pdfjs-dist/lib/web/text_layer_builder.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.TextLayerBuilder = void 0;

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

const EXPAND_DIVS_TIMEOUT = 300;

class TextLayerBuilder {
  constructor({
    textLayerDiv,
    eventBus,
    pageIndex,
    viewport,
    highlighter = null,
    enhanceTextSelection = false
  }) {
    this.textLayerDiv = textLayerDiv;
    this.eventBus = eventBus;
    this.textContent = null;
    this.textContentItemsStr = [];
    this.textContentStream = null;
    this.renderingDone = false;
    this.pageNumber = pageIndex + 1;
    this.viewport = viewport;
    this.textDivs = [];
    this.textLayerRenderTask = null;
    this.highlighter = highlighter;
    this.enhanceTextSelection = enhanceTextSelection;

    this._bindMouse();
  }

  _finishRendering() {
    this.renderingDone = true;

    if (!this.enhanceTextSelection) {
      const endOfContent = document.createElement("div");
      endOfContent.className = "endOfContent";
      this.textLayerDiv.appendChild(endOfContent);
    }

    this.eventBus.dispatch("textlayerrendered", {
      source: this,
      pageNumber: this.pageNumber,
      numTextDivs: this.textDivs.length
    });
  }

  render(timeout = 0) {
    if (!(this.textContent || this.textContentStream) || this.renderingDone) {
      return;
    }

    this.cancel();
    this.textDivs.length = 0;
    this.highlighter?.setTextMapping(this.textDivs, this.textContentItemsStr);
    const textLayerFrag = document.createDocumentFragment();
    this.textLayerRenderTask = (0, _pdf.renderTextLayer)({
      textContent: this.textContent,
      textContentStream: this.textContentStream,
      container: textLayerFrag,
      viewport: this.viewport,
      textDivs: this.textDivs,
      textContentItemsStr: this.textContentItemsStr,
      timeout,
      enhanceTextSelection: this.enhanceTextSelection
    });
    this.textLayerRenderTask.promise.then(() => {
      this.textLayerDiv.appendChild(textLayerFrag);

      this._finishRendering();

      this.highlighter?.enable();
    }, function (reason) {});
  }

  cancel() {
    if (this.textLayerRenderTask) {
      this.textLayerRenderTask.cancel();
      this.textLayerRenderTask = null;
    }

    this.highlighter?.disable();
  }

  setTextContentStream(readableStream) {
    this.cancel();
    this.textContentStream = readableStream;
  }

  setTextContent(textContent) {
    this.cancel();
    this.textContent = textContent;
  }

  _bindMouse() {
    const div = this.textLayerDiv;
    let expandDivsTimer = null;
    div.addEventListener("mousedown", evt => {
      if (this.enhanceTextSelection && this.textLayerRenderTask) {
        this.textLayerRenderTask.expandTextDivs(true);

        if (expandDivsTimer) {
          clearTimeout(expandDivsTimer);
          expandDivsTimer = null;
        }

        return;
      }

      const end = div.querySelector(".endOfContent");

      if (!end) {
        return;
      }

      let adjustTop = evt.target !== div;
      adjustTop = adjustTop && window.getComputedStyle(end).getPropertyValue("-moz-user-select") !== "none";

      if (adjustTop) {
        const divBounds = div.getBoundingClientRect();
        const r = Math.max(0, (evt.pageY - divBounds.top) / divBounds.height);
        end.style.top = (r * 100).toFixed(2) + "%";
      }

      end.classList.add("active");
    });
    div.addEventListener("mouseup", () => {
      if (this.enhanceTextSelection && this.textLayerRenderTask) {
        expandDivsTimer = setTimeout(() => {
          if (this.textLayerRenderTask) {
            this.textLayerRenderTask.expandTextDivs(false);
          }

          expandDivsTimer = null;
        }, EXPAND_DIVS_TIMEOUT);
        return;
      }

      const end = div.querySelector(".endOfContent");

      if (!end) {
        return;
      }

      end.style.top = "";
      end.classList.remove("active");
    });
  }

}

exports.TextLayerBuilder = TextLayerBuilder;