Move the Type2 utils to a new file and create a Stack object
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Vivien Nicolas
parent
74abf984d5
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3834c9be08
2 changed files with 457 additions and 525 deletions
352
PDFFontUtils.js
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352
PDFFontUtils.js
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/**
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* The Type2 reader code below is only used for debugging purpose since Type2
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* is only a CharString format and is never used directly as a Font file.
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*
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* So the code here is useful for dumping the data content of a .cff file in
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* order to investigate the similarity between a Type1 CharString and a Type2
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* CharString.
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*/
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/**
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* Build a charset by assigning the glyph name and the human readable form
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* of the glyph data.
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*/
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function readCharset(aStream, aCharstrings) {
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var charset = {};
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var format = aStream.getByte();
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if (format == 0) {
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charset[".notdef"] = readCharstringEncoding(aCharstrings[0]);
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var count = aCharstrings.length - 1;
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for (var i = 1; i < count + 1; i++) {
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var sid = aStream.getByte() << 8 | aStream.getByte();
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charset[CFFStrings[sid]] = readCharstringEncoding(aCharstrings[i]);
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log(CFFStrings[sid] + "::" + charset[CFFStrings[sid]]);
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}
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} else if (format == 1) {
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error("Charset Range are not supported");
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} else {
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error("Invalid charset format");
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}
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return charset;
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};
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/**
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* Take a Type2 binary charstring as input and transform it to a human
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* readable representation as specified by the 'The Type 2 Charstring Format',
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* chapter 3.1.
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*/
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function readCharstringEncoding(aString) {
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var charstringTokens = [];
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var count = aString.length;
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for (var i = 0; i < count; ) {
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var value = aString[i++];
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var token = null;
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if (value < 0) {
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continue;
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} else if (value <= 11) {
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token = CFFEncodingMap[value];
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} else if (value == 12) {
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token = CFFEncodingMap[value][aString[i++]];
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} else if (value <= 18) {
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token = CFFEncodingMap[value];
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} else if (value <= 20) {
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var mask = aString[i++];
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token = CFFEncodingMap[value];
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} else if (value <= 27) {
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token = CFFEncodingMap[value];
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} else if (value == 28) {
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token = aString[i++] << 8 | aString[i++];
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} else if (value <= 31) {
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token = CFFEncodingMap[value];
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} else if (value < 247) {
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token = parseInt(value) - 139;
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} else if (value < 251) {
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token = ((value - 247) * 256) + aString[i++] + 108;
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} else if (value < 255) {
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token = -((value - 251) * 256) - aString[i++] - 108;
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} else {// value == 255
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token = aString[i++] << 24 | aString[i++] << 16 |
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aString[i++] << 8 | aString[i];
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}
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charstringTokens.push(token);
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}
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return charstringTokens;
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};
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/**
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* Take a binary DICT Data as input and transform it into a human readable
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* form as specified by 'The Compact Font Format Specification', chapter 5.
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*/
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function readFontDictData(aString, aMap) {
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var fontDictDataTokens = [];
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var count = aString.length;
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for (var i = 0; i < count; i) {
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var value = aString[i++];
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var token = null;
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if (value == 12) {
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token = aMap[value][aString[i++]];
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} else if (value == 28) {
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token = aString[i++] << 8 | aString[i++];
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} else if (value == 29) {
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token = aString[i++] << 24 |
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aString[i++] << 16 |
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aString[i++] << 8 |
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aString[i++];
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} else if (value == 30) {
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token = "";
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var parsed = false;
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while (!parsed) {
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var byte = aString[i++];
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var nibbles = [parseInt(byte / 16), parseInt(byte % 16)];
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for (var j = 0; j < nibbles.length; j++) {
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var nibble = nibbles[j];
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switch (nibble) {
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case 0xA:
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token += ".";
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break;
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case 0xB:
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token += "E";
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break;
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case 0xC:
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token += "E-";
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break;
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case 0xD:
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break;
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case 0xE:
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token += "-";
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break;
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case 0xF:
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parsed = true;
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break;
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default:
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token += nibble;
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break;
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}
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}
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};
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token = parseFloat(token);
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} else if (value <= 31) {
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token = aMap[value];
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} else if (value <= 246) {
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token = parseInt(value) - 139;
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} else if (value <= 250) {
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token = ((value - 247) * 256) + aString[i++] + 108;
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} else if (value <= 254) {
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token = -((value - 251) * 256) - aString[i++] - 108;
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} else if (value == 255) {
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error("255 is not a valid DICT command");
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}
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fontDictDataTokens.push(token);
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}
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return fontDictDataTokens;
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};
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/**
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* Take a stream as input and return an array of objects.
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* In CFF an INDEX is a structure with the following format:
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* {
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* count: 2 bytes (Number of objects stored in INDEX),
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* offsize: 1 byte (Offset array element size),
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* offset: [count + 1] bytes (Offsets array),
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* data: - (Objects data)
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* }
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*
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* More explanation are given in the 'CFF Font Format Specification',
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* chapter 5.
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*/
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function readFontIndexData(aStream, aIsByte) {
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var count = aStream.getByte() << 8 | aStream.getByte();
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var offsize = aStream.getByte();
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function getNextOffset() {
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switch (offsize) {
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case 0:
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return 0;
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case 1:
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return aStream.getByte();
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case 2:
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return aStream.getByte() << 8 | aStream.getByte();
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case 3:
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return aStream.getByte() << 16 | aStream.getByte() << 8 |
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aStream.getByte();
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case 4:
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return aStream.getByte() << 24 | aStream.getByte() << 16 |
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aStream.getByte() << 8 | aStream.getByte();
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}
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};
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var offsets = [];
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for (var i = 0; i < count + 1; i++)
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offsets.push(getNextOffset());
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log("Found " + count + " objects at offsets :" + offsets + " (offsize: " + offsize + ")");
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// Now extract the objects
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var relativeOffset = aStream.pos;
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var objects = [];
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for (var i = 0; i < count; i++) {
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var offset = offsets[i];
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aStream.pos = relativeOffset + offset - 1;
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var data = [];
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var length = offsets[i + 1] - 1;
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for (var j = offset - 1; j < length; j++)
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data.push(aIsByte ? aStream.getByte() : aStream.getChar());
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objects.push(data);
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}
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return objects;
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};
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var Type2Parser = function(aFilePath) {
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var font = new Dict();
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// Turn on this flag for additional debugging logs
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var debug = true;
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function dump(aStr) {
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if (debug)
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log(aStr);
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};
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function parseAsToken(aString, aMap) {
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var decoded = readFontDictData(aString, aMap);
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log(decoded);
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var stack = [];
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var count = decoded.length;
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for (var i = 0; i < count; i++) {
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var token = decoded[i];
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if (IsNum(token)) {
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stack.push(token);
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} else {
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switch (token.operand) {
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case "SID":
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font.set(token.name, CFFStrings[stack.pop()]);
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break;
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case "number number":
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font.set(token.name, {
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offset: stack.pop(),
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size: stack.pop()
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});
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break;
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case "boolean":
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font.set(token.name, stack.pop());
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break;
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case "delta":
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font.set(token.name, stack.pop());
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break;
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default:
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if (token.operand && token.operand.length) {
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var array = [];
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for (var j = 0; j < token.operand.length; j++)
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array.push(stack.pop());
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font.set(token.name, array);
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} else {
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font.set(token.name, stack.pop());
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}
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break;
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}
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}
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}
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};
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this.parse = function(aStream) {
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font.set("major", aStream.getByte());
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font.set("minor", aStream.getByte());
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font.set("hdrSize", aStream.getByte());
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font.set("offsize", aStream.getByte());
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// Move the cursor after the header
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aStream.skip(font.get("hdrSize") - aStream.pos);
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// Read the NAME Index
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dump("Reading Index: Names");
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font.set("Names", readFontIndexData(aStream));
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// Read the Top Dict Index
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dump("Reading Index: TopDict");
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var topDict = readFontIndexData(aStream, true);
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// Read the String Index
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dump("Reading Index: Strings");
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var strings = readFontIndexData(aStream);
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// Fill up the Strings dictionary with the new unique strings
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for (var i = 0; i < strings.length; i++)
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CFFStrings.push(strings[i].join(""));
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// Parse the TopDict operator
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var objects = [];
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var count = topDict.length;
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for (var i = 0; i < count; i++)
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parseAsToken(topDict[i], CFFDictDataMap);
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// Read the Global Subr Index that comes just after the Strings Index
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// (cf. "The Compact Font Format Specification" Chapter 16)
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dump("Reading Global Subr Index");
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var subrs = readFontIndexData(aStream);
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// Reading Private Dict
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var private = font.get("Private");
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log("Reading Private Dict (offset: " + private.offset + " size: " + private.size + ")");
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aStream.pos = private.offset;
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var privateDict = [];
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for (var i = 0; i < private.size; i++)
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privateDict.push(aStream.getByte());
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parseAsToken(privateDict, CFFDictPrivateDataMap);
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for (var p in font.map)
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dump(p + "::" + font.get(p));
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// Read CharStrings Index
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var charStringsOffset = font.get("CharStrings");
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dump("Read CharStrings Index (offset: " + charStringsOffset + ")");
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aStream.pos = charStringsOffset;
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var charStrings = readFontIndexData(aStream, true);
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var charsetEntry = font.get("charset");
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if (charsetEntry == 0) {
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throw new Error("Need to support CFFISOAdobeCharset");
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} else if (charsetEntry == 1) {
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throw new Error("Need to support CFFExpert");
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} else if (charsetEntry == 2) {
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throw new Error("Need to support CFFExpertSubsetCharset");
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} else {
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aStream.pos = charsetEntry;
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var charset = readCharset(aStream, charStrings);
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}
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}
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};
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// XXX
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/*
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var xhr = new XMLHttpRequest();
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xhr.open("GET", "titi.cff", false);
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xhr.mozResponseType = xhr.responseType = "arraybuffer";
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xhr.expected = (document.URL.indexOf("file:") == 0) ? 0 : 200;
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xhr.send(null);
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var cffData = xhr.mozResponseArrayBuffer || xhr.mozResponse ||
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xhr.responseArrayBuffer || xhr.response;
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var cff = new Type2Parser("titi.cff");
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cff.parse(new Stream(cffData));
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*/
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