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Refactoring text layer builder

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Tim van der Meij 2014-06-21 22:53:26 +02:00
parent 456d219f2a
commit 2a052c4aad
1 changed files with 62 additions and 88 deletions
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150
web/text_layer_builder.js
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@ -19,25 +19,22 @@
var FIND_SCROLL_OFFSET_TOP = -50;
var FIND_SCROLL_OFFSET_LEFT = -400;
var MAX_TEXT_DIVS_TO_RENDER = 100000;
var RENDER_DELAY = 200; // ms
/**
* TextLayerBuilder provides text-selection
* functionality for the PDF. It does this
* by creating overlay divs over the PDF
* text. This divs contain text that matches
* the PDF text they are overlaying. This
* object also provides for a way to highlight
* text that is being searched for.
* 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.
*/
var TextLayerBuilder = function textLayerBuilder(options) {
var textLayerFrag = document.createDocumentFragment();
this.textLayerDiv = options.textLayerDiv;
this.layoutDone = false;
this.divContentDone = false;
this.pageIdx = options.pageIndex;
this.matches = [];
this.lastScrollSource = options.lastScrollSource;
this.lastScrollSource = options.lastScrollSource || null;
this.viewport = options.viewport;
this.isViewerInPresentationMode = options.isViewerInPresentationMode;
this.textDivs = [];
@ -46,31 +43,27 @@ var TextLayerBuilder = function textLayerBuilder(options) {
window.PDFFindController = null;
}
if (typeof this.lastScrollSource === 'undefined') {
this.lastScrollSource = null;
}
this.renderLayer = function textLayerBuilderRenderLayer() {
this.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 so many divs as it'd make the browser unusable
// even after the divs are rendered
var MAX_TEXT_DIVS_TO_RENDER = 100000;
if (textDivs.length > MAX_TEXT_DIVS_TO_RENDER) {
// 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) {
return;
}
for (var i = 0, ii = textDivs.length; i < ii; i++) {
for (var i = 0; i < textDivsLength; i++) {
var textDiv = textDivs[i];
if ('isWhitespace' in textDiv.dataset) {
if (textDiv.dataset.isWhitespace !== undefined) {
continue;
}
ctx.font = textDiv.style.fontSize + ' ' + textDiv.style.fontFamily;
var width = ctx.measureText(textDiv.textContent).width;
if (width > 0) {
textLayerFrag.appendChild(textDiv);
var textScale = textDiv.dataset.canvasWidth / width;
@ -87,19 +80,17 @@ var TextLayerBuilder = function textLayerBuilder(options) {
this.updateMatches();
};
this.setupRenderLayoutTimer = function textLayerSetupRenderLayoutTimer() {
// Schedule renderLayout() if user has been scrolling, otherwise
// run it right away
var RENDER_DELAY = 200; // in ms
this.setupRenderLayoutTimer =
function textLayerBuilder_setupRenderLayoutTimer() {
// Schedule renderLayout() if the user has been scrolling,
// otherwise run it right away.
var self = this;
var lastScroll = (this.lastScrollSource === null ?
0 : this.lastScrollSource.lastScroll);
if (Date.now() - lastScroll > RENDER_DELAY) {
// Render right away
if (Date.now() - lastScroll > RENDER_DELAY) { // Render right away
this.renderLayer();
} else {
// Schedule
} else { // Schedule
if (this.renderTimer) {
clearTimeout(this.renderTimer);
}
@ -109,7 +100,7 @@ var TextLayerBuilder = function textLayerBuilder(options) {
}
};
this.appendText = function textLayerBuilderAppendText(geom, styles) {
this.appendText = function textLayerBuilder_appendText(geom, styles) {
var style = styles[geom.fontName];
var textDiv = document.createElement('div');
this.textDivs.push(textDiv);
@ -140,35 +131,31 @@ var TextLayerBuilder = function textLayerBuilder(options) {
} else {
textDiv.dataset.canvasWidth = geom.width * this.viewport.scale;
}
};
this.setTextContent = function textLayerBuilderSetTextContent(textContent) {
this.setTextContent = function textLayerBuilder_setTextContent(textContent) {
this.textContent = textContent;
var textItems = textContent.items;
for (var i = 0; i < textItems.length; i++) {
for (var i = 0, len = textItems.length; i < len; i++) {
this.appendText(textItems[i], textContent.styles);
}
this.divContentDone = true;
this.setupRenderLayoutTimer();
};
this.convertMatches = function textLayerBuilderConvertMatches(matches) {
this.convertMatches = function textLayerBuilder_convertMatches(matches) {
var i = 0;
var iIndex = 0;
var bidiTexts = this.textContent.items;
var end = bidiTexts.length - 1;
var queryLen = (PDFFindController === null ?
0 : PDFFindController.state.query.length);
var ret = [];
// Loop over all the matches.
for (var m = 0; m < matches.length; m++) {
for (var m = 0, len = matches.length; m < len; m++) {
// Calculate the start position.
var matchIdx = matches[m];
// # Calculate the begin position.
// Loop over the divIdxs.
while (i !== end && matchIdx >= (iIndex + bidiTexts[i].str.length)) {
@ -176,9 +163,8 @@ var TextLayerBuilder = function textLayerBuilder(options) {
i++;
}
// TODO: Do proper handling here if something goes wrong.
if (i == bidiTexts.length) {
console.error('Could not find matching mapping');
if (i === bidiTexts.length) {
console.error('Could not find a matching mapping');
}
var match = {
@ -188,11 +174,11 @@ var TextLayerBuilder = function textLayerBuilder(options) {
}
};
// # Calculate the end position.
// Calculate the end position.
matchIdx += queryLen;
// Somewhat same array as above, but use a > instead of >= to get the end
// position right.
// 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++;
@ -219,32 +205,23 @@ var TextLayerBuilder = function textLayerBuilder(options) {
var prevEnd = null;
var isSelectedPage = (PDFFindController === null ?
false : (this.pageIdx === PDFFindController.selected.pageIdx));
var selectedMatchIdx = (PDFFindController === null ?
-1 : PDFFindController.selected.matchIdx);
var highlightAll = (PDFFindController === null ?
false : PDFFindController.state.highlightAll);
var infty = {
var infinity = {
divIdx: -1,
offset: undefined
};
function beginText(begin, className) {
var divIdx = begin.divIdx;
var div = textDivs[divIdx];
div.textContent = '';
textDivs[divIdx].textContent = '';
appendTextToDiv(divIdx, 0, begin.offset, className);
}
function appendText(from, to, className) {
appendTextToDiv(from.divIdx, from.offset, to.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) {
@ -257,12 +234,7 @@ var TextLayerBuilder = function textLayerBuilder(options) {
div.appendChild(node);
}
function highlightDiv(divIdx, className) {
textDivs[divIdx].className = className;
}
var i0 = selectedMatchIdx, i1 = i0 + 1, i;
var i0 = selectedMatchIdx, i1 = i0 + 1;
if (highlightAll) {
i0 = 0;
i1 = matches.length;
@ -271,36 +243,39 @@ var TextLayerBuilder = function textLayerBuilder(options) {
return;
}
for (i = i0; i < i1; i++) {
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 isSelected = (isSelectedPage && i === selectedMatchIdx);
var highlightSuffix = (isSelected ? ' selected' : '');
if (isSelected && !this.isViewerInPresentationMode) {
scrollIntoView(textDivs[begin.divIdx], { top: FIND_SCROLL_OFFSET_TOP,
left: FIND_SCROLL_OFFSET_LEFT });
scrollIntoView(textDivs[begin.divIdx],
{ top: FIND_SCROLL_OFFSET_TOP,
left: FIND_SCROLL_OFFSET_LEFT });
}
// Match inside new div.
if (!prevEnd || begin.divIdx !== prevEnd.divIdx) {
// If there was a previous div, then add the text at the end
// If there was a previous div, then add the text at the end.
if (prevEnd !== null) {
appendText(prevEnd, infty);
appendTextToDiv(prevEnd.divIdx, prevEnd.offset, infinity.offset);
}
// clears the divs and set the content until the begin point.
// Clear the divs and set the content until the starting point.
beginText(begin);
} else {
appendText(prevEnd, begin);
appendTextToDiv(prevEnd.divIdx, prevEnd.offset, begin.offset);
}
if (begin.divIdx === end.divIdx) {
appendText(begin, end, 'highlight' + highlightSuffix);
appendTextToDiv(begin.divIdx, begin.offset, end.offset,
'highlight' + highlightSuffix);
} else {
appendText(begin, infty, 'highlight begin' + highlightSuffix);
for (var n = begin.divIdx + 1; n < end.divIdx; n++) {
highlightDiv(n, 'highlight middle' + highlightSuffix);
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);
}
@ -308,27 +283,27 @@ var TextLayerBuilder = function textLayerBuilder(options) {
}
if (prevEnd) {
appendText(prevEnd, infty);
appendTextToDiv(prevEnd.divIdx, prevEnd.offset, infinity.offset);
}
};
this.updateMatches = function textLayerUpdateMatches() {
// Only show matches, once all rendering is done.
this.updateMatches = function textLayerBuilder_updateMatches() {
// Only show matches when all rendering is done.
if (!this.renderingDone) {
return;
}
// Clear out all matches.
// Clear all matches.
var matches = this.matches;
var textDivs = this.textDivs;
var bidiTexts = this.textContent.items;
var clearedUntilDivIdx = -1;
// Clear out all current matches.
for (var i = 0; i < matches.length; i++) {
// 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; n <= match.end.divIdx; n++) {
for (var n = begin, end = match.end.divIdx; n <= end; n++) {
var div = textDivs[n];
div.textContent = bidiTexts[n].str;
div.className = '';
@ -340,11 +315,10 @@ var TextLayerBuilder = function textLayerBuilder(options) {
return;
}
// Convert the matches on the page controller into the match format used
// for the textLayer.
this.matches = matches = (this.convertMatches(PDFFindController === null ?
[] : (PDFFindController.pageMatches[this.pageIdx] || [])));
// Convert the matches on the page controller into the match format
// used for the textLayer.
this.matches = this.convertMatches(PDFFindController === null ?
[] : (PDFFindController.pageMatches[this.pageIdx] || []));
this.renderMatches(this.matches);
};
};