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  11
  12 <h2>ZPB-TTF - TrueType font file access for Common Lisp</h2>
  13
  14 <blockquote>
  15 <h3>Abstract</h3>
  16
  17 <p>TrueType fonts have a <a
  18 href="http://developer.apple.com/fonts/TTRefMan/RM06/Chap6.html">publicly</a>
  19 <a
  20 href="http://www.microsoft.com/OpenType/OTSpec/otff.htm">documented</a>
  21 file format. ZPB-TTF is a TrueType file parser that provides an
  22 interface for reading typographic metrics, glyph outlines, and other
  23 information from the file. It is available under a BSD-like
  24 license.
  25
  26 The latest version is 1.0.3, released on July 18th, 2013.
  27
  28 <p>TrueType is a registered trademark of Apple Computer, Inc.
  29
  30 <p style='color: red'>Download shortcut: <a href='http://www.xach.com/lisp/zpb-ttf.tgz'>http://www.xach.com/lisp/zpb-ttf.tgz</a>
  31
  32 </blockquote>
  33
  34 <h3>Contents</h3>
  35
  36 <ol>
  37 <li> <a href='#sect-limitations'>Limitations</a>
  38 <li> <a href='#sect-overview'>Overview</a>
  39 <li><a href='#sect-glyph-example'>Glyph Example</a>
  40 <li> <a href='#sect-dictionary'>The ZPB-TTF Dictionary</a>
  41
  42 <ol>
  43 <li> <a href='#open-font-loader'><tt>open-font-loader</tt></a>
  44 <li> <a href='#close-font-loader'><tt>close-font-loader</tt></a>
  45 <li> <a href='#with-font-loader'><tt>with-font-loader</tt></a>
  46 <li> <a href='#glyph-count'><tt>glyph-count</tt></a>
  47 <li> <a href='#name-entry-value'><tt>name-entry-value</tt></a>
  48 <li> <a href='#find-name-entry'><tt>find-name-entry</tt></a>
  49 <li> <a href='#value'><tt>value</tt></a>
  50 <li> <a href='#italic-angle'><tt>italic-angle</tt></a>
  51 <li> <a href='#underline-thickness'><tt>underline-thickness</tt></a>
  52 <li> <a href='#underline-position'><tt>underline-position</tt></a>
  53 <li> <a href='#fixed-pitch-p'><tt>fixed-pitch-p</tt></a>
  54 <li> <a href='#units/em'><tt>units/em</tt></a>
  55 <li> <a href='#ascender'><tt>ascender</tt></a>
  56 <li> <a href='#descender'><tt>descender</tt></a>
  57 <li> <a href='#line-gap'><tt>line-gap</tt></a>
  58 <li> <a href='#postscript-name'><tt>postscript-name</tt></a>
  59 <li> <a href='#full-name'><tt>full-name</tt></a>
  60 <li> <a href='#family-name'><tt>family-name</tt></a>
  61 <li> <a href='#subfamily-name'><tt>subfamily-name</tt></a>
  62 <li> <a href='#all-kerning-pairs'><tt>all-kerning-pairs</tt></a>
  63 <li> <a href='#glyph-exists-p'><tt>glyph-exists-p</tt></a>
  64 <li> <a href='#index-glyph'><tt>index-glyph</tt></a>
  65 <li> <a href='#find-glyph'><tt>find-glyph</tt></a>
  66 <li> <a href='#bounding-box'><tt>bounding-box</tt></a>
  67 <li> <a href='#xmin-and-friends'><tt>xmin</tt></a>
  68 <li> <a href='#xmin-and-friends'><tt>ymin</tt></a>
  69 <li> <a href='#xmin-and-friends'><tt>xmax</tt></a>
  70 <li> <a href='#xmin-and-friends'><tt>ymax</tt></a>
  71 <li> <a href='#x-and-friends'><tt>x</tt></a>
  72 <li> <a href='#x-and-friends'><tt>y</tt></a>
  73 <li> <a href='#on-curve-p'><tt>on-curve-p</tt></a>
  74 <li> <a href='#contour-count'><tt>contour-count</tt></a>
  75 <li> <a href='#contour'><tt>contour</tt></a>
  76 <li> <a href='#contours'><tt>contours</tt></a>
  77 <li> <a href='#do-contours'><tt>do-contours</tt></a>
  78 <li> <a href='#explicit-contour-points'><tt>explicit-contour-points</tt></a>
  79 <li> <a href='#do-contour-segments'><tt>do-contour-segments</tt></a>
  80 <li> <a href='#do-contour-segments*'><tt>do-contour-segments*</tt></a>
  81 <li> <a href='#code-point'><tt>code-point</tt></a>
  82 <li> <a href='#font-index'><tt>font-index</tt></a>
  83 <li> <a href='#advance-width'><tt>advance-width</tt></a>
  84 <li> <a href='#left-side-bearing'><tt>left-side-bearing</tt></a>
  85 <li> <a href='#right-side-bearing'><tt>right-side-bearing</tt></a>
  86 <li> <a href='#kerning-offset'><tt>kerning-offset</tt></a>
  87 <li> <a href='#string-bounding-box'><tt>string-bounding-box</tt></a>
  88 </ol>
  89
  90 <li><a href='#sect-feedback'>Feedback</a>
  91
  92 </ol>
  93
  94
  95 <a name='sect-limitations'><h3>Limitations</h3></a>
  96
  97 <p>ZPB-TTF has the following limitations:
  98
  99 <ul>
 100
 101 <li>is not a rasterizer; it will not produce bitmaps
 102
 103 <li>is not a scaler; all units are unscaled values directly from the
 104 font file
 105
 106 <li>only works with fonts that have a Unicode character map
 107
 108 <li>has been tested on a limited number of fonts
 109
 110 </ul>
 111
 112
 113
 114 <a name='sect-overview'><h3>Overview</h3></a>
 115
 116 <p>Font files are loaded by creating <i>font loaders</i>. A font
 117 loader has information that applies to the font as a whole, such as
 118 its overall bounding box and other typographic metrics, the number of
 119 glyphs it contains, and a character map that can be used to convert a
 120 character set index into a glyph index meaningful to the font loader.
 121
 122 <p>A font loader can also be used to create and find <i>glyphs</i>. A
 123 glyph object has information about an individual glyph such as
 124 typographic metrics and its outline.
 125
 126 <p>Glyph outlines are made up of arrays of <i>control points</i>. An
 127 array of control points is called a <i>contour</i>. Contours define
 128 the shape of the glyph. For example, in most fonts, the glyph for the
 129 character <tt>#\I</tt> has one contour defining its outline. The glyph
 130 for the character <tt>#\O</tt> has two contours: one for the outer
 131 edge, and one for the inner edge.
 132
 133 <p>This documentation is not meant to be a substitute for the TrueType
 134 file format documentation. For file format details, see the
 135 specifications from either <a
 136 href="http://developer.apple.com/fonts/TTRefMan/RM06/Chap6.html">Apple</a>
 137 or <a
 138 href="http://www.microsoft.com/OpenType/OTSpec/otff.htm">Microsoft</a>.
 139
 140
 141 <a name='sect-glyph-example'><h3>Glyph Example</h3></a>
 142
 143 <p><img src="lambda.png">
 144
 145 <p>This image is a rendering of the Greek small letter lambda (U+03BB)
 146 from the <a href="http://www.identifont.com/show?WP">Times New
 147 Roman</a> TrueType font. The visualization was programmed by Frederic
 148 Jolliton and rendered
 149 with <a href="http://projects.tuxee.net/cl-vectors">CL-VECTORS</a>.
 150
 151 <p>The dark gray grid lines represent the axes of the glyph coordinate
 152 system. Light grid lines are drawn at intervals of 256 em-square
 153 units.
 154
 155 <p>Black squares represent the control points returned from <a
 156 href='#contour'><tt>CONTOUR</tt></a>. Solid black squares are points
 157 on the outline (<a href='#on-curve-p'><tt>ON-CURVE-P</tt></a> returns
 158 <i>true</i>), and hollow black squares are not on the outline. Solid
 159 red squares represent implicit control points on the glyph outline;
 160 they are not in the original contour, but they would be returned in a
 161 new contour created with <a
 162 href='#explicit-contour-points'><tt>EXPLICIT-CONTOUR-POINTS</tt></a>.
 163
 164 <p>The alternating blue and green portions of the glyph outline
 165 represent the separate segments whose start, control, and end points
 166 were bound with <a
 167 href='#do-contour-segments'><tt>DO-CONTOUR-SEGMENTS</tt></a>.
 168
 169
 170 <a name='sect-dictionary'><h3>The ZPB-TTF Dictionary</h3></a>
 171
 172 <p><a name='open-font-loader'>[Function]</a><br>
 173 <b>open-font-loader</b> <i>font-file-designator</i> => <i>font-loader</i>
 174
 175 <blockquote>
 176 Creates and returns a font-loader object from
 177 <i>font-file-designator</i>, which should be either a pathname,
 178 pathname namestring, a stream, or a font-loader object.
 179 </blockquote>
 180
 181
 182 <p><a name='close-font-loader'>[Function]</a><br>
 183 <b>close-font-loader</b> <i>font-loader</i> =>
 184
 185 <blockquote>
 186 Closes any open resources held by <i>font-loader</i>.
 187 </blockquote>
 188
 189
 190 <p><a name='with-font-loader'>[Macro]</a><br>
 191 <b>with-font-loader</b> <i>(font-loader font-loader-designator)</i> <tt>&body</tt> <i>body</i> =>
 192
 193 <blockquote>
 194 Performs <i>body</i> with <i>font-loader</i> bound to a font-loader
 195 object created as if with <tt>(open-font-loader</tt>
 196 <i>font-loader-designator</i></tt>). Automatically closes the
 197 font-loader when finished.
 198 </blockquote>
 199
 200
 201 <p><a name="glyph-count">[Function]</a><br>
 202 <b>glyph-count</b> <i>font-loader</i> => <i>number</i>
 203
 204 <blockquote>
 205 Returns the number of glyphs available in <i>font-loader</i>.
 206 </blockquote>
 207
 208
 209 <p><a name='name-entry-value'>[Function]</a><br>
 210 <b>name-entry-value</b> <i>name-designator</i> <i>font-loader</i> => <i>string</i>
 211
 212 <blockquote>
 213 Returns an entry from the TrueType "name" table, which contains
 214 human-readable values for copyright info, trademark notices, creator
 215 names, and the like.
 216
 217 <p><i>name-designator</i> may be either an integer ID from the table of
 218 NameIDs in the <a
 219 href="http://developer.apple.com/fonts/TTRefMan/RM06/Chap6name.html">TrueType
 220 "name" table specification</a>, or a keyword designating such an
 221 ID. Valid keywords and their IDs are:
 222
 223 <p><table cellpadding=3 cellspacing=0>
 224 <tr><th>Keyword</th><th align=right>&nbsp; ID</th></tr>
 225 <tr><td><tt>:COPYRIGHT-NOTICE</tt></td><td align=right>0</td></tr>
 226 <tr><td><tt>:FONT-FAMILY</tt></td><td align=right>1</td></tr>
 227 <tr><td><tt>:FONT-SUBFAMILY</tt></td><td align=right>2</td></tr>
 228 <tr><td><tt>:UNIQUE-SUBFAMILY</tt></td><td align=right>3</td></tr>
 229 <tr><td><tt>:FULL-NAME</tt></td><td align=right>4</td></tr>
 230 <tr><td><tt>:NAME-TABLE-VERSION</tt></td><td align=right>5</td></tr>
 231 <tr><td><tt>:POSTSCRIPT-NAME</tt></td><td align=right>6</td></tr>
 232 <tr><td><tt>:TRADEMARK-NOTICE</tt></td><td align=right>7</td></tr>
 233 <tr><td><tt>:MANUFACTURER-NAME</tt></td><td align=right>8</td></tr>
 234 <tr><td><tt>:DESIGNER</tt></td><td align=right>9</td></tr>
 235 <tr><td><tt>:DESCRIPTION</tt></td><td align=right>10</td></tr>
 236 <tr><td><tt>:VENDOR-URL</tt></td><td align=right>11</td></tr>
 237 <tr><td><tt>:DESIGNER-URL</tt></td><td align=right>12</td></tr>
 238 <tr><td><tt>:LICENSE-DESCRIPTION</tt></td><td align=right>13</td></tr>
 239 <tr><td><tt>:LICENCE-INFO-URL</tt></td><td align=right>14</td></tr>
 240 <tr><td><tt>:RESERVED</tt></td><td align=right>15</td></tr>
 241 <tr><td><tt>:PREFERRED-FAMILY</tt></td><td align=right>16</td></tr>
 242 <tr><td><tt>:PREFERRED-SUBFAMILY</tt></td><td align=right>17</td></tr>
 243 <tr><td><tt>:COMPATIBLE-FULL</tt></td><td align=right>18</td></tr>
 244 <tr><td><tt>:SAMPLE-TEXT</tt></td><td align=right>19</td></tr>
 245 </table>
 246
 247 <p>If the font does not provide any "name" table entry for the given
 248 <i>name-designator</i>, returns <tt>NIL</tt>.
 249
 250 </blockquote>
 251
 252
 253 <p><a name='find-name-entry'>[Function]</a><br>
 254 <b>find-name-entry</b> <i>platform-id language-id name-id font-loader</i> => <i>name-entry</i>
 255
 256 <blockquote>
 257 This is the low-level interface used by <a
 258 href="#name-entry-value"><tt>NAME-ENTRY-VALUE</tt></a>. <i>platform-id</i>,
 259 <i>language-id</i>, and <i>name-id</i> should be integer ID values from the <a
 260 href="http://developer.apple.com/fonts/TTRefMan/RM06/Chap6name.html">TrueType
 261 "name" table specification</a>. If the combination of IDs is found in
 262 the name table, a name-entry object is returned, otherwise
 263 <tt>NIL</tt> is returned.
 264 </blockquote>
 265
 266
 267 <p><a name='value'>[Function]</a><br>
 268 <b>value</b> <i>name-entry</i> => <i>string</i>
 269
 270 <blockquote>
 271 Returns the string value of a name-entry object.
 272 </blockquote>
 273
 274
 275 <p><a name="italic-angle">[Function]</a><br>
 276 <b>italic-angle</b> <i>font-loader</i> => <i>number</i>
 277
 278 <blockquote>
 279 Returns the typographic italic angle of <i>font-loader</i>.
 280 </blockquote>
 281
 282
 283 <p><a name="underline-thickness">[Function]</a><br>
 284 <b>underline-thickness</b> <i>font-loader</i> => <i>number</i>
 285
 286 <blockquote>
 287 Returns the typographic underline thickness of <i>font-loader</i>.
 288 </blockquote>
 289
 290
 291 <p><a name="underline-position">[Function]</a><br>
 292 <b>underline-position</b> <i>font-loader</i> => <i>number</i>
 293
 294 <blockquote>
 295 Returns the typographic underline position of <i>font-loader</i>.
 296 </blockquote>
 297
 298 <p><a name='fixed-pitch-p'>[Function]</a><br>
 299 <b>fixed-pitch-p</b> <i>font-loader</i> => <i>boolean</i>
 300
 301 <blockquote>
 302 Returns <i>true</i> if <i>font-loader</i> is fixed pitch (all glyphs
 303 have the same width).
 304 </blockquote>
 305
 306
 307 <p><a name="units/em">[Function]</a><br>
 308 <b>units/em</b> <i>font-loader</i> => <i>number</i>
 309
 310 <blockquote>
 311 Return the number of units in the typographic em-square of
 312 <i>font-loader</i>.
 313 </blockquote>
 314
 315
 316 <p><a name='ascender'>[Function]</a><br>
 317 <b>ascender</b> <i>font-loader</i> => <i>number</i>
 318
 319 <blockquote>
 320 Returns the typographic ascender value of <i>font-loader</i>.
 321 </blockquote>
 322
 323
 324 <p><a name='descender'>[Function]</a><br>
 325 <b>descender</b> <i>font-loader</i> => <i>number</i>
 326
 327 <blockquote>
 328 Returns the typographic descender value of <i>font-loader</i>.
 329 </blockquote>
 330
 331
 332 <p><a name='line-gap'>[Function]</a><br>
 333 <b>line-gap</b> <i>font-loader</i> => <i>number</i>
 334
 335 <blockquote>
 336 Returns the typographic line gap of <i>font-loader</i>.
 337 </blockquote>
 338
 339
 340 <p><a name='postscript-name'>[Generic function]</a><br>
 341 <b>postscript-name</b> <i>object</i> => <i>string</i>
 342
 343 <blockquote>
 344 Returns the Postscript name of <i>object</i>, which may be a glyph or a
 345 font-loader.
 346 </blockquote>
 347
 348
 349 <p><a name='full-name'>[Function]</a><br>
 350 <b>full-name</b> <i>font-loader</i> => <i>string</i>
 351
 352 <blockquote>
 353 Returns the full name of <i>font-loader</i>.
 354 </blockquote>
 355
 356
 357 <p><a name='family-name'>[Function]</a><br>
 358 <b>family-name</b> <i>font-loader</i> => <i>string</i>
 359
 360 <blockquote>
 361 Returns the family name of <i>font-loader</i>.
 362 </blockquote>
 363
 364
 365 <p><a name='subfamily-name'>[Function]</a><br>
 366 <b>subfamily-name</b> <i>font-loader</i> => <i>string</i>
 367
 368 <blockquote>
 369 Returns the subfamily name of <i>font-loader</i>.
 370 </blockquote>
 371
 372 <p><a name='all-kerning-pairs'>[Function]</a><br>
 373 <b>all-kerning-pairs</b> <i>font-loader</i> => <i>list</i>
 374
 375 <blockquote>
 376 Returns a list of all the kerning pairs available in
 377 <i>font-loader</i>. Each element of the list is itself a list, with
 378 three elements: a left glyph, a right glyph, and a numeric kerning
 379 offset.
 380 </blockquote>
 381
 382
 383 <p><a name="glyph-exists-p">[Function]</a><br>
 384 <b>glyph-exists-p</b> <i>character-designator font-loader</i> => <i>boolean</i>
 385
 386 <blockquote>
 387 Returns <i>true</i> if <i>font-loader</i> has glyph data for
 388 <i>character-designator</i>.
 389 </blockquote>
 390
 391
 392 <p><a name='index-glyph'>[Function]</a><br>
 393 <b>index-glyph</b> <i>index</i> <i>font-loader</i> => <i>glyph</i>
 394
 395 <blockquote>
 396 Returns the glyph at <i>index</i> in <i>font-loader</i>.
 397 </blockquote>
 398
 399
 400 <p><a name='find-glyph'>[Function]</a><br>
 401 <b>find-glyph</b> <i>character-designator</i> <i>font-loader</i> => <i>glyph</i>
 402
 403 <blockquote>
 404 Returns the glyph for <i>character-designator</i> in
 405 <i>font-loader</i>. If
 406 <i>character-designator</i> is an integer, it is treated as a Unicode
 407 code-point and the corresponding glyph is fetched from the font. If
 408 <i>character-designator</i> is a character, its <tt>char-code</tt> is used as
 409 a Unicode code-point for lookup.<br><b>Note:</b> If the
 410 <tt>char-code</tt>s of characters the Lisp implementation do not
 411 correspond to Unicode (or a subset), this may not return the expected
 412 glyph.
 413
 414 <p>If <i>font-loader</i> does not contain any glyphs for
 415 <i>character-designator</i>, the "missing glyph" glyph is returned. To
 416 test for the existence of a glyph without returning the "missing
 417 glyph" glyph, use <a
 418 href="#glyph-exists-p"><tt>GLYPH-EXISTS-P</tt></a>.
 419
 420 </blockquote>
 421
 422
 423 <p><a name='bounding-box'>[Generic function]</a><br>
 424 <b>bounding-box</b> <i>object</i> => <i>#(xmin ymin xmax ymax)</i>
 425
 426 <blockquote>
 427 Returns the bounding box of <i>object</i>, which may be a glyph or a
 428 font-loader.
 429 </blockquote>
 430
 431
 432 <p><a name='xmin-and-friends'>[Generic functions]</a><br>
 433 <b>xmin</b> <i>object</i> => <i>value</i><br>
 434 <b>ymin</b> <i>object</i> => <i>value</i><br>
 435 <b>xmax</b> <i>object</i> => <i>value</i><br>
 436 <b>ymax</b> <i>object</i> => <i>value</i><br>
 437
 438 <blockquote>
 439 Returns the horizontal and vertical extreme values for <i>object</i>, which
 440 may be a glyph or font-loader. If <i>object</i> is a four-element vector,
 441 each function is an accessor to the appropriate entry in the vector.
 442 </blockquote>
 443
 444
 445 <p><a name='x-and-y'>[Function]</a><br>
 446 <b>x</b> <i>control-point</i> => <i>number</i><br>
 447 <b>y</b> <i>control-point</i> => <i>number</i>
 448
 449 <blockquote>
 450 Returns the respective coordinate of <i>control-point</i>.
 451 </blockquote>
 452
 453
 454 <p><a name='on-curve-p'>[Function]</a><br>
 455 <b>on-curve-p</b> <i>control-point</i> => <i>boolean</i>
 456
 457 <blockquote>
 458 Returns <i>true</i> if <i>control-point</i> is on the contour outline.
 459 </blockquote>
 460
 461
 462 <p><a name='contour-count'>[Function]</a><br>
 463 <b>contour-count</b> <i>glyph</i> => <i>number</i>
 464
 465 <blockquote>
 466 Returns the number of contours of <i>glyph</i>. Some glyphs, such as the
 467 glyph for the Space character, may have zero contours.
 468 </blockquote>
 469
 470
 471 <p><a name='contour'>[Function]</a><br>
 472 <b>contour</b> <i>glyph</i> <i>index</i> => <i>vector</i>
 473
 474 <blockquote>
 475 Returns the <i>index</i>th contour from the contours of
 476 <i>glyph</i>. A contour is represented as a vector of control point
 477 objects. Each control point may be on (touching) or off (not touching)
 478 the the contour outline.
 479
 480 <p>TrueType files may store contours that have implicit control
 481 points. When two consecutive control points are off the contour
 482 outline, there is an implied control point at the midpoint between
 483 them on the contour curve.
 484 </blockquote>
 485
 486
 487 <p><a name='contours'>[Function]</a><br>
 488 <b>contours</b> <i>glyph</i> => <i>vector</i>
 489
 490 <blockquote>
 491 Returns all contours of glyph as a vector.
 492 </blockquote>
 493
 494
 495 <p><a name='do-contours'>[Macro]</a><br>
 496 <b>do-contours</b> <i>(contour glyph</i> <tt>&optional</tt>
 497 <i>result)</i> <tt>&body</tt> <i>body</i> => <i>result</i>
 498
 499 <blockquote>
 500 Performs <i>body</i> for each contour in <i>glyph</i>, with the
 501 contour bound to <i>contour</i>. Returns <i>result</i> (evaluated) at
 502 the end of processing.
 503 </blockquote>
 504
 505
 506 <p><a name="explicit-contour-points">[Function]</a><br>
 507 <b>explicit-contour-points</b> <i>contour</i> => <i>vector</i>
 508
 509 <blockquote>
 510 Returns a vector of points that is the same as <i>contour</i> with the implicit
 511 contour points inserted.
 512 </blockquote>
 513
 514
 515 <p><a name="do-contour-segments">[Macro]</a><br>
 516 <b>do-contour-segments</b> <i>(start control end) contour</i> <tt>&body</tt> <i>body</i> =>
 517
 518 <blockquote>
 519 For convenience, a TrueType contour may be thought of as being made up
 520 of connected segments. Each segment is either a straight line from one
 521 point on the outline to another, or a curved line that starts with a
 522 point on the outline, is controlled by a point off the outline, and
 523 ends with a point on the outline.
 524
 525 <p><tt>DO-CONTOUR-SEGMENTS</tt> performs <i>body</i> for each segment of
 526 <i>contour</i>, with the <i>start</i>, <i>control</i>, and <i>end</i>
 527 variables (not evaluated) bound to the start, control, and end points
 528 of the segment. If the segment is a straight line, <i>control</i> is
 529 bound to <tt>NIL</tt>.
 530
 531 <p>Contours of a glyph in a TrueType file may contain implied control
 532 points; two consecutive points off the outline may be treated as if
 533 there is there is an point on the outline at the midpoint between
 534 them. <tt>DO-CONTOUR-SEGMENTS</tt> synthesizes and binds any implicit
 535 points as needed when going through the contour segments. (See the <a
 536 href='#sect-glyph-example'>Glyph Example</a> for a visual explanation.)
 537
 538 <p>Segments are not a TrueType glyph concept. The term is used for
 539 convenience by ZPB-TTF.
 540
 541 </blockquote>
 542
 543
 544 <p><a name="do-contour-segments*">[Macro]</a><br>
 545 <b>do-contour-segments*</b> <i>(control end) contour</i> <tt>&body</tt> <i>body</i> =>
 546
 547 <blockquote>
 548 <tt>DO-CONTOUR-SEGMENTS*</tt> is like <a
 549 href="#do-contour-segments"><tt>DO-CONTOUR-SEGMENTS</tt></a>, except it does
 550 not bind a start variable.
 551 </blockquote>
 552
 553
 554 <p><a name='code-point'>[Function]</a><br>
 555 <b>code-point</b> <i>glyph</i> => <i>number</i>
 556
 557 <blockquote>
 558 Returns the Unicode code point of a character <i>glyph</i>
 559 represents. <b>Note:</b> Since font glyphs may represent more than one
 560 character, this value may not be exactly what you expect. <b>Note:</b>
 561 Since glyphs in a font do not necessarily correspond to a code point,
 562 or to a single code point, this may not always return a meaningful
 563 value.
 564 </blockquote>
 565
 566
 567 <p><a name='font-index'>[Function]</a><br>
 568 <b>font-index</b> <i>glyph</i> => <i>number</i>
 569
 570 <blockquote>
 571 Returns the integer index of <i>glyph</i> in its font loader.
 572 </blockquote>
 573
 574
 575 <p><a name='advance-width'>[Function]</a><br>
 576 <b>advance-width</b> <i>glyph</i> => <i>number</i>
 577
 578 <blockquote>
 579 Returns the typographic advance width of <i>glyph</i>.
 580 </blockquote>
 581
 582
 583 <p><a name='left-side-bearing'>[Function]</a><br>
 584 <b>left-side-bearing</b> <i>glyph</i> => <i>number</i>
 585
 586 <blockquote>
 587 Returns the typographic left side bearing of <i>glyph</i>.
 588 </blockquote>
 589
 590
 591 <p><a name='right-side-bearing'>[Function]</a><br>
 592 <b>right-side-bearing</b> <i>glyph</i> => <i>number</i>
 593
 594 <blockquote>
 595 Returns the typographic right side bearing of <i>glyph</i>.
 596 </blockquote>
 597
 598
 599 <p><a name='kerning-offset'>[Function]</a><br>
 600 <b>kerning-offset</b> <i>left-glyph</i> <i>right-glyph</i>
 601 <i>font-loader</i> => <i>number</i>
 602
 603 <blockquote>
 604 Returns the typographic kerning adjustment needed for the advance
 605 width when <i>left-glyph</i> and <i>right-glyph</i> appear next to
 606 each other.
 607 </blockquote>
 608
 609
 610 <p><a name='string-bounding-box'>[Function]</a><br>
 611 <b>string-bounding-box</b> <i>string</i> <i>font-loader</i>
 612  <tt>&amp;key</tt> (<i>kerning</i> <tt><i>t</i></tt>) =>
 613 <i>#(xmin ymin xmax ymax)</i>
 614
 615 <blockquote>
 616 Returns the bounding box for <i>string</i> in the natural unit size of
 617 <i>font-loader</i>. If <i>kerning</i> is <i>true</i>, the inter-glyph
 618 spacing will take kerning offsets into account when calculating the
 619 bounding box.
 620 </blockquote>
 621
 622
 623 <a name='sect-feedback'><h3>Feedback</h3></a>
 624
 625 <p>Please send bug reports, patches, questions, and any other feedback
 626 to <a href="mailto:xach@xach.com">Zachary Beane</a>.
 627
 628