f4daafc077
Square brackets are recommended to indicate optional parameters. Using them helps for automatically generating correct documentation.
432 lines
13 KiB
JavaScript
432 lines
13 KiB
JavaScript
/* Copyright 2012 Mozilla Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import { getGlobalEventBus } from './ui_utils';
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import { renderTextLayer } from 'pdfjs-lib';
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const EXPAND_DIVS_TIMEOUT = 300; // ms
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/**
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* @typedef {Object} TextLayerBuilderOptions
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* @property {HTMLDivElement} textLayerDiv - The text layer container.
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* @property {EventBus} eventBus - The application event bus.
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* @property {number} pageIndex - The page index.
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* @property {PageViewport} viewport - The viewport of the text layer.
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* @property {PDFFindController} findController
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* @property {boolean} enhanceTextSelection - Option to turn on improved
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* text selection.
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*/
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/**
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* The text layer builder provides text selection functionality for the PDF.
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* It does this by creating overlay divs over the PDF's text. These divs
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* contain text that matches the PDF text they are overlaying. This object
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* also provides a way to highlight text that is being searched for.
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*/
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class TextLayerBuilder {
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constructor({ textLayerDiv, eventBus, pageIndex, viewport,
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findController = null, enhanceTextSelection = false, }) {
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this.textLayerDiv = textLayerDiv;
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this.eventBus = eventBus || getGlobalEventBus();
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this.textContent = null;
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this.textContentItemsStr = [];
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this.textContentStream = null;
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this.renderingDone = false;
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this.pageIdx = pageIndex;
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this.pageNumber = this.pageIdx + 1;
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this.matches = [];
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this.viewport = viewport;
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this.textDivs = [];
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this.findController = findController;
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this.textLayerRenderTask = null;
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this.enhanceTextSelection = enhanceTextSelection;
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this._onUpdateTextLayerMatches = null;
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this._bindMouse();
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}
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/**
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* @private
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*/
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_finishRendering() {
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this.renderingDone = true;
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if (!this.enhanceTextSelection) {
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let endOfContent = document.createElement('div');
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endOfContent.className = 'endOfContent';
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this.textLayerDiv.appendChild(endOfContent);
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}
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this.eventBus.dispatch('textlayerrendered', {
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source: this,
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pageNumber: this.pageNumber,
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numTextDivs: this.textDivs.length,
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});
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}
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/**
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* Renders the text layer.
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*
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* @param {number} [timeout] - Wait for a specified amount of milliseconds
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* before rendering.
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*/
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render(timeout = 0) {
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if (!(this.textContent || this.textContentStream) || this.renderingDone) {
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return;
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}
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this.cancel();
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this.textDivs = [];
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let textLayerFrag = document.createDocumentFragment();
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this.textLayerRenderTask = renderTextLayer({
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textContent: this.textContent,
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textContentStream: this.textContentStream,
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container: textLayerFrag,
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viewport: this.viewport,
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textDivs: this.textDivs,
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textContentItemsStr: this.textContentItemsStr,
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timeout,
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enhanceTextSelection: this.enhanceTextSelection,
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});
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this.textLayerRenderTask.promise.then(() => {
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this.textLayerDiv.appendChild(textLayerFrag);
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this._finishRendering();
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this._updateMatches();
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}, function (reason) {
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// Cancelled or failed to render text layer; skipping errors.
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});
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if (!this._onUpdateTextLayerMatches) {
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this._onUpdateTextLayerMatches = (evt) => {
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if (evt.pageIndex === this.pageIdx || evt.pageIndex === -1) {
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this._updateMatches();
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}
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};
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this.eventBus.on('updatetextlayermatches',
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this._onUpdateTextLayerMatches);
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}
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}
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/**
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* Cancel rendering of the text layer.
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*/
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cancel() {
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if (this.textLayerRenderTask) {
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this.textLayerRenderTask.cancel();
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this.textLayerRenderTask = null;
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}
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if (this._onUpdateTextLayerMatches) {
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this.eventBus.off('updatetextlayermatches',
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this._onUpdateTextLayerMatches);
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this._onUpdateTextLayerMatches = null;
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}
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}
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setTextContentStream(readableStream) {
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this.cancel();
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this.textContentStream = readableStream;
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}
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setTextContent(textContent) {
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this.cancel();
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this.textContent = textContent;
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}
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_convertMatches(matches, matchesLength) {
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// Early exit if there is nothing to convert.
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if (!matches) {
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return [];
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}
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const { findController, textContentItemsStr, } = this;
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let i = 0, iIndex = 0;
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const end = textContentItemsStr.length - 1;
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const queryLen = findController.state.query.length;
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const result = [];
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for (let m = 0, mm = matches.length; m < mm; m++) {
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// Calculate the start position.
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let matchIdx = matches[m];
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// Loop over the divIdxs.
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while (i !== end &&
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matchIdx >= (iIndex + textContentItemsStr[i].length)) {
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iIndex += textContentItemsStr[i].length;
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i++;
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}
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if (i === textContentItemsStr.length) {
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console.error('Could not find a matching mapping');
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}
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let match = {
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begin: {
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divIdx: i,
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offset: matchIdx - iIndex,
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},
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};
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// Calculate the end position.
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if (matchesLength) { // Multiterm search.
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matchIdx += matchesLength[m];
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} else { // Phrase search.
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matchIdx += queryLen;
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}
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// Somewhat the same array as above, but use > instead of >= to get
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// the end position right.
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while (i !== end &&
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matchIdx > (iIndex + textContentItemsStr[i].length)) {
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iIndex += textContentItemsStr[i].length;
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i++;
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}
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match.end = {
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divIdx: i,
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offset: matchIdx - iIndex,
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};
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result.push(match);
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}
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return result;
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}
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_renderMatches(matches) {
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// Early exit if there is nothing to render.
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if (matches.length === 0) {
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return;
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}
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const { findController, pageIdx, textContentItemsStr, textDivs, } = this;
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const isSelectedPage = (pageIdx === findController.selected.pageIdx);
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const selectedMatchIdx = findController.selected.matchIdx;
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const highlightAll = findController.state.highlightAll;
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let prevEnd = null;
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let infinity = {
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divIdx: -1,
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offset: undefined,
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};
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function beginText(begin, className) {
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let divIdx = begin.divIdx;
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textDivs[divIdx].textContent = '';
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appendTextToDiv(divIdx, 0, begin.offset, className);
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}
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function appendTextToDiv(divIdx, fromOffset, toOffset, className) {
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let div = textDivs[divIdx];
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let content = textContentItemsStr[divIdx].substring(fromOffset, toOffset);
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let node = document.createTextNode(content);
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if (className) {
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let span = document.createElement('span');
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span.className = className;
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span.appendChild(node);
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div.appendChild(span);
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return;
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}
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div.appendChild(node);
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}
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let i0 = selectedMatchIdx, i1 = i0 + 1;
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if (highlightAll) {
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i0 = 0;
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i1 = matches.length;
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} else if (!isSelectedPage) {
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// Not highlighting all and this isn't the selected page, so do nothing.
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return;
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}
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for (let i = i0; i < i1; i++) {
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let match = matches[i];
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let begin = match.begin;
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let end = match.end;
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const isSelected = (isSelectedPage && i === selectedMatchIdx);
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const highlightSuffix = (isSelected ? ' selected' : '');
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if (isSelected) { // Attempt to scroll the selected match into view.
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findController.scrollMatchIntoView({
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element: textDivs[begin.divIdx],
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pageIndex: pageIdx,
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matchIndex: selectedMatchIdx,
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});
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}
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// Match inside new div.
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if (!prevEnd || begin.divIdx !== prevEnd.divIdx) {
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// If there was a previous div, then add the text at the end.
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if (prevEnd !== null) {
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appendTextToDiv(prevEnd.divIdx, prevEnd.offset, infinity.offset);
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}
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// Clear the divs and set the content until the starting point.
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beginText(begin);
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} else {
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appendTextToDiv(prevEnd.divIdx, prevEnd.offset, begin.offset);
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}
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if (begin.divIdx === end.divIdx) {
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appendTextToDiv(begin.divIdx, begin.offset, end.offset,
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'highlight' + highlightSuffix);
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} else {
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appendTextToDiv(begin.divIdx, begin.offset, infinity.offset,
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'highlight begin' + highlightSuffix);
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for (let n0 = begin.divIdx + 1, n1 = end.divIdx; n0 < n1; n0++) {
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textDivs[n0].className = 'highlight middle' + highlightSuffix;
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}
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beginText(end, 'highlight end' + highlightSuffix);
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}
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prevEnd = end;
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}
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if (prevEnd) {
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appendTextToDiv(prevEnd.divIdx, prevEnd.offset, infinity.offset);
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}
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}
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_updateMatches() {
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// Only show matches when all rendering is done.
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if (!this.renderingDone) {
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return;
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}
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const {
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findController, matches, pageIdx, textContentItemsStr, textDivs,
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} = this;
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let clearedUntilDivIdx = -1;
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// Clear all current matches.
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for (let i = 0, ii = matches.length; i < ii; i++) {
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let match = matches[i];
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let begin = Math.max(clearedUntilDivIdx, match.begin.divIdx);
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for (let n = begin, end = match.end.divIdx; n <= end; n++) {
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let div = textDivs[n];
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div.textContent = textContentItemsStr[n];
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div.className = '';
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}
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clearedUntilDivIdx = match.end.divIdx + 1;
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}
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if (!findController || !findController.highlightMatches) {
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return;
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}
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// Convert the matches on the `findController` into the match format
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// used for the textLayer.
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const pageMatches = findController.pageMatches[pageIdx] || null;
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const pageMatchesLength = findController.pageMatchesLength[pageIdx] || null;
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this.matches = this._convertMatches(pageMatches, pageMatchesLength);
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this._renderMatches(this.matches);
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}
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/**
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* Improves text selection by adding an additional div where the mouse was
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* clicked. This reduces flickering of the content if the mouse is slowly
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* dragged up or down.
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*
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* @private
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*/
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_bindMouse() {
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let div = this.textLayerDiv;
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let expandDivsTimer = null;
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div.addEventListener('mousedown', (evt) => {
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if (this.enhanceTextSelection && this.textLayerRenderTask) {
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this.textLayerRenderTask.expandTextDivs(true);
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if ((typeof PDFJSDev === 'undefined' ||
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!PDFJSDev.test('FIREFOX || MOZCENTRAL')) &&
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expandDivsTimer) {
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clearTimeout(expandDivsTimer);
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expandDivsTimer = null;
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}
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return;
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}
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let end = div.querySelector('.endOfContent');
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if (!end) {
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return;
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}
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if (typeof PDFJSDev === 'undefined' ||
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!PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
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// On non-Firefox browsers, the selection will feel better if the height
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// of the `endOfContent` div is adjusted to start at mouse click
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// location. This avoids flickering when the selection moves up.
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// However it does not work when selection is started on empty space.
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let adjustTop = evt.target !== div;
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if (typeof PDFJSDev === 'undefined' || PDFJSDev.test('GENERIC')) {
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adjustTop = adjustTop && window.getComputedStyle(end).
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getPropertyValue('-moz-user-select') !== 'none';
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}
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if (adjustTop) {
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let divBounds = div.getBoundingClientRect();
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let r = Math.max(0, (evt.pageY - divBounds.top) / divBounds.height);
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end.style.top = (r * 100).toFixed(2) + '%';
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}
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}
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end.classList.add('active');
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});
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div.addEventListener('mouseup', () => {
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if (this.enhanceTextSelection && this.textLayerRenderTask) {
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if (typeof PDFJSDev === 'undefined' ||
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!PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
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expandDivsTimer = setTimeout(() => {
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if (this.textLayerRenderTask) {
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this.textLayerRenderTask.expandTextDivs(false);
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}
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expandDivsTimer = null;
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}, EXPAND_DIVS_TIMEOUT);
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} else {
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this.textLayerRenderTask.expandTextDivs(false);
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}
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return;
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}
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let end = div.querySelector('.endOfContent');
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if (!end) {
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return;
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}
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if (typeof PDFJSDev === 'undefined' ||
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!PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
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end.style.top = '';
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}
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end.classList.remove('active');
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});
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}
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}
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/**
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* @implements IPDFTextLayerFactory
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*/
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class DefaultTextLayerFactory {
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/**
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* @param {HTMLDivElement} textLayerDiv
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* @param {number} pageIndex
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* @param {PageViewport} viewport
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* @param {boolean} enhanceTextSelection
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* @returns {TextLayerBuilder}
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*/
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createTextLayerBuilder(textLayerDiv, pageIndex, viewport,
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enhanceTextSelection = false) {
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return new TextLayerBuilder({
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textLayerDiv,
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pageIndex,
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viewport,
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enhanceTextSelection,
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});
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}
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}
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export {
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TextLayerBuilder,
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DefaultTextLayerFactory,
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};
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