pdf.js/PDFFontUtils.js
2011-06-10 20:45:42 +02:00

376 lines
11 KiB
JavaScript

/**
* The Type2 reader code below is only used for debugging purpose since Type2
* is only a CharString format and is never used directly as a Font file.
*
* So the code here is useful for dumping the data content of a .cff file in
* order to investigate the similarity between a Type1 CharString and a Type2
* CharString.
*/
/**
* Build a charset by assigning the glyph name and the human readable form
* of the glyph data.
*/
function readCharset(aStream, aCharstrings) {
var charset = {};
var format = aStream.getByte();
if (format == 0) {
charset[".notdef"] = readCharstringEncoding(aCharstrings[0]);
var count = aCharstrings.length - 1;
for (var i = 1; i < count + 1; i++) {
var sid = aStream.getByte() << 8 | aStream.getByte();
charset[CFFStrings[sid]] = readCharstringEncoding(aCharstrings[i]);
//log(CFFStrings[sid] + "::" + charset[CFFStrings[sid]]);
}
} else if (format == 1) {
error("Charset Range are not supported");
} else {
error("Invalid charset format");
}
return charset;
};
/**
* Take a Type2 binary charstring as input and transform it to a human
* readable representation as specified by the 'The Type 2 Charstring Format',
* chapter 3.1.
*/
function readCharstringEncoding(aString) {
var charstringTokens = [];
var count = aString.length;
for (var i = 0; i < count; ) {
var value = aString[i++];
var token = null;
if (value < 0) {
continue;
} else if (value <= 11) {
token = CFFEncodingMap[value];
} else if (value == 12) {
token = CFFEncodingMap[value][aString[i++]];
} else if (value <= 18) {
token = CFFEncodingMap[value];
} else if (value <= 20) {
var mask = aString[i++];
token = CFFEncodingMap[value];
} else if (value <= 27) {
token = CFFEncodingMap[value];
} else if (value == 28) {
token = aString[i++] << 8 | aString[i++];
} else if (value <= 31) {
token = CFFEncodingMap[value];
} else if (value < 247) {
token = parseInt(value) - 139;
} else if (value < 251) {
token = ((value - 247) * 256) + aString[i++] + 108;
} else if (value < 255) {
token = -((value - 251) * 256) - aString[i++] - 108;
} else {// value == 255
token = aString[i++] << 24 | aString[i++] << 16 |
aString[i++] << 8 | aString[i];
}
charstringTokens.push(token);
}
return charstringTokens;
};
/**
* Take a binary DICT Data as input and transform it into a human readable
* form as specified by 'The Compact Font Format Specification', chapter 5.
*/
function readFontDictData(aString, aMap) {
var fontDictDataTokens = [];
var count = aString.length;
for (var i = 0; i < count; i) {
var value = aString[i++];
var token = null;
if (value == 12) {
token = aMap[value][aString[i++]];
} else if (value == 28) {
token = aString[i++] << 8 | aString[i++];
} else if (value == 29) {
token = aString[i++] << 24 |
aString[i++] << 16 |
aString[i++] << 8 |
aString[i++];
} else if (value == 30) {
token = "";
var parsed = false;
while (!parsed) {
var byte = aString[i++];
var nibbles = [parseInt(byte / 16), parseInt(byte % 16)];
for (var j = 0; j < nibbles.length; j++) {
var nibble = nibbles[j];
switch (nibble) {
case 0xA:
token += ".";
break;
case 0xB:
token += "E";
break;
case 0xC:
token += "E-";
break;
case 0xD:
break;
case 0xE:
token += "-";
break;
case 0xF:
parsed = true;
break;
default:
token += nibble;
break;
}
}
};
token = parseFloat(token);
} else if (value <= 31) {
token = aMap[value];
} else if (value <= 246) {
token = parseInt(value) - 139;
} else if (value <= 250) {
token = ((value - 247) * 256) + aString[i++] + 108;
} else if (value <= 254) {
token = -((value - 251) * 256) - aString[i++] - 108;
} else if (value == 255) {
error("255 is not a valid DICT command");
}
fontDictDataTokens.push(token);
}
return fontDictDataTokens;
};
/**
* Take a stream as input and return an array of objects.
* In CFF an INDEX is a structure with the following format:
* {
* count: 2 bytes (Number of objects stored in INDEX),
* offsize: 1 byte (Offset array element size),
* offset: [count + 1] bytes (Offsets array),
* data: - (Objects data)
* }
*
* More explanation are given in the 'CFF Font Format Specification',
* chapter 5.
*/
function readFontIndexData(aStream, aIsByte) {
var count = aStream.getByte() << 8 | aStream.getByte();
var offsize = aStream.getByte();
function getNextOffset() {
switch (offsize) {
case 0:
return 0;
case 1:
return aStream.getByte();
case 2:
return aStream.getByte() << 8 | aStream.getByte();
case 3:
return aStream.getByte() << 16 | aStream.getByte() << 8 |
aStream.getByte();
case 4:
return aStream.getByte() << 24 | aStream.getByte() << 16 |
aStream.getByte() << 8 | aStream.getByte();
}
};
var offsets = [];
for (var i = 0; i < count + 1; i++)
offsets.push(getNextOffset());
log("Found " + count + " objects at offsets :" + offsets + " (offsize: " + offsize + ")");
// Now extract the objects
var relativeOffset = aStream.pos;
var objects = [];
for (var i = 0; i < count; i++) {
var offset = offsets[i];
aStream.pos = relativeOffset + offset - 1;
var data = [];
var length = offsets[i + 1] - 1;
for (var j = offset - 1; j < length; j++)
data.push(aIsByte ? aStream.getByte() : aStream.getChar());
objects.push(data);
}
return objects;
};
var Type2Parser = function(aFilePath) {
var font = new Dict();
// Turn on this flag for additional debugging logs
var debug = false;
function dump(aStr) {
if (debug)
log(aStr);
};
function parseAsToken(aString, aMap) {
var decoded = readFontDictData(aString, aMap);
var stack = [];
var count = decoded.length;
for (var i = 0; i < count; i++) {
var token = decoded[i];
if (IsNum(token)) {
stack.push(token);
} else {
switch (token.operand) {
case "SID":
font.set(token.name, CFFStrings[stack.pop()]);
break;
case "number number":
font.set(token.name, {
offset: stack.pop(),
size: stack.pop()
});
break;
case "boolean":
font.set(token.name, stack.pop());
break;
case "delta":
font.set(token.name, stack.pop());
break;
default:
if (token.operand && token.operand.length) {
var array = [];
for (var j = 0; j < token.operand.length; j++)
array.push(stack.pop());
font.set(token.name, array);
} else {
font.set(token.name, stack.pop());
}
break;
}
}
}
};
this.parse = function(aStream) {
font.set("major", aStream.getByte());
font.set("minor", aStream.getByte());
font.set("hdrSize", aStream.getByte());
font.set("offsize", aStream.getByte());
// Move the cursor after the header
aStream.skip(font.get("hdrSize") - aStream.pos);
// Read the NAME Index
dump("Reading Index: Names");
font.set("Names", readFontIndexData(aStream));
log("Names: " + font.get("Names"));
// Read the Top Dict Index
dump("Reading Index: TopDict");
var topDict = readFontIndexData(aStream, true);
log("TopDict: " + topDict);
// Read the String Index
dump("Reading Index: Strings");
var strings = readFontIndexData(aStream);
log("strings: " + strings);
// Fill up the Strings dictionary with the new unique strings
for (var i = 0; i < strings.length; i++)
CFFStrings.push(strings[i].join(""));
// Parse the TopDict operator
var objects = [];
var count = topDict.length;
for (var i = 0; i < count; i++)
parseAsToken(topDict[i], CFFDictDataMap);
// Read the Global Subr Index that comes just after the Strings Index
// (cf. "The Compact Font Format Specification" Chapter 16)
dump("Reading Global Subr Index");
var subrs = readFontIndexData(aStream);
// Reading Private Dict
var private = font.get("Private");
log("Reading Private Dict (offset: " + private.offset + " size: " + private.size + ")");
aStream.pos = private.offset;
var privateDict = [];
for (var i = 0; i < private.size; i++)
privateDict.push(aStream.getByte());
dump("private:" + privateDict);
parseAsToken(privateDict, CFFDictPrivateDataMap);
for (var p in font.map)
dump(p + "::" + font.get(p));
// Read CharStrings Index
var charStringsOffset = font.get("CharStrings");
dump("Read CharStrings Index (offset: " + charStringsOffset + ")");
aStream.pos = charStringsOffset;
var charStrings = readFontIndexData(aStream, true);
// Read Charset
dump("Read Charset for " + charStrings.length + " glyphs");
var charsetEntry = font.get("charset");
if (charsetEntry == 0) {
error("Need to support CFFISOAdobeCharset");
} else if (charsetEntry == 1) {
error("Need to support CFFExpert");
} else if (charsetEntry == 2) {
error("Need to support CFFExpertSubsetCharset");
} else {
aStream.pos = charsetEntry;
var charset = readCharset(aStream, charStrings);
}
}
};
var xhr = new XMLHttpRequest();
xhr.open("GET", "titi.cff", false);
xhr.mozResponseType = xhr.responseType = "arraybuffer";
xhr.expected = (document.URL.indexOf("file:") == 0) ? 0 : 200;
xhr.send(null);
var cffData = xhr.mozResponseArrayBuffer || xhr.mozResponse ||
xhr.responseArrayBuffer || xhr.response;
var cff = new Type2Parser("titi.cff");
//cff.parse(new Stream(cffData));
/**
* Write to a file (works only on Firefox in privilege mode");
*/
function writeToFile(aBytes, aFilePath) {
netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
var Cc = Components.classes,
Ci = Components.interfaces;
var file = Cc['@mozilla.org/file/local;1'].createInstance(Ci.nsILocalFile);
file.initWithPath(aFilePath);
var stream = Cc["@mozilla.org/network/file-output-stream;1"]
.createInstance(Ci.nsIFileOutputStream);
stream.init(file, 0x04 | 0x08 | 0x20, 0600, 0);
var bos = Cc["@mozilla.org/binaryoutputstream;1"]
.createInstance(Ci.nsIBinaryOutputStream);
bos.setOutputStream(stream);
bos.writeByteArray(aBytes, aBytes.length);
stream.close();
};