
          <div class="slider-knob-inner" value$="[[immediateValue]]"></div>
      </div>
    </div>

    <template is="dom-if" if="[[editable]]">
      <paper-input
        id="input"
        type="number"
        step="[[step]]"
        min="[[min]]"
        max="[[max]]"
        class="slider-input"
        disabled$="[[disabled]]"
        value="[[immediateValue]]"
        on-change="_changeValue"
        on-keydown="_inputKeyDown"
        no-label-float>
      </paper-input>
    </template>
  </template>

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

      behaviors: [
        Polymer.IronA11yKeysBehavior,
        Polymer.IronFormElementBehavior,
        Polymer.PaperInkyFocusBehavior,
        Polymer.IronRangeBehavior
      ],

      properties: {
        /**
         * If true, the slider thumb snaps to tick marks evenly spaced based
         * on the `step` property value.
         */
        snaps: {
          type: Boolean,
          value: false,
          notify: true
        },

        /**
         * If true, a pin with numeric value label is shown when the slider thumb
         * is pressed. Use for settings for which users need to know the exact
         * value of the setting.
         */
        pin: {
          type: Boolean,
          value: false,
          notify: true
        },

        /**
         * The number that represents the current secondary progress.
         */
        secondaryProgress: {
          type: Number,
          value: 0,
          notify: true,
          observer: '_secondaryProgressChanged'
        },

        /**
         * If true, an input is shown and user can use it to set the slider value.
         */
        editable: {
          type: Boolean,
          value: false
        },

        /**
         * The immediate value of the slider.  This value is updated while the user
         * is dragging the slider.
         */
        immediateValue: {
          type: Number,
          value: 0,
          readOnly: true,
          notify: true
        },

        /**
         * The maximum number of markers
         */
        maxMarkers: {
          type: Number,
          value: 0,
          notify: true
        },

        /**
         * If true, the knob is expanded
         */
        expand: {
          type: Boolean,
          value: false,
          readOnly: true
        },

        /**
         * True when the user is dragging the slider.
         */
        dragging: {
          type: Boolean,
          value: false,
          readOnly: true,
          notify: true
        },

        transiting: {
          type: Boolean,
          value: false,
          readOnly: true
        },

        markers: {
          type: Array,
          readOnly: true,
          value: function() {
              return [];
          }
        },
      },

      observers: [
        '_updateKnob(value, min, max, snaps, step)',
        '_valueChanged(value)',
        '_immediateValueChanged(immediateValue)',
        '_updateMarkers(maxMarkers, min, max, snaps)'
      ],

      hostAttributes: {
        role: 'slider',
        tabindex: 0
      },

      keyBindings: {
        'left': '_leftKey',
        'right': '_rightKey',
        'down pagedown home': '_decrementKey',
        'up pageup end': '_incrementKey'
      },

      /**
       * Increases value by `step` but not above `max`.
       * @method increment
       */
      increment: function() {
        this.value = this._clampValue(this.value + this.step);
      },

      /**
       * Decreases value by `step` but not below `min`.
       * @method decrement
       */
      decrement: function() {
        this.value = this._clampValue(this.value - this.step);
      },

      _updateKnob: function(value, min, max, snaps, step) {
        this.setAttribute('aria-valuemin', min);
        this.setAttribute('aria-valuemax', max);
        this.setAttribute('aria-valuenow', value);

        this._positionKnob(this._calcRatio(value) * 100);
      },

      _valueChanged: function() {
        this.fire('value-change', {composed: true});
      },

      _immediateValueChanged: function() {
        if (this.dragging) {
          this.fire('immediate-value-change', {composed: true});
        } else {
          this.value = this.immediateValue;
        }
      },

      _secondaryProgressChanged: function() {
        this.secondaryProgress = this._clampValue(this.secondaryProgress);
      },

      _expandKnob: function() {
        this._setExpand(true);
      },

      _resetKnob: function() {
        this.cancelDebouncer('expandKnob');
        this._setExpand(false);
      },

      _positionKnob: function(ratio) {
        this._setImmediateValue(this._calcStep(this._calcKnobPosition(ratio)));
        this._setRatio(this._calcRatio(this.immediateValue) * 100);

        this.$.sliderKnob.style.left = this.ratio + '%';
        if (this.dragging) {
          this._knobstartx = (this.ratio * this._w) / 100;
          this.translate3d(0, 0, 0, this.$.sliderKnob);
        }
      },

      _calcKnobPosition: function(ratio) {
        return (this.max - this.min) * ratio / 100 + this.min;
      },

      _onTrack: function(event) {
        event.stopPropagation();
        switch (event.detail.state) {
          case 'start':
            this._trackStart(event);
            break;
          case 'track':
            this._trackX(event);
            break;
          case 'end':
            this._trackEnd();
            break;
        }
      },

      _trackStart: function(event) {
        this._setTransiting(false);
        this._w = this.$.sliderBar.offsetWidth;
        this._x = this.ratio * this._w / 100;
        this._startx = this._x;
        this._knobstartx = this._startx;
        this._minx = - this._startx;
        this._maxx = this._w - this._startx;
        this.$.sliderKnob.classList.add('dragging');
        this._setDragging(true);
      },

      _trackX: function(event) {
        if (!this.dragging) {
          this._trackStart(event);
        }

        var direction = this._isRTL ? -1 : 1;
        var dx = Math.min(
            this._maxx, Math.max(this._minx, event.detail.dx * direction));
        this._x = this._startx + dx;

        var immediateValue = this._calcStep(this._calcKnobPosition(this._x / this._w * 100));
        this._setImmediateValue(immediateValue);

        // update knob's position
        var translateX = ((this._calcRatio(this.immediateValue) * this._w) - this._knobstartx);
        this.translate3d(translateX + 'px', 0, 0, this.$.sliderKnob);
      },

      _trackEnd: function() {
        var s = this.$.sliderKnob.style;

        this.$.sliderKnob.classList.remove('dragging');
        this._setDragging(false);
        this._resetKnob();
        this.value = this.immediateValue;

        s.transform = s.webkitTransform = '';

        this.fire('change', {composed: true});
      },

      _knobdown: function(event) {
        this._expandKnob();

        // cancel selection
        event.preventDefault();

        // set the focus manually because we will called prevent default
        this.focus();
      },

      _bardown: function(event) {
        this._w = this.$.sliderBar.offsetWidth;
        var rect = this.$.sliderBar.getBoundingClientRect();
        var ratio = (event.detail.x - rect.left) / this._w * 100;
        if (this._isRTL) {
          ratio = 100 - ratio;
        }
        var prevRatio = this.ratio;

        this._setTransiting(true);

        this._positionKnob(ratio);

        this.debounce('expandKnob', this._expandKnob, 60);

        // if the ratio doesn't change, sliderKnob's animation won't start
        // and `_knobTransitionEnd` won't be called
        // Therefore, we need to manually update the `transiting` state

        if (prevRatio === this.ratio) {
          this._setTransiting(false);
        }

        this.async(function() {
          this.fire('change', {composed: true});
        });

        // cancel selection
        event.preventDefault();

        // set the focus manually because we will called prevent default
        this.focus();
      },

      _knobTransitionEnd: function(event) {
        if (event.target === this.$.sliderKnob) {
          this._setTransiting(false);
        }
      },

      _updateMarkers: function(maxMarkers, min, max, snaps) {
        if (!snaps) {
          this._setMarkers([]);
        }
        var steps = Math.round((max - min) / this.step);
        if (steps > maxMarkers) {
          steps = maxMarkers;
        }
        if (steps < 0 || !isFinite(steps)) {
          steps = 0;
        }
        this._setMarkers(new Array(steps));
      },

      _mergeClasses: function(classes) {
        return Object.keys(classes).filter(
          function(className) {
            return classes[className];
          }).join(' ');
      },

      _getClassNames: function() {
        return this._mergeClasses({
          disabled: this.disabled,
          pin: this.pin,
          snaps: this.snaps,
          ring: this.immediateValue <= this.min,
          expand: this.expand,
          dragging: this.dragging,
          transiting: this.transiting,
          editable: this.editable
        });
      },

      get _isRTL() {
        if (this.__isRTL === undefined) {
          this.__isRTL = window.getComputedStyle(this)['direction'] === 'rtl';
        }
        return this.__isRTL;
      },

      _leftKey: function(event) {
        if (this._isRTL)
          this._incrementKey(event);
        else
          this._decrementKey(event);
      },

      _rightKey: function(event) {
        if (this._isRTL)
          this._decrementKey(event);
        else
          this._incrementKey(event);
      },

      _incrementKey: function(event) {
        if (!this.disabled) {
          if (event.detail.key === 'end') {
            this.value = this.max;
          } else {
            this.increment();
          }
          this.fire('change');
          event.preventDefault();
        }
      },

      _decrementKey: function(event) {
        if (!this.disabled) {
          if (event.detail.key === 'home') {
            this.value = this.min;
          } else {
            this.decrement();
          }
          this.fire('change');
          event.preventDefault();
        }
      },

      _changeValue: function(event) {
        this.value = event.target.value;
        this.fire('change', {composed: true});
      },

      _inputKeyDown: function(event) {
        event.stopPropagation();
      },

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

      // Hide the ripple when user is not interacting with keyboard.
      // This behavior is different from other ripple-y controls, but is
      // according to spec: https://www.google.com/design/spec/components/sliders.html
      _focusedChanged: function(receivedFocusFromKeyboard) {
        if (receivedFocusFromKeyboard) {
          this.ensureRipple();
        }
        if (this.hasRipple()) {
          // note, ripple must be un-hidden prior to setting `holdDown`
          if (receivedFocusFromKeyboard) {
            this._ripple.style.display = '';
          } else {
            this._ripple.style.display = 'none';
          }
          this._ripple.holdDown = receivedFocusFromKeyboard;
        }
      }
    });

    /**
     * Fired when the slider's value changes.
     *
     * @event value-change
     */

    /**
     * Fired when the slider's immediateValue changes. Only occurs while the
     * user is dragging.
     *
     * To detect changes to immediateValue that happen for any input (i.e.
     * dragging, tapping, clicking, etc.) listen for immediate-value-changed
     * instead.
     *
     * @event immediate-value-change
     */

    /**
     * Fired when the slider's value changes due to user interaction.
     *
     * Changes to the slider's value due to changes in an underlying
     * bound variable will not trigger this event.
     *
     * @event change
     */
  </script>
</dom-module>