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