pdfjs-dist/lib/web/pdf_single_page_viewer.js

/**
 * @licstart The following is the entire license notice for the
 * Javascript code in this page
 *
 * Copyright 2021 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.PDFSinglePageViewer = void 0;

var _base_viewer = require("./base_viewer.js");

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

class PDFSinglePageViewer extends _base_viewer.BaseViewer {
  constructor(options) {
    super(options);

    this.eventBus._on("pagesinit", evt => {
      this._ensurePageViewVisible();
    });
  }

  get _viewerElement() {
    return (0, _pdf.shadow)(this, "_viewerElement", this._shadowViewer);
  }

  get _pageWidthScaleFactor() {
    return 1;
  }

  _resetView() {
    super._resetView();

    this._previousPageNumber = 1;
    this._shadowViewer = document.createDocumentFragment();
    this._updateScrollDown = null;
  }

  _ensurePageViewVisible() {
    const pageView = this._pages[this._currentPageNumber - 1];
    const previousPageView = this._pages[this._previousPageNumber - 1];
    const viewerNodes = this.viewer.childNodes;

    switch (viewerNodes.length) {
      case 0:
        this.viewer.appendChild(pageView.div);
        break;

      case 1:
        if (viewerNodes[0] !== previousPageView.div) {
          throw new Error("_ensurePageViewVisible: Unexpected previously visible page.");
        }

        if (pageView === previousPageView) {
          break;
        }

        this._shadowViewer.appendChild(previousPageView.div);

        this.viewer.appendChild(pageView.div);
        this.container.scrollTop = 0;
        break;

      default:
        throw new Error("_ensurePageViewVisible: Only one page should be visible at a time.");
    }

    this._previousPageNumber = this._currentPageNumber;
  }

  _scrollUpdate() {
    if (this._updateScrollDown) {
      this._updateScrollDown();
    }

    super._scrollUpdate();
  }

  _scrollIntoView({
    pageDiv,
    pageSpot = null,
    pageNumber = null
  }) {
    if (pageNumber) {
      this._setCurrentPageNumber(pageNumber);
    }

    const scrolledDown = this._currentPageNumber >= this._previousPageNumber;

    this._ensurePageViewVisible();

    this.update();

    super._scrollIntoView({
      pageDiv,
      pageSpot,
      pageNumber
    });

    this._updateScrollDown = () => {
      this.scroll.down = scrolledDown;
      this._updateScrollDown = null;
    };
  }

  _getVisiblePages() {
    return this._getCurrentVisiblePage();
  }

  _updateHelper(visiblePages) {}

  get _isScrollModeHorizontal() {
    return (0, _pdf.shadow)(this, "_isScrollModeHorizontal", false);
  }

  _updateScrollMode() {}

  _updateSpreadMode() {}

  _getPageAdvance() {
    return 1;
  }

}

exports.PDFSinglePageViewer = PDFSinglePageViewer;