src/fontset.h

   1 /* Header for fontset handler.
   2    Copyright (C) 1998, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   3    Copyright (C) 1995, 1997, 2000
   4      National Institute of Advanced Industrial Science and Technology (AIST)
   5      Registration Number H14PRO021
   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 2, or (at your option)
  12 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; see the file COPYING.  If not, write to
  21 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  22 Boston, MA 02110-1301, USA.  */
  23
  24 #ifndef EMACS_FONTSET_H
  25 #define EMACS_FONTSET_H
  26
  27 /* This data type is used for the font_table field of window system
  28    depending data area (e.g. struct x_display_info on X window).  */
  29
  30 struct font_info
  31 {
  32   /* Pointer to window system dependent font structure.  On X window,
  33      this value should be coerced to (XFontStruct *).  */
  34   void *font;
  35
  36   /* Index number of the font.  */
  37   int font_idx;
  38
  39   /* Name to be used to find the font.  */
  40   char *name;
  41
  42   /* Full name of the font given by a window system.  */
  43   char *full_name;
  44
  45   /* Charset of characters displayed by the font.  */
  46   int charset;
  47
  48 #ifdef WINDOWSNT
  49   /* Codepage of characters that will be displayed by the font.  */
  50   int codepage;
  51 #endif
  52
  53   /* Maximum bound width over all existing characters of the font.  On
  54      X window, this is same as (font->max_bounds.width) */
  55   int size;
  56
  57   /* Height of the font.  On X window, this is the same as
  58      (font->ascent + font->descent).  */
  59   int height;
  60
  61   /* Width of the space glyph of the font.  */
  62   int space_width;
  63
  64   /* Average width of glyphs in the font.  */
  65   int average_width;
  66
  67   /* 1 iff `vertical-centering-font-regexp' matches this font name.
  68      In this case, we render characters at vartical center positions
  69      of lines.  */
  70   int vertical_centering;
  71
  72   /* Encodings of the font indexed by CHARSET.  The value is one of
  73      0, 1, 2, or 3:
  74         0: code points 0x20..0x7F or 0x2020..0x7F7F are used
  75         1: code points 0xA0..0xFF or 0xA0A0..0xFFFF are used
  76         2: code points 0x20A0..0x7FFF are used
  77         3: code points 0xA020..0xFF7F are used
  78      For instance, ASCII and Latin-1 characters may use the same font
  79      but different code points (ASCII uses 0x20..0x7F and Latin-1 uses
  80      0xA0..0xFF).
  81
  82      If the value can't be decided from information of the font, we
  83      consult `font-encoding-alist' to get of the corresponding charset
  84      whose default value is defined in lisp/fontset.el.  Since there's
  85      no charset whose id is 1, we use encoding[1] to store the
  86      encoding information decided by the font itself.
  87
  88      If the member `font_encoder' is not NULL, this member is ignored.
  89   */
  90   unsigned char encoding[MAX_CHARSET + 1];
  91
  92   /* The baseline position of a font is normally `ascent' value of the
  93      font.  However, there exists many fonts which don't set `ascent'
  94      an appropriate value to be used as baseline position.  This is
  95      typical in such ASCII fonts which are designed to be used with
  96      Chinese, Japanese, Korean characters.  When we use mixture of
  97      such fonts and normal fonts (having correct `ascent' value), a
  98      display line gets very ugly.  Since we have no way to fix it
  99      automatically, it is users responsibility to supply well designed
 100      fonts or correct `ascent' value of fonts.  But, the latter
 101      requires heavy work (modifying all bitmap data in BDF files).
 102      So, Emacs accepts a private font property
 103      `_MULE_BASELINE_OFFSET'.  If a font has this property, we
 104      calculate the baseline position by subtracting the value from
 105      `ascent'.  In other words, the value indicates how many bits
 106      higher we should draw a character of the font than normal ASCII
 107      text for a better looking.
 108
 109      We also have to consider the fact that the concept of `baseline'
 110      differs among languages to which each character belongs.  For
 111      instance, baseline should be at the bottom most position of all
 112      glyphs for Chinese, Japanese, and Korean.  But, many of existing
 113      fonts for those characters doesn't have correct `ascent' values
 114      because they are designed to be used with ASCII fonts.  To
 115      display characters of different language on the same line, the
 116      best way will be to arrange them in the middle of the line.  So,
 117      in such a case, again, we utilize the font property
 118      `_MULE_BASELINE_OFFSET'.  If the value is larger than `ascent' we
 119      calculate baseline so that a character is arranged in the middle
 120      of a line.  */
 121
 122   int baseline_offset;
 123
 124   /* Non zero means a character should be composed at a position
 125      relative to the height (or depth) of previous glyphs in the
 126      following cases:
 127         (1) The bottom of the character is higher than this value.  In
 128         this case, the character is drawn above the previous glyphs.
 129         (2) The top of the character is lower than 0 (i.e. baseline
 130         height).  In this case, the character is drawn beneath the
 131         previous glyphs.
 132
 133      This value is taken from a private font property
 134      `_MULE_RELATIVE_COMPOSE' which is introduced by Emacs.  */
 135   int relative_compose;
 136
 137   /* Non zero means an ascent value to be used for a character
 138      registered in char-table `use-default-ascent'.  */
 139   int default_ascent;
 140
 141   /* CCL program to calculate code points of the font.  */
 142   struct ccl_program *font_encoder;
 143 };
 144
 145 /* A value which may appear in the member `encoding' of struch
 146    font_info indicating that a font itself doesn't tell which encoding
 147    to be used.  */
 148 #define FONT_ENCODING_NOT_DECIDED 255
 149
 150 /* Forward declaration for prototypes.  */
 151 struct frame;
 152
 153 /* The following six are window system dependent functions.
 154    Initialization routine of each window system should set appropriate
 155    functions to these variables.  For instance, in case of X window,
 156    x_term_init does this.  */
 157
 158 /* Return a pointer to struct font_info of font FONT_IDX of frame F.  */
 159 extern struct font_info *(*get_font_info_func) P_ ((struct frame *f,
 160                                                     int font_idx));
 161
 162 /* Return a list of font names which matches PATTERN.  See the document of
 163    `x-list-fonts' for more detail.  */
 164 extern Lisp_Object (*list_fonts_func) P_ ((struct frame *f,
 165                                            Lisp_Object pattern,
 166                                            int size,
 167                                            int maxnames));
 168
 169 /* Load a font named NAME for frame F and return a pointer to the
 170    information of the loaded font.  If loading is failed, return -1.  */
 171 extern struct font_info *(*load_font_func) P_ ((struct frame *f,
 172                                                 char *name, int));
 173
 174 /* Return a pointer to struct font_info of a font named NAME for frame F.
 175    If no such font is loaded, return NULL.  */
 176 extern struct font_info *(*query_font_func) P_ ((struct frame *f, char *name));
 177
 178 /* Additional function for setting fontset or changing fontset
 179    contents of frame F.  This function may change the coordinate of
 180    the frame.  */
 181 extern void (*set_frame_fontset_func) P_ ((struct frame *f, Lisp_Object arg,
 182                                            Lisp_Object oldval));
 183
 184 /* To find a CCL program, fs_load_font calls this function.
 185    The argument is a pointer to the struct font_info.
 186    This function set the memer `encoder' of the structure.  */
 187 extern void (*find_ccl_program_func) P_ ((struct font_info *));
 188
 189 /* Check if any window system is used now.  */
 190 extern void (*check_window_system_func) P_ ((void));
 191
 192 struct face;
 193
 194 extern void free_face_fontset P_ ((FRAME_PTR, struct face *));
 195 extern Lisp_Object fontset_font_pattern P_ ((FRAME_PTR, int, int));
 196 extern int face_suitable_for_char_p P_ ((struct face *, int));
 197 extern int face_for_char P_ ((FRAME_PTR, struct face *, int));
 198 extern int make_fontset_for_ascii_face P_ ((FRAME_PTR, int));
 199 extern void set_default_ascii_font P_ ((Lisp_Object));
 200 extern struct font_info *fs_load_font P_ ((struct frame *, int, char *, int,
 201                                            struct face *));
 202 extern int fs_query_fontset P_ ((Lisp_Object, int));
 203 EXFUN (Fquery_fontset, 2);
 204 extern Lisp_Object list_fontsets P_ ((struct frame *, Lisp_Object, int));
 205
 206 extern Lisp_Object Qfontset;
 207 extern Lisp_Object Vuse_default_ascent;
 208 extern Lisp_Object Vignore_relative_composition;
 209 extern Lisp_Object Valternate_fontname_alist;
 210 extern Lisp_Object Vfontset_alias_alist;
 211 extern Lisp_Object Vvertical_centering_font_regexp;
 212
 213 /* Load a font named FONTNAME for displaying character C.  All fonts
 214    for frame F is stored in a table pointed by FONT_TABLE.  Return a
 215    pointer to the struct font_info of the loaded font.  If loading
 216    fails, return 0; If FONTNAME is NULL, the name is taken from the
 217    information of FONTSET.  If FONTSET is given, try to load a font
 218    whose size matches that of FONTSET, and, the font index is stored
 219    in the table for FONTSET.  */
 220
 221 #define FS_LOAD_FONT(f, c, fontname, fontset)  \
 222   fs_load_font (f, c, fontname, fontset, NULL)
 223
 224 #define FS_LOAD_FACE_FONT(f, c, fontname, face) \
 225   fs_load_font (f, c, fontname, -1, face)
 226
 227 /* Return an immutable id for font_info FONT_INFO on frame F.  The
 228    reason for this macro is hat one cannot hold pointers to font_info
 229    structures in other data structures, because the table is
 230    reallocated in x_list_fonts.  */
 231
 232 #define FONT_INFO_ID(F, FONT_INFO) \
 233      (FONT_INFO) - (FRAME_X_DISPLAY_INFO ((F))->font_table)
 234
 235 /* Given a font_info id ID, return a pointer to the font_info
 236    structure on frame F.  If ID is invalid, return null.  */
 237
 238 #define FONT_INFO_FROM_ID(F, ID)                                        \
 239      (((ID) >= 0 && (ID) < FRAME_X_DISPLAY_INFO ((F))->font_table_size) \
 240       ? (FRAME_X_DISPLAY_INFO ((F))->font_table + (ID))                 \
 241       : 0)
 242
 243 extern Lisp_Object fontset_name P_ ((int));
 244 extern Lisp_Object fontset_ascii P_ ((int));
 245 extern int fontset_height P_ ((int));
 246
 247 #endif /* EMACS_FONTSET_H */
 248
 249 /* arch-tag: c27cef7b-3cab-488a-8398-7a4daa96bb77
 250    (do not change this comment) */