-
Notifications
You must be signed in to change notification settings - Fork 10k
/
text_layer_builder.js
578 lines (518 loc) · 19.6 KB
/
text_layer_builder.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
/* -*- 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 textItems = this.textContent.items;
var textDivsLength = textDivs.length;
// 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;
}
for (var i = 0; i < textDivsLength; i++) {
if (textItems[i].width > 0) {
textLayerFrag.appendChild(textDivs[i]);
}
}
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, ctx) {
var style = styles[geom.fontName];
var textDiv = document.createElement('div');
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));
}
// Only build font string and set to context if different from last.
if (fontHeight !== ctx.lastFontHeight ||
style.fontFamily !== ctx.lastFontFamily) {
ctx.ctx.font = fontHeight + 'px ' + style.fontFamily;
ctx.lastFontHeight = fontHeight;
ctx.lastFontFamily = style.fontFamily;
}
// Save info about the div in the geom for fast access.
geom.divLeft = left;
geom.divTop = top;
if (angle) {
geom.divAngle = angle;
}
geom.vertical = style.vertical ? true : false;
geom.textScale = (geom.vertical ? geom.height : geom.width ) /
(ctx.ctx.measureText(geom.str).width / this.viewport.scale);
textDiv.style.left = left + 'px';
textDiv.style.top = top + 'px';
textDiv.style.fontSize = fontHeight + 'px';
textDiv.style.fontFamily = style.fontFamily;
textDiv.textContent = geom.str;
// Always set scaleX. Chrome has selection padding artifacts if not.
var transform = 'scaleX(' + geom.textScale + ')';
if (angle) {
transform = 'rotate(' + (angle * (180 / Math.PI)) + 'deg) ' +
transform;
}
CustomStyle.setProp('transform' , textDiv, transform);
// |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;
}
return textDiv;
},
setTextContent: function TextLayerBuilder_setTextContent(textContent) {
// This function will add the text divs and append them to the DOM
this.textContent = textContent;
var textItems = textContent.items;
var len = textItems.length;
// Construct an object to keep track of current fonts.
var canvas = document.createElement('canvas');
var ctx = {
ctx: canvas.getContext('2d'),
lastFontHeight: null,
lastFontFamily: null,
};
var EPSILON = 1e-5;
// Set in viewer.css.
var LINE_HEIGHT = 1.14;
var textDivs = []; // Just temporary
var dontDoPadding = false;
for (var i = 0; i < len; i++) {
textDivs.push(this.appendText(textItems[i], textContent.styles, ctx));
// If any divs are angled, don't pad.
if(Math.abs(textItems[i].transform[1]) > EPSILON) {
dontDoPadding = true;
}
}
// Get the page rotation in degrees.
var rotate = (360 + Math.atan2(this.viewport.transform[1],
this.viewport.transform[0]) / Math.PI * 180) % 360;
// Lock it into an integer so we can compare it.
rotate = Math.abs(rotate) < EPSILON ? 0 :
Math.abs(rotate - 90) < EPSILON ? 90 :
Math.abs(rotate - 180) < EPSILON ? 180 :
Math.abs(rotate - 270) < EPSILON ? 270 :
rotate;
var getDivPosition = rotate === 0 ? function (obj) {
return {
top: obj.divTop,
bottom: obj.divTop + obj.height * scale * LINE_HEIGHT,
right: obj.divLeft + obj.width * scale,
left: obj.divLeft
};
} : rotate === 90 ? function(obj) {
return {
top: obj.divLeft,
bottom: obj.divLeft - obj.height * scale * LINE_HEIGHT,
right: obj.divTop + obj.width * scale,
left: obj.divTop
};
} : rotate === 180 ? function (obj) {
return {
top: obj.divTop,
bottom: obj.divTop - obj.height * scale * LINE_HEIGHT,
left: obj.divLeft,
right: obj.divLeft - obj.width * scale
};
} : rotate === 270 ? function(obj) {
return {
top: obj.divLeft,
bottom: obj.divLeft + obj.height * scale * LINE_HEIGHT,
right: obj.divTop - obj.width * scale,
left: obj.divTop
};
} : null;
// Set the object to the top of the PDF page.
var toTopPage = rotate === 0 ? function (obj) {
divi.style.top = '0px';
} : rotate === 90 ? function (obj) {
divi.style.left = pageH + 'px';
} : rotate === 180 ? function (obj) {
divi.style.top = pageH + 'px';
} : rotate === 270 ? function(obj) {
divi.style.left = '0px';
} : null;
var toLeftPage = rotate === 0 ? function (obj, offset) {
obj.style.left = offset + 'px';
} : rotate === 90 ? function (obj, offset) {
obj.style.top = offset + 'px';
} : rotate === 180 ? function (obj, offset) {
obj.style.left = offset + 'px';
} : rotate === 270 ? function (obj, offset) {
obj.style.top = offset + 'px';
} : null;
var bounds = rotate === 0 ? {
top: 0,
bottom: this.textLayerDiv.offsetHeight,
right: this.textLayerDiv.offsetWidth,
left: 0
} : rotate === 90 ? {
top: this.textLayerDiv.offsetWidth,
bottom: 0,
right: this.textLayerDiv.offsetHeight,
left: 0
} : rotate === 180 ? {
top: this.textLayerDiv.offsetHeight,
bottom: 0,
right: 0,
left: this.textLayerDiv.offsetWidth
} : rotate === 270 ? {
top: 0,
bottom: this.textLayerDiv.offsetWidth,
right: 0,
left: this.textLayerDiv.offsetHeight
} : null;
var diffX = rotate === 0 ? function (far, near) {
return far - near;
} : rotate === 90 ? function (far, near) {
return far - near;
} : rotate === 180 ? function (far, near) {
return near - far;
} : rotate === 270 ? function (far, near) {
return near - far;
} : null;
var diffY = rotate === 0 ? function (far, near) {
return far - near;
} : rotate === 90 ? function (far, near) {
return near - far;
} : rotate === 180 ? function (far, near) {
return near - far;
} : rotate === 270 ? function (far, near) {
return far - near;
} : null;
// Set each element's padding to run to the nearest right and bottom
// element. The padding ensures that text selection works.
var pageW = this.textLayerDiv.offsetWidth;
var pageH = this.textLayerDiv.offsetHeight;
if (rotate === 90 || rotate === 270) {
var temp = pageW;
pageW = pageH;
pageH = temp;
}
var scale = this.viewport.scale;
for (i = dontDoPadding ? len : 0; i < len; i++) {
var geom = textItems[i];
var divi = textDivs[i];
var divPos = getDivPosition(geom);
var bottom = divPos.bottom;
var right = divPos.right;
var top = divPos.top;
var left = divPos.left;
var farRight = geom.right !== null ?
getDivPosition(textItems[geom.right]).left : bounds.right;
var farBottom = geom.bottom !== null ?
getDivPosition(textItems[geom.bottom]).top : bounds.bottom;
// Update Padding. Apply textScale as appropriate (horizontal only).
divi.style.paddingRight = Math.abs(farRight - right) /
geom.textScale + 'px';
divi.style.paddingBottom = Math.abs(farBottom - bottom) + 'px';
var paddingLeft = null;
// If there is nothing to the left, then pad to the left
if (geom.left === null) {
// Fix left padding, taking into account the text scaling.
paddingLeft = Math.abs(bounds.left - left) / geom.textScale;
divi.style.paddingLeft = paddingLeft + 'px';
toLeftPage(divi, bounds.left);
} else {
// Still need to make the following work with rotation.
var leftItem = textItems[geom.left];
if (leftItem.right !== null &&
leftItem.right !== i && (leftItem.top === null ||
diffY(getDivPosition(leftItem).top, top) <= 0) && (
leftItem.bottom === null ||diffY(getDivPosition(
textItems[leftItem.bottom]).top, bottom) >= 0)) {
// The left object is too tall for its right padding to reach this
// object. This object should extend its left padding to the right
// padding of the left-most object.
var farLeft = getDivPosition(textItems[leftItem.right]).left;
paddingLeft = Math.abs(left - farLeft) / geom.textScale;
// No text scaling here because scaling is based on the left.
toLeftPage(divi, farLeft);
divi.style.paddingLeft = paddingLeft + 'px';
}
}
// If there is nothing above us, then pad to the top
if (geom.top === null) {
toTopPage(divi);
var paddingTop = Math.abs(bounds.top - top);
divi.style.paddingTop = paddingTop + 'px';
}
}
this.textDivs = textDivs;
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
});
}
};