components/paper-input/paper-input-behavior.html

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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-behaviors/iron-control-state.html">

<script>

  // Generate unique, monotonically increasing IDs for labels (needed by
  // aria-labelledby) and add-ons.
  Polymer.PaperInputHelper = {};
  Polymer.PaperInputHelper.NextLabelID = 1;
  Polymer.PaperInputHelper.NextAddonID = 1;

  /**
   * Use `Polymer.PaperInputBehavior` to implement inputs with `<paper-input-container>`. This
   * behavior is implemented by `<paper-input>`. It exposes a number of properties from
   * `<paper-input-container>` and `<input is="iron-input">` and they should be bound in your
   * template.
   *
   * The input element can be accessed by the `inputElement` property if you need to access
   * properties or methods that are not exposed.
   * @polymerBehavior Polymer.PaperInputBehavior
   */
  Polymer.PaperInputBehaviorImpl = {

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

      /**
       * The label for this input. If you're using PaperInputBehavior to
       * implement your own paper-input-like element, bind this to
       * `<label>`'s content and `hidden` property, e.g.
       * `<label hidden$="[[!label]]">[[label]]</label>` in your `template`
       */
      label: {
        type: String
      },

      /**
       * The value for this input. If you're using PaperInputBehavior to
       * implement your own paper-input-like element, bind this to
       * the `<input is="iron-input">`'s `bindValue`
       * property, or the value property of your input that is `notify:true`.
       */
      value: {
        notify: true,
        type: String
      },

      /**
       * Set to true to disable this input. If you're using PaperInputBehavior to
       * implement your own paper-input-like element, bind this to
       * both the `<paper-input-container>`'s and the input's `disabled` property.
       */
      disabled: {
        type: Boolean,
        value: false
      },

      /**
       * Returns true if the value is invalid. If you're using PaperInputBehavior to
       * implement your own paper-input-like element, bind this to both the
       * `<paper-input-container>`'s and the input's `invalid` property.
       *
       * If `autoValidate` is true, the `invalid` attribute is managed automatically,
       * which can clobber attempts to manage it manually.
       */
      invalid: {
        type: Boolean,
        value: false,
        notify: true
      },

      /**
       * Set to true to prevent the user from entering invalid input. If you're
       * using PaperInputBehavior to  implement your own paper-input-like element,
       * bind this to `<input is="iron-input">`'s `preventInvalidInput` property.
       */
      preventInvalidInput: {
        type: Boolean
      },

      /**
       * Set this to specify the pattern allowed by `preventInvalidInput`. If
       * you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `allowedPattern`
       * property.
       */
      allowedPattern: {
        type: String
      },

      /**
       * The type of the input. The supported types are `text`, `number` and `password`.
       * If you're using PaperInputBehavior to implement your own paper-input-like element,
       * bind this to the `<input is="iron-input">`'s `type` property.
       */
      type: {
        type: String
      },

      /**
       * The datalist of the input (if any). This should match the id of an existing `<datalist>`.
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `list` property.
       */
      list: {
        type: String
      },

      /**
       * A pattern to validate the `input` with. If you're using PaperInputBehavior to
       * implement your own paper-input-like element, bind this to
       * the `<input is="iron-input">`'s `pattern` property.
       */
      pattern: {
        type: String
      },

      /**
       * Set to true to mark the input as required. If you're using PaperInputBehavior to
       * implement your own paper-input-like element, bind this to
       * the `<input is="iron-input">`'s `required` property.
       */
      required: {
        type: Boolean,
        value: false
      },

      /**
       * The error message to display when the input is invalid. If you're using
       * PaperInputBehavior to implement your own paper-input-like element,
       * bind this to the `<paper-input-error>`'s content, if using.
       */
      errorMessage: {
        type: String
      },

      /**
       * Set to true to show a character counter.
       */
      charCounter: {
        type: Boolean,
        value: false
      },

      /**
       * Set to true to disable the floating label. If you're using PaperInputBehavior to
       * implement your own paper-input-like element, bind this to
       * the `<paper-input-container>`'s `noLabelFloat` property.
       */
      noLabelFloat: {
        type: Boolean,
        value: false
      },

      /**
       * Set to true to always float the label. If you're using PaperInputBehavior to
       * implement your own paper-input-like element, bind this to
       * the `<paper-input-container>`'s `alwaysFloatLabel` property.
       */
      alwaysFloatLabel: {
        type: Boolean,
        value: false
      },

      /**
       * Set to true to auto-validate the input value. If you're using PaperInputBehavior to
       * implement your own paper-input-like element, bind this to
       * the `<paper-input-container>`'s `autoValidate` property.
       */
      autoValidate: {
        type: Boolean,
        value: false
      },

      /**
       * Name of the validator to use. If you're using PaperInputBehavior to
       * implement your own paper-input-like element, bind this to
       * the `<input is="iron-input">`'s `validator` property.
       */
      validator: {
        type: String
      },

      // HTMLInputElement attributes for binding if needed

      /**
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `autocomplete` property.
       */
      autocomplete: {
        type: String,
        value: 'off'
      },

      /**
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `autofocus` property.
       */
      autofocus: {
        type: Boolean,
        observer: '_autofocusChanged'
      },

      /**
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `inputmode` property.
       */
      inputmode: {
        type: String
      },

      /**
       * The minimum length of the input value.
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `minlength` property.
       */
      minlength: {
        type: Number
      },

      /**
       * The maximum length of the input value.
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `maxlength` property.
       */
      maxlength: {
        type: Number
      },

      /**
       * The minimum (numeric or date-time) input value.
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `min` property.
       */
      min: {
        type: String
      },

      /**
       * The maximum (numeric or date-time) input value.
       * Can be a String (e.g. `"2000-01-01"`) or a Number (e.g. `2`).
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `max` property.
       */
      max: {
        type: String
      },

      /**
       * Limits the numeric or date-time increments.
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `step` property.
       */
      step: {
        type: String
      },

      /**
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `name` property.
       */
      name: {
        type: String
      },

      /**
       * A placeholder string in addition to the label. If this is set, the label will always float.
       */
      placeholder: {
        type: String,
        // need to set a default so _computeAlwaysFloatLabel is run
        value: ''
      },

      /**
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `readonly` property.
       */
      readonly: {
        type: Boolean,
        value: false
      },

      /**
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `size` property.
       */
      size: {
        type: Number
      },

      // Nonstandard attributes for binding if needed

      /**
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `autocapitalize` property.
       */
      autocapitalize: {
        type: String,
        value: 'none'
      },

      /**
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `autocorrect` property.
       */
      autocorrect: {
        type: String,
        value: 'off'
      },

      /**
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `autosave` property,
       * used with type=search.
       */
      autosave: {
        type: String
      },

      /**
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `results` property,
       * used with type=search.
       */
      results: {
        type: Number
      },

      /**
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the `<input is="iron-input">`'s `accept` property,
       * used with type=file.
       */
      accept: {
        type: String
      },

      /**
       * If you're using PaperInputBehavior to implement your own paper-input-like
       * element, bind this to the`<input is="iron-input">`'s `multiple` property,
       * used with type=file.
       */
      multiple: {
        type: Boolean
      },

      _ariaDescribedBy: {
        type: String,
        value: ''
      },

      _ariaLabelledBy: {
        type: String,
        value: ''
      }

    },

    listeners: {
      'addon-attached': '_onAddonAttached',
    },

    keyBindings: {
      'shift+tab:keydown': '_onShiftTabDown'
    },

    hostAttributes: {
      tabindex: 0
    },

    /**
     * Returns a reference to the input element.
     */
    get inputElement() {
      return this.$.input;
    },

    /**
     * Returns a reference to the focusable element.
     */
    get _focusableElement() {
      return this.inputElement;
    },

    registered: function() {
      // These types have some default placeholder text; overlapping
      // the label on top of it looks terrible. Auto-float the label in this case.
      this._typesThatHaveText = ["date", "datetime", "datetime-local", "month",
          "time", "week", "file"];
    },

    attached: function() {
      this._updateAriaLabelledBy();

      if (this.inputElement &&
          this._typesThatHaveText.indexOf(this.inputElement.type) !== -1) {
        this.alwaysFloatLabel = true;
      }
    },

    _appendStringWithSpace: function(str, more) {
      if (str) {
        str = str + ' ' + more;
      } else {
        str = more;
      }
      return str;
    },

    _onAddonAttached: function(event) {
      var target = event.path ? event.path[0] : event.target;
      if (target.id) {
        this._ariaDescribedBy = this._appendStringWithSpace(this._ariaDescribedBy, target.id);
      } else {
        var id = 'paper-input-add-on-' + Polymer.PaperInputHelper.NextAddonID++;
        target.id = id;
        this._ariaDescribedBy = this._appendStringWithSpace(this._ariaDescribedBy, id);
      }
    },

    /**
     * Validates the input element and sets an error style if needed.
     *
     * @return {boolean}
     */
    validate: function() {
      return this.inputElement.validate();
    },

    /**
     * Forward focus to inputElement. Overriden from IronControlState.
     */
    _focusBlurHandler: function(event) {
      Polymer.IronControlState._focusBlurHandler.call(this, event);

      // Forward the focus to the nested input.
      if (this.focused && !this._shiftTabPressed)
        this._focusableElement.focus();
    },

    /**
     * Handler that is called when a shift+tab keypress is detected by the menu.
     *
     * @param {CustomEvent} event A key combination event.
     */
    _onShiftTabDown: function(event) {
      var oldTabIndex = this.getAttribute('tabindex');
      this._shiftTabPressed = true;
      this.setAttribute('tabindex', '-1');
      this.async(function() {
        this.setAttribute('tabindex', oldTabIndex);
        this._shiftTabPressed = false;
      }, 1);
    },

    /**
     * If `autoValidate` is true, then validates the element.
     */
    _handleAutoValidate: function() {
      if (this.autoValidate)
        this.validate();
    },

    /**
     * Restores the cursor to its original position after updating the value.
     * @param {string} newValue The value that should be saved.
     */
    updateValueAndPreserveCaret: function(newValue) {
      // Not all elements might have selection, and even if they have the
      // right properties, accessing them might throw an exception (like for
      // <input type=number>)
      try {
        var start = this.inputElement.selectionStart;
        this.value = newValue;

        // The cursor automatically jumps to the end after re-setting the value,
        // so restore it to its original position.
        this.inputElement.selectionStart = start;
        this.inputElement.selectionEnd = start;
      } catch (e) {
        // Just set the value and give up on the caret.
        this.value = newValue;
      }
    },

    _computeAlwaysFloatLabel: function(alwaysFloatLabel, placeholder) {
      return placeholder || alwaysFloatLabel;
    },

    _updateAriaLabelledBy: function() {
      var label = Polymer.dom(this.root).querySelector('label');
      if (!label) {
        this._ariaLabelledBy = '';
        return;
      }
      var labelledBy;
      if (label.id) {
        labelledBy = label.id;
      } else {
        labelledBy = 'paper-input-label-' + Polymer.PaperInputHelper.NextLabelID++;
        label.id = labelledBy;
      }
      this._ariaLabelledBy = labelledBy;
    },

    _onChange:function(event) {
      // In the Shadow DOM, the `change` event is not leaked into the
      // ancestor tree, so we must do this manually.
      // See https://w3c.github.io/webcomponents/spec/shadow/#events-that-are-not-leaked-into-ancestor-trees.
      if (this.shadowRoot) {
        this.fire(event.type, {sourceEvent: event}, {
          node: this,
          bubbles: event.bubbles,
          cancelable: event.cancelable
        });
      }
    },

    _autofocusChanged: function() {
      // Firefox doesn't respect the autofocus attribute if it's applied after
      // the page is loaded (Chrome/WebKit do respect it), preventing an
      // autofocus attribute specified in markup from taking effect when the
      // element is upgraded. As a workaround, if the autofocus property is set,
      // and the focus hasn't already been moved elsewhere, we take focus.
      if (this.autofocus && this._focusableElement) {

        // In IE 11, the default document.activeElement can be the page's
        // outermost html element, but there are also cases (under the
        // polyfill?) in which the activeElement is not a real HTMLElement, but
        // just a plain object. We identify the latter case as having no valid
        // activeElement.
        var activeElement = document.activeElement;
        var isActiveElementValid = activeElement instanceof HTMLElement;

        // Has some other element has already taken the focus?
        var isSomeElementActive = isActiveElementValid &&
            activeElement !== document.body &&
            activeElement !== document.documentElement; /* IE 11 */
        if (!isSomeElementActive) {
          // No specific element has taken the focus yet, so we can take it.
          this._focusableElement.focus();
        }
      }
    }
  };

  /** @polymerBehavior */
  Polymer.PaperInputBehavior = [
    Polymer.IronControlState,
    Polymer.IronA11yKeysBehavior,
    Polymer.PaperInputBehaviorImpl
  ];
</script>