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Treat fonts with the same font descriptor, encoding and unicode map as aliases

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Different fonts can point to the same font descriptor
(see https://github.com/mozilla/pdf.js/issues/4339 for details). With this
commit such fonts are treated as aliases if they have also the same encoding
and the same toUnicode map. The according info is stored on the font descriptor.
This change must also ensure that aliases use always the same font name
because translated fonts can get cleared depending on the CLEANUP_TIMEOUT setting.
This commit is contained in:
Christian Krebs 2014-03-03 18:44:45 +01:00
parent 608c6cea5a
commit 79f34b183c
6 changed files with 245 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

94
src/core/evaluator.js
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@ -17,11 +17,11 @@
/* globals assert, assertWellFormed, ColorSpace, DecodeStream, Dict, Encodings,
error, ErrorFont, Font, FONT_IDENTITY_MATRIX, fontCharsToUnicode,
FontFlags, ImageKind, info, isArray, isCmd, isDict, isEOF, isName,
isNum, isStream, isString, JpegStream, Lexer, Metrics, Name, Parser,
Pattern, PDFImage, PDFJS, serifFonts, stdFontMap, symbolsFonts,
getTilingPatternIR, warn, Util, Promise, LegacyPromise,
RefSetCache, isRef, TextRenderingMode, CMapFactory, OPS,
UNSUPPORTED_FEATURES, UnsupportedManager */
isNum, isStream, isString, JpegStream, Lexer, Metrics,
MurmurHash3_64, Name, Parser, Pattern, PDFImage, PDFJS, serifFonts,
stdFontMap, symbolsFonts, getTilingPatternIR, warn, Util, Promise,
LegacyPromise, RefSetCache, isRef, TextRenderingMode, CMapFactory,
OPS, UNSUPPORTED_FEATURES, UnsupportedManager */
'use strict';
@ -413,6 +413,36 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
if (!isDict(font)) {
return errorFont();
}
var preEvaluatedFont = this.preEvaluateFont(font, xref);
var descriptor = preEvaluatedFont.descriptor;
var fontID = fontRef.num + '_' + fontRef.gen;
if (isDict(descriptor)) {
if (!descriptor.fontAliases) {
descriptor.fontAliases = Object.create(null);
}
var fontAliases = descriptor.fontAliases;
var hash = preEvaluatedFont.hash;
if (fontAliases[hash]) {
var aliasFontRef = fontAliases[hash].aliasRef;
if (aliasFontRef && this.fontCache.has(aliasFontRef)) {
this.fontCache.putAlias(fontRef, aliasFontRef);
var cachedFont = this.fontCache.get(fontRef);
return cachedFont;
}
}
if (!fontAliases[hash]) {
fontAliases[hash] = {
fontID: Font.getFontID()
};
}
fontAliases[hash].aliasRef = fontRef;
fontID = fontAliases[hash].fontID;
}
// Workaround for bad PDF generators that don't reference fonts
// properly, i.e. by not using an object identifier.
// Check if the fontRef is a Dict (as opposed to a standard object),
@ -426,12 +456,12 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
// Keep track of each font we translated so the caller can
// load them asynchronously before calling display on a page.
font.loadedName = 'g_font_' + (fontRefIsDict ?
fontName.replace(/\W/g, '') : (fontRef.num + '_' + fontRef.gen));
fontName.replace(/\W/g, '') : fontID);
if (!font.translated) {
var translated;
try {
translated = this.translateFont(font, xref);
translated = this.translateFont(preEvaluatedFont, xref);
} catch (e) {
UnsupportedManager.notify(UNSUPPORTED_FEATURES.font);
translated = new ErrorFont(e instanceof Error ? e.message : e);
@ -1127,7 +1157,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
return widths;
},
translateFont: function PartialEvaluator_translateFont(dict, xref) {
preEvaluateFont: function PartialEvaluator_preEvaluateFont(dict, xref) {
var baseDict = dict;
var type = dict.get('Subtype');
assertWellFormed(isName(type), 'invalid font Subtype');
@ -1148,9 +1178,55 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
assertWellFormed(isName(type), 'invalid font Subtype');
composite = true;
}
var maxCharIndex = (composite ? 0xFFFF : 0xFF);
var descriptor = dict.get('FontDescriptor');
if (descriptor) {
var hash = new MurmurHash3_64();
var encoding = baseDict.getRaw('Encoding');
if (isName(encoding)) {
hash.update(encoding.name);
} else if (isRef(encoding)) {
hash.update(encoding.num + '_' + encoding.gen);
}
var toUnicode = dict.get('ToUnicode') || baseDict.get('ToUnicode');
if (isStream(toUnicode)) {
var stream = toUnicode.str || toUnicode;
var uint8array = stream.buffer ?
new Uint8Array(stream.buffer.buffer, 0, stream.bufferLength) :
new Uint8Array(stream.bytes.buffer,
stream.start, stream.end - stream.start);
hash.update(uint8array);
} else if (isName(toUnicode)) {
hash.update(toUnicode.name);
}
var widths = dict.get('Widths') || baseDict.get('Widths');
if (widths) {
var uint8array = new Uint8Array(new Uint32Array(widths).buffer);
hash.update(uint8array);
}
}
return {
descriptor: descriptor,
dict: dict,
baseDict: baseDict,
composite: composite,
hash: hash ? hash.hexdigest() : ''
};
},
translateFont: function PartialEvaluator_translateFont(preEvaluatedFont,
xref) {
var baseDict = preEvaluatedFont.baseDict;
var dict = preEvaluatedFont.dict;
var composite = preEvaluatedFont.composite;
var descriptor = preEvaluatedFont.descriptor;
var type = dict.get('Subtype');
var maxCharIndex = (composite ? 0xFFFF : 0xFF);
if (!descriptor) {
if (type.name == 'Type3') {
// FontDescriptor is only required for Type3 fonts when the document