pdfjs-dist/lib/web/base_viewer.js

/**
 * @licstart The following is the entire license notice for the
 * Javascript code in this page
 *
 * Copyright 2020 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.
 *
 * @licend The above is the entire license notice for the
 * Javascript code in this page
 */
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.BaseViewer = void 0;

var _ui_utils = require("./ui_utils.js");

var _pdf_rendering_queue = require("./pdf_rendering_queue.js");

var _annotation_layer_builder = require("./annotation_layer_builder.js");

var _pdf = require("../pdf");

var _pdf_page_view = require("./pdf_page_view.js");

var _pdf_link_service = require("./pdf_link_service.js");

var _text_layer_builder = require("./text_layer_builder.js");

const DEFAULT_CACHE_SIZE = 10;

function PDFPageViewBuffer(size) {
  const data = [];

  this.push = function (view) {
    const i = data.indexOf(view);

    if (i >= 0) {
      data.splice(i, 1);
    }

    data.push(view);

    if (data.length > size) {
      data.shift().destroy();
    }
  };

  this.resize = function (newSize, pagesToKeep) {
    size = newSize;

    if (pagesToKeep) {
      const pageIdsToKeep = new Set();

      for (let i = 0, iMax = pagesToKeep.length; i < iMax; ++i) {
        pageIdsToKeep.add(pagesToKeep[i].id);
      }

      (0, _ui_utils.moveToEndOfArray)(data, function (page) {
        return pageIdsToKeep.has(page.id);
      });
    }

    while (data.length > size) {
      data.shift().destroy();
    }
  };
}

function isSameScale(oldScale, newScale) {
  if (newScale === oldScale) {
    return true;
  }

  if (Math.abs(newScale - oldScale) < 1e-15) {
    return true;
  }

  return false;
}

class BaseViewer {
  constructor(options) {
    if (this.constructor === BaseViewer) {
      throw new Error("Cannot initialize BaseViewer.");
    }

    this._name = this.constructor.name;
    this.container = options.container;
    this.viewer = options.viewer || options.container.firstElementChild;
    this.eventBus = options.eventBus || (0, _ui_utils.getGlobalEventBus)();
    this.linkService = options.linkService || new _pdf_link_service.SimpleLinkService();
    this.downloadManager = options.downloadManager || null;
    this.findController = options.findController || null;
    this.removePageBorders = options.removePageBorders || false;
    this.textLayerMode = Number.isInteger(options.textLayerMode) ? options.textLayerMode : _ui_utils.TextLayerMode.ENABLE;
    this.imageResourcesPath = options.imageResourcesPath || "";
    this.renderInteractiveForms = options.renderInteractiveForms || false;
    this.enablePrintAutoRotate = options.enablePrintAutoRotate || false;
    this.renderer = options.renderer || _ui_utils.RendererType.CANVAS;
    this.enableWebGL = options.enableWebGL || false;
    this.useOnlyCssZoom = options.useOnlyCssZoom || false;
    this.maxCanvasPixels = options.maxCanvasPixels;
    this.l10n = options.l10n || _ui_utils.NullL10n;
    this.defaultRenderingQueue = !options.renderingQueue;

    if (this.defaultRenderingQueue) {
      this.renderingQueue = new _pdf_rendering_queue.PDFRenderingQueue();
      this.renderingQueue.setViewer(this);
    } else {
      this.renderingQueue = options.renderingQueue;
    }

    this.scroll = (0, _ui_utils.watchScroll)(this.container, this._scrollUpdate.bind(this));
    this.presentationModeState = _ui_utils.PresentationModeState.UNKNOWN;
    this._onBeforeDraw = this._onAfterDraw = null;

    this._resetView();

    if (this.removePageBorders) {
      this.viewer.classList.add("removePageBorders");
    }

    Promise.resolve().then(() => {
      this.eventBus.dispatch("baseviewerinit", {
        source: this
      });
    });
  }

  get pagesCount() {
    return this._pages.length;
  }

  getPageView(index) {
    return this._pages[index];
  }

  get pageViewsReady() {
    if (!this._pagesCapability.settled) {
      return false;
    }

    return this._pages.every(function (pageView) {
      return pageView && pageView.pdfPage;
    });
  }

  get currentPageNumber() {
    return this._currentPageNumber;
  }

  set currentPageNumber(val) {
    if (!Number.isInteger(val)) {
      throw new Error("Invalid page number.");
    }

    if (!this.pdfDocument) {
      return;
    }

    if (!this._setCurrentPageNumber(val, true)) {
      console.error(`${this._name}.currentPageNumber: "${val}" is not a valid page.`);
    }
  }

  _setCurrentPageNumber(val, resetCurrentPageView = false) {
    if (this._currentPageNumber === val) {
      if (resetCurrentPageView) {
        this._resetCurrentPageView();
      }

      return true;
    }

    if (!(0 < val && val <= this.pagesCount)) {
      return false;
    }

    this._currentPageNumber = val;
    this.eventBus.dispatch("pagechanging", {
      source: this,
      pageNumber: val,
      pageLabel: this._pageLabels && this._pageLabels[val - 1]
    });

    if (resetCurrentPageView) {
      this._resetCurrentPageView();
    }

    return true;
  }

  get currentPageLabel() {
    return this._pageLabels && this._pageLabels[this._currentPageNumber - 1];
  }

  set currentPageLabel(val) {
    if (!this.pdfDocument) {
      return;
    }

    let page = val | 0;

    if (this._pageLabels) {
      const i = this._pageLabels.indexOf(val);

      if (i >= 0) {
        page = i + 1;
      }
    }

    if (!this._setCurrentPageNumber(page, true)) {
      console.error(`${this._name}.currentPageLabel: "${val}" is not a valid page.`);
    }
  }

  get currentScale() {
    return this._currentScale !== _ui_utils.UNKNOWN_SCALE ? this._currentScale : _ui_utils.DEFAULT_SCALE;
  }

  set currentScale(val) {
    if (isNaN(val)) {
      throw new Error("Invalid numeric scale.");
    }

    if (!this.pdfDocument) {
      return;
    }

    this._setScale(val, false);
  }

  get currentScaleValue() {
    return this._currentScaleValue;
  }

  set currentScaleValue(val) {
    if (!this.pdfDocument) {
      return;
    }

    this._setScale(val, false);
  }

  get pagesRotation() {
    return this._pagesRotation;
  }

  set pagesRotation(rotation) {
    if (!(0, _ui_utils.isValidRotation)(rotation)) {
      throw new Error("Invalid pages rotation angle.");
    }

    if (!this.pdfDocument) {
      return;
    }

    if (this._pagesRotation === rotation) {
      return;
    }

    this._pagesRotation = rotation;
    const pageNumber = this._currentPageNumber;

    for (let i = 0, ii = this._pages.length; i < ii; i++) {
      const pageView = this._pages[i];
      pageView.update(pageView.scale, rotation);
    }

    if (this._currentScaleValue) {
      this._setScale(this._currentScaleValue, true);
    }

    this.eventBus.dispatch("rotationchanging", {
      source: this,
      pagesRotation: rotation,
      pageNumber
    });

    if (this.defaultRenderingQueue) {
      this.update();
    }
  }

  get firstPagePromise() {
    return this.pdfDocument ? this._firstPageCapability.promise : null;
  }

  get onePageRendered() {
    return this.pdfDocument ? this._onePageRenderedCapability.promise : null;
  }

  get pagesPromise() {
    return this.pdfDocument ? this._pagesCapability.promise : null;
  }

  get _setDocumentViewerElement() {
    throw new Error("Not implemented: _setDocumentViewerElement");
  }

  setDocument(pdfDocument) {
    if (this.pdfDocument) {
      this._cancelRendering();

      this._resetView();

      if (this.findController) {
        this.findController.setDocument(null);
      }
    }

    this.pdfDocument = pdfDocument;

    if (!pdfDocument) {
      return;
    }

    const pagesCount = pdfDocument.numPages;
    const firstPagePromise = pdfDocument.getPage(1);

    this._pagesCapability.promise.then(() => {
      this.eventBus.dispatch("pagesloaded", {
        source: this,
        pagesCount
      });
    });

    this._onBeforeDraw = evt => {
      const pageView = this._pages[evt.pageNumber - 1];

      if (!pageView) {
        return;
      }

      this._buffer.push(pageView);
    };

    this.eventBus._on("pagerender", this._onBeforeDraw);

    this._onAfterDraw = evt => {
      if (evt.cssTransform || this._onePageRenderedCapability.settled) {
        return;
      }

      this._onePageRenderedCapability.resolve();

      this.eventBus._off("pagerendered", this._onAfterDraw);

      this._onAfterDraw = null;
    };

    this.eventBus._on("pagerendered", this._onAfterDraw);

    firstPagePromise.then(firstPdfPage => {
      this._firstPageCapability.resolve(firstPdfPage);

      const scale = this.currentScale;
      const viewport = firstPdfPage.getViewport({
        scale: scale * _ui_utils.CSS_UNITS
      });
      const textLayerFactory = this.textLayerMode !== _ui_utils.TextLayerMode.DISABLE ? this : null;

      for (let pageNum = 1; pageNum <= pagesCount; ++pageNum) {
        const pageView = new _pdf_page_view.PDFPageView({
          container: this._setDocumentViewerElement,
          eventBus: this.eventBus,
          id: pageNum,
          scale,
          defaultViewport: viewport.clone(),
          renderingQueue: this.renderingQueue,
          textLayerFactory,
          textLayerMode: this.textLayerMode,
          annotationLayerFactory: this,
          imageResourcesPath: this.imageResourcesPath,
          renderInteractiveForms: this.renderInteractiveForms,
          renderer: this.renderer,
          enableWebGL: this.enableWebGL,
          useOnlyCssZoom: this.useOnlyCssZoom,
          maxCanvasPixels: this.maxCanvasPixels,
          l10n: this.l10n
        });

        this._pages.push(pageView);
      }

      const firstPageView = this._pages[0];

      if (firstPageView) {
        firstPageView.setPdfPage(firstPdfPage);
        this.linkService.cachePageRef(1, firstPdfPage.ref);
      }

      if (this._spreadMode !== _ui_utils.SpreadMode.NONE) {
        this._updateSpreadMode();
      }

      this._onePageRenderedCapability.promise.then(() => {
        if (this.findController) {
          this.findController.setDocument(pdfDocument);
        }

        if (pdfDocument.loadingParams["disableAutoFetch"] || pagesCount > 7500) {
          this._pagesCapability.resolve();

          return;
        }

        let getPagesLeft = pagesCount - 1;

        if (getPagesLeft <= 0) {
          this._pagesCapability.resolve();

          return;
        }

        for (let pageNum = 2; pageNum <= pagesCount; ++pageNum) {
          pdfDocument.getPage(pageNum).then(pdfPage => {
            const pageView = this._pages[pageNum - 1];

            if (!pageView.pdfPage) {
              pageView.setPdfPage(pdfPage);
            }

            this.linkService.cachePageRef(pageNum, pdfPage.ref);

            if (--getPagesLeft === 0) {
              this._pagesCapability.resolve();
            }
          }, reason => {
            console.error(`Unable to get page ${pageNum} to initialize viewer`, reason);

            if (--getPagesLeft === 0) {
              this._pagesCapability.resolve();
            }
          });
        }
      });

      this.eventBus.dispatch("pagesinit", {
        source: this
      });

      if (this.defaultRenderingQueue) {
        this.update();
      }
    }).catch(reason => {
      console.error("Unable to initialize viewer", reason);
    });
  }

  setPageLabels(labels) {
    if (!this.pdfDocument) {
      return;
    }

    if (!labels) {
      this._pageLabels = null;
    } else if (!(Array.isArray(labels) && this.pdfDocument.numPages === labels.length)) {
      this._pageLabels = null;
      console.error(`${this._name}.setPageLabels: Invalid page labels.`);
    } else {
      this._pageLabels = labels;
    }

    for (let i = 0, ii = this._pages.length; i < ii; i++) {
      const pageView = this._pages[i];
      const label = this._pageLabels && this._pageLabels[i];
      pageView.setPageLabel(label);
    }
  }

  _resetView() {
    this._pages = [];
    this._currentPageNumber = 1;
    this._currentScale = _ui_utils.UNKNOWN_SCALE;
    this._currentScaleValue = null;
    this._pageLabels = null;
    this._buffer = new PDFPageViewBuffer(DEFAULT_CACHE_SIZE);
    this._location = null;
    this._pagesRotation = 0;
    this._pagesRequests = new WeakMap();
    this._firstPageCapability = (0, _pdf.createPromiseCapability)();
    this._onePageRenderedCapability = (0, _pdf.createPromiseCapability)();
    this._pagesCapability = (0, _pdf.createPromiseCapability)();
    this._scrollMode = _ui_utils.ScrollMode.VERTICAL;
    this._spreadMode = _ui_utils.SpreadMode.NONE;

    if (this._onBeforeDraw) {
      this.eventBus._off("pagerender", this._onBeforeDraw);

      this._onBeforeDraw = null;
    }

    if (this._onAfterDraw) {
      this.eventBus._off("pagerendered", this._onAfterDraw);

      this._onAfterDraw = null;
    }

    this.viewer.textContent = "";

    this._updateScrollMode();
  }

  _scrollUpdate() {
    if (this.pagesCount === 0) {
      return;
    }

    this.update();
  }

  _scrollIntoView({
    pageDiv,
    pageSpot = null,
    pageNumber = null
  }) {
    (0, _ui_utils.scrollIntoView)(pageDiv, pageSpot);
  }

  _setScaleUpdatePages(newScale, newValue, noScroll = false, preset = false) {
    this._currentScaleValue = newValue.toString();

    if (isSameScale(this._currentScale, newScale)) {
      if (preset) {
        this.eventBus.dispatch("scalechanging", {
          source: this,
          scale: newScale,
          presetValue: newValue
        });
      }

      return;
    }

    for (let i = 0, ii = this._pages.length; i < ii; i++) {
      this._pages[i].update(newScale);
    }

    this._currentScale = newScale;

    if (!noScroll) {
      let page = this._currentPageNumber,
          dest;

      if (this._location && !(this.isInPresentationMode || this.isChangingPresentationMode)) {
        page = this._location.pageNumber;
        dest = [null, {
          name: "XYZ"
        }, this._location.left, this._location.top, null];
      }

      this.scrollPageIntoView({
        pageNumber: page,
        destArray: dest,
        allowNegativeOffset: true
      });
    }

    this.eventBus.dispatch("scalechanging", {
      source: this,
      scale: newScale,
      presetValue: preset ? newValue : undefined
    });

    if (this.defaultRenderingQueue) {
      this.update();
    }
  }

  _setScale(value, noScroll = false) {
    let scale = parseFloat(value);

    if (scale > 0) {
      this._setScaleUpdatePages(scale, value, noScroll, false);
    } else {
      const currentPage = this._pages[this._currentPageNumber - 1];

      if (!currentPage) {
        return;
      }

      const noPadding = this.isInPresentationMode || this.removePageBorders;
      let hPadding = noPadding ? 0 : _ui_utils.SCROLLBAR_PADDING;
      let vPadding = noPadding ? 0 : _ui_utils.VERTICAL_PADDING;

      if (!noPadding && this._isScrollModeHorizontal) {
        [hPadding, vPadding] = [vPadding, hPadding];
      }

      const pageWidthScale = (this.container.clientWidth - hPadding) / currentPage.width * currentPage.scale;
      const pageHeightScale = (this.container.clientHeight - vPadding) / currentPage.height * currentPage.scale;

      switch (value) {
        case "page-actual":
          scale = 1;
          break;

        case "page-width":
          scale = pageWidthScale;
          break;

        case "page-height":
          scale = pageHeightScale;
          break;

        case "page-fit":
          scale = Math.min(pageWidthScale, pageHeightScale);
          break;

        case "auto":
          const horizontalScale = (0, _ui_utils.isPortraitOrientation)(currentPage) ? pageWidthScale : Math.min(pageHeightScale, pageWidthScale);
          scale = Math.min(_ui_utils.MAX_AUTO_SCALE, horizontalScale);
          break;

        default:
          console.error(`${this._name}._setScale: "${value}" is an unknown zoom value.`);
          return;
      }

      this._setScaleUpdatePages(scale, value, noScroll, true);
    }
  }

  _resetCurrentPageView() {
    if (this.isInPresentationMode) {
      this._setScale(this._currentScaleValue, true);
    }

    const pageView = this._pages[this._currentPageNumber - 1];

    this._scrollIntoView({
      pageDiv: pageView.div
    });
  }

  scrollPageIntoView({
    pageNumber,
    destArray = null,
    allowNegativeOffset = false,
    ignoreDestinationZoom = false
  }) {
    if (!this.pdfDocument) {
      return;
    }

    const pageView = Number.isInteger(pageNumber) && this._pages[pageNumber - 1];

    if (!pageView) {
      console.error(`${this._name}.scrollPageIntoView: ` + `"${pageNumber}" is not a valid pageNumber parameter.`);
      return;
    }

    if (this.isInPresentationMode || !destArray) {
      this._setCurrentPageNumber(pageNumber, true);

      return;
    }

    let x = 0,
        y = 0;
    let width = 0,
        height = 0,
        widthScale,
        heightScale;
    const changeOrientation = pageView.rotation % 180 !== 0;
    const pageWidth = (changeOrientation ? pageView.height : pageView.width) / pageView.scale / _ui_utils.CSS_UNITS;
    const pageHeight = (changeOrientation ? pageView.width : pageView.height) / pageView.scale / _ui_utils.CSS_UNITS;
    let scale = 0;

    switch (destArray[1].name) {
      case "XYZ":
        x = destArray[2];
        y = destArray[3];
        scale = destArray[4];
        x = x !== null ? x : 0;
        y = y !== null ? y : pageHeight;
        break;

      case "Fit":
      case "FitB":
        scale = "page-fit";
        break;

      case "FitH":
      case "FitBH":
        y = destArray[2];
        scale = "page-width";

        if (y === null && this._location) {
          x = this._location.left;
          y = this._location.top;
        }

        break;

      case "FitV":
      case "FitBV":
        x = destArray[2];
        width = pageWidth;
        height = pageHeight;
        scale = "page-height";
        break;

      case "FitR":
        x = destArray[2];
        y = destArray[3];
        width = destArray[4] - x;
        height = destArray[5] - y;
        const hPadding = this.removePageBorders ? 0 : _ui_utils.SCROLLBAR_PADDING;
        const vPadding = this.removePageBorders ? 0 : _ui_utils.VERTICAL_PADDING;
        widthScale = (this.container.clientWidth - hPadding) / width / _ui_utils.CSS_UNITS;
        heightScale = (this.container.clientHeight - vPadding) / height / _ui_utils.CSS_UNITS;
        scale = Math.min(Math.abs(widthScale), Math.abs(heightScale));
        break;

      default:
        console.error(`${this._name}.scrollPageIntoView: ` + `"${destArray[1].name}" is not a valid destination type.`);
        return;
    }

    if (!ignoreDestinationZoom) {
      if (scale && scale !== this._currentScale) {
        this.currentScaleValue = scale;
      } else if (this._currentScale === _ui_utils.UNKNOWN_SCALE) {
        this.currentScaleValue = _ui_utils.DEFAULT_SCALE_VALUE;
      }
    }

    if (scale === "page-fit" && !destArray[4]) {
      this._scrollIntoView({
        pageDiv: pageView.div,
        pageNumber
      });

      return;
    }

    const boundingRect = [pageView.viewport.convertToViewportPoint(x, y), pageView.viewport.convertToViewportPoint(x + width, y + height)];
    let left = Math.min(boundingRect[0][0], boundingRect[1][0]);
    let top = Math.min(boundingRect[0][1], boundingRect[1][1]);

    if (!allowNegativeOffset) {
      left = Math.max(left, 0);
      top = Math.max(top, 0);
    }

    this._scrollIntoView({
      pageDiv: pageView.div,
      pageSpot: {
        left,
        top
      },
      pageNumber
    });
  }

  _updateLocation(firstPage) {
    const currentScale = this._currentScale;
    const currentScaleValue = this._currentScaleValue;
    const normalizedScaleValue = parseFloat(currentScaleValue) === currentScale ? Math.round(currentScale * 10000) / 100 : currentScaleValue;
    const pageNumber = firstPage.id;
    let pdfOpenParams = "#page=" + pageNumber;
    pdfOpenParams += "&zoom=" + normalizedScaleValue;
    const currentPageView = this._pages[pageNumber - 1];
    const container = this.container;
    const topLeft = currentPageView.getPagePoint(container.scrollLeft - firstPage.x, container.scrollTop - firstPage.y);
    const intLeft = Math.round(topLeft[0]);
    const intTop = Math.round(topLeft[1]);
    pdfOpenParams += "," + intLeft + "," + intTop;
    this._location = {
      pageNumber,
      scale: normalizedScaleValue,
      top: intTop,
      left: intLeft,
      rotation: this._pagesRotation,
      pdfOpenParams
    };
  }

  _updateHelper(visiblePages) {
    throw new Error("Not implemented: _updateHelper");
  }

  update() {
    const visible = this._getVisiblePages();

    const visiblePages = visible.views,
          numVisiblePages = visiblePages.length;

    if (numVisiblePages === 0) {
      return;
    }

    const newCacheSize = Math.max(DEFAULT_CACHE_SIZE, 2 * numVisiblePages + 1);

    this._buffer.resize(newCacheSize, visiblePages);

    this.renderingQueue.renderHighestPriority(visible);

    this._updateHelper(visiblePages);

    this._updateLocation(visible.first);

    this.eventBus.dispatch("updateviewarea", {
      source: this,
      location: this._location
    });
  }

  containsElement(element) {
    return this.container.contains(element);
  }

  focus() {
    this.container.focus();
  }

  get _isScrollModeHorizontal() {
    return this.isInPresentationMode ? false : this._scrollMode === _ui_utils.ScrollMode.HORIZONTAL;
  }

  get isInPresentationMode() {
    return this.presentationModeState === _ui_utils.PresentationModeState.FULLSCREEN;
  }

  get isChangingPresentationMode() {
    return this.presentationModeState === _ui_utils.PresentationModeState.CHANGING;
  }

  get isHorizontalScrollbarEnabled() {
    return this.isInPresentationMode ? false : this.container.scrollWidth > this.container.clientWidth;
  }

  get isVerticalScrollbarEnabled() {
    return this.isInPresentationMode ? false : this.container.scrollHeight > this.container.clientHeight;
  }

  _getCurrentVisiblePage() {
    if (!this.pagesCount) {
      return {
        views: []
      };
    }

    const pageView = this._pages[this._currentPageNumber - 1];
    const element = pageView.div;
    const view = {
      id: pageView.id,
      x: element.offsetLeft + element.clientLeft,
      y: element.offsetTop + element.clientTop,
      view: pageView
    };
    return {
      first: view,
      last: view,
      views: [view]
    };
  }

  _getVisiblePages() {
    return (0, _ui_utils.getVisibleElements)(this.container, this._pages, true, this._isScrollModeHorizontal);
  }

  isPageVisible(pageNumber) {
    if (!this.pdfDocument) {
      return false;
    }

    if (pageNumber < 1 || pageNumber > this.pagesCount) {
      console.error(`${this._name}.isPageVisible: "${pageNumber}" is out of bounds.`);
      return false;
    }

    return this._getVisiblePages().views.some(function (view) {
      return view.id === pageNumber;
    });
  }

  cleanup() {
    for (let i = 0, ii = this._pages.length; i < ii; i++) {
      if (this._pages[i] && this._pages[i].renderingState !== _pdf_rendering_queue.RenderingStates.FINISHED) {
        this._pages[i].reset();
      }
    }
  }

  _cancelRendering() {
    for (let i = 0, ii = this._pages.length; i < ii; i++) {
      if (this._pages[i]) {
        this._pages[i].cancelRendering();
      }
    }
  }

  _ensurePdfPageLoaded(pageView) {
    if (pageView.pdfPage) {
      return Promise.resolve(pageView.pdfPage);
    }

    if (this._pagesRequests.has(pageView)) {
      return this._pagesRequests.get(pageView);
    }

    const promise = this.pdfDocument.getPage(pageView.id).then(pdfPage => {
      if (!pageView.pdfPage) {
        pageView.setPdfPage(pdfPage);
      }

      this._pagesRequests.delete(pageView);

      return pdfPage;
    }).catch(reason => {
      console.error("Unable to get page for page view", reason);

      this._pagesRequests.delete(pageView);
    });

    this._pagesRequests.set(pageView, promise);

    return promise;
  }

  forceRendering(currentlyVisiblePages) {
    const visiblePages = currentlyVisiblePages || this._getVisiblePages();

    const scrollAhead = this._isScrollModeHorizontal ? this.scroll.right : this.scroll.down;
    const pageView = this.renderingQueue.getHighestPriority(visiblePages, this._pages, scrollAhead);

    if (pageView) {
      this._ensurePdfPageLoaded(pageView).then(() => {
        this.renderingQueue.renderView(pageView);
      });

      return true;
    }

    return false;
  }

  createTextLayerBuilder(textLayerDiv, pageIndex, viewport, enhanceTextSelection = false, eventBus) {
    return new _text_layer_builder.TextLayerBuilder({
      textLayerDiv,
      eventBus,
      pageIndex,
      viewport,
      findController: this.isInPresentationMode ? null : this.findController,
      enhanceTextSelection: this.isInPresentationMode ? false : enhanceTextSelection
    });
  }

  createAnnotationLayerBuilder(pageDiv, pdfPage, imageResourcesPath = "", renderInteractiveForms = false, l10n = _ui_utils.NullL10n) {
    return new _annotation_layer_builder.AnnotationLayerBuilder({
      pageDiv,
      pdfPage,
      imageResourcesPath,
      renderInteractiveForms,
      linkService: this.linkService,
      downloadManager: this.downloadManager,
      l10n
    });
  }

  get hasEqualPageSizes() {
    const firstPageView = this._pages[0];

    for (let i = 1, ii = this._pages.length; i < ii; ++i) {
      const pageView = this._pages[i];

      if (pageView.width !== firstPageView.width || pageView.height !== firstPageView.height) {
        return false;
      }
    }

    return true;
  }

  getPagesOverview() {
    const pagesOverview = this._pages.map(function (pageView) {
      const viewport = pageView.pdfPage.getViewport({
        scale: 1
      });
      return {
        width: viewport.width,
        height: viewport.height,
        rotation: viewport.rotation
      };
    });

    if (!this.enablePrintAutoRotate) {
      return pagesOverview;
    }

    const isFirstPagePortrait = (0, _ui_utils.isPortraitOrientation)(pagesOverview[0]);
    return pagesOverview.map(function (size) {
      if (isFirstPagePortrait === (0, _ui_utils.isPortraitOrientation)(size)) {
        return size;
      }

      return {
        width: size.height,
        height: size.width,
        rotation: (size.rotation + 90) % 360
      };
    });
  }

  get scrollMode() {
    return this._scrollMode;
  }

  set scrollMode(mode) {
    if (this._scrollMode === mode) {
      return;
    }

    if (!(0, _ui_utils.isValidScrollMode)(mode)) {
      throw new Error(`Invalid scroll mode: ${mode}`);
    }

    this._scrollMode = mode;
    this.eventBus.dispatch("scrollmodechanged", {
      source: this,
      mode
    });

    this._updateScrollMode(this._currentPageNumber);
  }

  _updateScrollMode(pageNumber = null) {
    const scrollMode = this._scrollMode,
          viewer = this.viewer;
    viewer.classList.toggle("scrollHorizontal", scrollMode === _ui_utils.ScrollMode.HORIZONTAL);
    viewer.classList.toggle("scrollWrapped", scrollMode === _ui_utils.ScrollMode.WRAPPED);

    if (!this.pdfDocument || !pageNumber) {
      return;
    }

    if (this._currentScaleValue && isNaN(this._currentScaleValue)) {
      this._setScale(this._currentScaleValue, true);
    }

    this._setCurrentPageNumber(pageNumber, true);

    this.update();
  }

  get spreadMode() {
    return this._spreadMode;
  }

  set spreadMode(mode) {
    if (this._spreadMode === mode) {
      return;
    }

    if (!(0, _ui_utils.isValidSpreadMode)(mode)) {
      throw new Error(`Invalid spread mode: ${mode}`);
    }

    this._spreadMode = mode;
    this.eventBus.dispatch("spreadmodechanged", {
      source: this,
      mode
    });

    this._updateSpreadMode(this._currentPageNumber);
  }

  _updateSpreadMode(pageNumber = null) {
    if (!this.pdfDocument) {
      return;
    }

    const viewer = this.viewer,
          pages = this._pages;
    viewer.textContent = "";

    if (this._spreadMode === _ui_utils.SpreadMode.NONE) {
      for (let i = 0, iMax = pages.length; i < iMax; ++i) {
        viewer.appendChild(pages[i].div);
      }
    } else {
      const parity = this._spreadMode - 1;
      let spread = null;

      for (let i = 0, iMax = pages.length; i < iMax; ++i) {
        if (spread === null) {
          spread = document.createElement("div");
          spread.className = "spread";
          viewer.appendChild(spread);
        } else if (i % 2 === parity) {
          spread = spread.cloneNode(false);
          viewer.appendChild(spread);
        }

        spread.appendChild(pages[i].div);
      }
    }

    if (!pageNumber) {
      return;
    }

    this._setCurrentPageNumber(pageNumber, true);

    this.update();
  }

}

exports.BaseViewer = BaseViewer;