src/fontset.h

   1 /* Header for fontset handler.
   2    Copyright (C) 1998, 2002, 2003, 2004, 2005,
   3                  2006 Free Software Foundation, Inc.
   4    Copyright (C) 1995, 1997, 2000
   5      National Institute of Advanced Industrial Science and Technology (AIST)
   6      Registration Number H14PRO021
   7
   8 This file is part of GNU Emacs.
   9
  10 GNU Emacs is free software; you can redistribute it and/or modify
  11 it under the terms of the GNU General Public License as published by
  12 the Free Software Foundation; either version 2, or (at your option)
  13 any later version.
  14
  15 GNU Emacs is distributed in the hope that it will be useful,
  16 but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 GNU General Public License for more details.
  19
  20 You should have received a copy of the GNU General Public License
  21 along with GNU Emacs; see the file COPYING.  If not, write to
  22 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  23 Boston, MA 02110-1301, USA.  */
  24
  25 #ifndef EMACS_FONTSET_H
  26 #define EMACS_FONTSET_H
  27
  28 /* This data type is used for the font_table field of window system
  29    depending data area (e.g. struct x_display_info on X window).  */
  30
  31 struct font_info
  32 {
  33   /* Pointer to window system dependent font structure.  On X window,
  34      this value should be coerced to (XFontStruct *).  */
  35   void *font;
  36
  37   /* Index number of the font.  */
  38   int font_idx;
  39
  40   /* Name to be used to find the font.  */
  41   char *name;
  42
  43   /* Full name of the font given by a window system.  */
  44   char *full_name;
  45
  46   /* Charset of characters displayed by the font.  */
  47   int charset;
  48
  49 #ifdef WINDOWSNT
  50   /* Codepage of characters that will be displayed by the font.  */
  51   int codepage;
  52 #endif
  53
  54   /* Maximum bound width over all existing characters of the font.  On
  55      X window, this is same as (font->max_bounds.width) */
  56   int size;
  57
  58   /* Height of the font.  On X window, this is the same as
  59      (font->ascent + font->descent).  */
  60   int height;
  61
  62   /* Width of the space glyph of the font.  */
  63   int space_width;
  64
  65   /* Average width of glyphs in the font.  */
  66   int average_width;
  67
  68   /* 1 iff `vertical-centering-font-regexp' matches this font name.
  69      In this case, we render characters at vartical center positions
  70      of lines.  */
  71   int vertical_centering;
  72
  73   /* Encodings of the font indexed by CHARSET.  The value is one of
  74      0, 1, 2, or 3:
  75         0: code points 0x20..0x7F or 0x2020..0x7F7F are used
  76         1: code points 0xA0..0xFF or 0xA0A0..0xFFFF are used
  77         2: code points 0x20A0..0x7FFF are used
  78         3: code points 0xA020..0xFF7F are used
  79      For instance, ASCII and Latin-1 characters may use the same font
  80      but different code points (ASCII uses 0x20..0x7F and Latin-1 uses
  81      0xA0..0xFF).
  82
  83      If the value can't be decided from information of the font, we
  84      consult `font-encoding-alist' to get of the corresponding charset
  85      whose default value is defined in lisp/fontset.el.  Since there's
  86      no charset whose id is 1, we use encoding[1] to store the
  87      encoding information decided by the font itself.
  88
  89      If the member `font_encoder' is not NULL, this member is ignored.
  90   */
  91   unsigned char encoding[MAX_CHARSET + 1];
  92
  93   /* The baseline position of a font is normally `ascent' value of the
  94      font.  However, there exists many fonts which don't set `ascent'
  95      an appropriate value to be used as baseline position.  This is
  96      typical in such ASCII fonts which are designed to be used with
  97      Chinese, Japanese, Korean characters.  When we use mixture of
  98      such fonts and normal fonts (having correct `ascent' value), a
  99      display line gets very ugly.  Since we have no way to fix it
 100      automatically, it is users responsibility to supply well designed
 101      fonts or correct `ascent' value of fonts.  But, the latter
 102      requires heavy work (modifying all bitmap data in BDF files).
 103      So, Emacs accepts a private font property
 104      `_MULE_BASELINE_OFFSET'.  If a font has this property, we
 105      calculate the baseline position by subtracting the value from
 106      `ascent'.  In other words, the value indicates how many bits
 107      higher we should draw a character of the font than normal ASCII
 108      text for a better looking.
 109
 110      We also have to consider the fact that the concept of `baseline'
 111      differs among languages to which each character belongs.  For
 112      instance, baseline should be at the bottom most position of all
 113      glyphs for Chinese, Japanese, and Korean.  But, many of existing
 114      fonts for those characters doesn't have correct `ascent' values
 115      because they are designed to be used with ASCII fonts.  To
 116      display characters of different language on the same line, the
 117      best way will be to arrange them in the middle of the line.  So,
 118      in such a case, again, we utilize the font property
 119      `_MULE_BASELINE_OFFSET'.  If the value is larger than `ascent' we
 120      calculate baseline so that a character is arranged in the middle
 121      of a line.  */
 122
 123   int baseline_offset;
 124
 125   /* Non zero means a character should be composed at a position
 126      relative to the height (or depth) of previous glyphs in the
 127      following cases:
 128         (1) The bottom of the character is higher than this value.  In
 129         this case, the character is drawn above the previous glyphs.
 130         (2) The top of the character is lower than 0 (i.e. baseline
 131         height).  In this case, the character is drawn beneath the
 132         previous glyphs.
 133
 134      This value is taken from a private font property
 135      `_MULE_RELATIVE_COMPOSE' which is introduced by Emacs.  */
 136   int relative_compose;
 137
 138   /* Non zero means an ascent value to be used for a character
 139      registered in char-table `use-default-ascent'.  */
 140   int default_ascent;
 141
 142   /* CCL program to calculate code points of the font.  */
 143   struct ccl_program *font_encoder;
 144 };
 145
 146 /* A value which may appear in the member `encoding' of struch
 147    font_info indicating that a font itself doesn't tell which encoding
 148    to be used.  */
 149 #define FONT_ENCODING_NOT_DECIDED 255
 150
 151 /* Forward declaration for prototypes.  */
 152 struct frame;
 153
 154 /* The following six are window system dependent functions.
 155    Initialization routine of each window system should set appropriate
 156    functions to these variables.  For instance, in case of X window,
 157    x_term_init does this.  */
 158
 159 /* Return a pointer to struct font_info of font FONT_IDX of frame F.  */
 160 extern struct font_info *(*get_font_info_func) P_ ((struct frame *f,
 161                                                     int font_idx));
 162
 163 /* Return a list of font names which matches PATTERN.  See the document of
 164    `x-list-fonts' for more detail.  */
 165 extern Lisp_Object (*list_fonts_func) P_ ((struct frame *f,
 166                                            Lisp_Object pattern,
 167                                            int size,
 168                                            int maxnames));
 169
 170 /* Load a font named NAME for frame F and return a pointer to the
 171    information of the loaded font.  If loading is failed, return -1.  */
 172 extern struct font_info *(*load_font_func) P_ ((struct frame *f,
 173                                                 char *name, int));
 174
 175 /* Return a pointer to struct font_info of a font named NAME for frame F.
 176    If no such font is loaded, return NULL.  */
 177 extern struct font_info *(*query_font_func) P_ ((struct frame *f, char *name));
 178
 179 /* Additional function for setting fontset or changing fontset
 180    contents of frame F.  This function may change the coordinate of
 181    the frame.  */
 182 extern void (*set_frame_fontset_func) P_ ((struct frame *f, Lisp_Object arg,
 183                                            Lisp_Object oldval));
 184
 185 /* To find a CCL program, fs_load_font calls this function.
 186    The argument is a pointer to the struct font_info.
 187    This function set the memer `encoder' of the structure.  */
 188 extern void (*find_ccl_program_func) P_ ((struct font_info *));
 189
 190 /* Check if any window system is used now.  */
 191 extern void (*check_window_system_func) P_ ((void));
 192
 193 struct face;
 194
 195 extern void free_face_fontset P_ ((FRAME_PTR, struct face *));
 196 extern Lisp_Object fontset_font_pattern P_ ((FRAME_PTR, int, int));
 197 extern int face_suitable_for_char_p P_ ((struct face *, int));
 198 extern int face_for_char P_ ((FRAME_PTR, struct face *, int));
 199 extern int make_fontset_for_ascii_face P_ ((FRAME_PTR, int));
 200 extern void set_default_ascii_font P_ ((Lisp_Object));
 201 extern struct font_info *fs_load_font P_ ((struct frame *, int, char *, int,
 202                                            struct face *));
 203 extern int fs_query_fontset P_ ((Lisp_Object, int));
 204 EXFUN (Fquery_fontset, 2);
 205 extern Lisp_Object list_fontsets P_ ((struct frame *, Lisp_Object, int));
 206
 207 extern Lisp_Object Qfontset;
 208 extern Lisp_Object Vuse_default_ascent;
 209 extern Lisp_Object Vignore_relative_composition;
 210 extern Lisp_Object Valternate_fontname_alist;
 211 extern Lisp_Object Vfontset_alias_alist;
 212 extern Lisp_Object Vvertical_centering_font_regexp;
 213
 214 /* Load a font named FONTNAME for displaying character C.  All fonts
 215    for frame F is stored in a table pointed by FONT_TABLE.  Return a
 216    pointer to the struct font_info of the loaded font.  If loading
 217    fails, return 0; If FONTNAME is NULL, the name is taken from the
 218    information of FONTSET.  If FONTSET is given, try to load a font
 219    whose size matches that of FONTSET, and, the font index is stored
 220    in the table for FONTSET.  */
 221
 222 #define FS_LOAD_FONT(f, c, fontname, fontset)  \
 223   fs_load_font (f, c, fontname, fontset, NULL)
 224
 225 #define FS_LOAD_FACE_FONT(f, c, fontname, face) \
 226   fs_load_font (f, c, fontname, -1, face)
 227
 228 /* Return an immutable id for font_info FONT_INFO on frame F.  The
 229    reason for this macro is hat one cannot hold pointers to font_info
 230    structures in other data structures, because the table is
 231    reallocated in x_list_fonts.  */
 232
 233 #define FONT_INFO_ID(F, FONT_INFO) \
 234      (FONT_INFO) - (FRAME_X_DISPLAY_INFO ((F))->font_table)
 235
 236 /* Given a font_info id ID, return a pointer to the font_info
 237    structure on frame F.  If ID is invalid, return null.  */
 238
 239 #define FONT_INFO_FROM_ID(F, ID)                                        \
 240      (((ID) >= 0 && (ID) < FRAME_X_DISPLAY_INFO ((F))->font_table_size) \
 241       ? (FRAME_X_DISPLAY_INFO ((F))->font_table + (ID))                 \
 242       : 0)
 243
 244 extern Lisp_Object fontset_name P_ ((int));
 245 extern Lisp_Object fontset_ascii P_ ((int));
 246 extern int fontset_height P_ ((int));
 247
 248 #endif /* EMACS_FONTSET_H */
 249
 250 /* arch-tag: c27cef7b-3cab-488a-8398-7a4daa96bb77
 251    (do not change this comment) */