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JavaScript

/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* Copyright 2012 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.
*/
/* globals CustomStyle, PDFJS */
'use strict';
var MAX_TEXT_DIVS_TO_RENDER = 100000;
var NonWhitespaceRegexp = /\S/;
function isAllWhitespace(str) {
return !NonWhitespaceRegexp.test(str);
}
/**
* @typedef {Object} TextLayerBuilderOptions
* @property {HTMLDivElement} textLayerDiv - The text layer container.
* @property {number} pageIndex - The page index.
* @property {PageViewport} viewport - The viewport of the text layer.
* @property {PDFFindController} findController
*/
/**
* TextLayerBuilder provides text-selection functionality for the PDF.
* It does this by creating overlay divs over the PDF text. These divs
* contain text that matches the PDF text they are overlaying. This object
* also provides a way to highlight text that is being searched for.
* @class
*/
var TextLayerBuilder = (function TextLayerBuilderClosure() {
function TextLayerBuilder(options) {
this.textLayerDiv = options.textLayerDiv;
this.renderingDone = false;
this.divContentDone = false;
this.pageIdx = options.pageIndex;
this.pageNumber = this.pageIdx + 1;
this.matches = [];
this.viewport = options.viewport;
this.textDivs = [];
this.findController = options.findController || null;
}
TextLayerBuilder.prototype = {
_finishRendering: function TextLayerBuilder_finishRendering() {
this.renderingDone = true;
var event = document.createEvent('CustomEvent');
event.initCustomEvent('textlayerrendered', true, true, {
pageNumber: this.pageNumber
});
this.textLayerDiv.dispatchEvent(event);
},
renderLayer: function TextLayerBuilder_renderLayer() {
var textLayerFrag = document.createDocumentFragment();
var textDivs = this.textDivs;
var textDivsLength = textDivs.length;
var canvas = document.createElement('canvas');
var ctx = canvas.getContext('2d');
// No point in rendering many divs as it would make the browser
// unusable even after the divs are rendered.
if (textDivsLength > MAX_TEXT_DIVS_TO_RENDER) {
this._finishRendering();
return;
}
var lastFontSize;
var lastFontFamily;
for (var i = 0; i < textDivsLength; i++) {
var textDiv = textDivs[i];
if (textDiv.dataset.isWhitespace !== undefined) {
continue;
}
var fontSize = textDiv.style.fontSize;
var fontFamily = textDiv.style.fontFamily;
// Only build font string and set to context if different from last.
if (fontSize !== lastFontSize || fontFamily !== lastFontFamily) {
ctx.font = fontSize + ' ' + fontFamily;
lastFontSize = fontSize;
lastFontFamily = fontFamily;
}
var width = ctx.measureText(textDiv.textContent).width;
if (width > 0) {
textLayerFrag.appendChild(textDiv);
var transform;
if (textDiv.dataset.canvasWidth !== undefined) {
// Dataset values come of type string.
var textScale = textDiv.dataset.canvasWidth / width;
transform = 'scaleX(' + textScale + ')';
} else {
transform = '';
}
var rotation = textDiv.dataset.angle;
if (rotation) {
transform = 'rotate(' + rotation + 'deg) ' + transform;
}
if (transform) {
CustomStyle.setProp('transform' , textDiv, transform);
}
}
}
this.textLayerDiv.appendChild(textLayerFrag);
this._finishRendering();
this.updateMatches();
},
/**
* Renders the text layer.
* @param {number} timeout (optional) if specified, the rendering waits
* for specified amount of ms.
*/
render: function TextLayerBuilder_render(timeout) {
if (!this.divContentDone || this.renderingDone) {
return;
}
if (this.renderTimer) {
clearTimeout(this.renderTimer);
this.renderTimer = null;
}
if (!timeout) { // Render right away
this.renderLayer();
} else { // Schedule
var self = this;
this.renderTimer = setTimeout(function() {
self.renderLayer();
self.renderTimer = null;
}, timeout);
}
},
appendText: function TextLayerBuilder_appendText(geom, styles) {
var style = styles[geom.fontName];
var textDiv = document.createElement('div');
this.textDivs.push(textDiv);
if (isAllWhitespace(geom.str)) {
textDiv.dataset.isWhitespace = true;
return;
}
var tx = PDFJS.Util.transform(this.viewport.transform, geom.transform);
var angle = Math.atan2(tx[1], tx[0]);
if (style.vertical) {
angle += Math.PI / 2;
}
var fontHeight = Math.sqrt((tx[2] * tx[2]) + (tx[3] * tx[3]));
var fontAscent = fontHeight;
if (style.ascent) {
fontAscent = style.ascent * fontAscent;
} else if (style.descent) {
fontAscent = (1 + style.descent) * fontAscent;
}
var left;
var top;
if (angle === 0) {
left = tx[4];
top = tx[5] - fontAscent;
} else {
left = tx[4] + (fontAscent * Math.sin(angle));
top = tx[5] - (fontAscent * Math.cos(angle));
}
textDiv.style.left = left + 'px';
textDiv.style.top = top + 'px';
textDiv.style.fontSize = fontHeight + 'px';
textDiv.style.fontFamily = style.fontFamily;
textDiv.textContent = geom.str;
// |fontName| is only used by the Font Inspector. This test will succeed
// when e.g. the Font Inspector is off but the Stepper is on, but it's
// not worth the effort to do a more accurate test.
if (PDFJS.pdfBug) {
textDiv.dataset.fontName = geom.fontName;
}
// Storing into dataset will convert number into string.
if (angle !== 0) {
textDiv.dataset.angle = angle * (180 / Math.PI);
}
// We don't bother scaling single-char text divs, because it has very
// little effect on text highlighting. This makes scrolling on docs with
// lots of such divs a lot faster.
if (textDiv.textContent.length > 1) {
if (style.vertical) {
textDiv.dataset.canvasWidth = geom.height * this.viewport.scale;
} else {
textDiv.dataset.canvasWidth = geom.width * this.viewport.scale;
}
}
},
setTextContent: function TextLayerBuilder_setTextContent(textContent) {
this.textContent = textContent;
var textItems = textContent.items;
for (var i = 0, len = textItems.length; i < len; i++) {
this.appendText(textItems[i], textContent.styles);
}
this.divContentDone = true;
},
convertMatches: function TextLayerBuilder_convertMatches(matches) {
var i = 0;
var iIndex = 0;
var bidiTexts = this.textContent.items;
var end = bidiTexts.length - 1;
var queryLen = (this.findController === null ?
0 : this.findController.state.query.length);
var ret = [];
for (var m = 0, len = matches.length; m < len; m++) {
// Calculate the start position.
var matchIdx = matches[m];
// Loop over the divIdxs.
while (i !== end && matchIdx >= (iIndex + bidiTexts[i].str.length)) {
iIndex += bidiTexts[i].str.length;
i++;
}
if (i === bidiTexts.length) {
console.error('Could not find a matching mapping');
}
var match = {
begin: {
divIdx: i,
offset: matchIdx - iIndex
}
};
// Calculate the end position.
matchIdx += queryLen;
// Somewhat the same array as above, but use > instead of >= to get
// the end position right.
while (i !== end && matchIdx > (iIndex + bidiTexts[i].str.length)) {
iIndex += bidiTexts[i].str.length;
i++;
}
match.end = {
divIdx: i,
offset: matchIdx - iIndex
};
ret.push(match);
}
return ret;
},
renderMatches: function TextLayerBuilder_renderMatches(matches) {
// Early exit if there is nothing to render.
if (matches.length === 0) {
return;
}
var bidiTexts = this.textContent.items;
var textDivs = this.textDivs;
var prevEnd = null;
var pageIdx = this.pageIdx;
var isSelectedPage = (this.findController === null ?
false : (pageIdx === this.findController.selected.pageIdx));
var selectedMatchIdx = (this.findController === null ?
-1 : this.findController.selected.matchIdx);
var highlightAll = (this.findController === null ?
false : this.findController.state.highlightAll);
var infinity = {
divIdx: -1,
offset: undefined
};
function beginText(begin, className) {
var divIdx = begin.divIdx;
textDivs[divIdx].textContent = '';
appendTextToDiv(divIdx, 0, begin.offset, className);
}
function appendTextToDiv(divIdx, fromOffset, toOffset, className) {
var div = textDivs[divIdx];
var content = bidiTexts[divIdx].str.substring(fromOffset, toOffset);
var node = document.createTextNode(content);
if (className) {
var span = document.createElement('span');
span.className = className;
span.appendChild(node);
div.appendChild(span);
return;
}
div.appendChild(node);
}
var i0 = selectedMatchIdx, i1 = i0 + 1;
if (highlightAll) {
i0 = 0;
i1 = matches.length;
} else if (!isSelectedPage) {
// Not highlighting all and this isn't the selected page, so do nothing.
return;
}
for (var i = i0; i < i1; i++) {
var match = matches[i];
var begin = match.begin;
var end = match.end;
var isSelected = (isSelectedPage && i === selectedMatchIdx);
var highlightSuffix = (isSelected ? ' selected' : '');
if (this.findController) {
this.findController.updateMatchPosition(pageIdx, i, textDivs,
begin.divIdx, end.divIdx);
}
// Match inside new div.
if (!prevEnd || begin.divIdx !== prevEnd.divIdx) {
// If there was a previous div, then add the text at the end.
if (prevEnd !== null) {
appendTextToDiv(prevEnd.divIdx, prevEnd.offset, infinity.offset);
}
// Clear the divs and set the content until the starting point.
beginText(begin);
} else {
appendTextToDiv(prevEnd.divIdx, prevEnd.offset, begin.offset);
}
if (begin.divIdx === end.divIdx) {
appendTextToDiv(begin.divIdx, begin.offset, end.offset,
'highlight' + highlightSuffix);
} else {
appendTextToDiv(begin.divIdx, begin.offset, infinity.offset,
'highlight begin' + highlightSuffix);
for (var n0 = begin.divIdx + 1, n1 = end.divIdx; n0 < n1; n0++) {
textDivs[n0].className = 'highlight middle' + highlightSuffix;
}
beginText(end, 'highlight end' + highlightSuffix);
}
prevEnd = end;
}
if (prevEnd) {
appendTextToDiv(prevEnd.divIdx, prevEnd.offset, infinity.offset);
}
},
updateMatches: function TextLayerBuilder_updateMatches() {
// Only show matches when all rendering is done.
if (!this.renderingDone) {
return;
}
// Clear all matches.
var matches = this.matches;
var textDivs = this.textDivs;
var bidiTexts = this.textContent.items;
var clearedUntilDivIdx = -1;
// Clear all current matches.
for (var i = 0, len = matches.length; i < len; i++) {
var match = matches[i];
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
});
}
};