src/fontset.h

   1 /* Header for fontset handler.
   2    Copyright (C) 1998, 2001, 2002, 2003, 2004, 2005,
   3                  2006, 2007  Free Software Foundation, Inc.
   4    Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   5      2005, 2006, 2007
   6      National Institute of Advanced Industrial Science and Technology (AIST)
   7      Registration Number H14PRO021
   8
   9 This file is part of GNU Emacs.
  10
  11 GNU Emacs is free software; you can redistribute it and/or modify
  12 it under the terms of the GNU General Public License as published by
  13 the Free Software Foundation; either version 3, or (at your option)
  14 any later version.
  15
  16 GNU Emacs is distributed in the hope that it will be useful,
  17 but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 GNU General Public License for more details.
  20
  21 You should have received a copy of the GNU General Public License
  22 along with GNU Emacs; see the file COPYING.  If not, write to
  23 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  24 Boston, MA 02110-1301, USA.  */
  25
  26 #ifndef EMACS_FONTSET_H
  27 #define EMACS_FONTSET_H
  28
  29 /* This data type is used for the font_table field of window system
  30    depending data area (e.g. struct x_display_info on X window).  */
  31
  32 struct font_info
  33 {
  34   /* Pointer to window system dependent font structure.  On X window,
  35      this value should be coerced to (XFontStruct *).  */
  36   void *font;
  37
  38   /* Index number of the font.  */
  39   int font_idx;
  40
  41   /* Name to be used to find the font.  */
  42   char *name;
  43
  44   /* Full name of the font given by a window system.  */
  45   char *full_name;
  46
  47   /* Charset of characters displayed by the font.  */
  48   int charset;
  49
  50 #ifdef WINDOWSNT
  51   /* Codepage of characters that will be displayed by the font.  */
  52   int codepage;
  53 #endif
  54
  55   /* Maximum bound width over all existing characters of the font.  On
  56      X window, this is same as (font->max_bounds.width) */
  57   int size;
  58
  59   /* Height of the font.  On X window, this is the same as
  60      (font->ascent + font->descent).  */
  61   int height;
  62
  63   /* Width of the space glyph of the font.  */
  64   int space_width;
  65
  66   /* Average width of glyphs in the font.  */
  67   int average_width;
  68
  69   /* 1 if `vertical-centering-font-regexp' matches this font name.
  70      In this case, we render characters at vartical center positions
  71      of lines.  */
  72   int vertical_centering;
  73
  74   /* Encodings of the font indexed by CHARSET.  The value is one of
  75      0, 1, 2, or 3:
  76         0: code points 0x20..0x7F or 0x2020..0x7F7F are used
  77         1: code points 0xA0..0xFF or 0xA0A0..0xFFFF are used
  78         2: code points 0x20A0..0x7FFF are used
  79         3: code points 0xA020..0xFF7F are used
  80      For instance, ASCII and Latin-1 characters may use the same font
  81      but different code points (ASCII uses 0x20..0x7F and Latin-1 uses
  82      0xA0..0xFF).
  83
  84      If the value can't be decided from information of the font, we
  85      consult `font-encoding-alist' to get of the corresponding charset
  86      whose default value is defined in lisp/fontset.el.  Since there's
  87      no charset whose id is 1, we use encoding[1] to store the
  88      encoding information decided by the font itself.
  89
  90      If the member `font_encoder' is not NULL, this member is ignored.
  91   */
  92   unsigned char encoding[MAX_CHARSET + 1];
  93
  94   /* The baseline position of a font is normally `ascent' value of the
  95      font.  However, there exists many fonts which don't set `ascent'
  96      an appropriate value to be used as baseline position.  This is
  97      typical in such ASCII fonts which are designed to be used with
  98      Chinese, Japanese, Korean characters.  When we use mixture of
  99      such fonts and normal fonts (having correct `ascent' value), a
 100      display line gets very ugly.  Since we have no way to fix it
 101      automatically, it is users responsibility to supply well designed
 102      fonts or correct `ascent' value of fonts.  But, the latter
 103      requires heavy work (modifying all bitmap data in BDF files).
 104      So, Emacs accepts a private font property
 105      `_MULE_BASELINE_OFFSET'.  If a font has this property, we
 106      calculate the baseline position by subtracting the value from
 107      `ascent'.  In other words, the value indicates how many bits
 108      higher we should draw a character of the font than normal ASCII
 109      text for a better looking.
 110
 111      We also have to consider the fact that the concept of `baseline'
 112      differs among languages to which each character belongs.  For
 113      instance, baseline should be at the bottom most position of all
 114      glyphs for Chinese, Japanese, and Korean.  But, many of existing
 115      fonts for those characters doesn't have correct `ascent' values
 116      because they are designed to be used with ASCII fonts.  To
 117      display characters of different language on the same line, the
 118      best way will be to arrange them in the middle of the line.  So,
 119      in such a case, again, we utilize the font property
 120      `_MULE_BASELINE_OFFSET'.  If the value is larger than `ascent' we
 121      calculate baseline so that a character is arranged in the middle
 122      of a line.  */
 123
 124   int baseline_offset;
 125
 126   /* Non zero means a character should be composed at a position
 127      relative to the height (or depth) of previous glyphs in the
 128      following cases:
 129         (1) The bottom of the character is higher than this value.  In
 130         this case, the character is drawn above the previous glyphs.
 131         (2) The top of the character is lower than 0 (i.e. baseline
 132         height).  In this case, the character is drawn beneath the
 133         previous glyphs.
 134
 135      This value is taken from a private font property
 136      `_MULE_RELATIVE_COMPOSE' which is introduced by Emacs.  */
 137   int relative_compose;
 138
 139   /* Non zero means an ascent value to be used for a character
 140      registered in char-table `use-default-ascent'.  */
 141   int default_ascent;
 142
 143   /* CCL program to calculate code points of the font.  */
 144   struct ccl_program *font_encoder;
 145 };
 146
 147 /* A value which may appear in the member `encoding' of struch
 148    font_info indicating that a font itself doesn't tell which encoding
 149    to be used.  */
 150 #define FONT_ENCODING_NOT_DECIDED 255
 151
 152 /* Forward declaration for prototypes.  */
 153 struct frame;
 154
 155 /* The following six are window system dependent functions.
 156    Initialization routine of each window system should set appropriate
 157    functions to these variables.  For instance, in case of X window,
 158    x_term_init does this.  */
 159
 160 /* Return a pointer to struct font_info of font FONT_IDX of frame F.  */
 161 extern struct font_info *(*get_font_info_func) P_ ((struct frame *f,
 162                                                     int font_idx));
 163
 164 /* Return a list of font names which matches PATTERN.  See the document of
 165    `x-list-fonts' for more detail.  */
 166 extern Lisp_Object (*list_fonts_func) P_ ((struct frame *f,
 167                                            Lisp_Object pattern,
 168                                            int size,
 169                                            int maxnames));
 170
 171 /* Load a font named NAME for frame F and return a pointer to the
 172    information of the loaded font.  If loading is failed, return -1.  */
 173 extern struct font_info *(*load_font_func) P_ ((struct frame *f,
 174                                                 char *name, int));
 175
 176 /* Return a pointer to struct font_info of a font named NAME for frame F.
 177    If no such font is loaded, return NULL.  */
 178 extern struct font_info *(*query_font_func) P_ ((struct frame *f, char *name));
 179
 180 /* Additional function for setting fontset or changing fontset
 181    contents of frame F.  This function may change the coordinate of
 182    the frame.  */
 183 extern void (*set_frame_fontset_func) P_ ((struct frame *f, Lisp_Object arg,
 184                                            Lisp_Object oldval));
 185
 186 /* To find a CCL program, fs_load_font calls this function.
 187    The argument is a pointer to the struct font_info.
 188    This function set the memer `encoder' of the structure.  */
 189 extern void (*find_ccl_program_func) P_ ((struct font_info *));
 190
 191 /* Check if any window system is used now.  */
 192 extern void (*check_window_system_func) P_ ((void));
 193
 194 struct face;
 195
 196 extern void free_face_fontset P_ ((FRAME_PTR, struct face *));
 197 extern Lisp_Object fontset_font_pattern P_ ((FRAME_PTR, int, int));
 198 extern int face_suitable_for_char_p P_ ((struct face *, int));
 199 extern int face_for_char P_ ((FRAME_PTR, struct face *, int));
 200 extern int make_fontset_for_ascii_face P_ ((FRAME_PTR, int));
 201 extern void set_default_ascii_font P_ ((Lisp_Object));
 202 extern struct font_info *fs_load_font P_ ((struct frame *, int, char *, int,
 203                                            struct face *));
 204 extern int fs_query_fontset P_ ((Lisp_Object, int));
 205 EXFUN (Fquery_fontset, 2);
 206 extern Lisp_Object list_fontsets P_ ((struct frame *, Lisp_Object, int));
 207
 208 extern Lisp_Object Qfontset;
 209 extern Lisp_Object Vuse_default_ascent;
 210 extern Lisp_Object Vignore_relative_composition;
 211 extern Lisp_Object Valternate_fontname_alist;
 212 extern Lisp_Object Vfontset_alias_alist;
 213 extern Lisp_Object Vvertical_centering_font_regexp;
 214
 215 /* Load a font named FONTNAME for displaying character C.  All fonts
 216    for frame F is stored in a table pointed by FONT_TABLE.  Return a
 217    pointer to the struct font_info of the loaded font.  If loading
 218    fails, return 0; If FONTNAME is NULL, the name is taken from the
 219    information of FONTSET.  If FONTSET is given, try to load a font
 220    whose size matches that of FONTSET, and, the font index is stored
 221    in the table for FONTSET.  */
 222
 223 #define FS_LOAD_FONT(f, c, fontname, fontset)  \
 224   fs_load_font (f, c, fontname, fontset, NULL)
 225
 226 #define FS_LOAD_FACE_FONT(f, c, fontname, face) \
 227   fs_load_font (f, c, fontname, -1, face)
 228
 229 /* Return an immutable id for font_info FONT_INFO on frame F.  The
 230    reason for this macro is hat one cannot hold pointers to font_info
 231    structures in other data structures, because the table is
 232    reallocated in x_list_fonts.  */
 233
 234 #define FONT_INFO_ID(F, FONT_INFO) \
 235      (FONT_INFO) - (FRAME_X_DISPLAY_INFO ((F))->font_table)
 236
 237 /* Given a font_info id ID, return a pointer to the font_info
 238    structure on frame F.  If ID is invalid, return null.  */
 239
 240 #define FONT_INFO_FROM_ID(F, ID)                                        \
 241      (((ID) >= 0 && (ID) < FRAME_X_DISPLAY_INFO ((F))->font_table_size) \
 242       ? (FRAME_X_DISPLAY_INFO ((F))->font_table + (ID))                 \
 243       : 0)
 244
 245 extern Lisp_Object fontset_name P_ ((int));
 246 extern Lisp_Object fontset_ascii P_ ((int));
 247 extern int fontset_height P_ ((int));
 248
 249 #endif /* EMACS_FONTSET_H */
 250
 251 /* arch-tag: c27cef7b-3cab-488a-8398-7a4daa96bb77
 252    (do not change this comment) */