pdfjs-dist/lib/web/pdf_rendering_queue.js

/**
 * @licstart The following is the entire license notice for the
 * JavaScript code in this page
 *
 * Copyright 2022 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.PDFRenderingQueue = void 0;

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

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

const CLEANUP_TIMEOUT = 30000;

class PDFRenderingQueue {
  constructor() {
    this.pdfViewer = null;
    this.pdfThumbnailViewer = null;
    this.onIdle = null;
    this.highestPriorityPage = null;
    this.idleTimeout = null;
    this.printing = false;
    this.isThumbnailViewEnabled = false;
  }

  setViewer(pdfViewer) {
    this.pdfViewer = pdfViewer;
  }

  setThumbnailViewer(pdfThumbnailViewer) {
    this.pdfThumbnailViewer = pdfThumbnailViewer;
  }

  isHighestPriority(view) {
    return this.highestPriorityPage === view.renderingId;
  }

  hasViewer() {
    return !!this.pdfViewer;
  }

  renderHighestPriority(currentlyVisiblePages) {
    if (this.idleTimeout) {
      clearTimeout(this.idleTimeout);
      this.idleTimeout = null;
    }

    if (this.pdfViewer.forceRendering(currentlyVisiblePages)) {
      return;
    }

    if (this.isThumbnailViewEnabled && this.pdfThumbnailViewer?.forceRendering()) {
      return;
    }

    if (this.printing) {
      return;
    }

    if (this.onIdle) {
      this.idleTimeout = setTimeout(this.onIdle.bind(this), CLEANUP_TIMEOUT);
    }
  }

  getHighestPriority(visible, views, scrolledDown, preRenderExtra = false) {
    const visibleViews = visible.views,
          numVisible = visibleViews.length;

    if (numVisible === 0) {
      return null;
    }

    for (let i = 0; i < numVisible; i++) {
      const view = visibleViews[i].view;

      if (!this.isViewFinished(view)) {
        return view;
      }
    }

    const firstId = visible.first.id,
          lastId = visible.last.id;

    if (lastId - firstId + 1 > numVisible) {
      const visibleIds = visible.ids;

      for (let i = 1, ii = lastId - firstId; i < ii; i++) {
        const holeId = scrolledDown ? firstId + i : lastId - i;

        if (visibleIds.has(holeId)) {
          continue;
        }

        const holeView = views[holeId - 1];

        if (!this.isViewFinished(holeView)) {
          return holeView;
        }
      }
    }

    let preRenderIndex = scrolledDown ? lastId : firstId - 2;
    let preRenderView = views[preRenderIndex];

    if (preRenderView && !this.isViewFinished(preRenderView)) {
      return preRenderView;
    }

    if (preRenderExtra) {
      preRenderIndex += scrolledDown ? 1 : -1;
      preRenderView = views[preRenderIndex];

      if (preRenderView && !this.isViewFinished(preRenderView)) {
        return preRenderView;
      }
    }

    return null;
  }

  isViewFinished(view) {
    return view.renderingState === _ui_utils.RenderingStates.FINISHED;
  }

  renderView(view) {
    switch (view.renderingState) {
      case _ui_utils.RenderingStates.FINISHED:
        return false;

      case _ui_utils.RenderingStates.PAUSED:
        this.highestPriorityPage = view.renderingId;
        view.resume();
        break;

      case _ui_utils.RenderingStates.RUNNING:
        this.highestPriorityPage = view.renderingId;
        break;

      case _ui_utils.RenderingStates.INITIAL:
        this.highestPriorityPage = view.renderingId;
        view.draw().finally(() => {
          this.renderHighestPriority();
        }).catch(reason => {
          if (reason instanceof _pdf.RenderingCancelledException) {
            return;
          }

          console.error(`renderView: "${reason}"`);
        });
        break;
    }

    return true;
  }

}

exports.PDFRenderingQueue = PDFRenderingQueue;