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   /* Vertical pixel width of the underline.  If is zero if that
 316      information is not in the font.  */
 317   int underline_thickness;
 318
 319   /* Vertical pixel position (relative to the baseline) of the
 320      underline.  If it is positive, it is below the baseline.  It is
 321      negative if that information is not in the font.  */
 322   int underline_position;
 323
 324   /* True if `vertical-centering-font-regexp' matches this font name.
 325      In this case, we render characters at vertical center positions
 326      of lines.  */
 327   bool vertical_centering;
 328
 329   /* The baseline position of a font is normally `ascent' value of the
 330      font.  However, there exist many fonts which don't set `ascent' to
 331      an appropriate value to be used as baseline position.  This is
 332      typical in such ASCII fonts which are designed to be used with
 333      Chinese, Japanese, Korean characters.  When we use mixture of
 334      such fonts and normal fonts (having correct `ascent' value), a
 335      display line gets very ugly.  Since we have no way to fix it
 336      automatically, it is user's responsibility to supply well designed
 337      fonts or correct `ascent' value of fonts.  But, the latter
 338      requires heavy work (modifying all bitmap data in BDF files).
 339      So, Emacs accepts a private font property
 340      `_MULE_BASELINE_OFFSET'.  If a font has this property, we
 341      calculate the baseline position by subtracting the value from
 342      `ascent'.  In other words, the value indicates how many pixels
 343      higher than normal ASCII text we should draw a character of the
 344      font for better appearance.
 345
 346      We also have to consider the fact that the concept of `baseline'
 347      differs among scripts to which each character belongs.  For
 348      instance, baseline should be at the bottom-most position of all
 349      glyphs for Chinese, Japanese, and Korean.  But, many of existing
 350      fonts for those characters don't have correct `ascent' values
 351      because they are designed to be used with ASCII fonts.  To
 352      display characters of different language on the same line, the
 353      best way will be to arrange them in the middle of the line.  So,
 354      in such a case, again, we utilize the font property
 355      `_MULE_BASELINE_OFFSET'.  If the value is larger than `ascent' we
 356      calculate baseline so that a character is arranged in the middle
 357      of a line.  */
 358   int baseline_offset;
 359
 360   /* Non-zero means a character should be composed at a position
 361      relative to the height (or depth) of previous glyphs in the
 362      following cases:
 363         (1) The bottom of the character is higher than this value.  In
 364         this case, the character is drawn above the previous glyphs.
 365         (2) The top of the character is lower than 0 (i.e. baseline
 366         height).  In this case, the character is drawn below the
 367         previous glyphs.
 368
 369      This value is taken from a private font property
 370      `_MULE_RELATIVE_COMPOSE' which is introduced by Emacs.  */
 371   int relative_compose;
 372
 373   /* Non-zero means an ascent value to be used for a character
 374      registered in char-table `use-default-ascent'.  */
 375   int default_ascent;
 376
 377   /* CCL program to calculate code points of the font.  */
 378   struct ccl_program *font_encoder;
 379
 380   /* Font-driver for the font.  */
 381   struct font_driver *driver;
 382
 383   /* Charset to encode a character code into a glyph code of the font.
 384      -1 means that the font doesn't require this information to encode
 385      a character.  */
 386   int encoding_charset;
 387
 388   /* Charset to check if a character code is supported by the font.
 389      -1 means that the contents of the font must be looked up to
 390      determine it.  */
 391   int repertory_charset;
 392
 393   /* There are more members in this structure, but they are private
 394      to the font-driver.  */
 395 };
 396
 397 enum font_spacing
 398   {
 399     FONT_SPACING_PROPORTIONAL = 0,
 400     FONT_SPACING_DUAL = 90,
 401     FONT_SPACING_MONO = 100,
 402     FONT_SPACING_CHARCELL = 110
 403   };
 404
 405 struct font_metrics
 406 {
 407   short lbearing, rbearing, width, ascent, descent;
 408 };
 409
 410 struct font_bitmap
 411 {
 412   int bits_per_pixel;
 413   int rows;
 414   int width;
 415   int pitch;
 416   unsigned char *buffer;
 417   int left;
 418   int top;
 419   int advance;
 420   void *extra;
 421 };
 422
 423 /* Predicates to check various font-related objects.  */
 424
 425 /* 1 iff X is one of font-spec, font-entity, and font-object.  */
 426 #define FONTP(x) PSEUDOVECTORP (x, PVEC_FONT)
 427 /* 1 iff X is font-spec.  */
 428 #define FONT_SPEC_P(x)  \
 429   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_SPEC_MAX)
 430 /* 1 iff X is font-entity.  */
 431 #define FONT_ENTITY_P(x)        \
 432   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_ENTITY_MAX)
 433 /* 1 iff X is font-object.  */
 434 #define FONT_OBJECT_P(x)        \
 435   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_OBJECT_MAX)
 436
 437 /* 1 iff ENTITY can't be loaded.  */
 438 #define FONT_ENTITY_NOT_LOADABLE(entity)        \
 439   EQ (AREF (entity, FONT_OBJLIST_INDEX), Qt)
 440
 441 /* Flag ENTITY not loadable.  */
 442 #define FONT_ENTITY_SET_NOT_LOADABLE(entity)    \
 443   ASET (entity, FONT_OBJLIST_INDEX, Qt)
 444
 445
 446 /* Check macros for various font-related objects.  */
 447
 448 #define CHECK_FONT(x)   \
 449   do { if (! FONTP (x)) wrong_type_argument (Qfont, x); } while (0)
 450 #define CHECK_FONT_SPEC(x)      \
 451   do { if (! FONT_SPEC_P (x)) wrong_type_argument (Qfont_spec, x); } while (0)
 452 #define CHECK_FONT_ENTITY(x)    \
 453   do { if (! FONT_ENTITY_P (x)) wrong_type_argument (Qfont_entity, x); } while (0)
 454 #define CHECK_FONT_OBJECT(x)    \
 455   do { if (! FONT_OBJECT_P (x)) wrong_type_argument (Qfont_object, x); } while (0)
 456
 457 #define CHECK_FONT_GET_OBJECT(x, font)  \
 458   do {                                  \
 459     CHECK_FONT_OBJECT (x);              \
 460     font = XFONT_OBJECT (x);            \
 461   } while (0)
 462
 463 #define XFONT_SPEC(p)   \
 464   (eassert (FONT_SPEC_P (p)), (struct font_spec *) XUNTAG (p, Lisp_Vectorlike))
 465 #define XFONT_ENTITY(p) \
 466   (eassert (FONT_ENTITY_P (p)), \
 467    (struct font_entity *) XUNTAG (p, Lisp_Vectorlike))
 468 #define XFONT_OBJECT(p) \
 469   (eassert (FONT_OBJECT_P (p)), (struct font *) XUNTAG (p, Lisp_Vectorlike))
 470 #define XSETFONT(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_FONT))
 471
 472 /* Number of pt per inch (from the TeXbook).  */
 473 #define PT_PER_INCH 72.27
 474
 475 /* Return a pixel size (integer) corresponding to POINT size (double)
 476    on resolution DPI.  */
 477 #define POINT_TO_PIXEL(POINT, DPI) ((POINT) * (DPI) / PT_PER_INCH + 0.5)
 478
 479 /* Return a point size corresponding to POINT size (integer)
 480    on resolution DPI.  Note that though point size is a double, we expect
 481    it to be rounded to an int, so we add 0.5 here.  If the desired value
 482    is tenths of points (as in xfld specs), then the pixel size should
 483    be multiplied BEFORE the conversion to avoid magnifying the error.  */
 484 #define PIXEL_TO_POINT(PIXEL, DPI) ((PIXEL) * PT_PER_INCH / (DPI) + 0.5)
 485
 486 /* Ignore the difference of font pixel sizes less than or equal to
 487    this value.  */
 488 #define FONT_PIXEL_SIZE_QUANTUM 1
 489
 490 #define FONT_INVALID_CODE 0xFFFFFFFF
 491
 492 /* Font driver.  Members specified as "optional" can be NULL.  */
 493
 494 struct font_driver
 495 {
 496   /* Symbol indicating the type of the font-driver.  */
 497   Lisp_Object type;
 498
 499   /* True iff the font's foundry, family, and adstyle names are case
 500      sensitive.  */
 501   bool case_sensitive;
 502
 503   /* Return a cache of font-entities on frame F.  The cache must be a
 504      cons whose cdr part is the actual cache area.  */
 505   Lisp_Object (*get_cache) (struct frame *f);
 506
 507   /* List fonts exactly matching with FONT_SPEC on FRAME.  The value
 508      is a list of font-entities.  The font properties to be considered
 509      are: :foundry, :family, :adstyle, :registry, :script, :lang, and
 510      :otf.  See the function `font-spec' for their meanings.  Note
 511      that the last three properties are stored in FONT_EXTRA_INDEX
 512      slot of FONT_SPEC.
 513
 514      The returned value is a list of font-entities.  Each font-entity
 515      has :type property whose value is the same as the above `type'.
 516      It also has these properties if they are available from the
 517      corresponding font; :foundry, :family, :adstyle, :registry,
 518      :weight, :slant, :width, :size, :dpi, :spacing, :avgwidth.  If
 519      the font is scalable, :size and :avgwidth must be 0.
 520
 521      The `open' method of the same font-backend is called with one of
 522      the returned font-entities.  If the backend needs additional
 523      information to be used in `open' method, this method can add any
 524      Lispy value by the property :font-entity to the entities.
 525
 526      This and the following `match' are the only APIs that allocate
 527      font-entities.  */
 528   Lisp_Object (*list) (struct frame *frame, Lisp_Object font_spec);
 529
 530   /* Return a font-entity most closely matching with FONT_SPEC on
 531      FRAME.  Which font property to consider, and how to calculate the
 532      closeness is determined by the font backend, thus
 533      `face-font-selection-order' is ignored here.
 534
 535      The properties that the font-entity has is the same as `list'
 536      method.  */
 537   Lisp_Object (*match) (struct frame *f, Lisp_Object spec);
 538
 539   /* Optional.
 540      List available families.  The value is a list of family names
 541      (symbols).  */
 542   Lisp_Object (*list_family) (struct frame *f);
 543
 544   /* Optional (if FONT_EXTRA_INDEX is not Lisp_Save_Value).
 545      Free FONT_EXTRA_INDEX field of FONT_ENTITY.  */
 546   void (*free_entity) (Lisp_Object font_entity);
 547
 548   /* Open a font specified by FONT_ENTITY on frame F.  If the font is
 549      scalable, open it with PIXEL_SIZE.  */
 550   Lisp_Object (*open) (struct frame *f, Lisp_Object font_entity,
 551                        int pixel_size);
 552
 553   /* Close FONT.  NOTE: this can be called by GC.  */
 554   void (*close) (struct font *font);
 555
 556   /* Optional (if FACE->extra is not used).
 557      Prepare FACE for displaying characters by FONT on frame F by
 558      storing some data in FACE->extra.  If successful, return 0.
 559      Otherwise, return -1.  */
 560   int (*prepare_face) (struct frame *f, struct face *face);
 561
 562   /* Optional.
 563      Done FACE for displaying characters by FACE->font on frame F.  */
 564   void (*done_face) (struct frame *f, struct face *face);
 565
 566   /* Optional.
 567      If FONT (FONT-ENTITY or FONT-OBJECT) has a glyph for character C
 568      (Unicode code point), return 1.  If not, return 0.  If FONT is
 569      FONT-ENTITY and it must be opened to check it, return -1.  */
 570   int (*has_char) (Lisp_Object font, int c);
 571
 572   /* Return a glyph code of FONT for character C (Unicode code point).
 573      If FONT doesn't have such a glyph, return FONT_INVALID_CODE.  */
 574   unsigned (*encode_char) (struct font *font, int c);
 575
 576   /* Compute the total metrics of the NGLYPHS glyphs specified by
 577      the font FONT and the sequence of glyph codes CODE, and store the
 578      result in METRICS.  */
 579   int (*text_extents) (struct font *font,
 580                        unsigned *code, int nglyphs,
 581                        struct font_metrics *metrics);
 582
 583 #ifdef HAVE_WINDOW_SYSTEM
 584
 585   /* Optional.
 586      Draw glyphs between FROM and TO of S->char2b at (X Y) pixel
 587      position of frame F with S->FACE and S->GC.  If WITH_BACKGROUND,
 588      fill the background in advance.  It is assured that WITH_BACKGROUND
 589      is false when (FROM > 0 || TO < S->nchars).  */
 590   int (*draw) (struct glyph_string *s, int from, int to,
 591                int x, int y, bool with_background);
 592
 593   /* Optional.
 594      Store bitmap data for glyph-code CODE of FONT in BITMAP.  It is
 595      intended that this method is called from the other font-driver
 596      for actual drawing.  */
 597   int (*get_bitmap) (struct font *font, unsigned code,
 598                      struct font_bitmap *bitmap,
 599                      int bits_per_pixel);
 600
 601   /* Optional.
 602      Free bitmap data in BITMAP.  */
 603   void (*free_bitmap) (struct font *font, struct font_bitmap *bitmap);
 604
 605 #endif /* HAVE_WINDOW_SYSTEM */
 606
 607   /* Optional.
 608      Return an outline data for glyph-code CODE of FONT.  The format
 609      of the outline data depends on the font-driver.  */
 610   void *(*get_outline) (struct font *font, unsigned code);
 611
 612   /* Optional.
 613      Free OUTLINE (that is obtained by the above method).  */
 614   void (*free_outline) (struct font *font, void *outline);
 615
 616   /* Optional.
 617      Get coordinates of the INDEXth anchor point of the glyph whose
 618      code is CODE.  Store the coordinates in *X and *Y.  Return 0 if
 619      the operations was successful.  Otherwise return -1.  */
 620   int (*anchor_point) (struct font *font, unsigned code, int index,
 621                        int *x, int *y);
 622
 623   /* Optional.
 624      Return a list describing which scripts/languages FONT
 625      supports by which GSUB/GPOS features of OpenType tables.  */
 626   Lisp_Object (*otf_capability) (struct font *font);
 627
 628   /* Optional.
 629      Apply FONT's OTF-FEATURES to the glyph string.
 630
 631      FEATURES specifies which OTF features to apply in this format:
 632         (SCRIPT LANGSYS GSUB-FEATURE GPOS-FEATURE)
 633      See the documentation of `font-drive-otf' for the details.
 634
 635      This method applies the specified features to the codes in the
 636      elements of GSTRING-IN (between FROMth and TOth).  The output
 637      codes are stored in GSTRING-OUT at the IDXth element and the
 638      following elements.
 639
 640      Return the number of output codes.  If none of the features are
 641      applicable to the input data, return 0.  If GSTRING-OUT is too
 642      short, return -1.  */
 643   int (*otf_drive) (struct font *font, Lisp_Object features,
 644                     Lisp_Object gstring_in, int from, int to,
 645                     Lisp_Object gstring_out, int idx, bool alternate_subst);
 646
 647   /* Optional.
 648      Make the font driver ready for frame F.  Usually this function
 649      makes some data specific to F and stores it in F by calling
 650      font_put_frame_data ().  */
 651   int (*start_for_frame) (struct frame *f);
 652
 653   /* Optional.
 654      End using the driver for frame F.  Usually this function free
 655      some data stored for F.  */
 656   int (*end_for_frame) (struct frame *f);
 657
 658   /* Optional.
 659
 660      Shape text in GSTRING.  See the docstring of
 661      `composition-get-gstring' for the format of GSTRING.  If the
 662      (N+1)th element of GSTRING is nil, input of shaping is from the
 663      1st to (N)th elements.  In each input glyph, FROM, TO, CHAR, and
 664      CODE are already set.
 665
 666      This function updates all fields of the input glyphs.  If the
 667      output glyphs (M) are more than the input glyphs (N), (N+1)th
 668      through (M)th elements of GSTRING are updated possibly by making
 669      a new glyph object and storing it in GSTRING.  If (M) is greater
 670      than the length of GSTRING, nil should be return.  In that case,
 671      this function is called again with the larger GSTRING.  */
 672   Lisp_Object (*shape) (Lisp_Object lgstring);
 673
 674   /* Optional.
 675
 676      If FONT is usable on frame F, return 0.  Otherwise return -1.
 677      This method is used only for debugging.  If this method is NULL,
 678      Emacs assumes that the font is usable on any frame.  */
 679   int (*check) (struct frame *f, struct font *font);
 680
 681   /* Optional.
 682
 683      Return the number of variation glyphs of character C supported by
 684      FONT.  VARIATIONS is an array of 256 elements.  If the variation
 685      selector N (1..256) defines a glyph, that glyph code is stored in
 686      the (N-1)th element of VARIATIONS.  */
 687   int (*get_variation_glyphs) (struct font *font,
 688                                int c, unsigned variations[256]);
 689
 690   void (*filter_properties) (Lisp_Object font, Lisp_Object properties);
 691
 692   /* Optional.
 693
 694      Return non-zero if FONT_OBJECT can be used as a (cached) font
 695      for ENTITY on frame F.  */
 696   bool (*cached_font_ok) (struct frame *f,
 697                           Lisp_Object font_object,
 698                           Lisp_Object entity);
 699 };
 700
 701
 702 /* Chain of font drivers.  There's one global font driver list
 703    (font_driver_list in font.c).  In addition, each frame has
 704    its own font driver list at F->font_driver_list.  */
 705
 706 struct font_driver_list
 707 {
 708   /* True iff this driver is currently used.  It is ignored in the global
 709      font driver list.*/
 710   bool on;
 711   /* Pointer to the font driver.  */
 712   struct font_driver *driver;
 713   /* Pointer to the next element of the chain.  */
 714   struct font_driver_list *next;
 715 };
 716
 717
 718 /* Chain of arbitrary data specific to each font driver.
 719    Each frame has its own font data list at F->font_data_list.  */
 720
 721 struct font_data_list
 722 {
 723   /* Pointer to the font driver.  */
 724   struct font_driver *driver;
 725   /* Data specific to the font driver.  */
 726   void *data;
 727   /* Pointer to the next element of the chain.  */
 728   struct font_data_list *next;
 729 };
 730
 731 extern Lisp_Object copy_font_spec (Lisp_Object);
 732 extern Lisp_Object merge_font_spec (Lisp_Object, Lisp_Object);
 733
 734 extern Lisp_Object font_make_entity (void);
 735 extern Lisp_Object font_make_object (int, Lisp_Object, int);
 736
 737 extern Lisp_Object find_font_encoding (Lisp_Object);
 738 extern int font_registry_charsets (Lisp_Object, struct charset **,
 739                                    struct charset **);
 740 extern int font_style_to_value (enum font_property_index prop,
 741                                 Lisp_Object name, bool noerror);
 742 extern Lisp_Object font_style_symbolic (Lisp_Object font,
 743                                         enum font_property_index prop,
 744                                         bool for_face);
 745
 746 extern bool font_match_p (Lisp_Object spec, Lisp_Object font);
 747 extern Lisp_Object font_list_entities (struct frame *, Lisp_Object);
 748
 749 extern Lisp_Object font_get_name (Lisp_Object font_object);
 750 extern Lisp_Object font_spec_from_name (Lisp_Object font_name);
 751 extern Lisp_Object font_get_frame (Lisp_Object font_object);
 752 extern int font_has_char (struct frame *, Lisp_Object, int);
 753
 754 extern void font_clear_prop (Lisp_Object *attrs,
 755                              enum font_property_index prop);
 756 extern Lisp_Object font_find_for_lface (struct frame *f, Lisp_Object *lface,
 757                                         Lisp_Object spec, int c);
 758 extern Lisp_Object font_open_for_lface (struct frame *f, Lisp_Object entity,
 759                                         Lisp_Object *lface,
 760                                         Lisp_Object spec);
 761 extern Lisp_Object font_load_for_lface (struct frame *f, Lisp_Object *lface,
 762                                         Lisp_Object spec);
 763 extern void font_prepare_for_face (struct frame *f, struct face *face);
 764 extern void font_done_for_face (struct frame *f, struct face *face);
 765 extern void clear_font_cache (struct frame *);
 766
 767 extern Lisp_Object font_open_by_spec (struct frame *f, Lisp_Object spec);
 768 extern Lisp_Object font_open_by_name (struct frame *f, Lisp_Object name);
 769
 770 extern Lisp_Object font_intern_prop (const char *str, ptrdiff_t len,
 771                                      bool force_symbol);
 772 extern void font_update_sort_order (int *order);
 773
 774 extern void font_parse_family_registry (Lisp_Object family,
 775                                         Lisp_Object registry,
 776                                         Lisp_Object spec);
 777
 778 extern int font_parse_xlfd (char *name, ptrdiff_t len, Lisp_Object font);
 779 extern ptrdiff_t font_unparse_xlfd (Lisp_Object font, int pixel_size,
 780                                     char *name, int bytes);
 781 extern int font_unparse_fcname (Lisp_Object font, int pixel_size,
 782                                 char *name, int bytes);
 783 extern void register_font_driver (struct font_driver *driver, struct frame *f);
 784 extern void free_font_driver_list (struct frame *f);
 785 extern Lisp_Object font_update_drivers (struct frame *f, Lisp_Object list);
 786 extern Lisp_Object font_range (ptrdiff_t, ptrdiff_t, ptrdiff_t *,
 787                                struct window *, struct face *,
 788                                Lisp_Object);
 789 extern void font_fill_lglyph_metrics (Lisp_Object, Lisp_Object);
 790
 791 extern Lisp_Object font_put_extra (Lisp_Object font, Lisp_Object prop,
 792                                    Lisp_Object val);
 793
 794 extern int font_put_frame_data (struct frame *f,
 795                                 struct font_driver *driver,
 796                                 void *data);
 797 extern void *font_get_frame_data (struct frame *f,
 798                                   struct font_driver *driver);
 799
 800 extern void font_filter_properties (Lisp_Object font,
 801                                     Lisp_Object alist,
 802                                     const char *const boolean_properties[],
 803                                     const char *const non_boolean_properties[]);
 804
 805 #ifdef HAVE_FREETYPE
 806 extern struct font_driver ftfont_driver;
 807 extern void syms_of_ftfont (void);
 808 #endif  /* HAVE_FREETYPE */
 809 #ifdef HAVE_X_WINDOWS
 810 extern struct font_driver xfont_driver;
 811 extern void syms_of_xfont (void);
 812 extern void syms_of_ftxfont (void);
 813 #ifdef HAVE_XFT
 814 extern Lisp_Object Qxft;
 815 extern struct font_driver xftfont_driver;
 816 extern void syms_of_xftfont (void);
 817 #elif defined HAVE_FREETYPE
 818 extern struct font_driver ftxfont_driver;
 819 #endif
 820 #ifdef HAVE_BDFFONT
 821 extern void syms_of_bdffont (void);
 822 #endif  /* HAVE_BDFFONT */
 823 #endif  /* HAVE_X_WINDOWS */
 824 #ifdef HAVE_NTGUI
 825 extern struct font_driver w32font_driver;
 826 extern struct font_driver uniscribe_font_driver;
 827 extern void syms_of_w32font (void);
 828 #endif  /* HAVE_NTGUI */
 829 #ifdef HAVE_NS
 830 extern Lisp_Object Qfontsize;
 831 extern struct font_driver nsfont_driver;
 832 extern void syms_of_nsfont (void);
 833 extern void syms_of_macfont (void);
 834 #endif  /* HAVE_NS */
 835
 836 #ifndef FONT_DEBUG
 837 #define FONT_DEBUG
 838 #endif
 839
 840 extern Lisp_Object QCfoundry;
 841
 842 extern void font_add_log (const char *, Lisp_Object, Lisp_Object);
 843 extern void font_deferred_log (const char *, Lisp_Object, Lisp_Object);
 844
 845 #define FONT_ADD_LOG(ACTION, ARG, RESULT)       \
 846   do {                                          \
 847     if (! EQ (Vfont_log, Qt))                   \
 848       font_add_log ((ACTION), (ARG), (RESULT)); \
 849   } while (0)
 850
 851 #define FONT_DEFERRED_LOG(ACTION, ARG, RESULT)          \
 852   do {                                                  \
 853     if (! EQ (Vfont_log, Qt))                           \
 854       font_deferred_log ((ACTION), (ARG), (RESULT));    \
 855   } while (0)
 856
 857 #endif  /* not EMACS_FONT_H */