pdf.js/web/pdf_presentation_mode.js

/* Copyright 2012 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.
 */

import { normalizeWheelEventDelta } from 'pdfjs-web/ui_utils';

var DELAY_BEFORE_RESETTING_SWITCH_IN_PROGRESS = 1500; // in ms
var DELAY_BEFORE_HIDING_CONTROLS = 3000; // in ms
var ACTIVE_SELECTOR = 'pdfPresentationMode';
var CONTROLS_SELECTOR = 'pdfPresentationModeControls';

/**
 * @typedef {Object} PDFPresentationModeOptions
 * @property {HTMLDivElement} container - The container for the viewer element.
 * @property {HTMLDivElement} viewer - (optional) The viewer element.
 * @property {PDFViewer} pdfViewer - The document viewer.
 * @property {EventBus} eventBus - The application event bus.
 * @property {Array} contextMenuItems - (optional) The menuitems that are added
 *   to the context menu in Presentation Mode.
 */

/**
 * @class
 */
var PDFPresentationMode = (function PDFPresentationModeClosure() {
  /**
   * @constructs PDFPresentationMode
   * @param {PDFPresentationModeOptions} options
   */
  function PDFPresentationMode(options) {
    this.container = options.container;
    this.viewer = options.viewer || options.container.firstElementChild;
    this.pdfViewer = options.pdfViewer;
    this.eventBus = options.eventBus;
    var contextMenuItems = options.contextMenuItems || null;

    this.active = false;
    this.args = null;
    this.contextMenuOpen = false;
    this.mouseScrollTimeStamp = 0;
    this.mouseScrollDelta = 0;
    this.touchSwipeState = null;

    if (contextMenuItems) {
      contextMenuItems.contextFirstPage.addEventListener('click',
          function PDFPresentationMode_contextFirstPageClick(e) {
        this.contextMenuOpen = false;
        this.eventBus.dispatch('firstpage');
      }.bind(this));
      contextMenuItems.contextLastPage.addEventListener('click',
          function PDFPresentationMode_contextLastPageClick(e) {
        this.contextMenuOpen = false;
        this.eventBus.dispatch('lastpage');
      }.bind(this));
      contextMenuItems.contextPageRotateCw.addEventListener('click',
          function PDFPresentationMode_contextPageRotateCwClick(e) {
        this.contextMenuOpen = false;
        this.eventBus.dispatch('rotatecw');
      }.bind(this));
      contextMenuItems.contextPageRotateCcw.addEventListener('click',
          function PDFPresentationMode_contextPageRotateCcwClick(e) {
        this.contextMenuOpen = false;
        this.eventBus.dispatch('rotateccw');
      }.bind(this));
    }
  }

  PDFPresentationMode.prototype = {
    /**
     * Request the browser to enter fullscreen mode.
     * @returns {boolean} Indicating if the request was successful.
     */
    request: function PDFPresentationMode_request() {
      if (this.switchInProgress || this.active ||
          !this.viewer.hasChildNodes()) {
        return false;
      }
      this._addFullscreenChangeListeners();
      this._setSwitchInProgress();
      this._notifyStateChange();

      if (this.container.requestFullscreen) {
        this.container.requestFullscreen();
      } else if (this.container.mozRequestFullScreen) {
        this.container.mozRequestFullScreen();
      } else if (this.container.webkitRequestFullscreen) {
        this.container.webkitRequestFullscreen(Element.ALLOW_KEYBOARD_INPUT);
      } else if (this.container.msRequestFullscreen) {
        this.container.msRequestFullscreen();
      } else {
        return false;
      }

      this.args = {
        page: this.pdfViewer.currentPageNumber,
        previousScale: this.pdfViewer.currentScaleValue,
      };

      return true;
    },

    /**
     * @private
     */
    _mouseWheel: function PDFPresentationMode_mouseWheel(evt) {
      if (!this.active) {
        return;
      }

      evt.preventDefault();

      var delta = normalizeWheelEventDelta(evt);

      var MOUSE_SCROLL_COOLDOWN_TIME = 50;
      var PAGE_SWITCH_THRESHOLD = 0.1;

      var currentTime = (new Date()).getTime();
      var storedTime = this.mouseScrollTimeStamp;

      // If we've already switched page, avoid accidentally switching again.
      if (currentTime > storedTime &&
          currentTime - storedTime < MOUSE_SCROLL_COOLDOWN_TIME) {
        return;
      }
      // If the scroll direction changed, reset the accumulated scroll delta.
      if ((this.mouseScrollDelta > 0 && delta < 0) ||
          (this.mouseScrollDelta < 0 && delta > 0)) {
        this._resetMouseScrollState();
      }
      this.mouseScrollDelta += delta;

      if (Math.abs(this.mouseScrollDelta) >= PAGE_SWITCH_THRESHOLD) {
        var totalDelta = this.mouseScrollDelta;
        this._resetMouseScrollState();
        var success = totalDelta > 0 ? this._goToPreviousPage()
                                     : this._goToNextPage();
        if (success) {
          this.mouseScrollTimeStamp = currentTime;
        }
      }
    },

    get isFullscreen() {
      return !!(document.fullscreenElement ||
                document.mozFullScreen ||
                document.webkitIsFullScreen ||
                document.msFullscreenElement);
    },

    /**
     * @private
     */
    _goToPreviousPage: function PDFPresentationMode_goToPreviousPage() {
      var page = this.pdfViewer.currentPageNumber;
      // If we're at the first page, we don't need to do anything.
      if (page <= 1) {
        return false;
      }
      this.pdfViewer.currentPageNumber = (page - 1);
      return true;
    },

    /**
     * @private
     */
    _goToNextPage: function PDFPresentationMode_goToNextPage() {
      var page = this.pdfViewer.currentPageNumber;
      // If we're at the last page, we don't need to do anything.
      if (page >= this.pdfViewer.pagesCount) {
        return false;
      }
      this.pdfViewer.currentPageNumber = (page + 1);
      return true;
    },

    /**
     * @private
     */
    _notifyStateChange: function PDFPresentationMode_notifyStateChange() {
      this.eventBus.dispatch('presentationmodechanged', {
        source: this,
        active: this.active,
        switchInProgress: !!this.switchInProgress
      });
    },

    /**
     * Used to initialize a timeout when requesting Presentation Mode,
     * i.e. when the browser is requested to enter fullscreen mode.
     * This timeout is used to prevent the current page from being scrolled
     * partially, or completely, out of view when entering Presentation Mode.
     * NOTE: This issue seems limited to certain zoom levels (e.g. page-width).
     * @private
     */
    _setSwitchInProgress: function PDFPresentationMode_setSwitchInProgress() {
      if (this.switchInProgress) {
        clearTimeout(this.switchInProgress);
      }
      this.switchInProgress = setTimeout(function switchInProgressTimeout() {
        this._removeFullscreenChangeListeners();
        delete this.switchInProgress;
        this._notifyStateChange();
      }.bind(this), DELAY_BEFORE_RESETTING_SWITCH_IN_PROGRESS);
    },

    /**
     * @private
     */
    _resetSwitchInProgress:
        function PDFPresentationMode_resetSwitchInProgress() {
      if (this.switchInProgress) {
        clearTimeout(this.switchInProgress);
        delete this.switchInProgress;
      }
    },

    /**
     * @private
     */
    _enter: function PDFPresentationMode_enter() {
      this.active = true;
      this._resetSwitchInProgress();
      this._notifyStateChange();
      this.container.classList.add(ACTIVE_SELECTOR);

      // Ensure that the correct page is scrolled into view when entering
      // Presentation Mode, by waiting until fullscreen mode in enabled.
      setTimeout(function enterPresentationModeTimeout() {
        this.pdfViewer.currentPageNumber = this.args.page;
        this.pdfViewer.currentScaleValue = 'page-fit';
      }.bind(this), 0);

      this._addWindowListeners();
      this._showControls();
      this.contextMenuOpen = false;
      this.container.setAttribute('contextmenu', 'viewerContextMenu');

      // Text selection is disabled in Presentation Mode, thus it's not possible
      // for the user to deselect text that is selected (e.g. with "Select all")
      // when entering Presentation Mode, hence we remove any active selection.
      window.getSelection().removeAllRanges();
    },

    /**
     * @private
     */
    _exit: function PDFPresentationMode_exit() {
      var page = this.pdfViewer.currentPageNumber;
      this.container.classList.remove(ACTIVE_SELECTOR);

      // Ensure that the correct page is scrolled into view when exiting
      // Presentation Mode, by waiting until fullscreen mode is disabled.
      setTimeout(function exitPresentationModeTimeout() {
        this.active = false;
        this._removeFullscreenChangeListeners();
        this._notifyStateChange();

        this.pdfViewer.currentScaleValue = this.args.previousScale;
        this.pdfViewer.currentPageNumber = page;
        this.args = null;
      }.bind(this), 0);

      this._removeWindowListeners();
      this._hideControls();
      this._resetMouseScrollState();
      this.container.removeAttribute('contextmenu');
      this.contextMenuOpen = false;
    },

    /**
     * @private
     */
    _mouseDown: function PDFPresentationMode_mouseDown(evt) {
      if (this.contextMenuOpen) {
        this.contextMenuOpen = false;
        evt.preventDefault();
        return;
      }
      if (evt.button === 0) {
        // Enable clicking of links in presentation mode. Please note:
        // Only links pointing to destinations in the current PDF document work.
        var isInternalLink = (evt.target.href &&
                              evt.target.classList.contains('internalLink'));
        if (!isInternalLink) {
          // Unless an internal link was clicked, advance one page.
          evt.preventDefault();
          this.pdfViewer.currentPageNumber += (evt.shiftKey ? -1 : 1);
        }
      }
    },

    /**
     * @private
     */
    _contextMenu: function PDFPresentationMode_contextMenu() {
      this.contextMenuOpen = true;
    },

    /**
     * @private
     */
    _showControls: function PDFPresentationMode_showControls() {
      if (this.controlsTimeout) {
        clearTimeout(this.controlsTimeout);
      } else {
        this.container.classList.add(CONTROLS_SELECTOR);
      }
      this.controlsTimeout = setTimeout(function showControlsTimeout() {
        this.container.classList.remove(CONTROLS_SELECTOR);
        delete this.controlsTimeout;
      }.bind(this), DELAY_BEFORE_HIDING_CONTROLS);
    },

    /**
     * @private
     */
    _hideControls: function PDFPresentationMode_hideControls() {
      if (!this.controlsTimeout) {
        return;
      }
      clearTimeout(this.controlsTimeout);
      this.container.classList.remove(CONTROLS_SELECTOR);
      delete this.controlsTimeout;
    },

    /**
     * Resets the properties used for tracking mouse scrolling events.
     * @private
     */
    _resetMouseScrollState:
        function PDFPresentationMode_resetMouseScrollState() {
      this.mouseScrollTimeStamp = 0;
      this.mouseScrollDelta = 0;
    },

    /**
     * @private
     */
    _touchSwipe: function PDFPresentationMode_touchSwipe(evt) {
      if (!this.active) {
        return;
      }

      // Must move at least these many CSS pixels for it to count as a swipe
      var SWIPE_MIN_DISTANCE_THRESHOLD = 50;
      // The swipe angle is allowed to deviate from the x or y axis by this much
      // before it is not considered a swipe in that direction any more.
      var SWIPE_ANGLE_THRESHOLD = Math.PI / 6;

      if (evt.touches.length > 1) {
        // Multiple touch points detected, cancel the swipe.
        this.touchSwipeState = null;
        return;
      }
      switch (evt.type) {
        case 'touchstart':
          this.touchSwipeState = {
            startX: evt.touches[0].pageX,
            startY: evt.touches[0].pageY,
            endX: evt.touches[0].pageX,
            endY: evt.touches[0].pageY
          };
          break;
        case 'touchmove':
          if (this.touchSwipeState === null) {
            return;
          }
          this.touchSwipeState.endX = evt.touches[0].pageX;
          this.touchSwipeState.endY = evt.touches[0].pageY;
          // Do a preventDefault to avoid the swipe from triggering browser
          // gestures (Chrome in particular has some sort of swipe gesture in
          // fullscreen mode).
          evt.preventDefault();
          break;
        case 'touchend':
          if (this.touchSwipeState === null) {
            return;
          }
          var delta = 0;
          var dx = this.touchSwipeState.endX - this.touchSwipeState.startX;
          var dy = this.touchSwipeState.endY - this.touchSwipeState.startY;
          var absAngle = Math.abs(Math.atan2(dy, dx));
          if (Math.abs(dx) > SWIPE_MIN_DISTANCE_THRESHOLD &&
              (absAngle <= SWIPE_ANGLE_THRESHOLD ||
               absAngle >= (Math.PI - SWIPE_ANGLE_THRESHOLD))) {
            // horizontal swipe
            delta = dx;
          } else if (Math.abs(dy) > SWIPE_MIN_DISTANCE_THRESHOLD &&
              Math.abs(absAngle - (Math.PI / 2)) <= SWIPE_ANGLE_THRESHOLD) {
            // vertical swipe
            delta = dy;
          }
          if (delta > 0) {
            this._goToPreviousPage();
          } else if (delta < 0) {
            this._goToNextPage();
          }
          break;
      }
    },

    /**
     * @private
     */
    _addWindowListeners: function PDFPresentationMode_addWindowListeners() {
      this.showControlsBind = this._showControls.bind(this);
      this.mouseDownBind = this._mouseDown.bind(this);
      this.mouseWheelBind = this._mouseWheel.bind(this);
      this.resetMouseScrollStateBind = this._resetMouseScrollState.bind(this);
      this.contextMenuBind = this._contextMenu.bind(this);
      this.touchSwipeBind = this._touchSwipe.bind(this);

      window.addEventListener('mousemove', this.showControlsBind);
      window.addEventListener('mousedown', this.mouseDownBind);
      window.addEventListener('wheel', this.mouseWheelBind);
      window.addEventListener('keydown', this.resetMouseScrollStateBind);
      window.addEventListener('contextmenu', this.contextMenuBind);
      window.addEventListener('touchstart', this.touchSwipeBind);
      window.addEventListener('touchmove', this.touchSwipeBind);
      window.addEventListener('touchend', this.touchSwipeBind);
    },

    /**
     * @private
     */
    _removeWindowListeners:
        function PDFPresentationMode_removeWindowListeners() {
      window.removeEventListener('mousemove', this.showControlsBind);
      window.removeEventListener('mousedown', this.mouseDownBind);
      window.removeEventListener('wheel', this.mouseWheelBind);
      window.removeEventListener('keydown', this.resetMouseScrollStateBind);
      window.removeEventListener('contextmenu', this.contextMenuBind);
      window.removeEventListener('touchstart', this.touchSwipeBind);
      window.removeEventListener('touchmove', this.touchSwipeBind);
      window.removeEventListener('touchend', this.touchSwipeBind);

      delete this.showControlsBind;
      delete this.mouseDownBind;
      delete this.mouseWheelBind;
      delete this.resetMouseScrollStateBind;
      delete this.contextMenuBind;
      delete this.touchSwipeBind;
    },

    /**
     * @private
     */
    _fullscreenChange: function PDFPresentationMode_fullscreenChange() {
      if (this.isFullscreen) {
        this._enter();
      } else {
        this._exit();
      }
    },

    /**
     * @private
     */
    _addFullscreenChangeListeners:
        function PDFPresentationMode_addFullscreenChangeListeners() {
      this.fullscreenChangeBind = this._fullscreenChange.bind(this);

      window.addEventListener('fullscreenchange', this.fullscreenChangeBind);
      window.addEventListener('mozfullscreenchange', this.fullscreenChangeBind);
      if (typeof PDFJSDev === 'undefined' ||
          !PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
        window.addEventListener('webkitfullscreenchange',
                                this.fullscreenChangeBind);
        window.addEventListener('MSFullscreenChange',
                                this.fullscreenChangeBind);
      }
    },

    /**
     * @private
     */
    _removeFullscreenChangeListeners:
        function PDFPresentationMode_removeFullscreenChangeListeners() {
      window.removeEventListener('fullscreenchange', this.fullscreenChangeBind);
      window.removeEventListener('mozfullscreenchange',
                                 this.fullscreenChangeBind);
      if (typeof PDFJSDev === 'undefined' ||
          !PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
        window.removeEventListener('webkitfullscreenchange',
                                this.fullscreenChangeBind);
        window.removeEventListener('MSFullscreenChange',
                                  this.fullscreenChangeBind);
      }

      delete this.fullscreenChangeBind;
    }
  };

  return PDFPresentationMode;
})();

export {
  PDFPresentationMode,
};