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