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