pdfjs-dist/web/overlay_manager.js

/* Copyright 2014 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

class OverlayManager {
  constructor() {
    this._overlays = {};
    this._active = null;
    this._keyDownBound = this._keyDown.bind(this);
  }

  get active() {
    return this._active;
  }

  /**
   * @param {string} name - The name of the overlay that is registered.
   * @param {HTMLDivElement} element - The overlay's DOM element.
   * @param {function} callerCloseMethod - (optional) The method that, if
   *                   present, calls `OverlayManager.close` from the object
   *                   registering the overlay. Access to this method is
   *                   necessary in order to run cleanup code when e.g.
   *                   the overlay is force closed. The default is `null`.
   * @param {boolean} canForceClose - (optional) Indicates if opening the
   *                  overlay closes an active overlay. The default is `false`.
   * @returns {Promise} A promise that is resolved when the overlay has been
   *                    registered.
   */
  register(name, element, callerCloseMethod = null, canForceClose = false) {
    return new Promise((resolve) => {
      let container;
      if (!name || !element || !(container = element.parentNode)) {
        throw new Error('Not enough parameters.');
      } else if (this._overlays[name]) {
        throw new Error('The overlay is already registered.');
      }
      this._overlays[name] = {
        element,
        container,
        callerCloseMethod,
        canForceClose,
      };
      resolve();
    });
  }

  /**
   * @param {string} name - The name of the overlay that is unregistered.
   * @returns {Promise} A promise that is resolved when the overlay has been
   *                    unregistered.
   */
  unregister(name) {
    return new Promise((resolve) => {
      if (!this._overlays[name]) {
        throw new Error('The overlay does not exist.');
      } else if (this._active === name) {
        throw new Error('The overlay cannot be removed while it is active.');
      }
      delete this._overlays[name];
      resolve();
    });
  }

  /**
   * @param {string} name - The name of the overlay that should be opened.
   * @returns {Promise} A promise that is resolved when the overlay has been
   *                    opened.
   */
  open(name) {
    return new Promise((resolve) => {
      if (!this._overlays[name]) {
        throw new Error('The overlay does not exist.');
      } else if (this._active) {
        if (this._overlays[name].canForceClose) {
          this._closeThroughCaller();
        } else if (this._active === name) {
          throw new Error('The overlay is already active.');
        } else {
          throw new Error('Another overlay is currently active.');
        }
      }
      this._active = name;
      this._overlays[this._active].element.classList.remove('hidden');
      this._overlays[this._active].container.classList.remove('hidden');

      window.addEventListener('keydown', this._keyDownBound);
      resolve();
    });
  }

  /**
   * @param {string} name - The name of the overlay that should be closed.
   * @returns {Promise} A promise that is resolved when the overlay has been
   *                    closed.
   */
  close(name) {
    return new Promise((resolve) => {
      if (!this._overlays[name]) {
        throw new Error('The overlay does not exist.');
      } else if (!this._active) {
        throw new Error('The overlay is currently not active.');
      } else if (this._active !== name) {
        throw new Error('Another overlay is currently active.');
      }
      this._overlays[this._active].container.classList.add('hidden');
      this._overlays[this._active].element.classList.add('hidden');
      this._active = null;

      window.removeEventListener('keydown', this._keyDownBound);
      resolve();
    });
  }

  /**
   * @private
   */
  _keyDown(evt) {
    if (this._active && evt.keyCode === 27) { // Esc key.
      this._closeThroughCaller();
      evt.preventDefault();
    }
  }

  /**
   * @private
   */
  _closeThroughCaller() {
    if (this._overlays[this._active].callerCloseMethod) {
      this._overlays[this._active].callerCloseMethod();
    }
    if (this._active) {
      this.close(this._active);
    }
  }
}

export {
  OverlayManager,
};