2 tfm-reader.cc -- implement Tex_font_metric_reader
4 source file of the GNU LilyPond music typesetter
6 (c) 1999--2005 Jan Nieuwenhuizen <janneke@gnu.org>
9 some code shamelessly copied from GNU fontutils-0.6/tfm/tfm_input.c
12 #include "tfm-reader.hh"
14 #include "string-convert.hh"
17 #define format_string String_convert::form_string
20 static const Real fix_to_real (Fix f);
22 Tex_font_metric_reader::Tex_font_metric_reader (String name)
26 for (int i = 0; i < TFM_SIZE; i++)
27 ascii_to_metric_idx_.push (-1);
37 Real r = f / FIX_UNITY + ((Real) (f % FIX_UNITY) / (Real) FIX_UNITY);
41 /* Most quantities are fixed-point fractions. */
44 Tex_font_metric_reader::get_U32_fix ()
46 return fix_to_real (input_.get_U32 ());
49 /* Dimensions are a `Fix' scaled by the design size. */
52 Tex_font_metric_reader::get_U32_fix_scaled ()
54 return get_U32_fix () * info_.design_size;
58 Tex_font_metric_reader::get_bcpl_string ()
60 U8 length_u8 = input_.get_U8 ();
61 String str = input_.get_string (length_u8);
65 /* Here we read the information at the beginning of the file. We store
66 the result into the static variables `global_info' and
69 Tex_font_metric_reader::read_header ()
71 U16 file_length = input_.get_U16 ();
73 U16 header_length = input_.get_U16 ();
75 info_.first_charcode = input_.get_U16 ();
76 info_.last_charcode = input_.get_U16 ();
77 U16 width_word_count = input_.get_U16 ();
78 U16 height_word_count = input_.get_U16 ();
79 U16 depth_word_count = input_.get_U16 ();
80 U16 italic_correction_word_count = input_.get_U16 ();
81 U16 lig_kern_word_count = input_.get_U16 ();
82 U16 kern_word_count = input_.get_U16 ();
83 (void)kern_word_count;
84 U16 extensible_word_count = input_.get_U16 ();
85 (void)extensible_word_count;
87 header_.param_word_count = input_.get_U16 ();
88 info_.parameter_count = header_.param_word_count;
90 header_.char_info_pos = (6 + header_length) * 4;
91 header_.width_pos = header_.char_info_pos
92 + (info_.last_charcode
93 - info_.first_charcode + 1) * 4;
94 header_.height_pos = header_.width_pos + width_word_count * 4;
95 header_.depth_pos = header_.height_pos + height_word_count * 4;
96 header_.italic_correction_pos = header_.depth_pos
97 + depth_word_count * 4;
98 header_.lig_kern_pos = header_.italic_correction_pos
99 + italic_correction_word_count * 4;
100 header_.kern_pos = header_.lig_kern_pos + lig_kern_word_count * 4;
101 /* We don't care about the extensible table. */
103 if (header_length < 2)
104 /* Not using ngettext's plural feature here, as this message is
105 more of a programming error. */
106 error (_f ("TFM header of `%s' has only %u word (s)",
107 input_.name_string ().to_str0 (), header_length));
109 info_.checksum = input_.get_U32 ();
110 info_.design_size = get_U32_fix ();
112 /* Although the coding scheme might be interesting to the caller, the
113 font family and face byte probably aren't. So we don't read them. */
114 info_.coding_scheme = header_length > 2
115 ? get_bcpl_string () : "unspecified";
118 /* Although TFM files are only usable by TeX if they have at least seven
119 parameters, that is not a requirement of the file format itself, so
120 we don't impose it. And they can have many more than seven, of
121 course. We do impose a limit of TFM_MAX_FONT_PARAMETERS. We assume
122 that `tfm_header' has already been filled in. */
125 Tex_font_metric_reader::read_params ()
127 /* If we have no font parameters at all, we're done. */
128 if (header_.param_word_count == 0)
132 /* Move to the beginning of the parameter table in the file. */
133 input_.seek_str0 (-4 * header_.param_word_count);
135 /* It's unlikely but possible that this TFM file has more fontdimens
136 than we can deal with. */
137 if (header_.param_word_count > TFM_MAX_FONTDIMENS)
139 warning (_f ("%s: TFM file has %u parameters, which is more than the %u I can handle",
140 input_.name_string ().to_str0 (),
141 header_.param_word_count,
142 TFM_MAX_FONTDIMENS));
143 header_.param_word_count = TFM_MAX_FONTDIMENS;
146 /* The first parameter is different than all the rest, because it
147 isn't scaled by the design size. */
148 info_.parameters[ (TFM_SLANT_PARAMETER) - 1] = get_U32_fix ();
150 for (Char_code i = 2; i <= header_.param_word_count; i++)
151 info_.parameters[i - 1] = get_U32_fix_scaled ();
154 /* Read every character in the TFM file, storing the result in the
155 static `tfm_char_table'. We return a copy of that variable. */
158 Tex_font_metric_reader::read_char_metrics ()
160 for (int i = info_.first_charcode; i <= info_.last_charcode; i++)
162 Tex_font_char_metric tfm_char = read_char_metric (i);
163 if (tfm_char.exists_)
164 ascii_to_metric_idx_[tfm_char.code_] = char_metrics_.size ();
165 char_metrics_.push (tfm_char);
169 /* Read the character CODE. If the character doesn't exist, return
170 NULL. If it does, save the information in `tfm_char_table', as well
174 Tex_font_metric_reader::read_char_metric (Char_code code)
176 Tex_font_char_metric tfm_char;
178 /* If the character is outside the declared bounds in the file, don't
180 if (code < info_.first_charcode || code > info_.last_charcode)
184 /* Move to the appropriate place in the `char_info' array. */
185 input_.seek_str0 (header_.char_info_pos + (code - info_.first_charcode) * 4);
187 /* Read the character. */
188 tfm_char = read_char ();
190 if (tfm_char.exists_)
191 tfm_char.code_ = code;
196 /* We assume we are positioned at the beginning of a `char_info' word.
197 We read that word to get the indexes into the dimension tables; then
198 we go read the tables to get the values (if the character exists). */
201 Tex_font_metric_reader::read_char ()
203 /* Read the char_info word. */
204 U8 width_index = input_.get_U8 ();
207 packed = input_.get_U8 ();
208 U8 height_index = (packed & 0xf0) >> 4;
209 U8 depth_index = packed & 0x0f;
211 packed = input_.get_U8 ();
212 U8 italic_correction_index = (packed & 0xfc) >> 6;
213 U8 tag = packed & 0x3;
215 U8 remainder = input_.get_U8 ();
217 Tex_font_char_metric tfm_char;
219 #define GET_CHAR_DIMEN(d) \
220 if (d##_index != 0) \
222 input_.seek_str0 (header_.d##_pos + d##_index * 4); \
223 tfm_char.d##_fix_ = input_.get_U32 (); \
224 tfm_char.d##_ = fix_to_real (tfm_char.d##_fix_) \
225 * info_.design_size; \
228 GET_CHAR_DIMEN (width);
229 GET_CHAR_DIMEN (height);
230 GET_CHAR_DIMEN (depth);
231 GET_CHAR_DIMEN (italic_correction);
233 /* The other condition for a character existing is that it be between
234 the first and last character codes given in the header. We've
235 already assumed that's true (or we couldn't be positioned at a
236 `char_info_word'). */
237 tfm_char.exists_ = width_index != 0;
241 input_.seek_str0 (header_.lig_kern_pos + remainder * 4);
242 read_lig_kern_program (&tfm_char.ligatures_, &tfm_char.kerns_);
245 /* We don't handle the other tags. */
249 /* Read a ligature/kern program at the current position, storing the
250 result into *LIGATURE and *KERN. We don't distinguish all the kinds
251 of ligatures that Metafont can output. */
253 #define STOP_FLAG 128
254 #define KERN_FLAG 128
257 Tex_font_metric_reader::read_lig_kern_program (Array<Tfm_ligature> *ligatures, Array<Tfm_kern> *kerns)
263 end_b = input_.get_U8 () >= STOP_FLAG;
265 U8 next_char = input_.get_U8 ();
266 bool kern_step_b = input_.get_U8 () >= KERN_FLAG;
267 U8 remainder = input_.get_U8 ();
271 Tfm_kern kern_element;
272 kern_element.character = next_char;
274 char const *old_pos = input_.pos_str0 ();
275 input_.seek_str0 (header_.kern_pos + remainder * 4);
276 kern_element.kern = get_U32_fix_scaled ();
277 input_.set_pos (old_pos);
279 kerns->push (kern_element);
283 Tfm_ligature ligature_element;
284 ligature_element.character = next_char;
285 ligature_element.ligature = remainder;
286 ligatures->push (ligature_element);