src/font.h

   1 /* font.h -- Interface definition for font handling.
   2    Copyright (C) 2006-2013 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 #include "frame.h"
  27
  28 /* We have three types of Lisp objects related to font.
  29
  30    FONT-SPEC
  31
  32         Pseudo vector (length FONT_SPEC_MAX) of font properties.  Some
  33         properties can be left unspecified (i.e. nil).  Emacs asks
  34         font-drivers to find a font by FONT-SPEC.  A fontset entry
  35         specifies requisite properties whereas a face specifies just
  36         preferable properties.
  37
  38    FONT-ENTITY
  39
  40         Pseudo vector (length FONT_ENTITY_MAX) of fully instantiated
  41         font properties that a font-driver returns upon a request of
  42         FONT-SPEC.
  43
  44         Note: Only the method `list' and `match' of a font-driver can
  45         create this object, and it should never be modified by Lisp.
  46
  47    FONT-OBJECT
  48
  49         Pseudo vector (length FONT_OBJECT_MAX) of an opened font.
  50
  51         Lisp object encapsulating "struct font".  This corresponds to
  52         an opened font.
  53
  54         Note: Only the method `open' of a font-driver can create this
  55         object, and it should never be modified by Lisp.  */
  56
  57 extern Lisp_Object Qfont_spec, Qfont_entity, Qfont_object;
  58
  59 /* An enumerator for each font property.  This is used as an index to
  60    the vector of FONT-SPEC and FONT-ENTITY.
  61
  62    Note: The order is important and should not be changed.  */
  63
  64 enum font_property_index
  65   {
  66     /* FONT-TYPE is a symbol indicating a font backend; currently `x',
  67        `xft', and `ftx' are available on X, `uniscribe' and `gdi' on
  68        Windows, and `ns' under Cocoa / GNUstep.  */
  69     FONT_TYPE_INDEX,
  70
  71     /* FONT-FOUNDRY is a foundry name (symbol).  */
  72     FONT_FOUNDRY_INDEX,
  73
  74     /* FONT-FAMILY is a family name (symbol).  */
  75     FONT_FAMILY_INDEX,
  76
  77     /* FONT-ADSTYLE is an additional style name (symbol).  */
  78     FONT_ADSTYLE_INDEX,
  79
  80     /* FONT-REGISTRY is a combination of a charset-registry and
  81        charset-encoding name (symbol).  */
  82     FONT_REGISTRY_INDEX,
  83
  84     /* FONT-WEIGHT is a numeric value of weight (e.g. medium, bold) of
  85        the font.  The lowest 8 bits is an index determining the
  86        symbolic name, and the higher bits is the actual numeric value
  87        defined in `font-weight-table'. */
  88     FONT_WEIGHT_INDEX,
  89
  90     /* FONT-SLANT is a numeric value of slant (e.g. r, i, o) of the
  91        font.  The lowest 8 bits is an index determining the symbolic
  92        name, and the higher bits is the actual numeric value defined
  93        in `font-slant-table'.  */
  94     FONT_SLANT_INDEX,
  95
  96     /* FONT-WIDTH is a numeric value of setwidth (e.g. normal) of the
  97        font.  The lowest 8 bits is an index determining the symbolic
  98        name, and the higher bits is the actual numeric value defined
  99        `font-width-table'.  */
 100     FONT_WIDTH_INDEX,
 101
 102     /* FONT-SIZE is a size of the font.  If integer, it is a pixel
 103        size.  For a font-spec, the value can be a float specifying
 104        the point size.  The value zero means that the font is
 105        scalable.  */
 106     FONT_SIZE_INDEX,
 107
 108     /* FONT-DPI is a resolution (dot per inch) for which the font is
 109        designed. */
 110     FONT_DPI_INDEX,
 111
 112     /* FONT-SPACING is a spacing (mono, proportional, charcell) of the
 113        font (integer; one of enum font_spacing).  */
 114     FONT_SPACING_INDEX,
 115
 116     /* FONT-AVGWIDTH is an average width (1/10 pixel unit) of the
 117        font.  */
 118     FONT_AVGWIDTH_INDEX,
 119
 120 #if 0
 121     /* The following two members are to substitute for the above 6
 122        members (FONT_WEIGHT_INDEX to FONT_AVGWIDTH_INDEX excluding
 123        FONT_SIZE_INDEX) if it is found that font-entities consumes too
 124        much memory.  */
 125
 126     /* FONT-STYLE is a 24-bit integer containing indices for
 127        style-related properties WEIGHT, SLANT, and WIDTH.  The lowest
 128        8 bits is an index to the weight table AREF (font_style_table,
 129        0), the next 8 bits is an index to the slant table AREF
 130        (font_style_table, 1), the highest 8 bits is an index to the
 131        slant table AREF (font_style_table, 2).  The index 0 indicates
 132        that the corresponding style is not specified.  This way, we
 133        can represent at most 255 different names for each style, which
 134        is surely sufficient.  */
 135     FONT_STYLE_INDEX,
 136
 137     /* FONT-METRICS is a 27-bit integer containing metrics-related
 138        properties DPI, AVGWIDTH, SPACING.  The lowest 12 bits is for
 139        DPI, the next 12 bits is for AVGWIDTH, the highest 3 bits is for
 140        SPACING.  In each bit field, the highest bit indicates that the
 141        corresponding value is set or not.  This way, we can represent
 142        DPI by 11-bit (0 to 2047), AVGWIDTH by 11-bit (0 to 2047),
 143        SPACING by 3-bit (0 for proportional, 1 for dual, 2 for mono, 3
 144        for charcell), which is surely sufficient.  */
 145     FONT_METRICS_INDEX,
 146 #endif
 147
 148     /* In a font-spec, the value is an alist of extra information of a
 149        font such as name, OpenType features, and language coverage.
 150        In addition, in a font-entity, the value may contain a pair
 151        (font-entity . INFO) where INFO is extra information to identify
 152        a font (font-driver dependent).  */
 153     FONT_EXTRA_INDEX,           /* alist                alist */
 154
 155     /* This value is the length of font-spec vector.  */
 156     FONT_SPEC_MAX,
 157
 158     /* The followings are used only for a font-entity and a font-object.  */
 159
 160     /* List of font-objects opened from the font-entity.  */
 161     FONT_OBJLIST_INDEX = FONT_SPEC_MAX,
 162
 163     /* Font-entity from which the font-object is opened.  */
 164     FONT_ENTITY_INDEX = FONT_SPEC_MAX,
 165
 166     /* This value is the length of font-entity vector.  */
 167     FONT_ENTITY_MAX,
 168
 169     /* The followings are used only for a font-object.  */
 170
 171     /* XLFD name of the font (string). */
 172     FONT_NAME_INDEX = FONT_ENTITY_MAX,
 173
 174     /* Full name of the font (string).  It is the name extracted from
 175        the opened font, and may be different from the above.  It may be
 176        nil if the opened font doesn't give a name.  */
 177     FONT_FULLNAME_INDEX,
 178
 179     /* File name of the font or nil if a file associated with the font
 180        is not available.  */
 181     FONT_FILE_INDEX,
 182
 183     /* Format of the font (symbol) or nil if unknown.  */
 184     FONT_FORMAT_INDEX,
 185
 186     /* This value is the length of font-object vector.  */
 187     FONT_OBJECT_MAX
 188   };
 189
 190 /* Return the numeric weight value of FONT.  */
 191 #define FONT_WEIGHT_NUMERIC(font)               \
 192   (INTEGERP (AREF ((font), FONT_WEIGHT_INDEX))  \
 193    ? (XINT (AREF ((font), FONT_WEIGHT_INDEX)) >> 8) : -1)
 194 /* Return the numeric slant value of FONT.  */
 195 #define FONT_SLANT_NUMERIC(font)                \
 196   (INTEGERP (AREF ((font), FONT_SLANT_INDEX))   \
 197    ? (XINT (AREF ((font), FONT_SLANT_INDEX)) >> 8) : -1)
 198 /* Return the numeric width value of FONT.  */
 199 #define FONT_WIDTH_NUMERIC(font)                \
 200   (INTEGERP (AREF ((font), FONT_WIDTH_INDEX))   \
 201    ? (XINT (AREF ((font), FONT_WIDTH_INDEX)) >> 8) : -1)
 202 /* Return the symbolic weight value of FONT.  */
 203 #define FONT_WEIGHT_SYMBOLIC(font)      \
 204   font_style_symbolic (font, FONT_WEIGHT_INDEX, 0)
 205 /* Return the symbolic slant value of FONT.  */
 206 #define FONT_SLANT_SYMBOLIC(font)       \
 207   font_style_symbolic (font, FONT_SLANT_INDEX, 0)
 208 /* Return the symbolic width value of FONT.  */
 209 #define FONT_WIDTH_SYMBOLIC(font)       \
 210   font_style_symbolic (font, FONT_WIDTH_INDEX, 0)
 211 /* Return the face-weight corresponding to the weight of FONT.  */
 212 #define FONT_WEIGHT_FOR_FACE(font)      \
 213   font_style_symbolic (font, FONT_WEIGHT_INDEX, 1)
 214 /* Return the face-slant corresponding to the slant of FONT.  */
 215 #define FONT_SLANT_FOR_FACE(font)       \
 216   font_style_symbolic (font, FONT_SLANT_INDEX, 1)
 217 /* Return the face-swidth corresponding to the slant of FONT.  */
 218 #define FONT_WIDTH_FOR_FACE(font)       \
 219   font_style_symbolic (font, FONT_WIDTH_INDEX, 1)
 220
 221 /* Return the numeric weight value corresponding ot the symbol NAME.  */
 222 #define FONT_WEIGHT_NAME_NUMERIC(name)  \
 223   (font_style_to_value (FONT_WEIGHT_INDEX, (name), 0) >> 8)
 224 /* Return the numeric slant value corresponding ot the symbol NAME.  */
 225 #define FONT_SLANT_NAME_NUMERIC(name)   \
 226   (font_style_to_value (FONT_SLANT_INDEX, (name), 0) >> 8)
 227 /* Return the numeric width value corresponding ot the symbol NAME.  */
 228 #define FONT_WIDTH_NAME_NUMERIC(name)   \
 229   (font_style_to_value (FONT_WIDTH_INDEX, (name), 0) >> 8)
 230
 231 /* Set the font property PROP of FONT to VAL.  PROP is one of
 232    style-related font property index (FONT_WEIGHT/SLANT/WIDTH_INDEX).
 233    VAL (integer or symbol) is the numeric or symbolic style value.  */
 234 #define FONT_SET_STYLE(font, prop, val) \
 235   ASET ((font), prop, make_number (font_style_to_value (prop, val, 1)))
 236
 237 #define FONT_WIDTH(f) ((f)->max_width)
 238 #define FONT_HEIGHT(f) ((f)->height)
 239 #define FONT_BASE(f) ((f)->ascent)
 240 #define FONT_DESCENT(f) ((f)->descent)
 241
 242 extern Lisp_Object QCspacing, QCdpi, QCscalable, QCotf, QClang, QCscript;
 243 extern Lisp_Object QCavgwidth, QCantialias, QCfont_entity;
 244 extern Lisp_Object Qp;
 245
 246
 247 /* Important character set symbols.  */
 248 extern Lisp_Object Qascii_0;
 249 extern Lisp_Object Qiso8859_1, Qiso10646_1, Qunicode_bmp, Qunicode_sip;
 250
 251 /* Special ADSTYLE properties to avoid fonts used for Latin characters.  */
 252 extern Lisp_Object Qja, Qko;
 253
 254 /* Structure for a font-spec.  */
 255
 256 struct font_spec
 257 {
 258   struct vectorlike_header header;
 259   Lisp_Object props[FONT_SPEC_MAX];
 260 };
 261
 262 /* Structure for a font-entity.  */
 263
 264 struct font_entity
 265 {
 266   struct vectorlike_header header;
 267   Lisp_Object props[FONT_ENTITY_MAX];
 268 };
 269
 270 /* A value which may appear in the member `encoding' of struct font
 271    indicating that a font itself doesn't tell which encoding to be
 272    used.  */
 273 #define FONT_ENCODING_NOT_DECIDED 255
 274
 275 /* Structure for a font-object.  */
 276
 277 struct font
 278 {
 279   struct vectorlike_header header;
 280
 281   /* All Lisp_Object components must come first.
 282      That ensures they are all aligned normally.  */
 283
 284   Lisp_Object props[FONT_OBJECT_MAX];
 285
 286   /* Beyond here, there should be no more Lisp_Object components.  */
 287
 288   /* Minimum and maximum glyph widths, in pixels.  Some font backends,
 289      such as xft, lack the information to easily compute minimum and
 290      maximum widths over all characters; in that case, these values
 291      are approximate.  */
 292   int min_width;
 293   int max_width;
 294
 295   /* By which pixel size the font is opened.  */
 296   int pixel_size;
 297
 298   /* Height of the font.  On X window, this is the same as
 299      (font->ascent + font->descent).  */
 300   int height;
 301
 302   /* Width of the space glyph of the font.  If the font doesn't have a
 303      SPACE glyph, the value is 0.  */
 304   int space_width;
 305
 306   /* Average width of glyphs in the font.  If the font itself doesn't
 307      have that information but has glyphs of ASCII characters, the
 308      value is the average width of those glyphs.  Otherwise, the value
 309      is 0.  */
 310   int average_width;
 311
 312   /* Ascent and descent of the font (in pixels).  */
 313   int ascent, descent;
 314
 315   /* The following members makes sense on graphic displays only.  */
 316
 317 #if defined (HAVE_WINDOW_SYSTEM)
 318
 319   /* Vertical pixel width of the underline.  If is zero if that
 320      information is not in the font.  */
 321   int underline_thickness;
 322
 323   /* Vertical pixel position (relative to the baseline) of the
 324      underline.  If it is positive, it is below the baseline.  It is
 325      negative if that information is not in the font.  */
 326   int underline_position;
 327
 328   /* True if `vertical-centering-font-regexp' matches this font name.
 329      In this case, we render characters at vertical center positions
 330      of lines.  */
 331   bool vertical_centering;
 332
 333   /* The baseline position of a font is normally `ascent' value of the
 334      font.  However, there exist many fonts which don't set `ascent' to
 335      an appropriate value to be used as baseline position.  This is
 336      typical in such ASCII fonts which are designed to be used with
 337      Chinese, Japanese, Korean characters.  When we use mixture of
 338      such fonts and normal fonts (having correct `ascent' value), a
 339      display line gets very ugly.  Since we have no way to fix it
 340      automatically, it is user's responsibility to supply well designed
 341      fonts or correct `ascent' value of fonts.  But, the latter
 342      requires heavy work (modifying all bitmap data in BDF files).
 343      So, Emacs accepts a private font property
 344      `_MULE_BASELINE_OFFSET'.  If a font has this property, we
 345      calculate the baseline position by subtracting the value from
 346      `ascent'.  In other words, the value indicates how many pixels
 347      higher than normal ASCII text we should draw a character of the
 348      font for better appearance.
 349
 350      We also have to consider the fact that the concept of `baseline'
 351      differs among scripts to which each character belongs.  For
 352      instance, baseline should be at the bottom-most position of all
 353      glyphs for Chinese, Japanese, and Korean.  But, many of existing
 354      fonts for those characters don't have correct `ascent' values
 355      because they are designed to be used with ASCII fonts.  To
 356      display characters of different language on the same line, the
 357      best way will be to arrange them in the middle of the line.  So,
 358      in such a case, again, we utilize the font property
 359      `_MULE_BASELINE_OFFSET'.  If the value is larger than `ascent' we
 360      calculate baseline so that a character is arranged in the middle
 361      of a line.  */
 362   int baseline_offset;
 363
 364   /* Non-zero means a character should be composed at a position
 365      relative to the height (or depth) of previous glyphs in the
 366      following cases:
 367         (1) The bottom of the character is higher than this value.  In
 368         this case, the character is drawn above the previous glyphs.
 369         (2) The top of the character is lower than 0 (i.e. baseline
 370         height).  In this case, the character is drawn below the
 371         previous glyphs.
 372
 373      This value is taken from a private font property
 374      `_MULE_RELATIVE_COMPOSE' which is introduced by Emacs.  */
 375   int relative_compose;
 376
 377   /* Non-zero means an ascent value to be used for a character
 378      registered in char-table `use-default-ascent'.  */
 379   int default_ascent;
 380
 381   /* Charset to encode a character code into a glyph code of the font.
 382      -1 means that the font doesn't require this information to encode
 383      a character.  */
 384   int encoding_charset;
 385
 386   /* Charset to check if a character code is supported by the font.
 387      -1 means that the contents of the font must be looked up to
 388      determine it.  */
 389   int repertory_charset;
 390
 391 #endif /* HAVE_WINDOW_SYSTEM */
 392
 393   /* Font-driver for the font.  */
 394   struct font_driver *driver;
 395
 396   /* There are more members in this structure, but they are private
 397      to the font-driver.  */
 398 };
 399
 400 enum font_spacing
 401   {
 402     FONT_SPACING_PROPORTIONAL = 0,
 403     FONT_SPACING_DUAL = 90,
 404     FONT_SPACING_MONO = 100,
 405     FONT_SPACING_CHARCELL = 110
 406   };
 407
 408 struct font_metrics
 409 {
 410   short lbearing, rbearing, width, ascent, descent;
 411 };
 412
 413 struct font_bitmap
 414 {
 415   int bits_per_pixel;
 416   int rows;
 417   int width;
 418   int pitch;
 419   unsigned char *buffer;
 420   int left;
 421   int top;
 422   int advance;
 423 };
 424
 425 /* Predicates to check various font-related objects.  */
 426
 427 /* 1 iff X is one of font-spec, font-entity, and font-object.  */
 428 #define FONTP(x) PSEUDOVECTORP (x, PVEC_FONT)
 429 /* 1 iff X is font-spec.  */
 430 #define FONT_SPEC_P(x)  \
 431   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_SPEC_MAX)
 432 /* 1 iff X is font-entity.  */
 433 #define FONT_ENTITY_P(x)        \
 434   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_ENTITY_MAX)
 435 /* 1 iff X is font-object.  */
 436 #define FONT_OBJECT_P(x)        \
 437   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_OBJECT_MAX)
 438
 439 /* 1 iff ENTITY can't be loaded.  */
 440 #define FONT_ENTITY_NOT_LOADABLE(entity)        \
 441   EQ (AREF (entity, FONT_OBJLIST_INDEX), Qt)
 442
 443 /* Flag ENTITY not loadable.  */
 444 #define FONT_ENTITY_SET_NOT_LOADABLE(entity)    \
 445   ASET (entity, FONT_OBJLIST_INDEX, Qt)
 446
 447
 448 /* Check macros for various font-related objects.  */
 449
 450 #define CHECK_FONT(x)   \
 451   do { if (! FONTP (x)) wrong_type_argument (Qfont, x); } while (0)
 452 #define CHECK_FONT_SPEC(x)      \
 453   do { if (! FONT_SPEC_P (x)) wrong_type_argument (Qfont_spec, x); } while (0)
 454 #define CHECK_FONT_ENTITY(x)    \
 455   do { if (! FONT_ENTITY_P (x)) wrong_type_argument (Qfont_entity, x); } while (0)
 456 #define CHECK_FONT_OBJECT(x)    \
 457   do { if (! FONT_OBJECT_P (x)) wrong_type_argument (Qfont_object, x); } while (0)
 458
 459 #define CHECK_FONT_GET_OBJECT(x, font)  \
 460   do {                                  \
 461     CHECK_FONT_OBJECT (x);              \
 462     font = XFONT_OBJECT (x);            \
 463   } while (0)
 464
 465 #define XFONT_SPEC(p)   \
 466   (eassert (FONT_SPEC_P (p)), (struct font_spec *) XUNTAG (p, Lisp_Vectorlike))
 467 #define XFONT_ENTITY(p) \
 468   (eassert (FONT_ENTITY_P (p)), \
 469    (struct font_entity *) XUNTAG (p, Lisp_Vectorlike))
 470 #define XFONT_OBJECT(p) \
 471   (eassert (FONT_OBJECT_P (p)), (struct font *) XUNTAG (p, Lisp_Vectorlike))
 472 #define XSETFONT(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_FONT))
 473
 474 /* Number of pt per inch (from the TeXbook).  */
 475 #define PT_PER_INCH 72.27
 476
 477 /* Return a pixel size (integer) corresponding to POINT size (double)
 478    on resolution DPI.  */
 479 #define POINT_TO_PIXEL(POINT, DPI) ((POINT) * (DPI) / PT_PER_INCH + 0.5)
 480
 481 /* Return a point size corresponding to POINT size (integer)
 482    on resolution DPI.  Note that though point size is a double, we expect
 483    it to be rounded to an int, so we add 0.5 here.  If the desired value
 484    is tenths of points (as in xfld specs), then the pixel size should
 485    be multiplied BEFORE the conversion to avoid magnifying the error.  */
 486 #define PIXEL_TO_POINT(PIXEL, DPI) ((PIXEL) * PT_PER_INCH / (DPI) + 0.5)
 487
 488 /* Ignore the difference of font pixel sizes less than or equal to
 489    this value.  */
 490 #define FONT_PIXEL_SIZE_QUANTUM 1
 491
 492 #define FONT_INVALID_CODE 0xFFFFFFFF
 493
 494 /* Font driver.  Members specified as "optional" can be NULL.  */
 495
 496 struct font_driver
 497 {
 498   /* Symbol indicating the type of the font-driver.  */
 499   Lisp_Object type;
 500
 501   /* True iff the font's foundry, family, and adstyle names are case
 502      sensitive.  */
 503   bool case_sensitive;
 504
 505   /* Return a cache of font-entities on frame F.  The cache must be a
 506      cons whose cdr part is the actual cache area.  */
 507   Lisp_Object (*get_cache) (struct frame *f);
 508
 509   /* List fonts exactly matching with FONT_SPEC on FRAME.  The value
 510      is a list of font-entities.  The font properties to be considered
 511      are: :foundry, :family, :adstyle, :registry, :script, :lang, and
 512      :otf.  See the function `font-spec' for their meanings.  Note
 513      that the last three properties are stored in FONT_EXTRA_INDEX
 514      slot of FONT_SPEC.
 515
 516      The returned value is a list of font-entities.  Each font-entity
 517      has :type property whose value is the same as the above `type'.
 518      It also has these properties if they are available from the
 519      corresponding font; :foundry, :family, :adstyle, :registry,
 520      :weight, :slant, :width, :size, :dpi, :spacing, :avgwidth.  If
 521      the font is scalable, :size and :avgwidth must be 0.
 522
 523      The `open' method of the same font-backend is called with one of
 524      the returned font-entities.  If the backend needs additional
 525      information to be used in `open' method, this method can add any
 526      Lispy value by the property :font-entity to the entities.
 527
 528      This and the following `match' are the only APIs that allocate
 529      font-entities.  */
 530   Lisp_Object (*list) (struct frame *frame, Lisp_Object font_spec);
 531
 532   /* Return a font-entity most closely matching with FONT_SPEC on
 533      FRAME.  Which font property to consider, and how to calculate the
 534      closeness is determined by the font backend, thus
 535      `face-font-selection-order' is ignored here.
 536
 537      The properties that the font-entity has is the same as `list'
 538      method.  */
 539   Lisp_Object (*match) (struct frame *f, Lisp_Object spec);
 540
 541   /* Optional.
 542      List available families.  The value is a list of family names
 543      (symbols).  */
 544   Lisp_Object (*list_family) (struct frame *f);
 545
 546   /* Optional (if FONT_EXTRA_INDEX is not Lisp_Save_Value).
 547      Free FONT_EXTRA_INDEX field of FONT_ENTITY.  */
 548   void (*free_entity) (Lisp_Object font_entity);
 549
 550   /* Open a font specified by FONT_ENTITY on frame F.  If the font is
 551      scalable, open it with PIXEL_SIZE.  */
 552   Lisp_Object (*open) (struct frame *f, Lisp_Object font_entity,
 553                        int pixel_size);
 554
 555   /* Close FONT.  NOTE: this can be called by GC.  */
 556   void (*close) (struct font *font);
 557
 558   /* Optional (if FACE->extra is not used).
 559      Prepare FACE for displaying characters by FONT on frame F by
 560      storing some data in FACE->extra.  If successful, return 0.
 561      Otherwise, return -1.  */
 562   int (*prepare_face) (struct frame *f, struct face *face);
 563
 564   /* Optional.
 565      Done FACE for displaying characters by FACE->font on frame F.  */
 566   void (*done_face) (struct frame *f, struct face *face);
 567
 568   /* Optional.
 569      If FONT (FONT-ENTITY or FONT-OBJECT) has a glyph for character C
 570      (Unicode code point), return 1.  If not, return 0.  If FONT is
 571      FONT-ENTITY and it must be opened to check it, return -1.  */
 572   int (*has_char) (Lisp_Object font, int c);
 573
 574   /* Return a glyph code of FONT for character C (Unicode code point).
 575      If FONT doesn't have such a glyph, return FONT_INVALID_CODE.  */
 576   unsigned (*encode_char) (struct font *font, int c);
 577
 578   /* Compute the total metrics of the NGLYPHS glyphs specified by
 579      the font FONT and the sequence of glyph codes CODE, and store the
 580      result in METRICS.  */
 581   int (*text_extents) (struct font *font,
 582                        unsigned *code, int nglyphs,
 583                        struct font_metrics *metrics);
 584
 585 #ifdef HAVE_WINDOW_SYSTEM
 586
 587   /* Optional.
 588      Draw glyphs between FROM and TO of S->char2b at (X Y) pixel
 589      position of frame F with S->FACE and S->GC.  If WITH_BACKGROUND,
 590      fill the background in advance.  It is assured that WITH_BACKGROUND
 591      is false when (FROM > 0 || TO < S->nchars).  */
 592   int (*draw) (struct glyph_string *s, int from, int to,
 593                int x, int y, bool with_background);
 594
 595   /* Optional.
 596      Store bitmap data for glyph-code CODE of FONT in BITMAP.  It is
 597      intended that this method is called from the other font-driver
 598      for actual drawing.  */
 599   int (*get_bitmap) (struct font *font, unsigned code,
 600                      struct font_bitmap *bitmap,
 601                      int bits_per_pixel);
 602
 603   /* Optional.
 604      Free bitmap data in BITMAP.  */
 605   void (*free_bitmap) (struct font *font, struct font_bitmap *bitmap);
 606
 607 #endif /* HAVE_WINDOW_SYSTEM */
 608
 609   /* Optional.
 610      Return an outline data for glyph-code CODE of FONT.  The format
 611      of the outline data depends on the font-driver.  */
 612   void *(*get_outline) (struct font *font, unsigned code);
 613
 614   /* Optional.
 615      Free OUTLINE (that is obtained by the above method).  */
 616   void (*free_outline) (struct font *font, void *outline);
 617
 618   /* Optional.
 619      Get coordinates of the INDEXth anchor point of the glyph whose
 620      code is CODE.  Store the coordinates in *X and *Y.  Return 0 if
 621      the operations was successful.  Otherwise return -1.  */
 622   int (*anchor_point) (struct font *font, unsigned code, int index,
 623                        int *x, int *y);
 624
 625   /* Optional.
 626      Return a list describing which scripts/languages FONT
 627      supports by which GSUB/GPOS features of OpenType tables.  */
 628   Lisp_Object (*otf_capability) (struct font *font);
 629
 630   /* Optional.
 631      Apply FONT's OTF-FEATURES to the glyph string.
 632
 633      FEATURES specifies which OTF features to apply in this format:
 634         (SCRIPT LANGSYS GSUB-FEATURE GPOS-FEATURE)
 635      See the documentation of `font-drive-otf' for the details.
 636
 637      This method applies the specified features to the codes in the
 638      elements of GSTRING-IN (between FROMth and TOth).  The output
 639      codes are stored in GSTRING-OUT at the IDXth element and the
 640      following elements.
 641
 642      Return the number of output codes.  If none of the features are
 643      applicable to the input data, return 0.  If GSTRING-OUT is too
 644      short, return -1.  */
 645   int (*otf_drive) (struct font *font, Lisp_Object features,
 646                     Lisp_Object gstring_in, int from, int to,
 647                     Lisp_Object gstring_out, int idx, bool alternate_subst);
 648
 649   /* Optional.
 650      Make the font driver ready for frame F.  Usually this function
 651      makes some data specific to F and stores it in F by calling
 652      font_put_frame_data ().  */
 653   int (*start_for_frame) (struct frame *f);
 654
 655   /* Optional.
 656      End using the driver for frame F.  Usually this function free
 657      some data stored for F.  */
 658   int (*end_for_frame) (struct frame *f);
 659
 660   /* Optional.
 661
 662      Shape text in GSTRING.  See the docstring of
 663      `composition-get-gstring' for the format of GSTRING.  If the
 664      (N+1)th element of GSTRING is nil, input of shaping is from the
 665      1st to (N)th elements.  In each input glyph, FROM, TO, CHAR, and
 666      CODE are already set.
 667
 668      This function updates all fields of the input glyphs.  If the
 669      output glyphs (M) are more than the input glyphs (N), (N+1)th
 670      through (M)th elements of GSTRING are updated possibly by making
 671      a new glyph object and storing it in GSTRING.  If (M) is greater
 672      than the length of GSTRING, nil should be return.  In that case,
 673      this function is called again with the larger GSTRING.  */
 674   Lisp_Object (*shape) (Lisp_Object lgstring);
 675
 676   /* Optional.
 677
 678      If FONT is usable on frame F, return 0.  Otherwise return -1.
 679      This method is used only for debugging.  If this method is NULL,
 680      Emacs assumes that the font is usable on any frame.  */
 681   int (*check) (struct frame *f, struct font *font);
 682
 683   /* Optional.
 684
 685      Return the number of variation glyphs of character C supported by
 686      FONT.  VARIATIONS is an array of 256 elements.  If the variation
 687      selector N (1..256) defines a glyph, that glyph code is stored in
 688      the (N-1)th element of VARIATIONS.  */
 689   int (*get_variation_glyphs) (struct font *font,
 690                                int c, unsigned variations[256]);
 691
 692   void (*filter_properties) (Lisp_Object font, Lisp_Object properties);
 693
 694   /* Optional.
 695
 696      Return non-zero if FONT_OBJECT can be used as a (cached) font
 697      for ENTITY on frame F.  */
 698   bool (*cached_font_ok) (struct frame *f,
 699                           Lisp_Object font_object,
 700                           Lisp_Object entity);
 701 };
 702
 703
 704 /* Chain of font drivers.  There's one global font driver list
 705    (font_driver_list in font.c).  In addition, each frame has
 706    its own font driver list at F->font_driver_list.  */
 707
 708 struct font_driver_list
 709 {
 710   /* True iff this driver is currently used.  It is ignored in the global
 711      font driver list.*/
 712   bool on;
 713   /* Pointer to the font driver.  */
 714   struct font_driver *driver;
 715   /* Pointer to the next element of the chain.  */
 716   struct font_driver_list *next;
 717 };
 718
 719
 720 /* Chain of arbitrary data specific to each font driver.
 721    Each frame has its own font data list at F->font_data_list.  */
 722
 723 struct font_data_list
 724 {
 725   /* Pointer to the font driver.  */
 726   struct font_driver *driver;
 727   /* Data specific to the font driver.  */
 728   void *data;
 729   /* Pointer to the next element of the chain.  */
 730   struct font_data_list *next;
 731 };
 732
 733 extern Lisp_Object copy_font_spec (Lisp_Object);
 734 extern Lisp_Object merge_font_spec (Lisp_Object, Lisp_Object);
 735
 736 extern Lisp_Object font_make_entity (void);
 737 extern Lisp_Object font_make_object (int, Lisp_Object, int);
 738
 739 extern Lisp_Object find_font_encoding (Lisp_Object);
 740 extern int font_registry_charsets (Lisp_Object, struct charset **,
 741                                    struct charset **);
 742 extern int font_style_to_value (enum font_property_index prop,
 743                                 Lisp_Object name, bool noerror);
 744 extern Lisp_Object font_style_symbolic (Lisp_Object font,
 745                                         enum font_property_index prop,
 746                                         bool for_face);
 747
 748 extern bool font_match_p (Lisp_Object spec, Lisp_Object font);
 749 extern Lisp_Object font_list_entities (struct frame *, Lisp_Object);
 750
 751 extern Lisp_Object font_get_name (Lisp_Object font_object);
 752 extern Lisp_Object font_spec_from_name (Lisp_Object font_name);
 753 extern Lisp_Object font_get_frame (Lisp_Object font_object);
 754 extern int font_has_char (struct frame *, Lisp_Object, int);
 755
 756 extern void font_clear_prop (Lisp_Object *attrs,
 757                              enum font_property_index prop);
 758 extern Lisp_Object font_find_for_lface (struct frame *f, Lisp_Object *lface,
 759                                         Lisp_Object spec, int c);
 760 extern Lisp_Object font_open_for_lface (struct frame *f, Lisp_Object entity,
 761                                         Lisp_Object *lface,
 762                                         Lisp_Object spec);
 763 extern Lisp_Object font_load_for_lface (struct frame *f, Lisp_Object *lface,
 764                                         Lisp_Object spec);
 765 extern void font_prepare_for_face (struct frame *f, struct face *face);
 766 extern void font_done_for_face (struct frame *f, struct face *face);
 767 extern void clear_font_cache (struct frame *);
 768
 769 extern Lisp_Object font_open_by_spec (struct frame *f, Lisp_Object spec);
 770 extern Lisp_Object font_open_by_name (struct frame *f, Lisp_Object name);
 771
 772 extern Lisp_Object font_intern_prop (const char *str, ptrdiff_t len,
 773                                      bool force_symbol);
 774 extern void font_update_sort_order (int *order);
 775
 776 extern void font_parse_family_registry (Lisp_Object family,
 777                                         Lisp_Object registry,
 778                                         Lisp_Object spec);
 779
 780 extern int font_parse_xlfd (char *name, ptrdiff_t len, Lisp_Object font);
 781 extern ptrdiff_t font_unparse_xlfd (Lisp_Object font, int pixel_size,
 782                                     char *name, int bytes);
 783 extern int font_unparse_fcname (Lisp_Object font, int pixel_size,
 784                                 char *name, int bytes);
 785 extern void register_font_driver (struct font_driver *driver, struct frame *f);
 786 extern void free_font_driver_list (struct frame *f);
 787 extern Lisp_Object font_update_drivers (struct frame *f, Lisp_Object list);
 788 extern Lisp_Object font_range (ptrdiff_t, ptrdiff_t, ptrdiff_t *,
 789                                struct window *, struct face *,
 790                                Lisp_Object);
 791 extern void font_fill_lglyph_metrics (Lisp_Object, Lisp_Object);
 792
 793 extern Lisp_Object font_put_extra (Lisp_Object font, Lisp_Object prop,
 794                                    Lisp_Object val);
 795
 796 extern int font_put_frame_data (struct frame *f,
 797                                 struct font_driver *driver,
 798                                 void *data);
 799 extern void *font_get_frame_data (struct frame *f,
 800                                   struct font_driver *driver);
 801
 802 extern void font_filter_properties (Lisp_Object font,
 803                                     Lisp_Object alist,
 804                                     const char *const boolean_properties[],
 805                                     const char *const non_boolean_properties[]);
 806
 807 #ifdef HAVE_FREETYPE
 808 extern struct font_driver ftfont_driver;
 809 extern void syms_of_ftfont (void);
 810 #endif  /* HAVE_FREETYPE */
 811 #ifdef HAVE_X_WINDOWS
 812 extern struct font_driver xfont_driver;
 813 extern void syms_of_xfont (void);
 814 extern void syms_of_ftxfont (void);
 815 #ifdef HAVE_XFT
 816 extern Lisp_Object Qxft;
 817 extern struct font_driver xftfont_driver;
 818 extern void syms_of_xftfont (void);
 819 #elif defined HAVE_FREETYPE
 820 extern struct font_driver ftxfont_driver;
 821 #endif
 822 #ifdef HAVE_BDFFONT
 823 extern void syms_of_bdffont (void);
 824 #endif  /* HAVE_BDFFONT */
 825 #endif  /* HAVE_X_WINDOWS */
 826 #ifdef HAVE_NTGUI
 827 extern struct font_driver w32font_driver;
 828 extern struct font_driver uniscribe_font_driver;
 829 extern void syms_of_w32font (void);
 830 #endif  /* HAVE_NTGUI */
 831 #ifdef HAVE_NS
 832 extern Lisp_Object Qfontsize;
 833 extern struct font_driver nsfont_driver;
 834 extern void syms_of_nsfont (void);
 835 extern void syms_of_macfont (void);
 836 #endif  /* HAVE_NS */
 837
 838 #ifndef FONT_DEBUG
 839 #define FONT_DEBUG
 840 #endif
 841
 842 extern Lisp_Object QCfoundry;
 843
 844 extern void font_add_log (const char *, Lisp_Object, Lisp_Object);
 845 extern void font_deferred_log (const char *, Lisp_Object, Lisp_Object);
 846
 847 #define FONT_ADD_LOG(ACTION, ARG, RESULT)       \
 848   do {                                          \
 849     if (! EQ (Vfont_log, Qt))                   \
 850       font_add_log ((ACTION), (ARG), (RESULT)); \
 851   } while (0)
 852
 853 #define FONT_DEFERRED_LOG(ACTION, ARG, RESULT)          \
 854   do {                                                  \
 855     if (! EQ (Vfont_log, Qt))                           \
 856       font_deferred_log ((ACTION), (ARG), (RESULT));    \
 857   } while (0)
 858
 859 #endif  /* not EMACS_FONT_H */