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/*************************************************************************
** TFM.cpp **
** **
** This file is part of dvisvgm -- a fast DVI to SVG converter **
** Copyright (C) 2005-2022 Martin Gieseking <martin.gieseking@uos.de> **
** **
** This program is free software; you can redistribute it and/or **
** modify it under the terms of the GNU General Public License as **
** published by the Free Software Foundation; either version 3 of **
** the License, or (at your option) any later version. **
** **
** This program is distributed in the hope that it will be useful, but **
** WITHOUT ANY WARRANTY; without even the implied warranty of **
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the **
** GNU General Public License for more details. **
** **
** You should have received a copy of the GNU General Public License **
** along with this program; if not, see <http://www.gnu.org/licenses/>. **
*************************************************************************/
#include <fstream>
#include <vector>
#include "FileFinder.hpp"
#include "Length.hpp"
#include "Message.hpp"
#include "StreamReader.hpp"
#include "TFM.hpp"
using namespace std;
/** Reads a sequence of n TFM words (4 Bytes each).
* @param[in] reader the TFM data is read from this object
* @param[out] v the read words
* @param[in] n number of words to be read */
template <typename T>
static void read_words (StreamReader &reader, vector<T> &v, unsigned n) {
v.clear();
v.resize(n);
for (unsigned i=0; i < n; i++)
v[i] = reader.readUnsigned(4);
}
TFM::TFM (istream &is) : _checksum(0), _firstChar(0), _lastChar(0), _designSize(0), _ascent(0), _descent(0) {
if (!is)
return;
is.seekg(0);
StreamReader reader(is);
uint16_t lf = uint16_t(reader.readUnsigned(2)); // length of entire file in 4 byte words
uint16_t lh = uint16_t(reader.readUnsigned(2)); // length of header in 4 byte words
_firstChar= uint16_t(reader.readUnsigned(2)); // smallest character code in font
_lastChar = uint16_t(reader.readUnsigned(2)); // largest character code in font
uint16_t nw = uint16_t(reader.readUnsigned(2)); // number of words in width table
uint16_t nh = uint16_t(reader.readUnsigned(2)); // number of words in height table
uint16_t nd = uint16_t(reader.readUnsigned(2)); // number of words in depth table
uint16_t ni = uint16_t(reader.readUnsigned(2)); // number of words in italic corr. table
uint16_t nl = uint16_t(reader.readUnsigned(2)); // number of words in lig/kern table
uint16_t nk = uint16_t(reader.readUnsigned(2)); // number of words in kern table
uint16_t ne = uint16_t(reader.readUnsigned(2)); // number of words in ext. char table
uint16_t np = uint16_t(reader.readUnsigned(2)); // number of font parameter words
if (6+lh+(_lastChar-_firstChar+1)+nw+nh+nd+ni+nl+nk+ne+np != lf)
throw FontMetricException("inconsistent length values");
if (_firstChar >= _lastChar || _lastChar > 255 || ne > 256)
throw FontMetricException("character codes out of range");
readHeader(reader);
is.seekg(24+lh*4); // move to char info table
readTables(reader, nw, nh, nd, ni);
is.seekg(4*(lf-np), ios::beg); // move to param section
readParameters(reader, np);
}
void TFM::readHeader (StreamReader &reader) {
_checksum = reader.readUnsigned(4);
_designSize = double(FixWord(reader.readUnsigned(4)))*Length::pt2bp;
}
void TFM::readTables (StreamReader &reader, int nw, int nh, int nd, int ni) {
read_words(reader, _charInfoTable, _lastChar-_firstChar+1);
read_words(reader, _widthTable, nw);
read_words(reader, _heightTable, nh);
read_words(reader, _depthTable, nd);
read_words(reader, _italicTable, ni);
for (FixWord h : _heightTable)
_ascent = max(_ascent, h);
for (FixWord d : _depthTable)
_descent = max(_descent, d);
}
/** Read the values from the param section of the TFM file.
* @param[in] reader read from this stream
* @param[in] np number of paramaters to read */
void TFM::readParameters (StreamReader &reader, int np) {
_params.resize(7);
np = min(np, 7);
for (int i=0; i < np; i++)
_params[i] = reader.readUnsigned(4);
for (int i=np; i < 7; i++)
_params[i] = 0;
}
/** Returns the optimal space width between words (in PS point units). */
double TFM::getSpace () const {
return _params.empty() ? 0 : double(_params[1])*_designSize;
}
/** Returns the amount of glue stretching between words (in PS point units). */
double TFM::getSpaceStretch () const {
return _params.empty() ? 0 : double(_params[2])*_designSize;
}
/** Returns the amount of glue shrinking between words (in PS point units). */
double TFM::getSpaceShrink () const {
return _params.empty() ? 0 : double(_params[3])*_designSize;
}
/** Returns the size of one EM unit (in PS point units). */
double TFM::getQuad () const {
if (_params.empty() || _params[5] == 0)
return _designSize;
return double(_params[5])*_designSize;
}
/** Returns the index to the entry of the character info table that describes the metric of a given character.
* @param[in] c character whose index is retrieved
* @return table index for character c, or -1 if there's no entry */
int TFM::charIndex (int c) const {
if (c < _firstChar || c > _lastChar || size_t(c-_firstChar) >= _charInfoTable.size())
return -1;
return c-_firstChar;
}
// the char info word for each character consists of 4 bytes holding the following information:
// width index w, height index (h), depth index (d), italic correction index (it),
// tag (tg) and a remainder:
//
// byte 1 | byte 2 | byte 3 | byte 4
// xxxxxxxx | xxxx xxxx | xxxxxx xx | xxxxxxxx
// w | h d | it tg | remainder
/** Returns the width of char c in PS point units. */
double TFM::getCharWidth (int c) const {
int index = charIndex(c);
if (index < 0)
return 0;
index = (_charInfoTable[index] >> 24) & 0xFF;
return double(_widthTable[index]) * _designSize;
}
/** Returns the height of char c in PS point units. */
double TFM::getCharHeight (int c) const {
int index = charIndex(c);
if (index < 0)
return 0;
index = (_charInfoTable[index] >> 20) & 0x0F;
return double(_heightTable[index]) * _designSize;
}
/** Returns the depth of char c in PS point units. */
double TFM::getCharDepth (int c) const {
int index = charIndex(c);
if (index < 0)
return 0;
index = (_charInfoTable[index] >> 16) & 0x0F;
return double(_depthTable[index]) * _designSize;
}
/** Returns the italic correction of char c in PS point units. */
double TFM::getItalicCorr (int c) const {
int index = charIndex(c);
if (index < 0)
return 0;
index = (_charInfoTable[index] >> 10) & 0x3F;
return double(_italicTable[index]) * _designSize;
}
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