@difizen/mana-core/es/view/focus-tracker.js

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var _dec, _class;
function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
function _defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, _toPropertyKey(descriptor.key), descriptor); } }
function _createClass(Constructor, protoProps, staticProps) { if (protoProps) _defineProperties(Constructor.prototype, protoProps); if (staticProps) _defineProperties(Constructor, staticProps); Object.defineProperty(Constructor, "prototype", { writable: false }); return Constructor; }
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import { Iterable } from '@difizen/mana-common';
import { Emitter } from '@difizen/mana-common';
import { singleton } from '@difizen/mana-syringe';
/**
 * A class which tracks focus among a set of views.
 *
 * This class is useful when code needs to keep track of the most
 * recently focused view(s) among a set of related views.
 */
export var FocusTracker = (_dec = singleton(), _dec(_class = /*#__PURE__*/function () {
  function FocusTracker() {
    _classCallCheck(this, FocusTracker);
    this.counter = 0;
    this._views = [];
    this._activeView = null;
    this._currentView = null;
    this.numbers = new Map();
    this.nodes = new Map();
    this.activeChangedEmitter = new Emitter();
    this.currentChangedEmitter = new Emitter();
  }
  _createClass(FocusTracker, [{
    key: "currentChanged",
    get:
    /**
     * A signal emitted when the current view has changed.
     */
    function get() {
      return this.currentChangedEmitter.event;
    }

    /**
     * A signal emitted when the active view has changed.
     */
  }, {
    key: "activeChanged",
    get: function get() {
      return this.activeChangedEmitter.event;
    }

    /**
     * A flag indicating whether the tracker is disposed.
     */
  }, {
    key: "isDisposed",
    get: function get() {
      return this.counter < 0;
    }

    /**
     * The current view in the tracker.
     *
     * #### Notes
     * The current view is the view among the tracked views which
     * has the *descendant node* which has most recently been focused.
     *
     * The current view will not be updated if the node loses focus. It
     * will only be updated when a different tracked view gains focus.
     *
     * If the current view is removed from the tracker, the previous
     * current view will be restored.
     *
     * This behavior is intended to follow a user's conceptual model of
     * a semantically "current" view, where the "last thing of type X"
     * to be interacted with is the "current instance of X", regardless
     * of whether that instance still has focus.
     */
  }, {
    key: "currentView",
    get: function get() {
      return this._currentView;
    }

    /**
     * The active view in the tracker.
     *
     * #### Notes
     * The active view is the view among the tracked views which
     * has the *descendant node* which is currently focused.
     */
  }, {
    key: "activeView",
    get: function get() {
      return this._activeView;
    }

    /**
     * A read only array of the views being tracked.
     */
  }, {
    key: "views",
    get: function get() {
      return this._views;
    }

    /**
     * Dispose of the resources held by the tracker.
     */
  }, {
    key: "dispose",
    value: function dispose() {
      var _this = this;
      // Do nothing if the tracker is already disposed.
      if (this.counter < 0) {
        return;
      }

      // Mark the tracker as disposed.
      this.counter = -1;

      // Clear the listeners for the tracker.
      this.activeChangedEmitter.dispose();
      this.currentChangedEmitter.dispose();

      // Remove all event listeners.
      this._views.forEach(function (view) {
        var _view$container, _view$container2;
        (_view$container = view.container) === null || _view$container === void 0 || (_view$container = _view$container.current) === null || _view$container === void 0 || _view$container.removeEventListener('focus', _this, true);
        (_view$container2 = view.container) === null || _view$container2 === void 0 || (_view$container2 = _view$container2.current) === null || _view$container2 === void 0 || _view$container2.removeEventListener('blur', _this, true);
      });

      // Clear the internal data structures.
      this._activeView = null;
      this._currentView = null;
      this.nodes.clear();
      this.numbers.clear();
      this._views.length = 0;
    }

    /**
     * Get the focus number for a particular view in the tracker.
     *
     * @param view - The view of interest.
     *
     * @returns The focus number for the given view, or `-1` if the
     *   view has not had focus since being added to the tracker, or
     *   is not contained by the tracker.
     *
     * #### Notes
     * The focus number indicates the relative order in which the views
     * have gained focus. A view with a larger number has gained focus
     * more recently than a view with a smaller number.
     *
     * The `currentView` will always have the largest focus number.
     *
     * All views start with a focus number of `-1`, which indicates that
     * the view has not been focused since being added to the tracker.
     */
  }, {
    key: "focusNumber",
    value: function focusNumber(view) {
      var n = this.numbers.get(view);
      return n === undefined ? -1 : n;
    }

    /**
     * Test whether the focus tracker contains a given view.
     *
     * @param view - The view of interest.
     *
     * @returns `true` if the view is tracked, `false` otherwise.
     */
  }, {
    key: "has",
    value: function has(view) {
      return this.numbers.has(view);
    }

    /**
     * Add a view to the focus tracker.
     *
     * @param view - The view of interest.
     *
     * #### Notes
     * A view will be automatically removed from the tracker if it
     * is disposed after being added.
     *
     * If the view is already tracked, this is a no-op.
     */
  }, {
    key: "add",
    value: function add(view) {
      var _view$container3,
        _view$container4,
        _view$container6,
        _view$container7,
        _this2 = this;
      // Do nothing if the view is already tracked.
      if (this.numbers.has(view)) {
        return;
      }

      // Test whether the view has focus.
      var focused = (_view$container3 = view.container) === null || _view$container3 === void 0 || (_view$container3 = _view$container3.current) === null || _view$container3 === void 0 ? void 0 : _view$container3.contains(document.activeElement);

      // Set up the initial focus number.
      var n = focused ? this.counter++ : -1;

      // Add the view to the internal data structures.
      this._views.push(view);
      this.numbers.set(view, n);
      if ((_view$container4 = view.container) !== null && _view$container4 !== void 0 && _view$container4.current) {
        var _view$container5;
        this.nodes.set((_view$container5 = view.container) === null || _view$container5 === void 0 ? void 0 : _view$container5.current, view);
      }

      // Set up the event listeners. The capturing phase must be used
      // since the 'focus' and 'blur' events don't bubble and Firefox
      // doesn't support the 'focusin' or 'focusout' events.
      (_view$container6 = view.container) === null || _view$container6 === void 0 || (_view$container6 = _view$container6.current) === null || _view$container6 === void 0 || _view$container6.addEventListener('focus', this, true);
      (_view$container7 = view.container) === null || _view$container7 === void 0 || (_view$container7 = _view$container7.current) === null || _view$container7 === void 0 || _view$container7.addEventListener('blur', this, true);

      // Connect the disposed signal handler.
      view.onDisposed(function () {
        return _this2.onViewDisposed;
      });

      // Set the current and active views if needed.
      if (focused) {
        this.setViews(view, view);
      }
    }

    /**
     * Remove a view from the focus tracker.
     *
     * #### Notes
     * If the view is the `currentView`, the previous current view
     * will become the new `currentView`.
     *
     * A view will be automatically removed from the tracker if it
     * is disposed after being added.
     *
     * If the view is not tracked, this is a no-op.
     */
  }, {
    key: "remove",
    value: function remove(view) {
      var _view$container8,
        _view$container9,
        _view$container10,
        _this3 = this;
      // Bail early if the view is not tracked.
      if (!this.numbers.has(view)) {
        return;
      }

      // Disconnect the disposed signal handler.
      // view.disposed.disconnect(this.onViewDisposed, this);

      // Remove the event listeners.
      (_view$container8 = view.container) === null || _view$container8 === void 0 || (_view$container8 = _view$container8.current) === null || _view$container8 === void 0 || _view$container8.removeEventListener('focus', this, true);
      (_view$container9 = view.container) === null || _view$container9 === void 0 || (_view$container9 = _view$container9.current) === null || _view$container9 === void 0 || _view$container9.removeEventListener('blur', this, true);

      // Remove the view from the internal data structures.
      this._views.splice(this._views.indexOf(view), 1);
      if ((_view$container10 = view.container) !== null && _view$container10 !== void 0 && _view$container10.current) {
        var _view$container11;
        this.nodes.delete((_view$container11 = view.container) === null || _view$container11 === void 0 ? void 0 : _view$container11.current);
      }
      this.numbers.delete(view);

      // Bail early if the view is not the current view.
      if (this._currentView !== view) {
        return;
      }

      // Filter the views for those which have had focus.
      var valid = this._views.filter(function (w) {
        return _this3.numbers.get(w) !== -1;
      });

      // Get the valid view with the max focus number.
      var previous = Iterable.max(valid, function (first, second) {
        var a = _this3.numbers.get(first);
        var b = _this3.numbers.get(second);
        return a - b;
      }) || null;

      // Set the current and active views.
      this.setViews(previous, null);
    }

    /**
     * Handle the DOM events for the focus tracker.
     *
     * @param event - The DOM event sent to the panel.
     *
     * #### Notes
     * This method implements the DOM `EventListener` interface and is
     * called in response to events on the tracked nodes. It should
     * not be called directly by user code.
     */
  }, {
    key: "handleEvent",
    value: function handleEvent(event) {
      switch (event.type) {
        case 'focus':
          this.handleFocusEvent(event);
          break;
        case 'blur':
          this.handleBlurEvent(event);
          break;
      }
    }

    /**
     * Set the current and active views for the tracker.
     */
  }, {
    key: "setViews",
    value: function setViews(current, active) {
      // Swap the current view.
      var oldCurrent = this._currentView;
      this._currentView = current;

      // Swap the active view.
      var oldActive = this._activeView;
      this._activeView = active;

      // Emit the `currentChanged` signal if needed.
      if (oldCurrent !== current) {
        this.currentChangedEmitter.fire({
          oldValue: oldCurrent,
          newValue: current
        });
      }

      // Emit the `activeChanged` signal if needed.
      if (oldActive !== active) {
        this.activeChangedEmitter.fire({
          oldValue: oldActive,
          newValue: active
        });
      }
    }

    /**
     * Handle the `'focus'` event for a tracked view.
     */
  }, {
    key: "handleFocusEvent",
    value: function handleFocusEvent(event) {
      // Find the view which gained focus, which is known to exist.
      var view = this.nodes.get(event.currentTarget);

      // Update the focus number if necessary.
      if (view !== this._currentView) {
        this.numbers.set(view, this.counter++);
      }

      // Set the current and active views.
      this.setViews(view, view);
    }

    /**
     * Handle the `'blur'` event for a tracked view.
     */
  }, {
    key: "handleBlurEvent",
    value: function handleBlurEvent(event) {
      var _view$container12;
      // Find the view which lost focus, which is known to exist.
      var view = this.nodes.get(event.currentTarget);

      // Get the node which being focused after this blur.
      var focusTarget = event.relatedTarget;

      // If no other node is being focused, clear the active view.
      if (!focusTarget) {
        this.setViews(this._currentView, null);
        return;
      }

      // Bail if the focus view is not changing.
      if ((_view$container12 = view.container) !== null && _view$container12 !== void 0 && (_view$container12 = _view$container12.current) !== null && _view$container12 !== void 0 && _view$container12.contains(focusTarget)) {
        return;
      }

      // If no tracked view is being focused, clear the active view.
      if (!this._views.find(function (v) {
        var _v$container;
        return (_v$container = v.container) === null || _v$container === void 0 || (_v$container = _v$container.current) === null || _v$container === void 0 ? void 0 : _v$container.contains(focusTarget);
      })) {
        this.setViews(this._currentView, null);
        return;
      }
    }

    /**
     * Handle the `disposed` signal for a tracked view.
     */
  }, {
    key: "onViewDisposed",
    value: function onViewDisposed(sender) {
      this.remove(sender);
    }
  }]);
  return FocusTracker;
}()) || _class);

/**
 * The namespace for the `FocusTracker` class statics.
 */