src/fontset.h

   1 /* Header for fontset handler.
   2    Copyright (C) 1995, 1997, 2000 Electrotechnical Laboratory, JAPAN.
   3    Licensed to the Free Software Foundation.
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU Emacs is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Emacs; see the file COPYING.  If not, write to
  19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 #ifndef EMACS_FONTSET_H
  23 #define EMACS_FONTSET_H
  24
  25 /* This data type is used for the font_table field of window system
  26    depending data area (e.g. struct x_display_info on X window).  */
  27
  28 struct font_info
  29 {
  30   /* Pointer to window system dependent font structure.  On X window,
  31      this value should be coerced to (XFontStruct *).  */
  32   void *font;
  33
  34   /* Index number of the font.  */
  35   int font_idx;
  36
  37   /* Name to be used to find the font.  */
  38   char *name;
  39
  40   /* Full name of the font given by a window system.  */
  41   char *full_name;
  42
  43   /* Charset of characters displayed by the font.  */
  44   int charset;
  45
  46 #ifdef WINDOWSNT
  47   /* Codepage of characters that will be displayed by the font.  */
  48   int codepage;
  49 #endif
  50
  51   /* Maximum bound width over all existing characters of the font.  On
  52      X window, this is same as (font->max_bounds.width) */
  53   int size;
  54
  55   /* Height of the font.  On X window, this is the same as
  56      (font->ascent + font->descent).  */
  57   int height;
  58
  59   /* 1 iff `vertical-centering-font-regexp' matches this font name.
  60      In this case, we render characters at vartical center positions
  61      of lines.  */
  62   int vertical_centering;
  63
  64   /* Encodings of the font indexed by CHARSET.  The value is one of
  65      0, 1, 2, or 3:
  66         0: code points 0x20..0x7F or 0x2020..0x7F7F are used
  67         1: code points 0xA0..0xFF or 0xA0A0..0xFFFF are used
  68         2: code points 0x20A0..0x7FFF are used
  69         3: code points 0xA020..0xFF7F are used
  70      For instance, ASCII and Latin-1 characters may use the same font
  71      but different code points (ASCII uses 0x20..0x7F and Latin-1 uses
  72      0xA0..0xFF).
  73
  74      If the value can't be decided from information of the font, we
  75      consult `font-encoding-alist' to get of the corresponding charset
  76      whose default value is defined in lisp/fontset.el.  Since there's
  77      no charset whose id is 1, we use encoding[1] to store the
  78      encoding information decided by the font itself.
  79
  80      If the member `font_encoder' is not NULL, this member is ignored.
  81   */
  82   unsigned char encoding[MAX_CHARSET + 1];
  83
  84   /* The baseline position of a font is normally `ascent' value of the
  85      font.  However, there exists many fonts which don't set `ascent'
  86      an appropriate value to be used as baseline position.  This is
  87      typical in such ASCII fonts which are designed to be used with
  88      Chinese, Japanese, Korean characters.  When we use mixture of
  89      such fonts and normal fonts (having correct `ascent' value), a
  90      display line gets very ugly.  Since we have no way to fix it
  91      automatically, it is users responsibility to supply well designed
  92      fonts or correct `ascent' value of fonts.  But, the latter
  93      requires heavy work (modifying all bitmap data in BDF files).
  94      So, Emacs accepts a private font property
  95      `_MULE_BASELINE_OFFSET'.  If a font has this property, we
  96      calculate the baseline position by subtracting the value from
  97      `ascent'.  In other words, the value indicates how many bits
  98      higher we should draw a character of the font than normal ASCII
  99      text for a better looking.
 100
 101      We also have to consider the fact that the concept of `baseline'
 102      differs among languages to which each character belongs.  For
 103      instance, baseline should be at the bottom most position of all
 104      glyphs for Chinese, Japanese, and Korean.  But, many of existing
 105      fonts for those characters doesn't have correct `ascent' values
 106      because they are designed to be used with ASCII fonts.  To
 107      display characters of different language on the same line, the
 108      best way will be to arrange them in the middle of the line.  So,
 109      in such a case, again, we utilize the font property
 110      `_MULE_BASELINE_OFFSET'.  If the value is larger than `ascent' we
 111      calculate baseline so that a character is arranged in the middle
 112      of a line.  */
 113
 114   int baseline_offset;
 115
 116   /* Non zero means a character should be composed at a position
 117      relative to the height (or depth) of previous glyphs in the
 118      following cases:
 119         (1) The bottom of the character is higher than this value.  In
 120         this case, the character is drawn above the previous glyphs.
 121         (2) The top of the character is lower than 0 (i.e. baseline
 122         height).  In this case, the character is drawn beneath the
 123         previous glyphs.
 124
 125      This value is taken from a private font property
 126      `_MULE_RELATIVE_COMPOSE' which is introduced by Emacs.  */
 127   int relative_compose;
 128
 129   /* Non zero means an ascent value to be used for a character
 130      registered in char-table `use-default-ascent'.  */
 131   int default_ascent;
 132
 133   /* CCL program to calculate code points of the font.  */
 134   struct ccl_program *font_encoder;
 135 };
 136
 137 /* A value which may appear in the member `encoding' of struch
 138    font_info indicating that a font itself doesn't tell which encoding
 139    to be used.  */
 140 #define FONT_ENCODING_NOT_DECIDED 255
 141
 142 /* Forward declaration for prototypes.  */
 143 struct frame;
 144
 145 /* The following six are window system dependent functions.
 146    Initialization routine of each window system should set appropriate
 147    functions to these variables.  For instance, in case of X window,
 148    x_term_init does this.  */
 149
 150 /* Return a pointer to struct font_info of font FONT_IDX of frame F.  */
 151 extern struct font_info *(*get_font_info_func) P_ ((struct frame *f,
 152                                                     int font_idx));
 153
 154 /* Return a list of font names which matches PATTERN.  See the document of
 155    `x-list-fonts' for more detail.  */
 156 extern Lisp_Object (*list_fonts_func) P_ ((struct frame *f,
 157                                            Lisp_Object pattern,
 158                                            int size,
 159                                            int maxnames));
 160
 161 /* Load a font named NAME for frame F and return a pointer to the
 162    information of the loaded font.  If loading is failed, return -1.  */
 163 extern struct font_info *(*load_font_func) P_ ((struct frame *f,
 164                                                 char *name, int));
 165
 166 /* Return a pointer to struct font_info of a font named NAME for frame F.
 167    If no such font is loaded, return NULL.  */
 168 extern struct font_info *(*query_font_func) P_ ((struct frame *f, char *name));
 169
 170 /* Additional function for setting fontset or changing fontset
 171    contents of frame F.  This function may change the coordinate of
 172    the frame.  */
 173 extern void (*set_frame_fontset_func) P_ ((struct frame *f, Lisp_Object arg,
 174                                            Lisp_Object oldval));
 175
 176 /* To find a CCL program, fs_load_font calls this function.
 177    The argument is a pointer to the struct font_info.
 178    This function set the memer `encoder' of the structure.  */
 179 extern void (*find_ccl_program_func) P_ ((struct font_info *));
 180
 181 /* Check if any window system is used now.  */
 182 extern void (*check_window_system_func) P_ ((void));
 183
 184 struct face;
 185
 186 extern void free_face_fontset P_ ((FRAME_PTR, struct face *));
 187 extern Lisp_Object fontset_font_pattern P_ ((FRAME_PTR, int, int));
 188 extern int face_suitable_for_char_p P_ ((struct face *, int));
 189 extern int face_for_char P_ ((FRAME_PTR, struct face *, int));
 190 extern int make_fontset_for_ascii_face P_ ((FRAME_PTR, int));
 191 extern struct font_info *fs_load_font P_ ((struct frame *, int, char *, int,
 192                                            struct face *));
 193 extern int fs_query_fontset P_ ((Lisp_Object, int));
 194 EXFUN (Fquery_fontset, 2);
 195 extern Lisp_Object list_fontsets P_ ((struct frame *, Lisp_Object, int));
 196
 197 extern Lisp_Object Qfontset;
 198 extern Lisp_Object Vuse_default_ascent;
 199 extern Lisp_Object Vignore_relative_composition;
 200 extern Lisp_Object Valternate_fontname_alist;
 201 extern Lisp_Object Vfontset_alias_alist;
 202 extern Lisp_Object Vvertical_centering_font_regexp;
 203
 204 /* Load a font named FONTNAME for displaying character C.  All fonts
 205    for frame F is stored in a table pointed by FONT_TABLE.  Return a
 206    pointer to the struct font_info of the loaded font.  If loading
 207    fails, return 0; If FONTNAME is NULL, the name is taken from the
 208    information of FONTSET.  If FONTSET is given, try to load a font
 209    whose size matches that of FONTSET, and, the font index is stored
 210    in the table for FONTSET.  */
 211
 212 #define FS_LOAD_FONT(f, c, fontname, fontset)  \
 213   fs_load_font (f, c, fontname, fontset, NULL)
 214
 215 #define FS_LOAD_FACE_FONT(f, c, fontname, face) \
 216   fs_load_font (f, c, fontname, -1, face)
 217
 218 /* Return an immutable id for font_info FONT_INFO on frame F.  The
 219    reason for this macro is hat one cannot hold pointers to font_info
 220    structures in other data structures, because the table is
 221    reallocated in x_list_fonts.  */
 222
 223 #define FONT_INFO_ID(F, FONT_INFO) \
 224      (FONT_INFO) - (FRAME_X_DISPLAY_INFO ((F))->font_table)
 225
 226 /* Given a font_info id ID, return a pointer to the font_info
 227    structure on frame F.  If ID is invalid, return null.  */
 228
 229 #define FONT_INFO_FROM_ID(F, ID)                                        \
 230      (((ID) >= 0 && (ID) < FRAME_X_DISPLAY_INFO ((F))->font_table_size) \
 231       ? (FRAME_X_DISPLAY_INFO ((F))->font_table + (ID))                 \
 232       : 0)
 233
 234 extern Lisp_Object fontset_name P_ ((int));
 235 extern Lisp_Object fontset_ascii P_ ((int));
 236 extern int fontset_height P_ ((int));
 237
 238 #endif /* EMACS_FONTSET_H */