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 #ifdef HAVE_NS
 269   struct font_driver *driver;
 270 #endif
 271 };
 272
 273 /* A value which may appear in the member `encoding' of struct font
 274    indicating that a font itself doesn't tell which encoding to be
 275    used.  */
 276 #define FONT_ENCODING_NOT_DECIDED 255
 277
 278 /* Structure for a font-object.  */
 279
 280 struct font
 281 {
 282   struct vectorlike_header header;
 283
 284   /* All Lisp_Object components must come first.
 285      That ensures they are all aligned normally.  */
 286
 287   Lisp_Object props[FONT_OBJECT_MAX];
 288
 289   /* Beyond here, there should be no more Lisp_Object components.  */
 290
 291   /* Minimum and maximum glyph widths, in pixels.  Some font backends,
 292      such as xft, lack the information to easily compute minimum and
 293      maximum widths over all characters; in that case, these values
 294      are approximate.  */
 295   int min_width;
 296   int max_width;
 297
 298   /* By which pixel size the font is opened.  */
 299   int pixel_size;
 300
 301   /* Height of the font.  On X window, this is the same as
 302      (font->ascent + font->descent).  */
 303   int height;
 304
 305   /* Width of the space glyph of the font.  If the font doesn't have a
 306      SPACE glyph, the value is 0.  */
 307   int space_width;
 308
 309   /* Average width of glyphs in the font.  If the font itself doesn't
 310      have that information but has glyphs of ASCII characters, the
 311      value is the average width of those glyphs.  Otherwise, the value
 312      is 0.  */
 313   int average_width;
 314
 315   /* Ascent and descent of the font (in pixels).  */
 316   int ascent, descent;
 317
 318   /* The following members makes sense on graphic displays only.  */
 319
 320 #if defined (HAVE_WINDOW_SYSTEM)
 321
 322   /* The frame where the font was opened.  */
 323   struct frame *frame;
 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 /* 1 iff X is one of font-spec, font-entity, and font-object.  */
 434 #define FONTP(x) PSEUDOVECTORP (x, PVEC_FONT)
 435 /* 1 iff X is font-spec.  */
 436 #define FONT_SPEC_P(x)  \
 437   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_SPEC_MAX)
 438 /* 1 iff X is font-entity.  */
 439 #define FONT_ENTITY_P(x)        \
 440   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_ENTITY_MAX)
 441 /* 1 iff X is font-object.  */
 442 #define FONT_OBJECT_P(x)        \
 443   (FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_OBJECT_MAX)
 444
 445 /* 1 iff ENTITY can't be loaded.  */
 446 #define FONT_ENTITY_NOT_LOADABLE(entity)        \
 447   EQ (AREF (entity, FONT_OBJLIST_INDEX), Qt)
 448
 449 /* Flag ENTITY not loadable.  */
 450 #define FONT_ENTITY_SET_NOT_LOADABLE(entity)    \
 451   ASET (entity, FONT_OBJLIST_INDEX, Qt)
 452
 453
 454 /* Check macros for various font-related objects.  */
 455
 456 #define CHECK_FONT(x)   \
 457   do { if (! FONTP (x)) wrong_type_argument (Qfont, x); } while (0)
 458 #define CHECK_FONT_SPEC(x)      \
 459   do { if (! FONT_SPEC_P (x)) wrong_type_argument (Qfont_spec, x); } while (0)
 460 #define CHECK_FONT_ENTITY(x)    \
 461   do { if (! FONT_ENTITY_P (x)) wrong_type_argument (Qfont_entity, x); } while (0)
 462 #define CHECK_FONT_OBJECT(x)    \
 463   do { if (! FONT_OBJECT_P (x)) wrong_type_argument (Qfont_object, x); } while (0)
 464
 465 #define CHECK_FONT_GET_OBJECT(x, font)  \
 466   do {                                  \
 467     CHECK_FONT_OBJECT (x);              \
 468     font = XFONT_OBJECT (x);            \
 469   } while (0)
 470
 471 #define XFONT_SPEC(p)   \
 472   (eassert (FONT_SPEC_P (p)), (struct font_spec *) XUNTAG (p, Lisp_Vectorlike))
 473 #define XFONT_ENTITY(p) \
 474   (eassert (FONT_ENTITY_P (p)), \
 475    (struct font_entity *) XUNTAG (p, Lisp_Vectorlike))
 476 #define XFONT_OBJECT(p) \
 477   (eassert (FONT_OBJECT_P (p)), (struct font *) XUNTAG (p, Lisp_Vectorlike))
 478 #define XSETFONT(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_FONT))
 479
 480 /* Number of pt per inch (from the TeXbook).  */
 481 #define PT_PER_INCH 72.27
 482
 483 /* Return a pixel size (integer) corresponding to POINT size (double)
 484    on resolution DPI.  */
 485 #define POINT_TO_PIXEL(POINT, DPI) ((POINT) * (DPI) / PT_PER_INCH + 0.5)
 486
 487 /* Return a point size corresponding to POINT size (integer)
 488    on resolution DPI.  Note that though point size is a double, we expect
 489    it to be rounded to an int, so we add 0.5 here.  If the desired value
 490    is tenths of points (as in xfld specs), then the pixel size should
 491    be multiplied BEFORE the conversion to avoid magnifying the error.  */
 492 #define PIXEL_TO_POINT(PIXEL, DPI) ((PIXEL) * PT_PER_INCH / (DPI) + 0.5)
 493
 494 /* Ignore the difference of font pixel sizes less than or equal to
 495    this value.  */
 496 #define FONT_PIXEL_SIZE_QUANTUM 1
 497
 498 #define FONT_INVALID_CODE 0xFFFFFFFF
 499
 500 /* Font driver.  Members specified as "optional" can be NULL.  */
 501
 502 struct font_driver
 503 {
 504   /* Symbol indicating the type of the font-driver.  */
 505   Lisp_Object type;
 506
 507   /* True iff the font's foundry, family, and adstyle names are case
 508      sensitive.  */
 509   bool case_sensitive;
 510
 511   /* Return a cache of font-entities on frame F.  The cache must be a
 512      cons whose cdr part is the actual cache area.  */
 513   Lisp_Object (*get_cache) (struct frame *f);
 514
 515   /* List fonts exactly matching with FONT_SPEC on FRAME.  The value
 516      is a list of font-entities.  The font properties to be considered
 517      are: :foundry, :family, :adstyle, :registry, :script, :lang, and
 518      :otf.  See the function `font-spec' for their meanings.  Note
 519      that the last three properties are stored in FONT_EXTRA_INDEX
 520      slot of FONT_SPEC.
 521
 522      The returned value is a list of font-entities.  Each font-entity
 523      has :type property whose value is the same as the above `type'.
 524      It also has these properties if they are available from the
 525      corresponding font; :foundry, :family, :adstyle, :registry,
 526      :weight, :slant, :width, :size, :dpi, :spacing, :avgwidth.  If
 527      the font is scalable, :size and :avgwidth must be 0.
 528
 529      The `open' method of the same font-backend is called with one of
 530      the returned font-entities.  If the backend needs additional
 531      information to be used in `open' method, this method can add any
 532      Lispy value by the property :font-entity to the entities.
 533
 534      This and the following `match' are the only APIs that allocate
 535      font-entities.  */
 536   Lisp_Object (*list) (struct frame *frame, Lisp_Object font_spec);
 537
 538   /* Return a font-entity most closely matching with FONT_SPEC on
 539      FRAME.  Which font property to consider, and how to calculate the
 540      closeness is determined by the font backend, thus
 541      `face-font-selection-order' is ignored here.
 542
 543      The properties that the font-entity has is the same as `list'
 544      method.  */
 545   Lisp_Object (*match) (struct frame *f, Lisp_Object spec);
 546
 547   /* Optional.
 548      List available families.  The value is a list of family names
 549      (symbols).  */
 550   Lisp_Object (*list_family) (struct frame *f);
 551
 552   /* Optional (if FONT_EXTRA_INDEX is not Lisp_Save_Value).
 553      Free FONT_EXTRA_INDEX field of FONT_ENTITY.  */
 554   void (*free_entity) (Lisp_Object font_entity);
 555
 556   /* Open a font specified by FONT_ENTITY on frame F.  If the font is
 557      scalable, open it with PIXEL_SIZE.  */
 558   Lisp_Object (*open) (struct frame *f, Lisp_Object font_entity,
 559                        int pixel_size);
 560
 561   /* Close FONT.  NOTE: this can be called by GC.  */
 562   void (*close) (struct font *font);
 563
 564   /* Optional (if FACE->extra is not used).
 565      Prepare FACE for displaying characters by FONT on frame F by
 566      storing some data in FACE->extra.  If successful, return 0.
 567      Otherwise, return -1.  */
 568   int (*prepare_face) (struct frame *f, struct face *face);
 569
 570   /* Optional.
 571      Done FACE for displaying characters by FACE->font on frame F.  */
 572   void (*done_face) (struct frame *f, struct face *face);
 573
 574   /* Optional.
 575      If FONT (FONT-ENTITY or FONT-OBJECT) has a glyph for character C
 576      (Unicode code point), return 1.  If not, return 0.  If FONT is
 577      FONT-ENTITY and it must be opened to check it, return -1.  */
 578   int (*has_char) (Lisp_Object font, int c);
 579
 580   /* Return a glyph code of FONT for character C (Unicode code point).
 581      If FONT doesn't have such a glyph, return FONT_INVALID_CODE.  */
 582   unsigned (*encode_char) (struct font *font, int c);
 583
 584   /* Compute the total metrics of the NGLYPHS glyphs specified by
 585      the font FONT and the sequence of glyph codes CODE, and store the
 586      result in METRICS.  */
 587   int (*text_extents) (struct font *font,
 588                        unsigned *code, int nglyphs,
 589                        struct font_metrics *metrics);
 590
 591 #ifdef HAVE_WINDOW_SYSTEM
 592
 593   /* Optional.
 594      Draw glyphs between FROM and TO of S->char2b at (X Y) pixel
 595      position of frame F with S->FACE and S->GC.  If WITH_BACKGROUND,
 596      fill the background in advance.  It is assured that WITH_BACKGROUND
 597      is false when (FROM > 0 || TO < S->nchars).  */
 598   int (*draw) (struct glyph_string *s, int from, int to,
 599                int x, int y, bool with_background);
 600
 601   /* Optional.
 602      Store bitmap data for glyph-code CODE of FONT in BITMAP.  It is
 603      intended that this method is called from the other font-driver
 604      for actual drawing.  */
 605   int (*get_bitmap) (struct font *font, unsigned code,
 606                      struct font_bitmap *bitmap,
 607                      int bits_per_pixel);
 608
 609   /* Optional.
 610      Free bitmap data in BITMAP.  */
 611   void (*free_bitmap) (struct font *font, struct font_bitmap *bitmap);
 612
 613 #endif /* HAVE_WINDOW_SYSTEM */
 614
 615   /* Optional.
 616      Return an outline data for glyph-code CODE of FONT.  The format
 617      of the outline data depends on the font-driver.  */
 618   void *(*get_outline) (struct font *font, unsigned code);
 619
 620   /* Optional.
 621      Free OUTLINE (that is obtained by the above method).  */
 622   void (*free_outline) (struct font *font, void *outline);
 623
 624   /* Optional.
 625      Get coordinates of the INDEXth anchor point of the glyph whose
 626      code is CODE.  Store the coordinates in *X and *Y.  Return 0 if
 627      the operations was successful.  Otherwise return -1.  */
 628   int (*anchor_point) (struct font *font, unsigned code, int index,
 629                        int *x, int *y);
 630
 631   /* Optional.
 632      Return a list describing which scripts/languages FONT
 633      supports by which GSUB/GPOS features of OpenType tables.  */
 634   Lisp_Object (*otf_capability) (struct font *font);
 635
 636   /* Optional.
 637      Apply FONT's OTF-FEATURES to the glyph string.
 638
 639      FEATURES specifies which OTF features to apply in this format:
 640         (SCRIPT LANGSYS GSUB-FEATURE GPOS-FEATURE)
 641      See the documentation of `font-drive-otf' for the details.
 642
 643      This method applies the specified features to the codes in the
 644      elements of GSTRING-IN (between FROMth and TOth).  The output
 645      codes are stored in GSTRING-OUT at the IDXth element and the
 646      following elements.
 647
 648      Return the number of output codes.  If none of the features are
 649      applicable to the input data, return 0.  If GSTRING-OUT is too
 650      short, return -1.  */
 651   int (*otf_drive) (struct font *font, Lisp_Object features,
 652                     Lisp_Object gstring_in, int from, int to,
 653                     Lisp_Object gstring_out, int idx, bool alternate_subst);
 654
 655   /* Optional.
 656      Make the font driver ready for frame F.  Usually this function
 657      makes some data specific to F and stores it in F by calling
 658      font_put_frame_data ().  */
 659   int (*start_for_frame) (struct frame *f);
 660
 661   /* Optional.
 662      End using the driver for frame F.  Usually this function free
 663      some data stored for F.  */
 664   int (*end_for_frame) (struct frame *f);
 665
 666   /* Optional.
 667
 668      Shape text in GSTRING.  See the docstring of
 669      `composition-get-gstring' for the format of GSTRING.  If the
 670      (N+1)th element of GSTRING is nil, input of shaping is from the
 671      1st to (N)th elements.  In each input glyph, FROM, TO, CHAR, and
 672      CODE are already set.
 673
 674      This function updates all fields of the input glyphs.  If the
 675      output glyphs (M) are more than the input glyphs (N), (N+1)th
 676      through (M)th elements of GSTRING are updated possibly by making
 677      a new glyph object and storing it in GSTRING.  If (M) is greater
 678      than the length of GSTRING, nil should be return.  In that case,
 679      this function is called again with the larger GSTRING.  */
 680   Lisp_Object (*shape) (Lisp_Object lgstring);
 681
 682   /* Optional.
 683
 684      If FONT is usable on frame F, return 0.  Otherwise return -1.
 685      This method is used only for debugging.  If this method is NULL,
 686      Emacs assumes that the font is usable on any frame.  */
 687   int (*check) (struct frame *f, struct font *font);
 688
 689   /* Optional.
 690
 691      Return the number of variation glyphs of character C supported by
 692      FONT.  VARIATIONS is an array of 256 elements.  If the variation
 693      selector N (1..256) defines a glyph, that glyph code is stored in
 694      the (N-1)th element of VARIATIONS.  */
 695   int (*get_variation_glyphs) (struct font *font,
 696                                int c, unsigned variations[256]);
 697
 698   void (*filter_properties) (Lisp_Object font, Lisp_Object properties);
 699
 700   /* Optional.
 701
 702      Return non-zero if FONT_OBJECT can be used as a (cached) font
 703      for ENTITY on frame F.  */
 704   bool (*cached_font_ok) (struct frame *f,
 705                           Lisp_Object font_object,
 706                           Lisp_Object entity);
 707 };
 708
 709
 710 /* Chain of font drivers.  There's one global font driver list
 711    (font_driver_list in font.c).  In addition, each frame has
 712    its own font driver list at F->font_driver_list.  */
 713
 714 struct font_driver_list
 715 {
 716   /* True iff this driver is currently used.  It is ignored in the global
 717      font driver list.*/
 718   bool on;
 719   /* Pointer to the font driver.  */
 720   struct font_driver *driver;
 721   /* Pointer to the next element of the chain.  */
 722   struct font_driver_list *next;
 723 };
 724
 725
 726 /* Chain of arbitrary data specific to each font driver.
 727    Each frame has its own font data list at F->font_data_list.  */
 728
 729 struct font_data_list
 730 {
 731   /* Pointer to the font driver.  */
 732   struct font_driver *driver;
 733   /* Data specific to the font driver.  */
 734   void *data;
 735   /* Pointer to the next element of the chain.  */
 736   struct font_data_list *next;
 737 };
 738
 739 extern Lisp_Object copy_font_spec (Lisp_Object);
 740 extern Lisp_Object merge_font_spec (Lisp_Object, Lisp_Object);
 741
 742 extern Lisp_Object font_make_entity (void);
 743 extern Lisp_Object font_make_object (int, Lisp_Object, int);
 744 extern void font_close_object (Lisp_Object);
 745
 746 extern Lisp_Object find_font_encoding (Lisp_Object);
 747 extern int font_registry_charsets (Lisp_Object, struct charset **,
 748                                    struct charset **);
 749 extern int font_style_to_value (enum font_property_index prop,
 750                                 Lisp_Object name, bool noerror);
 751 extern Lisp_Object font_style_symbolic (Lisp_Object font,
 752                                         enum font_property_index prop,
 753                                         bool for_face);
 754
 755 extern bool font_match_p (Lisp_Object spec, Lisp_Object font);
 756 extern Lisp_Object font_list_entities (struct frame *, Lisp_Object);
 757
 758 extern Lisp_Object font_get_name (Lisp_Object font_object);
 759 extern Lisp_Object font_spec_from_name (Lisp_Object font_name);
 760 extern Lisp_Object font_get_frame (Lisp_Object font_object);
 761 extern int font_has_char (struct frame *, Lisp_Object, int);
 762
 763 extern void font_clear_prop (Lisp_Object *attrs,
 764                              enum font_property_index prop);
 765 extern Lisp_Object font_find_for_lface (struct frame *f, Lisp_Object *lface,
 766                                         Lisp_Object spec, int c);
 767 extern Lisp_Object font_open_for_lface (struct frame *f, Lisp_Object entity,
 768                                         Lisp_Object *lface,
 769                                         Lisp_Object spec);
 770 extern Lisp_Object font_load_for_lface (struct frame *f, Lisp_Object *lface,
 771                                         Lisp_Object spec);
 772 extern void font_prepare_for_face (struct frame *f, struct face *face);
 773 extern void font_done_for_face (struct frame *f, struct face *face);
 774 extern void clear_font_cache (struct frame *);
 775
 776 extern Lisp_Object font_open_by_spec (struct frame *f, Lisp_Object spec);
 777 extern Lisp_Object font_open_by_name (struct frame *f, Lisp_Object name);
 778
 779 extern Lisp_Object font_intern_prop (const char *str, ptrdiff_t len,
 780                                      bool force_symbol);
 781 extern void font_update_sort_order (int *order);
 782
 783 extern void font_parse_family_registry (Lisp_Object family,
 784                                         Lisp_Object registry,
 785                                         Lisp_Object spec);
 786
 787 extern int font_parse_xlfd (char *name, ptrdiff_t len, Lisp_Object font);
 788 extern ptrdiff_t font_unparse_xlfd (Lisp_Object font, int pixel_size,
 789                                     char *name, int bytes);
 790 extern int font_unparse_fcname (Lisp_Object font, int pixel_size,
 791                                 char *name, int bytes);
 792 extern void register_font_driver (struct font_driver *driver, struct frame *f);
 793 extern void free_font_driver_list (struct frame *f);
 794 extern Lisp_Object font_update_drivers (struct frame *f, Lisp_Object list);
 795 extern Lisp_Object font_range (ptrdiff_t, ptrdiff_t, ptrdiff_t *,
 796                                struct window *, struct face *,
 797                                Lisp_Object);
 798 extern void font_fill_lglyph_metrics (Lisp_Object, Lisp_Object);
 799
 800 extern Lisp_Object font_put_extra (Lisp_Object font, Lisp_Object prop,
 801                                    Lisp_Object val);
 802
 803 extern int font_put_frame_data (struct frame *f,
 804                                 struct font_driver *driver,
 805                                 void *data);
 806 extern void *font_get_frame_data (struct frame *f,
 807                                   struct font_driver *driver);
 808
 809 extern void font_filter_properties (Lisp_Object font,
 810                                     Lisp_Object alist,
 811                                     const char *const boolean_properties[],
 812                                     const char *const non_boolean_properties[]);
 813
 814 #ifdef HAVE_FREETYPE
 815 extern struct font_driver ftfont_driver;
 816 extern void syms_of_ftfont (void);
 817 #endif  /* HAVE_FREETYPE */
 818 #ifdef HAVE_X_WINDOWS
 819 extern struct font_driver xfont_driver;
 820 extern void syms_of_xfont (void);
 821 extern void syms_of_ftxfont (void);
 822 #ifdef HAVE_XFT
 823 extern Lisp_Object Qxft;
 824 extern struct font_driver xftfont_driver;
 825 extern void syms_of_xftfont (void);
 826 #elif defined HAVE_FREETYPE
 827 extern struct font_driver ftxfont_driver;
 828 #endif
 829 #ifdef HAVE_BDFFONT
 830 extern void syms_of_bdffont (void);
 831 #endif  /* HAVE_BDFFONT */
 832 #endif  /* HAVE_X_WINDOWS */
 833 #ifdef HAVE_NTGUI
 834 extern struct font_driver w32font_driver;
 835 extern struct font_driver uniscribe_font_driver;
 836 extern void syms_of_w32font (void);
 837 #endif  /* HAVE_NTGUI */
 838 #ifdef HAVE_NS
 839 extern Lisp_Object Qfontsize;
 840 extern struct font_driver nsfont_driver;
 841 extern void syms_of_nsfont (void);
 842 extern void syms_of_macfont (void);
 843 #endif  /* HAVE_NS */
 844
 845 #ifndef FONT_DEBUG
 846 #define FONT_DEBUG
 847 #endif
 848
 849 extern Lisp_Object QCfoundry;
 850
 851 extern void font_add_log (const char *, Lisp_Object, Lisp_Object);
 852 extern void font_deferred_log (const char *, Lisp_Object, Lisp_Object);
 853
 854 #define FONT_ADD_LOG(ACTION, ARG, RESULT)       \
 855   do {                                          \
 856     if (! EQ (Vfont_log, Qt))                   \
 857       font_add_log ((ACTION), (ARG), (RESULT)); \
 858   } while (0)
 859
 860 #define FONT_DEFERRED_LOG(ACTION, ARG, RESULT)          \
 861   do {                                                  \
 862     if (! EQ (Vfont_log, Qt))                           \
 863       font_deferred_log ((ACTION), (ARG), (RESULT));    \
 864   } while (0)
 865
 866 #endif  /* not EMACS_FONT_H */