paper-checkbox.js

/**
@license
Copyright (c) 2016 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
subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
*/
import '@polymer/polymer/polymer-legacy.js';
import '@polymer/paper-styles/default-theme.js';

import {PaperCheckedElementBehavior} from '@polymer/paper-behaviors/paper-checked-element-behavior.js';
import {PaperInkyFocusBehaviorImpl} from '@polymer/paper-behaviors/paper-inky-focus-behavior.js';
import {Polymer} from '@polymer/polymer/lib/legacy/polymer-fn.js';
import {html} from '@polymer/polymer/lib/utils/html-tag.js';
import {afterNextRender} from '@polymer/polymer/lib/utils/render-status.js';

const template = html`<style>
  :host {
    display: inline-block;
    white-space: nowrap;
    cursor: pointer;
    --calculated-paper-checkbox-size: var(--paper-checkbox-size, 18px);
    /* -1px is a sentinel for the default and is replaced in \`attached\`. */
    --calculated-paper-checkbox-ink-size: var(--paper-checkbox-ink-size, -1px);
    @apply --paper-font-common-base;
    line-height: 0;
    -webkit-tap-highlight-color: transparent;
  }

  :host([hidden]) {
    display: none !important;
  }

  :host(:focus) {
    outline: none;
  }

  .hidden {
    display: none;
  }

  #checkboxContainer {
    display: inline-block;
    position: relative;
    width: var(--calculated-paper-checkbox-size);
    height: var(--calculated-paper-checkbox-size);
    min-width: var(--calculated-paper-checkbox-size);
    margin: var(--paper-checkbox-margin, initial);
    vertical-align: var(--paper-checkbox-vertical-align, middle);
    background-color: var(--paper-checkbox-unchecked-background-color, transparent);
  }

  #ink {
    position: absolute;

    /* Center the ripple in the checkbox by negative offsetting it by
     * (inkWidth - rippleWidth) / 2 */
    top: calc(0px - (var(--calculated-paper-checkbox-ink-size) - var(--calculated-paper-checkbox-size)) / 2);
    left: calc(0px - (var(--calculated-paper-checkbox-ink-size) - var(--calculated-paper-checkbox-size)) / 2);
    width: var(--calculated-paper-checkbox-ink-size);
    height: var(--calculated-paper-checkbox-ink-size);
    color: var(--paper-checkbox-unchecked-ink-color, var(--primary-text-color));
    opacity: 0.6;
    pointer-events: none;
  }

  #ink:dir(rtl) {
    right: calc(0px - (var(--calculated-paper-checkbox-ink-size) - var(--calculated-paper-checkbox-size)) / 2);
    left: auto;
  }

  #ink[checked] {
    color: var(--paper-checkbox-checked-ink-color, var(--primary-color));
  }

  #checkbox {
    position: relative;
    box-sizing: border-box;
    height: 100%;
    border: solid 2px;
    border-color: var(--paper-checkbox-unchecked-color, var(--primary-text-color));
    border-radius: 2px;
    pointer-events: none;
    -webkit-transition: background-color 140ms, border-color 140ms;
    transition: background-color 140ms, border-color 140ms;

    -webkit-transition-duration: var(--paper-checkbox-animation-duration, 140ms);
    transition-duration: var(--paper-checkbox-animation-duration, 140ms);
  }

  /* checkbox checked animations */
  #checkbox.checked #checkmark {
    -webkit-animation: checkmark-expand 140ms ease-out forwards;
    animation: checkmark-expand 140ms ease-out forwards;

    -webkit-animation-duration: var(--paper-checkbox-animation-duration, 140ms);
    animation-duration: var(--paper-checkbox-animation-duration, 140ms);
  }

  @-webkit-keyframes checkmark-expand {
    0% {
      -webkit-transform: scale(0, 0) rotate(45deg);
    }
    100% {
      -webkit-transform: scale(1, 1) rotate(45deg);
    }
  }

  @keyframes checkmark-expand {
    0% {
      transform: scale(0, 0) rotate(45deg);
    }
    100% {
      transform: scale(1, 1) rotate(45deg);
    }
  }

  #checkbox.checked {
    background-color: var(--paper-checkbox-checked-color, var(--primary-color));
    border-color: var(--paper-checkbox-checked-color, var(--primary-color));
  }

  #checkmark {
    position: absolute;
    width: 36%;
    height: 70%;
    border-style: solid;
    border-top: none;
    border-left: none;
    border-right-width: calc(2/15 * var(--calculated-paper-checkbox-size));
    border-bottom-width: calc(2/15 * var(--calculated-paper-checkbox-size));
    border-color: var(--paper-checkbox-checkmark-color, white);
    -webkit-transform-origin: 97% 86%;
    transform-origin: 97% 86%;
    box-sizing: content-box; /* protect against page-level box-sizing */
  }

  #checkmark:dir(rtl) {
    -webkit-transform-origin: 50% 14%;
    transform-origin: 50% 14%;
  }

  /* label */
  #checkboxLabel {
    position: relative;
    display: inline-block;
    vertical-align: middle;
    padding-left: var(--paper-checkbox-label-spacing, 8px);
    white-space: normal;
    line-height: normal;
    color: var(--paper-checkbox-label-color, var(--primary-text-color));
    @apply --paper-checkbox-label;
  }

  :host([checked]) #checkboxLabel {
    color: var(--paper-checkbox-label-checked-color, var(--paper-checkbox-label-color, var(--primary-text-color)));
    @apply --paper-checkbox-label-checked;
  }

  #checkboxLabel:dir(rtl) {
    padding-right: var(--paper-checkbox-label-spacing, 8px);
    padding-left: 0;
  }

  #checkboxLabel[hidden] {
    display: none;
  }

  /* disabled state */

  :host([disabled]) #checkbox {
    opacity: 0.5;
    border-color: var(--paper-checkbox-unchecked-color, var(--primary-text-color));
  }

  :host([disabled][checked]) #checkbox {
    background-color: var(--paper-checkbox-unchecked-color, var(--primary-text-color));
    opacity: 0.5;
  }

  :host([disabled]) #checkboxLabel  {
    opacity: 0.65;
  }

  /* invalid state */
  #checkbox.invalid:not(.checked) {
    border-color: var(--paper-checkbox-error-color, var(--error-color));
  }
</style>

<div id="checkboxContainer">
  <div id="checkbox" class$="[[_computeCheckboxClass(checked, invalid)]]">
    <div id="checkmark" class$="[[_computeCheckmarkClass(checked)]]"></div>
  </div>
</div>

<div id="checkboxLabel"><slot></slot></div>`;
template.setAttribute('strip-whitespace', '');

/**
Material design:
[Checkbox](https://www.google.com/design/spec/components/selection-controls.html#selection-controls-checkbox)

`paper-checkbox` is a button that can be either checked or unchecked. User can
tap the checkbox to check or uncheck it. Usually you use checkboxes to allow
user to select multiple options from a set. If you have a single ON/OFF option,
avoid using a single checkbox and use `paper-toggle-button` instead.

Example:

    <paper-checkbox>label</paper-checkbox>

    <paper-checkbox checked> label</paper-checkbox>

### Styling

The following custom properties and mixins are available for styling:

Custom property | Description | Default
----------------|-------------|----------
`--paper-checkbox-unchecked-background-color` | Checkbox background color when the input is not checked | `transparent`
`--paper-checkbox-unchecked-color` | Checkbox border color when the input is not checked | `--primary-text-color`
`--paper-checkbox-unchecked-ink-color` | Selected/focus ripple color when the input is not checked | `--primary-text-color`
`--paper-checkbox-checked-color` | Checkbox color when the input is checked | `--primary-color`
`--paper-checkbox-checked-ink-color` | Selected/focus ripple color when the input is checked | `--primary-color`
`--paper-checkbox-checkmark-color` | Checkmark color | `white`
`--paper-checkbox-label-color` | Label color | `--primary-text-color`
`--paper-checkbox-label-checked-color` | Label color when the input is checked | `--paper-checkbox-label-color`
`--paper-checkbox-label-spacing` | Spacing between the label and the checkbox | `8px`
`--paper-checkbox-label` | Mixin applied to the label | `{}`
`--paper-checkbox-label-checked` | Mixin applied to the label when the input is checked | `{}`
`--paper-checkbox-error-color` | Checkbox color when invalid | `--error-color`
`--paper-checkbox-size` | Size of the checkbox | `18px`
`--paper-checkbox-ink-size` | Size of the ripple | `48px`
`--paper-checkbox-margin` | Margin around the checkbox container | `initial`
`--paper-checkbox-vertical-align` | Vertical alignment of the checkbox container | `middle`

This element applies the mixin `--paper-font-common-base` but does not import
`paper-styles/typography.html`. In order to apply the `Roboto` font to this
element, make sure you've imported `paper-styles/typography.html`.

@demo demo/index.html
*/
Polymer({
  _template: template,

  is: 'paper-checkbox',

  behaviors: [PaperCheckedElementBehavior],

  /** @private */
  hostAttributes: {role: 'checkbox', 'aria-checked': false, tabindex: 0},

  properties: {
    /**
     * Fired when the checked state changes due to user interaction.
     *
     * @event change
     */

    /**
     * Fired when the checked state changes.
     *
     * @event iron-change
     */
    ariaActiveAttribute: {type: String, value: 'aria-checked'}
  },

  /** @override */
  attached: function() {
    // Wait until styles have resolved to check for the default sentinel.
    // See polymer#4009 for more details.
    afterNextRender(this, function() {
      var inkSize =
          this.getComputedStyleValue('--calculated-paper-checkbox-ink-size')
              .trim();
      // If unset, compute and set the default `--paper-checkbox-ink-size`.
      if (inkSize === '-1px') {
        var checkboxSizeText =
            this.getComputedStyleValue('--calculated-paper-checkbox-size')
                .trim();

        var units = 'px';
        var unitsMatches = checkboxSizeText.match(/[A-Za-z]+$/);
        if (unitsMatches !== null) {
          units = unitsMatches[0];
        }

        var checkboxSize = parseFloat(checkboxSizeText);
        var defaultInkSize = (8 / 3) * checkboxSize;

        if (units === 'px') {
          defaultInkSize = Math.floor(defaultInkSize);

          // The checkbox and ripple need to have the same parity so that their
          // centers align.
          if (defaultInkSize % 2 !== checkboxSize % 2) {
            defaultInkSize++;
          }
        }

        this.updateStyles({
          '--paper-checkbox-ink-size': defaultInkSize + units,
        });
      }
    });
  },

  _computeCheckboxClass: function(checked, invalid) {
    var className = '';
    if (checked) {
      className += 'checked ';
    }
    if (invalid) {
      className += 'invalid';
    }
    return className;
  },

  _computeCheckmarkClass: function(checked) {
    return checked ? '' : 'hidden';
  },

  // create ripple inside the checkboxContainer
  _createRipple: function() {
    this._rippleContainer = this.$.checkboxContainer;
    return PaperInkyFocusBehaviorImpl._createRipple.call(this);
  }

});