pdfjs-lib/lib/web/text_layer_builder.js

Generic build of Mozilla's PDF.js library.

/**
 * @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.TextLayerBuilder = void 0;
var _pdf = require("../pdf");
class TextLayerBuilder {
  #rotation = 0;
  #scale = 0;
  #textContentSource = null;
  constructor({
    highlighter = null,
    accessibilityManager = null,
    isOffscreenCanvasSupported = true
  }) {
    this.textContentItemsStr = [];
    this.renderingDone = false;
    this.textDivs = [];
    this.textDivProperties = new WeakMap();
    this.textLayerRenderTask = null;
    this.highlighter = highlighter;
    this.accessibilityManager = accessibilityManager;
    this.isOffscreenCanvasSupported = isOffscreenCanvasSupported;
    this.div = document.createElement("div");
    this.div.className = "textLayer";
    this.hide();
  }
  #finishRendering() {
    this.renderingDone = true;
    const endOfContent = document.createElement("div");
    endOfContent.className = "endOfContent";
    this.div.append(endOfContent);
    this.#bindMouse();
  }
  get numTextDivs() {
    return this.textDivs.length;
  }
  async render(viewport) {
    if (!this.#textContentSource) {
      throw new Error('No "textContentSource" parameter specified.');
    }
    const scale = viewport.scale * (globalThis.devicePixelRatio || 1);
    const {
      rotation
    } = viewport;
    if (this.renderingDone) {
      const mustRotate = rotation !== this.#rotation;
      const mustRescale = scale !== this.#scale;
      if (mustRotate || mustRescale) {
        this.hide();
        (0, _pdf.updateTextLayer)({
          container: this.div,
          viewport,
          textDivs: this.textDivs,
          textDivProperties: this.textDivProperties,
          isOffscreenCanvasSupported: this.isOffscreenCanvasSupported,
          mustRescale,
          mustRotate
        });
        this.#scale = scale;
        this.#rotation = rotation;
      }
      this.show();
      return;
    }
    this.cancel();
    this.highlighter?.setTextMapping(this.textDivs, this.textContentItemsStr);
    this.accessibilityManager?.setTextMapping(this.textDivs);
    this.textLayerRenderTask = (0, _pdf.renderTextLayer)({
      textContentSource: this.#textContentSource,
      container: this.div,
      viewport,
      textDivs: this.textDivs,
      textDivProperties: this.textDivProperties,
      textContentItemsStr: this.textContentItemsStr,
      isOffscreenCanvasSupported: this.isOffscreenCanvasSupported
    });
    await this.textLayerRenderTask.promise;
    this.#finishRendering();
    this.#scale = scale;
    this.#rotation = rotation;
    this.show();
    this.accessibilityManager?.enable();
  }
  hide() {
    if (!this.div.hidden) {
      this.highlighter?.disable();
      this.div.hidden = true;
    }
  }
  show() {
    if (this.div.hidden && this.renderingDone) {
      this.div.hidden = false;
      this.highlighter?.enable();
    }
  }
  cancel() {
    if (this.textLayerRenderTask) {
      this.textLayerRenderTask.cancel();
      this.textLayerRenderTask = null;
    }
    this.highlighter?.disable();
    this.accessibilityManager?.disable();
    this.textContentItemsStr.length = 0;
    this.textDivs.length = 0;
    this.textDivProperties = new WeakMap();
  }
  setTextContentSource(source) {
    this.cancel();
    this.#textContentSource = source;
  }
  #bindMouse() {
    const {
      div
    } = this;
    div.addEventListener("mousedown", evt => {
      const end = div.querySelector(".endOfContent");
      if (!end) {
        return;
      }
      let adjustTop = evt.target !== div;
      adjustTop &&= 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", () => {
      const end = div.querySelector(".endOfContent");
      if (!end) {
        return;
      }
      end.style.top = "";
      end.classList.remove("active");
    });
  }
}
exports.TextLayerBuilder = TextLayerBuilder;