src/font.h

   1 /* font.h -- Interface definition for font handling.
   2    Copyright (C) 2006-2014 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 INLINE_HEADER_BEGIN
  29
  30 /* We have three types of Lisp objects related to font.
  31
  32    FONT-SPEC
  33
  34         Pseudo vector (length FONT_SPEC_MAX) of font properties.  Some
  35         properties can be left unspecified (i.e. nil).  Emacs asks
  36         font-drivers to find a font by FONT-SPEC.  A fontset entry
  37         specifies requisite properties whereas a face specifies just
  38         preferable properties.
  39
  40    FONT-ENTITY
  41
  42         Pseudo vector (length FONT_ENTITY_MAX) of fully instantiated
  43         font properties that a font-driver returns upon a request of
  44         FONT-SPEC.
  45
  46         Note: Only the method `list' and `match' of a font-driver can
  47         create this object, and it should never be modified by Lisp.
  48
  49    FONT-OBJECT
  50
  51         Pseudo vector (length FONT_OBJECT_MAX) of an opened font.
  52
  53         Lisp object encapsulating "struct font".  This corresponds to
  54         an opened font.
  55
  56         Note: Only the method `open' of a font-driver can create this
  57         object, and it should never be modified by Lisp.  */
  58
  59 extern Lisp_Object Qfont_spec, Qfont_entity, Qfont_object;
  60
  61 /* An enumerator for each font property.  This is used as an index to
  62    the vector of FONT-SPEC and FONT-ENTITY.
  63
  64    Note: The order is important and should not be changed.  */
  65
  66 enum font_property_index
  67   {
  68     /* FONT-TYPE is a symbol indicating a font backend; currently `x',
  69        `xft', and `ftx' are available on X, `uniscribe' and `gdi' on
  70        Windows, and `ns' under Cocoa / GNUstep.  */
  71     FONT_TYPE_INDEX,
  72
  73     /* FONT-FOUNDRY is a foundry name (symbol).  */
  74     FONT_FOUNDRY_INDEX,
  75
  76     /* FONT-FAMILY is a family name (symbol).  */
  77     FONT_FAMILY_INDEX,
  78
  79     /* FONT-ADSTYLE is an additional style name (symbol).  */
  80     FONT_ADSTYLE_INDEX,
  81
  82     /* FONT-REGISTRY is a combination of a charset-registry and
  83        charset-encoding name (symbol).  */
  84     FONT_REGISTRY_INDEX,
  85
  86     /* FONT-WEIGHT is a numeric value of weight (e.g. medium, bold) of
  87        the font.  The lowest 8 bits is an index determining the
  88        symbolic name, and the higher bits is the actual numeric value
  89        defined in `font-weight-table'. */
  90     FONT_WEIGHT_INDEX,
  91
  92     /* FONT-SLANT is a numeric value of slant (e.g. r, i, o) of the
  93        font.  The lowest 8 bits is an index determining the symbolic
  94        name, and the higher bits is the actual numeric value defined
  95        in `font-slant-table'.  */
  96     FONT_SLANT_INDEX,
  97
  98     /* FONT-WIDTH is a numeric value of setwidth (e.g. normal) of the
  99        font.  The lowest 8 bits is an index determining the symbolic
 100        name, and the higher bits is the actual numeric value defined
 101        `font-width-table'.  */
 102     FONT_WIDTH_INDEX,
 103
 104     /* FONT-SIZE is a size of the font.  If integer, it is a pixel
 105        size.  For a font-spec, the value can be a float specifying
 106        the point size.  The value zero means that the font is
 107        scalable.  */
 108     FONT_SIZE_INDEX,
 109
 110     /* FONT-DPI is a resolution (dot per inch) for which the font is
 111        designed. */
 112     FONT_DPI_INDEX,
 113
 114     /* FONT-SPACING is a spacing (mono, proportional, charcell) of the
 115        font (integer; one of enum font_spacing).  */
 116     FONT_SPACING_INDEX,
 117
 118     /* FONT-AVGWIDTH is an average width (1/10 pixel unit) of the
 119        font.  */
 120     FONT_AVGWIDTH_INDEX,
 121
 122 #if false
 123     /* The following two members are to substitute for the above 6
 124        members (FONT_WEIGHT_INDEX to FONT_AVGWIDTH_INDEX excluding
 125        FONT_SIZE_INDEX) if it is found that font-entities consumes too
 126        much memory.  */
 127
 128     /* FONT-STYLE is a 24-bit integer containing indices for
 129        style-related properties WEIGHT, SLANT, and WIDTH.  The lowest
 130        8 bits is an index to the weight table AREF (font_style_table,
 131        0), the next 8 bits is an index to the slant table AREF
 132        (font_style_table, 1), the highest 8 bits is an index to the
 133        slant table AREF (font_style_table, 2).  The index 0 indicates
 134        that the corresponding style is not specified.  This way, we
 135        can represent at most 255 different names for each style, which
 136        is surely sufficient.  */
 137     FONT_STYLE_INDEX,
 138
 139     /* FONT-METRICS is a 27-bit integer containing metrics-related
 140        properties DPI, AVGWIDTH, SPACING.  The lowest 12 bits is for
 141        DPI, the next 12 bits is for AVGWIDTH, the highest 3 bits is for
 142        SPACING.  In each bit field, the highest bit indicates that the
 143        corresponding value is set or not.  This way, we can represent
 144        DPI by 11-bit (0 to 2047), AVGWIDTH by 11-bit (0 to 2047),
 145        SPACING by 3-bit (0 for proportional, 1 for dual, 2 for mono, 3
 146        for charcell), which is surely sufficient.  */
 147     FONT_METRICS_INDEX,
 148 #endif
 149
 150     /* In a font-spec, the value is an alist of extra information of a
 151        font such as name, OpenType features, and language coverage.
 152        In addition, in a font-entity, the value may contain a pair
 153        (font-entity . INFO) where INFO is extra information to identify
 154        a font (font-driver dependent).  */
 155     FONT_EXTRA_INDEX,           /* alist                alist */
 156
 157     /* This value is the length of font-spec vector.  */
 158     FONT_SPEC_MAX,
 159
 160     /* The followings are used only for a font-entity and a font-object.  */
 161
 162     /* List of font-objects opened from the font-entity.  */
 163     FONT_OBJLIST_INDEX = FONT_SPEC_MAX,
 164
 165     /* Font-entity from which the font-object is opened.  */
 166     FONT_ENTITY_INDEX = FONT_SPEC_MAX,
 167
 168     /* This value is the length of font-entity vector.  */
 169     FONT_ENTITY_MAX,
 170
 171     /* The followings are used only for a font-object.  */
 172
 173     /* XLFD name of the font (string). */
 174     FONT_NAME_INDEX = FONT_ENTITY_MAX,
 175
 176     /* Full name of the font (string).  It is the name extracted from
 177        the opened font, and may be different from the above.  It may be
 178        nil if the opened font doesn't give a name.  */
 179     FONT_FULLNAME_INDEX,
 180
 181     /* File name of the font or nil if a file associated with the font
 182        is not available.  */
 183     FONT_FILE_INDEX,
 184
 185     /* Format of the font (symbol) or nil if unknown.  */
 186     FONT_FORMAT_INDEX,
 187
 188     /* This value is the length of font-object vector.  */
 189     FONT_OBJECT_MAX
 190   };
 191
 192 /* Return the numeric weight value of FONT.  */
 193 #define FONT_WEIGHT_NUMERIC(font)               \
 194   (INTEGERP (AREF ((font), FONT_WEIGHT_INDEX))  \
 195    ? (XINT (AREF ((font), FONT_WEIGHT_INDEX)) >> 8) : -1)
 196 /* Return the numeric slant value of FONT.  */
 197 #define FONT_SLANT_NUMERIC(font)                \
 198   (INTEGERP (AREF ((font), FONT_SLANT_INDEX))   \
 199    ? (XINT (AREF ((font), FONT_SLANT_INDEX)) >> 8) : -1)
 200 /* Return the numeric width value of FONT.  */
 201 #define FONT_WIDTH_NUMERIC(font)                \
 202   (INTEGERP (AREF ((font), FONT_WIDTH_INDEX))   \
 203    ? (XINT (AREF ((font), FONT_WIDTH_INDEX)) >> 8) : -1)
 204 /* Return the symbolic weight value of FONT.  */
 205 #define FONT_WEIGHT_SYMBOLIC(font)      \
 206   font_style_symbolic (font, FONT_WEIGHT_INDEX, false)
 207 /* Return the symbolic slant value of FONT.  */
 208 #define FONT_SLANT_SYMBOLIC(font)       \
 209   font_style_symbolic (font, FONT_SLANT_INDEX, false)
 210 /* Return the symbolic width value of FONT.  */
 211 #define FONT_WIDTH_SYMBOLIC(font)       \
 212   font_style_symbolic (font, FONT_WIDTH_INDEX, false)
 213 /* Return the face-weight corresponding to the weight of FONT.  */
 214 #define FONT_WEIGHT_FOR_FACE(font)      \
 215   font_style_symbolic (font, FONT_WEIGHT_INDEX, true)
 216 /* Return the face-slant corresponding to the slant of FONT.  */
 217 #define FONT_SLANT_FOR_FACE(font)       \
 218   font_style_symbolic (font, FONT_SLANT_INDEX, true)
 219 /* Return the face-swidth corresponding to the slant of FONT.  */
 220 #define FONT_WIDTH_FOR_FACE(font)       \
 221   font_style_symbolic (font, FONT_WIDTH_INDEX, true)
 222
 223 /* Return the numeric weight value corresponding ot the symbol NAME.  */
 224 #define FONT_WEIGHT_NAME_NUMERIC(name)  \
 225   (font_style_to_value (FONT_WEIGHT_INDEX, (name), false) >> 8)
 226 /* Return the numeric slant value corresponding ot the symbol NAME.  */
 227 #define FONT_SLANT_NAME_NUMERIC(name)   \
 228   (font_style_to_value (FONT_SLANT_INDEX, (name), false) >> 8)
 229 /* Return the numeric width value corresponding ot the symbol NAME.  */
 230 #define FONT_WIDTH_NAME_NUMERIC(name)   \
 231   (font_style_to_value (FONT_WIDTH_INDEX, (name), false) >> 8)
 232
 233 /* Set the font property PROP of FONT to VAL.  PROP is one of
 234    style-related font property index (FONT_WEIGHT/SLANT/WIDTH_INDEX).
 235    VAL (integer or symbol) is the numeric or symbolic style value.  */
 236 #define FONT_SET_STYLE(font, prop, val) \
 237   ASET ((font), prop, make_number (font_style_to_value (prop, val, true)))
 238
 239 #ifndef MSDOS
 240 #define FONT_WIDTH(f) ((f)->max_width)
 241 #else
 242 #define FONT_WIDTH(f) 1
 243 #endif
 244 #define FONT_HEIGHT(f) ((f)->height)
 245 #define FONT_BASE(f) ((f)->ascent)
 246 #define FONT_DESCENT(f) ((f)->descent)
 247
 248 extern Lisp_Object QCspacing, QCdpi, QCscalable, QCotf, QClang, QCscript;
 249 extern Lisp_Object QCavgwidth, QCantialias, QCfont_entity;
 250 extern Lisp_Object Qp;
 251
 252
 253 /* Important character set symbols.  */
 254 extern Lisp_Object Qascii_0;
 255 extern Lisp_Object Qiso8859_1, Qiso10646_1, Qunicode_bmp, Qunicode_sip;
 256
 257 /* Special ADSTYLE properties to avoid fonts used for Latin characters.  */
 258 extern Lisp_Object Qja, Qko;
 259
 260 /* Structure for a font-spec.  */
 261
 262 struct font_spec
 263 {
 264   struct vectorlike_header header;
 265   Lisp_Object props[FONT_SPEC_MAX];
 266 };
 267
 268 /* Structure for a font-entity.  */
 269
 270 struct font_entity
 271 {
 272   struct vectorlike_header header;
 273   Lisp_Object props[FONT_ENTITY_MAX];
 274 };
 275
 276 /* A value which may appear in the member `encoding' of struct font
 277    indicating that a font itself doesn't tell which encoding to be
 278    used.  */
 279 #define FONT_ENCODING_NOT_DECIDED 255
 280
 281 /* Structure for a font-object.  */
 282
 283 struct font
 284 {
 285   struct vectorlike_header header;
 286
 287   /* All Lisp_Object components must come first.
 288      That ensures they are all aligned normally.  */
 289
 290   Lisp_Object props[FONT_OBJECT_MAX];
 291
 292   /* Beyond here, there should be no more Lisp_Object components.  */
 293
 294   /* Minimum and maximum glyph widths, in pixels.  Some font backends,
 295      such as xft, lack the information to easily compute minimum and
 296      maximum widths over all characters; in that case, these values
 297      are approximate.  */
 298   int min_width;
 299   int max_width;
 300
 301   /* By which pixel size the font is opened.  */
 302   int pixel_size;
 303
 304   /* Height of the font.  On X window, this is the same as
 305      (font->ascent + font->descent).  */
 306   int height;
 307
 308   /* Width of the space glyph of the font.  If the font doesn't have a
 309      SPACE glyph, the value is 0.  */
 310   int space_width;
 311
 312   /* Average width of glyphs in the font.  If the font itself doesn't
 313      have that information but has glyphs of ASCII characters, the
 314      value is the average width of those glyphs.  Otherwise, the value
 315      is 0.  */
 316   int average_width;
 317
 318   /* Ascent and descent of the font (in pixels).  */
 319   int ascent, descent;
 320
 321   /* The following members makes sense on graphic displays only.  */
 322
 323 #if defined (HAVE_WINDOW_SYSTEM)
 324
 325   /* Vertical pixel width of the underline.  If is zero if that
 326      information is not in the font.  */
 327   int underline_thickness;
 328
 329   /* Vertical pixel position (relative to the baseline) of the
 330      underline.  If it is positive, it is below the baseline.  It is
 331      negative if that information is not in the font.  */
 332   int underline_position;
 333
 334   /* True if `vertical-centering-font-regexp' matches this font name.
 335      In this case, we render characters at vertical center positions
 336      of lines.  */
 337   bool vertical_centering;
 338
 339   /* The baseline position of a font is normally `ascent' value of the
 340      font.  However, there exist many fonts which don't set `ascent' to
 341      an appropriate value to be used as baseline position.  This is
 342      typical in such ASCII fonts which are designed to be used with
 343      Chinese, Japanese, Korean characters.  When we use mixture of
 344      such fonts and normal fonts (having correct `ascent' value), a
 345      display line gets very ugly.  Since we have no way to fix it
 346      automatically, it is user's responsibility to supply well designed
 347      fonts or correct `ascent' value of fonts.  But, the latter
 348      requires heavy work (modifying all bitmap data in BDF files).
 349      So, Emacs accepts a private font property
 350      `_MULE_BASELINE_OFFSET'.  If a font has this property, we
 351      calculate the baseline position by subtracting the value from
 352      `ascent'.  In other words, the value indicates how many pixels
 353      higher than normal ASCII text we should draw a character of the
 354      font for better appearance.
 355
 356      We also have to consider the fact that the concept of `baseline'
 357      differs among scripts to which each character belongs.  For
 358      instance, baseline should be at the bottom-most position of all
 359      glyphs for Chinese, Japanese, and Korean.  But, many of existing
 360      fonts for those characters don't have correct `ascent' values
 361      because they are designed to be used with ASCII fonts.  To
 362      display characters of different language on the same line, the
 363      best way will be to arrange them in the middle of the line.  So,
 364      in such a case, again, we utilize the font property
 365      `_MULE_BASELINE_OFFSET'.  If the value is larger than `ascent' we
 366      calculate baseline so that a character is arranged in the middle
 367      of a line.  */
 368   int baseline_offset;
 369
 370   /* Non-zero means a character should be composed at a position
 371      relative to the height (or depth) of previous glyphs in the
 372      following cases:
 373         (1) The bottom of the character is higher than this value.  In
 374         this case, the character is drawn above the previous glyphs.
 375         (2) The top of the character is lower than 0 (i.e. baseline
 376         height).  In this case, the character is drawn below the
 377         previous glyphs.
 378
 379      This value is taken from a private font property
 380      `_MULE_RELATIVE_COMPOSE' which is introduced by Emacs.  */
 381   int relative_compose;
 382
 383   /* Non-zero means an ascent value to be used for a character
 384      registered in char-table `use-default-ascent'.  */
 385   int default_ascent;
 386
 387   /* Charset to encode a character code into a glyph code of the font.
 388      -1 means that the font doesn't require this information to encode
 389      a character.  */
 390   int encoding_charset;
 391
 392   /* Charset to check if a character code is supported by the font.
 393      -1 means that the contents of the font must be looked up to
 394      determine it.  */
 395   int repertory_charset;
 396
 397 #endif /* HAVE_WINDOW_SYSTEM */
 398
 399   /* Font-driver for the font.  */
 400   struct font_driver *driver;
 401
 402   /* There are more members in this structure, but they are private
 403      to the font-driver.  */
 404 };
 405
 406 enum font_spacing
 407   {
 408     FONT_SPACING_PROPORTIONAL = 0,
 409     FONT_SPACING_DUAL = 90,
 410     FONT_SPACING_MONO = 100,
 411     FONT_SPACING_CHARCELL = 110
 412   };
 413
 414 struct font_metrics
 415 {
 416   short lbearing, rbearing, width, ascent, descent;
 417 };
 418
 419 struct font_bitmap
 420 {
 421   int bits_per_pixel;
 422   int rows;
 423   int width;
 424   int pitch;
 425   unsigned char *buffer;
 426   int left;
 427   int top;
 428   int advance;
 429 };
 430
 431 /* Predicates to check various font-related objects.  */
 432
 433 /* True iff X is one of font-spec, font-entity, and font-object.  */
 434 #define FONTP(x) PSEUDOVECTORP (x, PVEC_FONT)
 435 /* True iff X is font-spec.  */
 436 #define FONT_SPEC_P(x)  \
 437   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_SPEC_MAX)
 438 /* True iff X is font-entity.  */
 439 #define FONT_ENTITY_P(x)        \
 440   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_ENTITY_MAX)
 441 /* True iff X is font-object.  */
 442 #define FONT_OBJECT_P(x)        \
 443   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_OBJECT_MAX)
 444
 445 /* True 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 (false)
 458 #define CHECK_FONT_SPEC(x)      \
 459   do { if (! FONT_SPEC_P (x)) wrong_type_argument (Qfont_spec, x); } \
 460   while (false)
 461 #define CHECK_FONT_ENTITY(x)    \
 462   do { if (! FONT_ENTITY_P (x)) wrong_type_argument (Qfont_entity, x); } \
 463   while (false)
 464 #define CHECK_FONT_OBJECT(x)    \
 465   do { if (! FONT_OBJECT_P (x)) wrong_type_argument (Qfont_object, x); } \
 466   while (false)
 467
 468 #define CHECK_FONT_GET_OBJECT(x, font)  \
 469   do {                                  \
 470     CHECK_FONT_OBJECT (x);              \
 471     font = XFONT_OBJECT (x);            \
 472   } while (false)
 473
 474 #define XFONT_SPEC(p)   \
 475   (eassert (FONT_SPEC_P (p)), (struct font_spec *) XUNTAG (p, Lisp_Vectorlike))
 476 #define XFONT_ENTITY(p) \
 477   (eassert (FONT_ENTITY_P (p)), \
 478    (struct font_entity *) XUNTAG (p, Lisp_Vectorlike))
 479 #define XFONT_OBJECT(p) \
 480   (eassert (FONT_OBJECT_P (p)), (struct font *) XUNTAG (p, Lisp_Vectorlike))
 481 #define XSETFONT(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_FONT))
 482
 483 /* Number of pt per inch (from the TeXbook).  */
 484 #define PT_PER_INCH 72.27
 485
 486 /* Return a pixel size (integer) corresponding to POINT size (double)
 487    on resolution DPI.  */
 488 #define POINT_TO_PIXEL(POINT, DPI) ((POINT) * (DPI) / PT_PER_INCH + 0.5)
 489
 490 /* Return a point size corresponding to POINT size (integer)
 491    on resolution DPI.  Note that though point size is a double, we expect
 492    it to be rounded to an int, so we add 0.5 here.  If the desired value
 493    is tenths of points (as in xfld specs), then the pixel size should
 494    be multiplied BEFORE the conversion to avoid magnifying the error.  */
 495 #define PIXEL_TO_POINT(PIXEL, DPI) ((PIXEL) * PT_PER_INCH / (DPI) + 0.5)
 496
 497 /* Ignore the difference of font pixel sizes less than or equal to
 498    this value.  */
 499 #define FONT_PIXEL_SIZE_QUANTUM 1
 500
 501 #define FONT_INVALID_CODE 0xFFFFFFFF
 502
 503 /* Font driver.  Members specified as "optional" can be NULL.  */
 504
 505 struct font_driver
 506 {
 507   /* Symbol indicating the type of the font-driver.  */
 508   Lisp_Object type;
 509
 510   /* True iff the font's foundry, family, and adstyle names are case
 511      sensitive.  */
 512   bool case_sensitive;
 513
 514   /* Return a cache of font-entities on frame F.  The cache must be a
 515      cons whose cdr part is the actual cache area.  */
 516   Lisp_Object (*get_cache) (struct frame *f);
 517
 518   /* List fonts exactly matching with FONT_SPEC on FRAME.  The value
 519      is a list of font-entities.  The font properties to be considered
 520      are: :foundry, :family, :adstyle, :registry, :script, :lang, and
 521      :otf.  See the function `font-spec' for their meanings.  Note
 522      that the last three properties are stored in FONT_EXTRA_INDEX
 523      slot of FONT_SPEC.
 524
 525      The returned value is a list of font-entities.  Each font-entity
 526      has :type property whose value is the same as the above `type'.
 527      It also has these properties if they are available from the
 528      corresponding font; :foundry, :family, :adstyle, :registry,
 529      :weight, :slant, :width, :size, :dpi, :spacing, :avgwidth.  If
 530      the font is scalable, :size and :avgwidth must be 0.
 531
 532      The `open' method of the same font-backend is called with one of
 533      the returned font-entities.  If the backend needs additional
 534      information to be used in `open' method, this method can add any
 535      Lispy value by the property :font-entity to the entities.
 536
 537      This and the following `match' are the only APIs that allocate
 538      font-entities.  */
 539   Lisp_Object (*list) (struct frame *frame, Lisp_Object font_spec);
 540
 541   /* Return a font-entity most closely matching with FONT_SPEC on
 542      FRAME.  Which font property to consider, and how to calculate the
 543      closeness is determined by the font backend, thus
 544      `face-font-selection-order' is ignored here.
 545
 546      The properties that the font-entity has is the same as `list'
 547      method.  */
 548   Lisp_Object (*match) (struct frame *f, Lisp_Object spec);
 549
 550   /* Optional.
 551      List available families.  The value is a list of family names
 552      (symbols).  */
 553   Lisp_Object (*list_family) (struct frame *f);
 554
 555   /* Optional (if FONT_EXTRA_INDEX is not Lisp_Save_Value).
 556      Free FONT_EXTRA_INDEX field of FONT_ENTITY.  */
 557   void (*free_entity) (Lisp_Object font_entity);
 558
 559   /* Open a font specified by FONT_ENTITY on frame F.  If the font is
 560      scalable, open it with PIXEL_SIZE.  */
 561   Lisp_Object (*open) (struct frame *f, Lisp_Object font_entity,
 562                        int pixel_size);
 563
 564   /* Close FONT.  NOTE: this can be called by GC.  */
 565   void (*close) (struct font *font);
 566
 567   /* Optional (if FACE->extra is not used).
 568      Prepare FACE for displaying characters by FONT on frame F by
 569      storing some data in FACE->extra.  If successful, return 0.
 570      Otherwise, return -1.  */
 571   int (*prepare_face) (struct frame *f, struct face *face);
 572
 573   /* Optional.
 574      Done FACE for displaying characters by FACE->font on frame F.  */
 575   void (*done_face) (struct frame *f, struct face *face);
 576
 577   /* Optional.
 578      If FONT (FONT-ENTITY or FONT-OBJECT) has a glyph for character C
 579      (Unicode code point), return 1.  If not, return 0.  If FONT is
 580      FONT-ENTITY and it must be opened to check it, return -1.  */
 581   int (*has_char) (Lisp_Object font, int c);
 582
 583   /* Return a glyph code of FONT for character C (Unicode code point).
 584      If FONT doesn't have such a glyph, return FONT_INVALID_CODE.  */
 585   unsigned (*encode_char) (struct font *font, int c);
 586
 587   /* Compute the total metrics of the NGLYPHS glyphs specified by
 588      the font FONT and the sequence of glyph codes CODE, and store the
 589      result in METRICS.  */
 590   int (*text_extents) (struct font *font,
 591                        unsigned *code, int nglyphs,
 592                        struct font_metrics *metrics);
 593
 594 #ifdef HAVE_WINDOW_SYSTEM
 595
 596   /* Optional.
 597      Draw glyphs between FROM and TO of S->char2b at (X Y) pixel
 598      position of frame F with S->FACE and S->GC.  If WITH_BACKGROUND,
 599      fill the background in advance.  It is assured that WITH_BACKGROUND
 600      is false when (FROM > 0 || TO < S->nchars).  */
 601   int (*draw) (struct glyph_string *s, int from, int to,
 602                int x, int y, bool with_background);
 603
 604   /* Optional.
 605      Store bitmap data for glyph-code CODE of FONT in BITMAP.  It is
 606      intended that this method is called from the other font-driver
 607      for actual drawing.  */
 608   int (*get_bitmap) (struct font *font, unsigned code,
 609                      struct font_bitmap *bitmap,
 610                      int bits_per_pixel);
 611
 612   /* Optional.
 613      Free bitmap data in BITMAP.  */
 614   void (*free_bitmap) (struct font *font, struct font_bitmap *bitmap);
 615
 616 #endif /* HAVE_WINDOW_SYSTEM */
 617
 618   /* Optional.
 619      Return an outline data for glyph-code CODE of FONT.  The format
 620      of the outline data depends on the font-driver.  */
 621   void *(*get_outline) (struct font *font, unsigned code);
 622
 623   /* Optional.
 624      Free OUTLINE (that is obtained by the above method).  */
 625   void (*free_outline) (struct font *font, void *outline);
 626
 627   /* Optional.
 628      Get coordinates of the INDEXth anchor point of the glyph whose
 629      code is CODE.  Store the coordinates in *X and *Y.  Return 0 if
 630      the operations was successful.  Otherwise return -1.  */
 631   int (*anchor_point) (struct font *font, unsigned code, int index,
 632                        int *x, int *y);
 633
 634   /* Optional.
 635      Return a list describing which scripts/languages FONT
 636      supports by which GSUB/GPOS features of OpenType tables.  */
 637   Lisp_Object (*otf_capability) (struct font *font);
 638
 639   /* Optional.
 640      Apply FONT's OTF-FEATURES to the glyph string.
 641
 642      FEATURES specifies which OTF features to apply in this format:
 643         (SCRIPT LANGSYS GSUB-FEATURE GPOS-FEATURE)
 644      See the documentation of `font-drive-otf' for the details.
 645
 646      This method applies the specified features to the codes in the
 647      elements of GSTRING-IN (between FROMth and TOth).  The output
 648      codes are stored in GSTRING-OUT at the IDXth element and the
 649      following elements.
 650
 651      Return the number of output codes.  If none of the features are
 652      applicable to the input data, return 0.  If GSTRING-OUT is too
 653      short, return -1.  */
 654   int (*otf_drive) (struct font *font, Lisp_Object features,
 655                     Lisp_Object gstring_in, int from, int to,
 656                     Lisp_Object gstring_out, int idx, bool alternate_subst);
 657
 658   /* Optional.
 659      Make the font driver ready for frame F.  Usually this function
 660      makes some data specific to F and stores it in F by calling
 661      font_put_frame_data ().  */
 662   int (*start_for_frame) (struct frame *f);
 663
 664   /* Optional.
 665      End using the driver for frame F.  Usually this function free
 666      some data stored for F.  */
 667   int (*end_for_frame) (struct frame *f);
 668
 669   /* Optional.
 670
 671      Shape text in GSTRING.  See the docstring of
 672      `composition-get-gstring' for the format of GSTRING.  If the
 673      (N+1)th element of GSTRING is nil, input of shaping is from the
 674      1st to (N)th elements.  In each input glyph, FROM, TO, CHAR, and
 675      CODE are already set.
 676
 677      This function updates all fields of the input glyphs.  If the
 678      output glyphs (M) are more than the input glyphs (N), (N+1)th
 679      through (M)th elements of GSTRING are updated possibly by making
 680      a new glyph object and storing it in GSTRING.  If (M) is greater
 681      than the length of GSTRING, nil should be return.  In that case,
 682      this function is called again with the larger GSTRING.  */
 683   Lisp_Object (*shape) (Lisp_Object lgstring);
 684
 685   /* Optional.
 686
 687      If FONT is usable on frame F, return 0.  Otherwise return -1.
 688      This method is used only for debugging.  If this method is NULL,
 689      Emacs assumes that the font is usable on any frame.  */
 690   int (*check) (struct frame *f, struct font *font);
 691
 692   /* Optional.
 693
 694      Return the number of variation glyphs of character C supported by
 695      FONT.  VARIATIONS is an array of 256 elements.  If the variation
 696      selector N (1..256) defines a glyph, that glyph code is stored in
 697      the (N-1)th element of VARIATIONS.  */
 698   int (*get_variation_glyphs) (struct font *font,
 699                                int c, unsigned variations[256]);
 700
 701   void (*filter_properties) (Lisp_Object font, Lisp_Object properties);
 702
 703   /* Optional.
 704
 705      Return non-zero if FONT_OBJECT can be used as a (cached) font
 706      for ENTITY on frame F.  */
 707   bool (*cached_font_ok) (struct frame *f,
 708                           Lisp_Object font_object,
 709                           Lisp_Object entity);
 710 };
 711
 712
 713 /* Chain of font drivers.  There's one global font driver list
 714    (font_driver_list in font.c).  In addition, each frame has
 715    its own font driver list at F->font_driver_list.  */
 716
 717 struct font_driver_list
 718 {
 719   /* True iff this driver is currently used.  It is ignored in the global
 720      font driver list.*/
 721   bool on;
 722   /* Pointer to the font driver.  */
 723   struct font_driver *driver;
 724   /* Pointer to the next element of the chain.  */
 725   struct font_driver_list *next;
 726 };
 727
 728
 729 /* Chain of arbitrary data specific to each font driver.
 730    Each frame has its own font data list at F->font_data_list.  */
 731
 732 struct font_data_list
 733 {
 734   /* Pointer to the font driver.  */
 735   struct font_driver *driver;
 736   /* Data specific to the font driver.  */
 737   void *data;
 738   /* Pointer to the next element of the chain.  */
 739   struct font_data_list *next;
 740 };
 741
 742 extern Lisp_Object copy_font_spec (Lisp_Object);
 743 extern Lisp_Object merge_font_spec (Lisp_Object, Lisp_Object);
 744
 745 extern Lisp_Object font_make_entity (void);
 746 extern Lisp_Object font_make_object (int, Lisp_Object, int);
 747
 748 extern Lisp_Object find_font_encoding (Lisp_Object);
 749 extern int font_registry_charsets (Lisp_Object, struct charset **,
 750                                    struct charset **);
 751 extern int font_style_to_value (enum font_property_index prop,
 752                                 Lisp_Object name, bool noerror);
 753 extern Lisp_Object font_style_symbolic (Lisp_Object font,
 754                                         enum font_property_index prop,
 755                                         bool for_face);
 756
 757 extern bool font_match_p (Lisp_Object spec, Lisp_Object font);
 758 extern Lisp_Object font_list_entities (struct frame *, Lisp_Object);
 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 (struct frame *, 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 (struct frame *f, Lisp_Object *lface,
 768                                         Lisp_Object spec, int c);
 769 extern Lisp_Object font_open_for_lface (struct frame *f, Lisp_Object entity,
 770                                         Lisp_Object *lface,
 771                                         Lisp_Object spec);
 772 extern Lisp_Object font_load_for_lface (struct frame *f, Lisp_Object *lface,
 773                                         Lisp_Object spec);
 774 extern void font_prepare_for_face (struct frame *f, struct face *face);
 775 extern void font_done_for_face (struct frame *f, struct face *face);
 776 extern void clear_font_cache (struct frame *);
 777
 778 extern Lisp_Object font_open_by_spec (struct frame *f, Lisp_Object spec);
 779 extern Lisp_Object font_open_by_name (struct frame *f, Lisp_Object name);
 780
 781 extern Lisp_Object font_intern_prop (const char *str, ptrdiff_t len,
 782                                      bool force_symbol);
 783 extern void font_update_sort_order (int *order);
 784
 785 extern void font_parse_family_registry (Lisp_Object family,
 786                                         Lisp_Object registry,
 787                                         Lisp_Object spec);
 788
 789 extern int font_parse_xlfd (char *name, ptrdiff_t len, Lisp_Object font);
 790 extern ptrdiff_t font_unparse_xlfd (Lisp_Object font, int pixel_size,
 791                                     char *name, int bytes);
 792 extern int font_unparse_fcname (Lisp_Object font, int pixel_size,
 793                                 char *name, int bytes);
 794 extern void register_font_driver (struct font_driver *driver, struct frame *f);
 795 extern void free_font_driver_list (struct frame *f);
 796 #ifdef ENABLE_CHECKING
 797 extern bool valid_font_driver (struct font_driver *);
 798 #else
 799 INLINE bool
 800 valid_font_driver (struct font_driver *d)
 801 {
 802   return true;
 803 }
 804 #endif
 805 extern Lisp_Object font_update_drivers (struct frame *f, Lisp_Object list);
 806 extern Lisp_Object font_range (ptrdiff_t, ptrdiff_t, ptrdiff_t *,
 807                                struct window *, struct face *,
 808                                Lisp_Object);
 809 extern void font_fill_lglyph_metrics (Lisp_Object, Lisp_Object);
 810
 811 extern Lisp_Object font_put_extra (Lisp_Object font, Lisp_Object prop,
 812                                    Lisp_Object val);
 813
 814 extern int font_put_frame_data (struct frame *f,
 815                                 struct font_driver *driver,
 816                                 void *data);
 817 extern void *font_get_frame_data (struct frame *f,
 818                                   struct font_driver *driver);
 819
 820 extern void font_filter_properties (Lisp_Object font,
 821                                     Lisp_Object alist,
 822                                     const char *const boolean_properties[],
 823                                     const char *const non_boolean_properties[]);
 824
 825 #ifdef HAVE_FREETYPE
 826 extern struct font_driver ftfont_driver;
 827 extern void syms_of_ftfont (void);
 828 #endif  /* HAVE_FREETYPE */
 829 #ifdef HAVE_X_WINDOWS
 830 extern struct font_driver xfont_driver;
 831 extern void syms_of_xfont (void);
 832 extern void syms_of_ftxfont (void);
 833 #ifdef HAVE_XFT
 834 extern Lisp_Object Qxft;
 835 extern struct font_driver xftfont_driver;
 836 extern void syms_of_xftfont (void);
 837 #elif defined HAVE_FREETYPE
 838 extern struct font_driver ftxfont_driver;
 839 #endif
 840 #ifdef HAVE_BDFFONT
 841 extern void syms_of_bdffont (void);
 842 #endif  /* HAVE_BDFFONT */
 843 #endif  /* HAVE_X_WINDOWS */
 844 #ifdef HAVE_NTGUI
 845 extern struct font_driver w32font_driver;
 846 extern struct font_driver uniscribe_font_driver;
 847 extern void syms_of_w32font (void);
 848 #endif  /* HAVE_NTGUI */
 849 #ifdef HAVE_NS
 850 extern Lisp_Object Qfontsize;
 851 extern struct font_driver nsfont_driver;
 852 extern void syms_of_nsfont (void);
 853 extern void syms_of_macfont (void);
 854 #endif  /* HAVE_NS */
 855
 856 #ifndef FONT_DEBUG
 857 #define FONT_DEBUG
 858 #endif
 859
 860 extern Lisp_Object QCfoundry;
 861
 862 extern void font_add_log (const char *, Lisp_Object, Lisp_Object);
 863 extern void font_deferred_log (const char *, Lisp_Object, Lisp_Object);
 864
 865 #define FONT_ADD_LOG(ACTION, ARG, RESULT)       \
 866   do {                                          \
 867     if (! EQ (Vfont_log, Qt))                   \
 868       font_add_log ((ACTION), (ARG), (RESULT)); \
 869   } while (false)
 870
 871 #define FONT_DEFERRED_LOG(ACTION, ARG, RESULT)          \
 872   do {                                                  \
 873     if (! EQ (Vfont_log, Qt))                           \
 874       font_deferred_log ((ACTION), (ARG), (RESULT));    \
 875   } while (false)
 876
 877 INLINE_HEADER_END
 878
 879 #endif  /* not EMACS_FONT_H */