src/font.h

   1 /* font.h -- Interface definition for font handling.
   2    Copyright (C) 2006-2012 Free Software Foundation, Inc.
   3    Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011
   4      National Institute of Advanced Industrial Science and Technology (AIST)
   5      Registration Number H13PRO009
   6
   7 This file is part of GNU Emacs.
   8
   9 GNU Emacs is free software: you can redistribute it and/or modify
  10 it under the terms of the GNU General Public License as published by
  11 the Free Software Foundation, either version 3 of the License, or
  12 (at your option) any later version.
  13
  14 GNU Emacs is distributed in the hope that it will be useful,
  15 but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 GNU General Public License for more details.
  18
  19 You should have received a copy of the GNU General Public License
  20 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22 #ifndef EMACS_FONT_H
  23 #define EMACS_FONT_H
  24
  25 #include "ccl.h"
  26
  27 /* We have three types of Lisp objects related to font.
  28
  29    FONT-SPEC
  30
  31         Pseudo vector (length FONT_SPEC_MAX) of font properties.  Some
  32         properties can be left unspecified (i.e. nil).  Emacs asks
  33         font-drivers to find a font by FONT-SPEC.  A fontset entry
  34         specifies requisite properties whereas a face specifies just
  35         preferable properties.
  36
  37    FONT-ENTITY
  38
  39         Pseudo vector (length FONT_ENTITY_MAX) of fully instantiated
  40         font properties that a font-driver returns upon a request of
  41         FONT-SPEC.
  42
  43         Note: Only the method `list' and `match' of a font-driver can
  44         create this object, and it should never be modified by Lisp.
  45
  46    FONT-OBJECT
  47
  48         Pseudo vector (length FONT_OBJECT_MAX) of an opened font.
  49
  50         Lisp object encapsulating "struct font".  This corresponds to
  51         an opened font.
  52
  53         Note: Only the method `open' of a font-driver can create this
  54         object, and it should never be modified by Lisp.  */
  55
  56 extern Lisp_Object Qfont_spec, Qfont_entity, Qfont_object;
  57
  58
  59 struct font_driver;
  60 struct font;
  61 struct glyph_string;
  62
  63 /* An enumerator for each font property.  This is used as an index to
  64    the vector of FONT-SPEC and FONT-ENTITY.
  65
  66    Note: The order is important and should not be changed.  */
  67
  68 enum font_property_index
  69   {
  70     /* FONT-TYPE is a symbol indicating a font backend; currently `x',
  71        `xft', and `ftx' are available on X, `uniscribe' and `gdi' on
  72        Windows, and `ns' under Cocoa / GNUstep.  */
  73     FONT_TYPE_INDEX,
  74
  75     /* FONT-FOUNDRY is a foundry name (symbol).  */
  76     FONT_FOUNDRY_INDEX,
  77
  78     /* FONT-FAMILY is a family name (symbol).  */
  79     FONT_FAMILY_INDEX,
  80
  81     /* FONT-ADSTYLE is an additional style name (symbol).  */
  82     FONT_ADSTYLE_INDEX,
  83
  84     /* FONT-REGISTRY is a combination of a charset-registry and
  85        charset-encoding name (symbol).  */
  86     FONT_REGISTRY_INDEX,
  87
  88     /* FONT-WEIGHT is a numeric value of weight (e.g. medium, bold) of
  89        the font.  The lowest 8 bits is an index determining the
  90        symbolic name, and the higher bits is the actual numeric value
  91        defined in `font-weight-table'. */
  92     FONT_WEIGHT_INDEX,
  93
  94     /* FONT-SLANT is a numeric value of slant (e.g. r, i, o) of the
  95        font.  The lowest 8 bits is an index determining the symbolic
  96        name, and the higher bits is the actual numeric value defined
  97        in `font-slant-table'.  */
  98     FONT_SLANT_INDEX,
  99
 100     /* FONT-WIDTH is a numeric value of setwidth (e.g. normal) of the
 101        font.  The lowest 8 bits is an index determining the symbolic
 102        name, and the higher bits is the actual numeric value defined
 103        `font-width-table'.  */
 104     FONT_WIDTH_INDEX,
 105
 106     /* FONT-SIZE is a size of the font.  If integer, it is a pixel
 107        size.  For a font-spec, the value can be a float specifying
 108        the point size.  The value zero means that the font is
 109        scalable.  */
 110     FONT_SIZE_INDEX,
 111
 112     /* FONT-DPI is a resolution (dot per inch) for which the font is
 113        designed. */
 114     FONT_DPI_INDEX,
 115
 116     /* FONT-SPACING is a spacing (mono, proportional, charcell) of the
 117        font (integer; one of enum font_spacing).  */
 118     FONT_SPACING_INDEX,
 119
 120     /* FONT-AVGWIDTH is an average width (1/10 pixel unit) of the
 121        font.  */
 122     FONT_AVGWIDTH_INDEX,
 123
 124 #if 0
 125     /* The following two members are to substitute for the above 6
 126        members (FONT_WEIGHT_INDEX to FONT_AVGWIDTH_INDEX excluding
 127        FONT_SIZE_INDEX) if it is found that font-entities consumes too
 128        much memory.  */
 129
 130     /* FONT-STYLE is a 24-bit integer containing indices for
 131        style-related properties WEIGHT, SLANT, and WIDTH.  The lowest
 132        8 bits is an index to the weight table AREF (font_style_table,
 133        0), the next 8 bits is an index to the slant table AREF
 134        (font_style_table, 1), the highest 8 bits is an index to the
 135        slant table AREF (font_style_table, 2).  The index 0 indicates
 136        that the corresponding style is not specified.  This way, we
 137        can represent at most 255 different names for each style, which
 138        is surely sufficient.  */
 139     FONT_STYLE_INDEX,
 140
 141     /* FONT-METRICS is a 27-bit integer containing metrics-related
 142        properties DPI, AVGWIDTH, SPACING.  The lowest 12 bits is for
 143        DPI, the next 12 bits is for AVGWIDTH, the highest 3 bits is for
 144        SPACING.  In each bit field, the highest bit indicates that the
 145        corresponding value is set or not.  This way, we can represent
 146        DPI by 11-bit (0 to 2047), AVGWIDTH by 11-bit (0 to 2047),
 147        SPACING by 3-bit (0 for proportional, 1 for dual, 2 for mono, 3
 148        for charcell), which is surely sufficient.  */
 149     FONT_METRICS_INDEX,
 150 #endif
 151
 152     /* In a font-spec, the value is an alist of extra information of a
 153        font such as name, OpenType features, and language coverage.
 154        In addition, in a font-entity, the value may contain a pair
 155        (font-entity . INFO) where INFO is extra information to identify
 156        a font (font-driver dependent).  */
 157     FONT_EXTRA_INDEX,           /* alist                alist */
 158
 159     /* This value is the length of font-spec vector.  */
 160     FONT_SPEC_MAX,
 161
 162     /* The followings are used only for a font-entity and a font-object.  */
 163
 164     /* List of font-objects opened from the font-entity.  */
 165     FONT_OBJLIST_INDEX = FONT_SPEC_MAX,
 166
 167     /* Font-entity from which the font-object is opened.  */
 168     FONT_ENTITY_INDEX = FONT_SPEC_MAX,
 169
 170     /* This value is the length of font-entity vector.  */
 171     FONT_ENTITY_MAX,
 172
 173     /* The followings are used only for a font-object.  */
 174
 175     /* XLFD name of the font (string). */
 176     FONT_NAME_INDEX = FONT_ENTITY_MAX,
 177
 178     /* Full name of the font (string).  It is the name extracted from
 179        the opened font, and may be different from the above.  It may be
 180        nil if the opened font doesn't give a name.  */
 181     FONT_FULLNAME_INDEX,
 182
 183     /* File name of the font or nil if a file associated with the font
 184        is not available.  */
 185     FONT_FILE_INDEX,
 186
 187     /* Format of the font (symbol) or nil if unknown.  */
 188     FONT_FORMAT_INDEX,
 189
 190     /* This value is the length of font-object vector.  */
 191     FONT_OBJECT_MAX
 192   };
 193
 194 /* Return the numeric weight value of FONT.  */
 195 #define FONT_WEIGHT_NUMERIC(font)               \
 196   (INTEGERP (AREF ((font), FONT_WEIGHT_INDEX))  \
 197    ? (XINT (AREF ((font), FONT_WEIGHT_INDEX)) >> 8) : -1)
 198 /* Return the numeric slant value of FONT.  */
 199 #define FONT_SLANT_NUMERIC(font)                \
 200   (INTEGERP (AREF ((font), FONT_SLANT_INDEX))   \
 201    ? (XINT (AREF ((font), FONT_SLANT_INDEX)) >> 8) : -1)
 202 /* Return the numeric width value of FONT.  */
 203 #define FONT_WIDTH_NUMERIC(font)                \
 204   (INTEGERP (AREF ((font), FONT_WIDTH_INDEX))   \
 205    ? (XINT (AREF ((font), FONT_WIDTH_INDEX)) >> 8) : -1)
 206 /* Return the symbolic weight value of FONT.  */
 207 #define FONT_WEIGHT_SYMBOLIC(font)      \
 208   font_style_symbolic (font, FONT_WEIGHT_INDEX, 0)
 209 /* Return the symbolic slant value of FONT.  */
 210 #define FONT_SLANT_SYMBOLIC(font)       \
 211   font_style_symbolic (font, FONT_SLANT_INDEX, 0)
 212 /* Return the symbolic width value of FONT.  */
 213 #define FONT_WIDTH_SYMBOLIC(font)       \
 214   font_style_symbolic (font, FONT_WIDTH_INDEX, 0)
 215 /* Return the face-weight corresponding to the weight of FONT.  */
 216 #define FONT_WEIGHT_FOR_FACE(font)      \
 217   font_style_symbolic (font, FONT_WEIGHT_INDEX, 1)
 218 /* Return the face-slant corresponding to the slant of FONT.  */
 219 #define FONT_SLANT_FOR_FACE(font)       \
 220   font_style_symbolic (font, FONT_SLANT_INDEX, 1)
 221 /* Return the face-swidth corresponding to the slant of FONT.  */
 222 #define FONT_WIDTH_FOR_FACE(font)       \
 223   font_style_symbolic (font, FONT_WIDTH_INDEX, 1)
 224
 225 /* Return the numeric weight value corresponding ot the symbol NAME.  */
 226 #define FONT_WEIGHT_NAME_NUMERIC(name)  \
 227   (font_style_to_value (FONT_WEIGHT_INDEX, (name), 0) >> 8)
 228 /* Return the numeric slant value corresponding ot the symbol NAME.  */
 229 #define FONT_SLANT_NAME_NUMERIC(name)   \
 230   (font_style_to_value (FONT_SLANT_INDEX, (name), 0) >> 8)
 231 /* Return the numeric width value corresponding ot the symbol NAME.  */
 232 #define FONT_WIDTH_NAME_NUMERIC(name)   \
 233   (font_style_to_value (FONT_WIDTH_INDEX, (name), 0) >> 8)
 234
 235 /* Set the font property PROP of FONT to VAL.  PROP is one of
 236    style-related font property index (FONT_WEIGHT/SLANT/WIDTH_INDEX).
 237    VAL (integer or symbol) is the numeric or symbolic style value.  */
 238 #define FONT_SET_STYLE(font, prop, val) \
 239   ASET ((font), prop, make_number (font_style_to_value (prop, val, 1)))
 240
 241 extern Lisp_Object QCspacing, QCdpi, QCscalable, QCotf, QClang, QCscript;
 242 extern Lisp_Object QCavgwidth, QCantialias, QCfont_entity;
 243 extern Lisp_Object Qp;
 244
 245
 246 /* Important character set symbols.  */
 247 extern Lisp_Object Qascii_0;
 248 extern Lisp_Object Qiso8859_1, Qiso10646_1, Qunicode_bmp, Qunicode_sip;
 249
 250 /* Special ADSTYLE properties to avoid fonts used for Latin characters.  */
 251 extern Lisp_Object Qja, Qko;
 252
 253 /* Structure for a font-spec.  */
 254
 255 struct font_spec
 256 {
 257   struct vectorlike_header header;
 258   Lisp_Object props[FONT_SPEC_MAX];
 259 };
 260
 261 /* Structure for a font-entity.  */
 262
 263 struct font_entity
 264 {
 265   struct vectorlike_header header;
 266   Lisp_Object props[FONT_ENTITY_MAX];
 267 };
 268
 269 /* A value which may appear in the member `encoding' of struct font
 270    indicating that a font itself doesn't tell which encoding to be
 271    used.  */
 272 #define FONT_ENCODING_NOT_DECIDED 255
 273
 274 /* Structure for a font-object.  */
 275
 276 struct font
 277 {
 278   struct vectorlike_header header;
 279
 280   /* All Lisp_Object components must come first.
 281      That ensures they are all aligned normally.  */
 282
 283   Lisp_Object props[FONT_OBJECT_MAX];
 284
 285   /* Beyond here, there should be no more Lisp_Object components.  */
 286
 287   /* Maximum bound width over all existing characters of the font.  On
 288      X window, this is same as (font->max_bounds.width).  */
 289   int max_width;
 290
 291   /* By which pixel size the font is opened.  */
 292   int pixel_size;
 293
 294   /* Height of the font.  On X window, this is the same as
 295      (font->ascent + font->descent).  */
 296   int height;
 297
 298   /* Width of the space glyph of the font.  If the font doesn't have a
 299      SPACE glyph, the value is 0.  */
 300   int space_width;
 301
 302   /* Average width of glyphs in the font.  If the font itself doesn't
 303      have that information but has glyphs of ASCII characters, the
 304      value is the average with of those glyphs.  Otherwise, the value
 305      is 0.  */
 306   int average_width;
 307
 308   /* Minimum glyph width (in pixels).  */
 309   int min_width;
 310
 311   /* Ascent and descent of the font (in pixels).  */
 312   int ascent, descent;
 313
 314   /* Vertical pixel width of the underline.  If is zero if that
 315      information is not in the font.  */
 316   int underline_thickness;
 317
 318   /* Vertical pixel position (relative to the baseline) of the
 319      underline.  If it is positive, it is below the baseline.  It is
 320      negative if that information is not in the font.  */
 321   int underline_position;
 322
 323   /* 1 if `vertical-centering-font-regexp' matches this font name.
 324      In this case, we render characters at vertical center positions
 325      of lines.  */
 326   int vertical_centering;
 327
 328   /* Encoding type of the font.  The value is one of
 329      0, 1, 2, or 3:
 330         0: code points 0x20..0x7F or 0x2020..0x7F7F are used
 331         1: code points 0xA0..0xFF or 0xA0A0..0xFFFF are used
 332         2: code points 0x20A0..0x7FFF are used
 333         3: code points 0xA020..0xFF7F are used
 334      If the member `font_encoder' is not NULL, this member is ignored.  */
 335   unsigned char encoding_type;
 336
 337   /* The baseline position of a font is normally `ascent' value of the
 338      font.  However, there exist many fonts which don't set `ascent' to
 339      an appropriate value to be used as baseline position.  This is
 340      typical in such ASCII fonts which are designed to be used with
 341      Chinese, Japanese, Korean characters.  When we use mixture of
 342      such fonts and normal fonts (having correct `ascent' value), a
 343      display line gets very ugly.  Since we have no way to fix it
 344      automatically, it is user's responsibility to supply well designed
 345      fonts or correct `ascent' value of fonts.  But, the latter
 346      requires heavy work (modifying all bitmap data in BDF files).
 347      So, Emacs accepts a private font property
 348      `_MULE_BASELINE_OFFSET'.  If a font has this property, we
 349      calculate the baseline position by subtracting the value from
 350      `ascent'.  In other words, the value indicates how many pixels
 351      higher than normal ASCII text we should draw a character of the
 352      font for better appearance.
 353
 354      We also have to consider the fact that the concept of `baseline'
 355      differs among scripts to which each character belongs.  For
 356      instance, baseline should be at the bottom-most position of all
 357      glyphs for Chinese, Japanese, and Korean.  But, many of existing
 358      fonts for those characters don't have correct `ascent' values
 359      because they are designed to be used with ASCII fonts.  To
 360      display characters of different language on the same line, the
 361      best way will be to arrange them in the middle of the line.  So,
 362      in such a case, again, we utilize the font property
 363      `_MULE_BASELINE_OFFSET'.  If the value is larger than `ascent' we
 364      calculate baseline so that a character is arranged in the middle
 365      of a line.  */
 366   int baseline_offset;
 367
 368   /* Non-zero means a character should be composed at a position
 369      relative to the height (or depth) of previous glyphs in the
 370      following cases:
 371         (1) The bottom of the character is higher than this value.  In
 372         this case, the character is drawn above the previous glyphs.
 373         (2) The top of the character is lower than 0 (i.e. baseline
 374         height).  In this case, the character is drawn below the
 375         previous glyphs.
 376
 377      This value is taken from a private font property
 378      `_MULE_RELATIVE_COMPOSE' which is introduced by Emacs.  */
 379   int relative_compose;
 380
 381   /* Non-zero means an ascent value to be used for a character
 382      registered in char-table `use-default-ascent'.  */
 383   int default_ascent;
 384
 385   /* CCL program to calculate code points of the font.  */
 386   struct ccl_program *font_encoder;
 387
 388   /* Font-driver for the font.  */
 389   struct font_driver *driver;
 390
 391   /* Charset to encode a character code into a glyph code of the font.
 392      -1 means that the font doesn't require this information to encode
 393      a character.  */
 394   int encoding_charset;
 395
 396   /* Charset to check if a character code is supported by the font.
 397      -1 means that the contents of the font must be looked up to
 398      determine it.  */
 399   int repertory_charset;
 400
 401   /* There are more members in this structure, but they are private
 402      to the font-driver.  */
 403 };
 404
 405 enum font_spacing
 406   {
 407     FONT_SPACING_PROPORTIONAL = 0,
 408     FONT_SPACING_DUAL = 90,
 409     FONT_SPACING_MONO = 100,
 410     FONT_SPACING_CHARCELL = 110
 411   };
 412
 413 struct font_metrics
 414 {
 415   short lbearing, rbearing, width, ascent, descent;
 416 };
 417
 418 struct font_bitmap
 419 {
 420   int bits_per_pixel;
 421   int rows;
 422   int width;
 423   int pitch;
 424   unsigned char *buffer;
 425   int left;
 426   int top;
 427   int advance;
 428   void *extra;
 429 };
 430
 431 /* Predicates to check various font-related objects.  */
 432
 433 /* 1 iff X is one of font-spec, font-entity, and font-object.  */
 434 #define FONTP(x) PSEUDOVECTORP (x, PVEC_FONT)
 435 /* 1 iff X is font-spec.  */
 436 #define FONT_SPEC_P(x)  \
 437   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_SPEC_MAX)
 438 /* 1 iff X is font-entity.  */
 439 #define FONT_ENTITY_P(x)        \
 440   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_ENTITY_MAX)
 441 /* 1 iff X is font-object.  */
 442 #define FONT_OBJECT_P(x)        \
 443   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_OBJECT_MAX)
 444
 445 /* 1 iff ENTITY can't be loaded.  */
 446 #define FONT_ENTITY_NOT_LOADABLE(entity)        \
 447   EQ (AREF (entity, FONT_OBJLIST_INDEX), Qt)
 448
 449 /* Flag ENTITY not loadable.  */
 450 #define FONT_ENTITY_SET_NOT_LOADABLE(entity)    \
 451   ASET (entity, FONT_OBJLIST_INDEX, Qt)
 452
 453
 454 /* Check macros for various font-related objects.  */
 455
 456 #define CHECK_FONT(x)   \
 457   do { if (! FONTP (x)) wrong_type_argument (Qfont, x); } while (0)
 458 #define CHECK_FONT_SPEC(x)      \
 459   do { if (! FONT_SPEC_P (x)) wrong_type_argument (Qfont_spec, x); } while (0)
 460 #define CHECK_FONT_ENTITY(x)    \
 461   do { if (! FONT_ENTITY_P (x)) wrong_type_argument (Qfont_entity, x); } while (0)
 462 #define CHECK_FONT_OBJECT(x)    \
 463   do { if (! FONT_OBJECT_P (x)) wrong_type_argument (Qfont_object, x); } while (0)
 464
 465 #define CHECK_FONT_GET_OBJECT(x, font)  \
 466   do {                                  \
 467     CHECK_FONT_OBJECT (x);              \
 468     font = XFONT_OBJECT (x);            \
 469   } while (0)
 470
 471 #define XFONT_SPEC(p)   \
 472   (eassert (FONT_SPEC_P(p)), (struct font_spec *) XPNTR (p))
 473 #define XFONT_ENTITY(p) \
 474   (eassert (FONT_ENTITY_P(p)), (struct font_entity *) XPNTR (p))
 475 #define XFONT_OBJECT(p) \
 476   (eassert (FONT_OBJECT_P(p)), (struct font *) XPNTR (p))
 477 #define XSETFONT(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_FONT))
 478
 479 /* Number of pt per inch (from the TeXbook).  */
 480 #define PT_PER_INCH 72.27
 481
 482 /* Return a pixel size (integer) corresponding to POINT size (double)
 483    on resolution DPI.  */
 484 #define POINT_TO_PIXEL(POINT, DPI) ((POINT) * (DPI) / PT_PER_INCH + 0.5)
 485
 486 /* Return a point size corresponding to POINT size (integer)
 487    on resolution DPI.  Note that though point size is a double, we expect
 488    it to be rounded to an int, so we add 0.5 here.  If the desired value
 489    is tenths of points (as in xfld specs), then the pixel size should
 490    be multiplied BEFORE the conversion to avoid magnifying the error.  */
 491 #define PIXEL_TO_POINT(PIXEL, DPI) ((PIXEL) * PT_PER_INCH / (DPI) + 0.5)
 492
 493 /* Ignore the difference of font pixel sizes less than or equal to
 494    this value.  */
 495 #define FONT_PIXEL_SIZE_QUANTUM 1
 496
 497 struct face;
 498
 499 #define FONT_INVALID_CODE 0xFFFFFFFF
 500
 501 /* Font driver.  Members specified as "optional" can be NULL.  */
 502
 503 struct font_driver
 504 {
 505   /* Symbol indicating the type of the font-driver.  */
 506   Lisp_Object type;
 507
 508   /* 1 iff the font's foundry, family, and adstyle names are case
 509      sensitive.  */
 510   int case_sensitive;
 511
 512   /* Return a cache of font-entities on frame F.  The cache must be a
 513      cons whose cdr part is the actual cache area.  */
 514   Lisp_Object (*get_cache) (FRAME_PTR F);
 515
 516   /* List fonts exactly matching with FONT_SPEC on FRAME.  The value
 517      is a list of font-entities.  The font properties to be considered
 518      are: :foundry, :family, :adstyle, :registry, :script, :lang, and
 519      :otf.  See the function `font-spec' for their meanings.  Note
 520      that the last three properties are stored in FONT_EXTRA_INDEX
 521      slot of FONT_SPEC.
 522
 523      The returned value is a list of font-entities.  Each font-entity
 524      has :type property whose value is the same as the above `type'.
 525      It also has these properties if they are available from the
 526      corresponding font; :foundry, :family, :adstyle, :registry,
 527      :weight, :slant, :width, :size, :dpi, :spacing, :avgwidth.  If
 528      the font is scalable, :size and :avgwidth must be 0.
 529
 530      The `open' method of the same font-backend is called with one of
 531      the returned font-entities.  If the backend needs additional
 532      information to be used in `open' method, this method can add any
 533      Lispy value by the property :font-entity to the entities.
 534
 535      This and the following `match' are the only APIs that allocate
 536      font-entities.  */
 537   Lisp_Object (*list) (Lisp_Object frame, Lisp_Object font_spec);
 538
 539   /* Return a font-entity most closely matching with FONT_SPEC on
 540      FRAME.  Which font property to consider, and how to calculate the
 541      closeness is determined by the font backend, thus
 542      `face-font-selection-order' is ignored here.
 543
 544      The properties that the font-entity has is the same as `list'
 545      method.  */
 546   Lisp_Object (*match) (Lisp_Object frame, Lisp_Object font_spec);
 547
 548   /* Optional.
 549      List available families.  The value is a list of family names
 550      (symbols).  */
 551   Lisp_Object (*list_family) (Lisp_Object frame);
 552
 553   /* Optional (if FONT_EXTRA_INDEX is not Lisp_Save_Value).
 554      Free FONT_EXTRA_INDEX field of FONT_ENTITY.  */
 555   void (*free_entity) (Lisp_Object font_entity);
 556
 557   /* Open a font specified by FONT_ENTITY on frame F.  If the font is
 558      scalable, open it with PIXEL_SIZE.  */
 559   Lisp_Object (*open) (FRAME_PTR f, Lisp_Object font_entity,
 560                        int pixel_size);
 561
 562   /* Close FONT on frame F.  */
 563   void (*close) (FRAME_PTR f, struct font *font);
 564
 565   /* Optional (if FACE->extra is not used).
 566      Prepare FACE for displaying characters by FONT on frame F by
 567      storing some data in FACE->extra.  If successful, return 0.
 568      Otherwise, return -1.  */
 569   int (*prepare_face) (FRAME_PTR f, struct face *face);
 570
 571   /* Optional.
 572      Done FACE for displaying characters by FACE->font on frame F.  */
 573   void (*done_face) (FRAME_PTR f, struct face *face);
 574
 575   /* Optional.
 576      If FONT (FONT-ENTITY or FONT-OBJECT) has a glyph for character C
 577      (Unicode code point), return 1.  If not, return 0.  If FONT is
 578      FONT-ENTITY and it must be opened to check it, return -1.  */
 579   int (*has_char) (Lisp_Object font, int c);
 580
 581   /* Return a glyph code of FONT for character C (Unicode code point).
 582      If FONT doesn't have such a glyph, return FONT_INVALID_CODE.  */
 583   unsigned (*encode_char) (struct font *font, int c);
 584
 585   /* Compute the total metrics of the NGLYPHS glyphs specified by
 586      the font FONT and the sequence of glyph codes CODE, and store the
 587      result in METRICS.  */
 588   int (*text_extents) (struct font *font,
 589                        unsigned *code, int nglyphs,
 590                        struct font_metrics *metrics);
 591
 592   /* Optional.
 593      Draw glyphs between FROM and TO of S->char2b at (X Y) pixel
 594      position of frame F with S->FACE and S->GC.  If WITH_BACKGROUND
 595      is nonzero, fill the background in advance.  It is assured that
 596      WITH_BACKGROUND is zero when (FROM > 0 || TO < S->nchars).  */
 597   int (*draw) (struct glyph_string *s, int from, int to,
 598                int x, int y, int with_background);
 599
 600   /* Optional.
 601      Store bitmap data for glyph-code CODE of FONT in BITMAP.  It is
 602      intended that this method is called from the other font-driver
 603      for actual drawing.  */
 604   int (*get_bitmap) (struct font *font, unsigned code,
 605                      struct font_bitmap *bitmap,
 606                      int bits_per_pixel);
 607
 608   /* Optional.
 609      Free bitmap data in BITMAP.  */
 610   void (*free_bitmap) (struct font *font, struct font_bitmap *bitmap);
 611
 612   /* Optional.
 613      Return an outline data for glyph-code CODE of FONT.  The format
 614      of the outline data depends on the font-driver.  */
 615   void *(*get_outline) (struct font *font, unsigned code);
 616
 617   /* Optional.
 618      Free OUTLINE (that is obtained by the above method).  */
 619   void (*free_outline) (struct font *font, void *outline);
 620
 621   /* Optional.
 622      Get coordinates of the INDEXth anchor point of the glyph whose
 623      code is CODE.  Store the coordinates in *X and *Y.  Return 0 if
 624      the operations was successful.  Otherwise return -1.  */
 625   int (*anchor_point) (struct font *font, unsigned code, int index,
 626                        int *x, int *y);
 627
 628   /* Optional.
 629      Return a list describing which scripts/languages FONT
 630      supports by which GSUB/GPOS features of OpenType tables.  */
 631   Lisp_Object (*otf_capability) (struct font *font);
 632
 633   /* Optional.
 634      Apply FONT's OTF-FEATURES to the glyph string.
 635
 636      FEATURES specifies which OTF features to apply in this format:
 637         (SCRIPT LANGSYS GSUB-FEATURE GPOS-FEATURE)
 638      See the documentation of `font-drive-otf' for the details.
 639
 640      This method applies the specified features to the codes in the
 641      elements of GSTRING-IN (between FROMth and TOth).  The output
 642      codes are stored in GSTRING-OUT at the IDXth element and the
 643      following elements.
 644
 645      Return the number of output codes.  If none of the features are
 646      applicable to the input data, return 0.  If GSTRING-OUT is too
 647      short, return -1.  */
 648   int (*otf_drive) (struct font *font, Lisp_Object features,
 649                     Lisp_Object gstring_in, int from, int to,
 650                     Lisp_Object gstring_out, int idx, int alternate_subst);
 651
 652   /* Optional.
 653      Make the font driver ready for frame F.  Usually this function
 654      makes some data specific to F and stores it in F by calling
 655      font_put_frame_data ().  */
 656   int (*start_for_frame) (FRAME_PTR f);
 657
 658   /* Optional.
 659      End using the driver for frame F.  Usually this function free
 660      some data stored for F.  */
 661   int (*end_for_frame) (FRAME_PTR f);
 662
 663   /* Optional.
 664
 665      Shape text in GSTRING.  See the docstring of
 666      `composition-get-gstring' for the format of GSTRING.  If the
 667      (N+1)th element of GSTRING is nil, input of shaping is from the
 668      1st to (N)th elements.  In each input glyph, FROM, TO, CHAR, and
 669      CODE are already set.
 670
 671      This function updates all fields of the input glyphs.  If the
 672      output glyphs (M) are more than the input glyphs (N), (N+1)th
 673      through (M)th elements of GSTRING are updated possibly by making
 674      a new glyph object and storing it in GSTRING.  If (M) is greater
 675      than the length of GSTRING, nil should be return.  In that case,
 676      this function is called again with the larger GSTRING.  */
 677   Lisp_Object (*shape) (Lisp_Object lgstring);
 678
 679   /* Optional.
 680
 681      If FONT is usable on frame F, return 0.  Otherwise return -1.
 682      This method is used only for debugging.  If this method is NULL,
 683      Emacs assumes that the font is usable on any frame.  */
 684   int (*check) (FRAME_PTR F, struct font *font);
 685
 686   /* Optional.
 687
 688      Return the number of variation glyphs of character C supported by
 689      FONT.  VARIATIONS is an array of 256 elements.  If the variation
 690      selector N (1..256) defines a glyph, that glyph code is stored in
 691      the (N-1)th element of VARIATIONS.  */
 692   int (*get_variation_glyphs) (struct font *font,
 693                                int c, unsigned variations[256]);
 694
 695   void (*filter_properties) (Lisp_Object font, Lisp_Object properties);
 696
 697   /* Optional.
 698
 699      Return non-zero if FONT_OBJECT can be used as a (cached) font
 700      for ENTITY on frame F.  */
 701   int (*cached_font_ok) (struct frame *f,
 702                          Lisp_Object font_object,
 703                          Lisp_Object entity);
 704 };
 705
 706
 707 /* Chain of font drivers.  There's one global font driver list
 708    (font_driver_list in font.c).  In addition, each frame has its own
 709    font driver list at FRAME_PTR->font_driver_list.  */
 710
 711 struct font_driver_list
 712 {
 713   /* 1 iff this driver is currently used.  It is ignored in the global
 714      font driver list.*/
 715   int on;
 716   /* Pointer to the font driver.  */
 717   struct font_driver *driver;
 718   /* Pointer to the next element of the chain.  */
 719   struct font_driver_list *next;
 720 };
 721
 722
 723 /* Chain of arbitrary data specific to each font driver.  Each frame
 724    has its own font data list at FRAME_PTR->font_data_list.  */
 725
 726 struct font_data_list
 727 {
 728   /* Pointer to the font driver.  */
 729   struct font_driver *driver;
 730   /* Data specific to the font driver.  */
 731   void *data;
 732   /* Pointer to the next element of the chain.  */
 733   struct font_data_list *next;
 734 };
 735
 736 EXFUN (Ffont_spec, MANY);
 737 extern Lisp_Object copy_font_spec (Lisp_Object);
 738 extern Lisp_Object merge_font_spec (Lisp_Object, Lisp_Object);
 739 EXFUN (Ffont_get, 2);
 740 EXFUN (Ffont_put, 3);
 741 EXFUN (Flist_fonts, 4);
 742 EXFUN (Ffont_xlfd_name, 2);
 743
 744 extern Lisp_Object font_make_entity (void);
 745 extern Lisp_Object font_make_object (int, Lisp_Object, int);
 746
 747 extern Lisp_Object find_font_encoding (Lisp_Object);
 748 extern int font_registry_charsets (Lisp_Object, struct charset **,
 749                                    struct charset **);
 750 extern int font_style_to_value (enum font_property_index prop,
 751                                 Lisp_Object name, int noerror);
 752 extern Lisp_Object font_style_symbolic (Lisp_Object font,
 753                                         enum font_property_index prop,
 754                                         int for_face);
 755
 756 extern int font_match_p (Lisp_Object spec, Lisp_Object font);
 757 extern Lisp_Object font_list_entities (Lisp_Object frame,
 758                                        Lisp_Object spec);
 759
 760 extern Lisp_Object font_get_name (Lisp_Object font_object);
 761 extern Lisp_Object font_spec_from_name (Lisp_Object font_name);
 762 extern Lisp_Object font_get_frame (Lisp_Object font_object);
 763 extern int font_has_char (FRAME_PTR, Lisp_Object, int);
 764
 765 extern void font_clear_prop (Lisp_Object *attrs,
 766                              enum font_property_index prop);
 767 extern Lisp_Object font_find_for_lface (FRAME_PTR f, Lisp_Object *lface,
 768                                         Lisp_Object spec, int c);
 769 extern Lisp_Object font_open_for_lface (FRAME_PTR f, Lisp_Object entity,
 770                                         Lisp_Object *lface,
 771                                         Lisp_Object spec);
 772 extern Lisp_Object font_load_for_lface (FRAME_PTR f, Lisp_Object *lface,
 773                                         Lisp_Object spec);
 774 extern void font_prepare_for_face (FRAME_PTR f, struct face *face);
 775 extern void font_done_for_face (FRAME_PTR f, struct face *face);
 776
 777 extern Lisp_Object font_open_by_spec (FRAME_PTR f, Lisp_Object spec);
 778 extern Lisp_Object font_open_by_name (FRAME_PTR f, const char *name);
 779
 780 extern Lisp_Object font_intern_prop (const char *str, ptrdiff_t len,
 781                                      int force_symbol);
 782 extern void font_update_sort_order (int *order);
 783
 784 extern void font_parse_family_registry (Lisp_Object family,
 785                                         Lisp_Object registry,
 786                                         Lisp_Object spec);
 787
 788 extern int font_parse_xlfd (char *name, Lisp_Object font);
 789 extern int font_unparse_xlfd (Lisp_Object font, int pixel_size,
 790                               char *name, int bytes);
 791 extern int font_unparse_fcname (Lisp_Object font, int pixel_size,
 792                                 char *name, int bytes);
 793 extern void register_font_driver (struct font_driver *driver, FRAME_PTR f);
 794 extern void free_font_driver_list (FRAME_PTR f);
 795 extern Lisp_Object font_update_drivers (FRAME_PTR f, Lisp_Object list);
 796 extern Lisp_Object font_range (EMACS_INT, EMACS_INT *,
 797                                struct window *, struct face *,
 798                                Lisp_Object);
 799 extern void font_fill_lglyph_metrics (Lisp_Object, Lisp_Object);
 800
 801 extern Lisp_Object font_put_extra (Lisp_Object font, Lisp_Object prop,
 802                                    Lisp_Object val);
 803
 804 extern int font_put_frame_data (FRAME_PTR f,
 805                                 struct font_driver *driver,
 806                                 void *data);
 807 extern void *font_get_frame_data (FRAME_PTR f,
 808                                   struct font_driver *driver);
 809
 810 extern void font_filter_properties (Lisp_Object font,
 811                                     Lisp_Object alist,
 812                                     const char *const boolean_properties[],
 813                                     const char *const non_boolean_properties[]);
 814
 815 #ifdef HAVE_FREETYPE
 816 extern struct font_driver ftfont_driver;
 817 extern void syms_of_ftfont (void);
 818 #endif  /* HAVE_FREETYPE */
 819 #ifdef HAVE_X_WINDOWS
 820 extern struct font_driver xfont_driver;
 821 extern void syms_of_xfont (void);
 822 extern void syms_of_ftxfont (void);
 823 #ifdef HAVE_XFT
 824 extern struct font_driver xftfont_driver;
 825 extern void syms_of_xftfont (void);
 826 #elif defined HAVE_FREETYPE
 827 extern struct font_driver ftxfont_driver;
 828 #endif
 829 #ifdef HAVE_BDFFONT
 830 extern void syms_of_bdffont (void);
 831 #endif  /* HAVE_BDFFONT */
 832 #endif  /* HAVE_X_WINDOWS */
 833 #ifdef WINDOWSNT
 834 extern struct font_driver w32font_driver;
 835 extern struct font_driver uniscribe_font_driver;
 836 extern void syms_of_w32font (void);
 837 #endif  /* WINDOWSNT */
 838 #ifdef HAVE_NS
 839 extern Lisp_Object Qfontsize;
 840 extern struct font_driver nsfont_driver;
 841 extern void syms_of_nsfont (void);
 842 #endif  /* HAVE_NS */
 843
 844 #ifndef FONT_DEBUG
 845 #define FONT_DEBUG
 846 #endif
 847
 848 extern Lisp_Object QCfoundry;
 849
 850 extern void font_add_log (const char *, Lisp_Object, Lisp_Object);
 851 extern void font_deferred_log (const char *, Lisp_Object, Lisp_Object);
 852
 853 #define FONT_ADD_LOG(ACTION, ARG, RESULT)       \
 854   do {                                          \
 855     if (! EQ (Vfont_log, Qt))                   \
 856       font_add_log ((ACTION), (ARG), (RESULT)); \
 857   } while (0)
 858
 859 #define FONT_DEFERRED_LOG(ACTION, ARG, RESULT)          \
 860   do {                                                  \
 861     if (! EQ (Vfont_log, Qt))                           \
 862       font_deferred_log ((ACTION), (ARG), (RESULT));    \
 863   } while (0)
 864
 865 #ifdef FONT_DEBUG
 866 #define font_assert(X)  do {if (!(X)) abort ();} while (0)
 867 #else  /* not FONT_DEBUG */
 868 #define font_assert(X)  (void) 0
 869 #endif  /* not FONT_DEBUG */
 870
 871 #endif  /* not EMACS_FONT_H */