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420 lines
14 KiB
JavaScript
420 lines
14 KiB
JavaScript
5 years ago
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/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* 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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/* globals CustomStyle, PDFJS */
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'use strict';
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var MAX_TEXT_DIVS_TO_RENDER = 100000;
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var NonWhitespaceRegexp = /\S/;
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function isAllWhitespace(str) {
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return !NonWhitespaceRegexp.test(str);
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}
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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 {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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*/
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/**
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* TextLayerBuilder provides text-selection functionality for the PDF.
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* It does this by creating overlay divs over the PDF 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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* @class
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*/
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var TextLayerBuilder = (function TextLayerBuilderClosure() {
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function TextLayerBuilder(options) {
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this.textLayerDiv = options.textLayerDiv;
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this.renderingDone = false;
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this.divContentDone = false;
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this.pageIdx = options.pageIndex;
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this.pageNumber = this.pageIdx + 1;
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this.matches = [];
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this.viewport = options.viewport;
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this.textDivs = [];
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this.findController = options.findController || null;
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}
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TextLayerBuilder.prototype = {
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_finishRendering: function TextLayerBuilder_finishRendering() {
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this.renderingDone = true;
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var event = document.createEvent('CustomEvent');
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event.initCustomEvent('textlayerrendered', true, true, {
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pageNumber: this.pageNumber
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});
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this.textLayerDiv.dispatchEvent(event);
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},
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renderLayer: function TextLayerBuilder_renderLayer() {
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var textLayerFrag = document.createDocumentFragment();
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var textDivs = this.textDivs;
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var textDivsLength = textDivs.length;
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var canvas = document.createElement('canvas');
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var ctx = canvas.getContext('2d');
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// No point in rendering many divs as it would make the browser
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// unusable even after the divs are rendered.
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if (textDivsLength > MAX_TEXT_DIVS_TO_RENDER) {
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this._finishRendering();
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return;
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}
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var lastFontSize;
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var lastFontFamily;
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for (var i = 0; i < textDivsLength; i++) {
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var textDiv = textDivs[i];
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if (textDiv.dataset.isWhitespace !== undefined) {
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continue;
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}
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var fontSize = textDiv.style.fontSize;
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var fontFamily = textDiv.style.fontFamily;
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// Only build font string and set to context if different from last.
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if (fontSize !== lastFontSize || fontFamily !== lastFontFamily) {
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ctx.font = fontSize + ' ' + fontFamily;
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lastFontSize = fontSize;
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lastFontFamily = fontFamily;
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}
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var width = ctx.measureText(textDiv.textContent).width;
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if (width > 0) {
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textLayerFrag.appendChild(textDiv);
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var transform;
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if (textDiv.dataset.canvasWidth !== undefined) {
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// Dataset values come of type string.
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var textScale = textDiv.dataset.canvasWidth / width;
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transform = 'scaleX(' + textScale + ')';
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} else {
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transform = '';
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}
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var rotation = textDiv.dataset.angle;
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if (rotation) {
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transform = 'rotate(' + rotation + 'deg) ' + transform;
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}
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if (transform) {
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CustomStyle.setProp('transform' , textDiv, transform);
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}
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}
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}
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this.textLayerDiv.appendChild(textLayerFrag);
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this._finishRendering();
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this.updateMatches();
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},
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/**
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* Renders the text layer.
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* @param {number} timeout (optional) if specified, the rendering waits
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* for specified amount of ms.
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*/
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render: function TextLayerBuilder_render(timeout) {
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if (!this.divContentDone || this.renderingDone) {
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return;
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}
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if (this.renderTimer) {
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clearTimeout(this.renderTimer);
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this.renderTimer = null;
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}
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if (!timeout) { // Render right away
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this.renderLayer();
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} else { // Schedule
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var self = this;
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this.renderTimer = setTimeout(function() {
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self.renderLayer();
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self.renderTimer = null;
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}, timeout);
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}
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},
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appendText: function TextLayerBuilder_appendText(geom, styles) {
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var style = styles[geom.fontName];
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var textDiv = document.createElement('div');
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this.textDivs.push(textDiv);
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if (isAllWhitespace(geom.str)) {
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textDiv.dataset.isWhitespace = true;
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return;
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}
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var tx = PDFJS.Util.transform(this.viewport.transform, geom.transform);
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var angle = Math.atan2(tx[1], tx[0]);
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if (style.vertical) {
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angle += Math.PI / 2;
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}
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var fontHeight = Math.sqrt((tx[2] * tx[2]) + (tx[3] * tx[3]));
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var fontAscent = fontHeight;
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if (style.ascent) {
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fontAscent = style.ascent * fontAscent;
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} else if (style.descent) {
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fontAscent = (1 + style.descent) * fontAscent;
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}
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var left;
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var top;
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if (angle === 0) {
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left = tx[4];
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top = tx[5] - fontAscent;
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} else {
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left = tx[4] + (fontAscent * Math.sin(angle));
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top = tx[5] - (fontAscent * Math.cos(angle));
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}
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textDiv.style.left = left + 'px';
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textDiv.style.top = top + 'px';
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textDiv.style.fontSize = fontHeight + 'px';
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textDiv.style.fontFamily = style.fontFamily;
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textDiv.textContent = geom.str;
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// |fontName| is only used by the Font Inspector. This test will succeed
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// when e.g. the Font Inspector is off but the Stepper is on, but it's
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// not worth the effort to do a more accurate test.
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if (PDFJS.pdfBug) {
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textDiv.dataset.fontName = geom.fontName;
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}
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// Storing into dataset will convert number into string.
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if (angle !== 0) {
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textDiv.dataset.angle = angle * (180 / Math.PI);
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}
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// We don't bother scaling single-char text divs, because it has very
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// little effect on text highlighting. This makes scrolling on docs with
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// lots of such divs a lot faster.
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if (textDiv.textContent.length > 1) {
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if (style.vertical) {
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textDiv.dataset.canvasWidth = geom.height * this.viewport.scale;
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} else {
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textDiv.dataset.canvasWidth = geom.width * this.viewport.scale;
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}
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}
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},
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setTextContent: function TextLayerBuilder_setTextContent(textContent) {
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this.textContent = textContent;
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var textItems = textContent.items;
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for (var i = 0, len = textItems.length; i < len; i++) {
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this.appendText(textItems[i], textContent.styles);
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}
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this.divContentDone = true;
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},
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convertMatches: function TextLayerBuilder_convertMatches(matches) {
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var i = 0;
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var iIndex = 0;
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var bidiTexts = this.textContent.items;
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var end = bidiTexts.length - 1;
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var queryLen = (this.findController === null ?
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0 : this.findController.state.query.length);
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var ret = [];
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for (var m = 0, len = matches.length; m < len; m++) {
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// Calculate the start position.
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var matchIdx = matches[m];
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// Loop over the divIdxs.
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while (i !== end && matchIdx >= (iIndex + bidiTexts[i].str.length)) {
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iIndex += bidiTexts[i].str.length;
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i++;
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}
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if (i === bidiTexts.length) {
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console.error('Could not find a matching mapping');
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}
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var 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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matchIdx += queryLen;
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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 && matchIdx > (iIndex + bidiTexts[i].str.length)) {
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iIndex += bidiTexts[i].str.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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ret.push(match);
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}
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return ret;
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},
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renderMatches: function TextLayerBuilder_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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var bidiTexts = this.textContent.items;
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var textDivs = this.textDivs;
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var prevEnd = null;
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var pageIdx = this.pageIdx;
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var isSelectedPage = (this.findController === null ?
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false : (pageIdx === this.findController.selected.pageIdx));
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var selectedMatchIdx = (this.findController === null ?
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-1 : this.findController.selected.matchIdx);
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var highlightAll = (this.findController === null ?
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false : this.findController.state.highlightAll);
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var 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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var 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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var div = textDivs[divIdx];
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var content = bidiTexts[divIdx].str.substring(fromOffset, toOffset);
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var node = document.createTextNode(content);
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if (className) {
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var 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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var 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 (var i = i0; i < i1; i++) {
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var match = matches[i];
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var begin = match.begin;
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var end = match.end;
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var isSelected = (isSelectedPage && i === selectedMatchIdx);
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var highlightSuffix = (isSelected ? ' selected' : '');
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if (this.findController) {
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this.findController.updateMatchPosition(pageIdx, i, textDivs,
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begin.divIdx, end.divIdx);
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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 (var 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: function TextLayerBuilder_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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// Clear all matches.
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var matches = this.matches;
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var textDivs = this.textDivs;
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var bidiTexts = this.textContent.items;
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var clearedUntilDivIdx = -1;
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// Clear all current matches.
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for (var i = 0, len = matches.length; i < len; i++) {
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var match = matches[i];
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var begin = Math.max(clearedUntilDivIdx, match.begin.divIdx);
|
||
|
|
for (var n = begin, end = match.end.divIdx; n <= end; n++) {
|
||
|
|
var div = textDivs[n];
|
||
|
|
div.textContent = bidiTexts[n].str;
|
||
|
|
div.className = '';
|
||
|
|
}
|
||
|
|
clearedUntilDivIdx = match.end.divIdx + 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (this.findController === null || !this.findController.active) {
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
// Convert the matches on the page controller into the match format
|
||
|
|
// used for the textLayer.
|
||
|
|
this.matches = this.convertMatches(this.findController === null ?
|
||
|
|
[] : (this.findController.pageMatches[this.pageIdx] || []));
|
||
|
|
this.renderMatches(this.matches);
|
||
|
|
}
|
||
|
|
};
|
||
|
|
return TextLayerBuilder;
|
||
|
|
})();
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @constructor
|
||
|
|
* @implements IPDFTextLayerFactory
|
||
|
|
*/
|
||
|
|
function DefaultTextLayerFactory() {}
|
||
|
|
DefaultTextLayerFactory.prototype = {
|
||
|
|
/**
|
||
|
|
* @param {HTMLDivElement} textLayerDiv
|
||
|
|
* @param {number} pageIndex
|
||
|
|
* @param {PageViewport} viewport
|
||
|
|
* @returns {TextLayerBuilder}
|
||
|
|
*/
|
||
|
|
createTextLayerBuilder: function (textLayerDiv, pageIndex, viewport) {
|
||
|
|
return new TextLayerBuilder({
|
||
|
|
textLayerDiv: textLayerDiv,
|
||
|
|
pageIndex: pageIndex,
|
||
|
|
viewport: viewport
|
||
|
|
});
|
||
|
|
}
|
||
|
|
};
|