paper-button.js

/**
@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 subject to an additional IP rights grant
found at http://polymer.github.io/PATENTS.txt
*/
import '@polymer/iron-flex-layout/iron-flex-layout.js';
import '@polymer/paper-styles/element-styles/paper-material-styles.js';

import {PaperButtonBehavior, PaperButtonBehaviorImpl} from '@polymer/paper-behaviors/paper-button-behavior.js';
import {Polymer} from '@polymer/polymer/lib/legacy/polymer-fn.js';
import {html} from '@polymer/polymer/polymer-legacy.js';

const template = html`
  <style include="paper-material-styles">
    /* Need to specify the same specificity as the styles imported from paper-material. */
    :host {
      @apply --layout-inline;
      @apply --layout-center-center;
      position: relative;
      box-sizing: border-box;
      min-width: 5.14em;
      margin: 0 0.29em;
      background: transparent;
      -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
      -webkit-tap-highlight-color: transparent;
      font: inherit;
      text-transform: uppercase;
      outline-width: 0;
      border-radius: 3px;
      -moz-user-select: none;
      -ms-user-select: none;
      -webkit-user-select: none;
      user-select: none;
      cursor: pointer;
      z-index: 0;
      padding: 0.7em 0.57em;

      @apply --paper-font-common-base;
      @apply --paper-button;
    }

    :host([elevation="1"]) {
      @apply --paper-material-elevation-1;
    }

    :host([elevation="2"]) {
      @apply --paper-material-elevation-2;
    }

    :host([elevation="3"]) {
      @apply --paper-material-elevation-3;
    }

    :host([elevation="4"]) {
      @apply --paper-material-elevation-4;
    }

    :host([elevation="5"]) {
      @apply --paper-material-elevation-5;
    }

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

    :host([raised].keyboard-focus) {
      font-weight: bold;
      @apply --paper-button-raised-keyboard-focus;
    }

    :host(:not([raised]).keyboard-focus) {
      font-weight: bold;
      @apply --paper-button-flat-keyboard-focus;
    }

    :host([disabled]) {
      background: none;
      color: #a8a8a8;
      cursor: auto;
      pointer-events: none;

      @apply --paper-button-disabled;
    }

    :host([disabled][raised]) {
      background: #eaeaea;
    }


    :host([animated]) {
      @apply --shadow-transition;
    }

    paper-ripple {
      color: var(--paper-button-ink-color);
    }
  </style>

  <slot></slot>`;

template.setAttribute('strip-whitespace', '');

/**
Material design:
[Buttons](https://www.google.com/design/spec/components/buttons.html)

`paper-button` is a button. When the user touches the button, a ripple effect
emanates from the point of contact. It may be flat or raised. A raised button is
styled with a shadow.

Example:

    <paper-button>Flat button</paper-button>
    <paper-button raised>Raised button</paper-button>
    <paper-button noink>No ripple effect</paper-button>
    <paper-button toggles>Toggle-able button</paper-button>

A button that has `toggles` true will remain `active` after being clicked (and
will have an `active` attribute set). For more information, see the
`IronButtonState` behavior.

You may use custom DOM in the button body to create a variety of buttons. For
example, to create a button with an icon and some text:

    <paper-button>
      <iron-icon icon="favorite"></iron-icon>
      custom button content
    </paper-button>

To use `paper-button` as a link, wrap it in an anchor tag. Since `paper-button`
will already receive focus, you may want to prevent the anchor tag from
receiving focus as well by setting its tabindex to -1.

    <a href="https://www.polymer-project.org/" tabindex="-1">
      <paper-button raised>Polymer Project</paper-button>
    </a>

### Styling

Style the button with CSS as you would a normal DOM element.

    paper-button.fancy {
      background: green;
      color: yellow;
    }

    paper-button.fancy:hover {
      background: lime;
    }

    paper-button[disabled],
    paper-button[toggles][active] {
      background: red;
    }

By default, the ripple is the same color as the foreground at 25% opacity. You
may customize the color using the `--paper-button-ink-color` custom property.

The following custom properties and mixins are also available for styling:

Custom property | Description | Default
----------------|-------------|----------
`--paper-button-ink-color` | Background color of the ripple | `Based on the button's color`
`--paper-button` | Mixin applied to the button | `{}`
`--paper-button-disabled` | Mixin applied to the disabled button. Note that you can also use the `paper-button[disabled]` selector | `{}`
`--paper-button-flat-keyboard-focus` | Mixin applied to a flat button after it's been focused using the keyboard | `{}`
`--paper-button-raised-keyboard-focus` | Mixin applied to a raised button after it's been focused using the keyboard | `{}`

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

  is: 'paper-button',

  behaviors: [PaperButtonBehavior],

  properties: {
    /**
     * If true, the button should be styled with a shadow.
     */
    raised: {
      type: Boolean,
      reflectToAttribute: true,
      value: false,
      observer: '_calculateElevation',
    }
  },

  _calculateElevation: function() {
    if (!this.raised) {
      this._setElevation(0);
    } else {
      PaperButtonBehaviorImpl._calculateElevation.apply(this);
    }
  }

  /**
  Fired when the animation finishes.
  This is useful if you want to wait until
  the ripple animation finishes to perform some action.

  @event transitionend
  Event param: {{node: Object}} detail Contains the animated node.
  */
});