src/fontset.h

   1 /* Header for fontset handler.
   2    Copyright (C) 1995, 1997 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 _FONTSET_H
  23 #define _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 same as (font->ascent
  51      + font->descent).  */
  52   int height;
  53
  54   /* Encodings of the font indexed by CHARSET.  The value an integer
  55      0, 1, 2, or 3:
  56         0: code points 0x20..0x7F or 0x2020..0x7F7F are used
  57         1: code points 0xA0..0xFF or 0xA0A0..0xFFFF are used
  58         2: code points 0x20A0..0x7FFF are used
  59         3: code points 0xA020..0xFF7F are used
  60      For instance, ASCII and Latin-1 characters may use the same font
  61      but different code points (ASCII uses 0x20..0x7F and Latin-1 uses
  62      0xA0..0xFF).
  63
  64      If the value can't be decided from information of the font, we
  65      consult `font-encoding-alist' to get of the corresponding charset
  66      whose default value is defined in lisp/fontset.el.  Since there's
  67      no charset whose id is 1, we use encoding[1] to store the
  68      encoding information decided by the font itself.  */
  69   unsigned char encoding[MAX_CHARSET + 1];
  70
  71   /* The baseline position of a font is normally `ascent' value of the
  72      font.  However, there exists many fonts which don't set `ascent'
  73      an appropriate value to be used as baseline position.  This is
  74      typical in such ASCII fonts which are designed to be used with
  75      Chinese, Japanese, Korean characters.  When we use mixture of
  76      such fonts and normal fonts (having correct `ascent' value), a
  77      display line gets very ugly.  Since we have no way to fix it
  78      automatically, it is users responsibility to supply well designed
  79      fonts or correct `ascent' value of fonts.  But, the latter
  80      requires heavy work (modifying all bitmap data in BDF files).
  81      So, Emacs accepts a private font property
  82      `_MULE_BASELINE_OFFSET'.  If a font has this property, we
  83      calculate the baseline position by subtracting the value from
  84      `ascent'.  In other words, the value indicates how many bits
  85      higher we should draw a character of the font than normal ASCII
  86      text for a better looking.
  87
  88      We also have to consider the fact that the concept of `baseline'
  89      differs among languages to which each character belongs.  For
  90      instance, baseline should be at the bottom most position of all
  91      glyphs for Chinese, Japanese, and Korean.  But, many of existing
  92      fonts for those characters doesn't have correct `ascent' values
  93      because they are designed to be used with ASCII fonts.  To
  94      display characters of different language on the same line, the
  95      best way will be to arrange them in the middle of the line.  So,
  96      in such a case, again, we utilize the font property
  97      `_MULE_BASELINE_OFFSET'.  If the value is larger than `ascent' we
  98      calculate baseline so that a character is arranged in the middle
  99      of a line.  */
 100
 101   int baseline_offset;
 102
 103   /* Non zero means a character should be composed at a position
 104      relative to the height (or depth) of previous glyphs in the
 105      following cases:
 106         (1) The bottom of the character is higher than this value.  In
 107         this case, the character is drawn above the previous glyphs.
 108         (2) The top of the character is lower than 0 (i.e. baseline
 109         height).  In this case, the character is drawn beneath the
 110         previous glyphs.
 111
 112      This value is taken from a private font property
 113      `_MULE_RELATIVE_COMPOSE' which is introduced by Emacs.  */
 114   int relative_compose;
 115
 116   /* Non zero means an ascent value to be used for a character
 117      registered in char-table `use-default-ascent'.  */
 118   int default_ascent;
 119
 120   /* CCL program to calculate code points of the font.  */
 121   struct ccl_program *font_encoder;
 122 };
 123
 124 /* A value which may appear in the member encoding of struch font_info
 125    indicating that a font itself doesn't tell which encoding to be
 126    used.  */
 127 #define FONT_ENCODING_NOT_DECIDED 255
 128
 129 #define FONT_NOT_OPENED -1
 130 #define FONT_NOT_FOUND  -2
 131
 132 struct fontset_info
 133 {
 134   /* Name of the fontset.  */
 135   char *name;
 136
 137   /* Size of the fontset.  This is the same as the size of ASCII font
 138      of this fontset.  */
 139   int size;
 140
 141   /* Height of the tallest font in the fontset.  */
 142   int height;
 143
 144   /* Table of font name for each character set.  */
 145   char *fontname[MAX_CHARSET + 1];
 146
 147   /* Table of index numbers of fonts indexed by charset.  If a font is
 148      not yet loaded, the value is -1 (FONT_NOT_OPENED).  If font
 149      loading is failed, the value is -2 (FONT_NOT_FOUND).  */
 150   int font_indexes[MAX_CHARSET + 1];
 151 };
 152
 153 /* This data type is used for the fontset_data field of struct frame.  */
 154
 155 struct fontset_data
 156 {
 157   /* A table of pointers to all the fontsets.  */
 158   struct fontset_info **fontset_table;
 159
 160   /* The current capacity of fontset_table.  */
 161   int fontset_table_size;
 162
 163   /* The number of fontsets actually stored in fontset_table.
 164      fontset_table[n] is used and valid iff 0 <= n < n_fontsets.
 165      0 <= n_fontsets <= fontset_table_size.  */
 166   int n_fontsets;
 167 };
 168
 169 /* Forward declaration for prototypes.  */
 170 struct frame;
 171
 172 /* The following six are window system dependent functions.
 173    Initialization routine of each window system should set appropriate
 174    functions to these variables.  For instance, in case of X window,
 175    x_term_init does this.  */
 176
 177 /* Return a pointer to struct font_info of font FONT_IDX of frame F.  */
 178 extern struct font_info *(*get_font_info_func) P_ ((struct frame *f,
 179                                                     int font_idx));
 180
 181 /* Return a list of font names which matches PATTERN.  See the document of
 182    `x-list-fonts' for more detail.  */
 183 extern Lisp_Object (*list_fonts_func) P_ ((Lisp_Object pattern,
 184                                            Lisp_Object face,
 185                                            Lisp_Object frame,
 186                                            Lisp_Object width));
 187
 188 /* Load a font named NAME for frame F and return a pointer to the
 189    information of the loaded font.  If loading is failed, return -1.  */
 190 extern struct font_info *(*load_font_func) P_ ((struct frame *f,
 191                                                 char *name, int));
 192
 193 /* Return a pointer to struct font_info of a font named NAME for frame F.
 194    If no such font is loaded, return NULL.  */
 195 extern struct font_info *(*query_font_func) P_ ((struct frame *f, char *name));
 196
 197 /* Additional function for setting fontset or changing fontset
 198    contents of frame F.  This function may change the coordinate of
 199    the frame.  */
 200 extern void (*set_frame_fontset_func) P_ ((struct frame *f, Lisp_Object arg,
 201                                            Lisp_Object oldval));
 202
 203 /* To find a CCL program, fs_load_font calls this function.
 204    The argument is a pointer to the struct font_info.
 205    This function set the memer `encoder' of the structure.  */
 206 extern void (*find_ccl_program_func) P_ ((struct font_info *));
 207
 208 /* Check if any window system is used now.  */
 209 extern void (*check_window_system_func) P_ ((void));
 210
 211 extern struct fontset_data *alloc_fontset_data P_ ((void));
 212 extern void free_fontset_data P_ ((struct fontset_data *));
 213 extern struct font_info *fs_load_font P_ ((struct frame *, struct font_info *,
 214                                            int, char *, int));
 215 extern int fs_query_fontset P_ ((struct frame *, char *));
 216 extern int fs_register_fontset P_ ((struct frame *, Lisp_Object));
 217 EXFUN (Fquery_fontset, 2);
 218 extern Lisp_Object list_fontsets P_ ((struct frame *, Lisp_Object, int));
 219 extern Lisp_Object Vglobal_fontset_alist;
 220
 221 extern Lisp_Object Qfontset;
 222 extern Lisp_Object Vuse_default_ascent;
 223 extern Lisp_Object Vignore_relative_composition;
 224 extern Lisp_Object Valternate_fontname_alist;
 225 extern Lisp_Object Vhighlight_wrong_size_font;
 226 extern Lisp_Object Vclip_large_size_font;
 227
 228 extern int font_idx_temp;
 229
 230 /* Load a font named FONTNAME for displaying CHARSET on frame F.
 231    All fonts for frame F is stored in a table pointed by FONT_TABLE.
 232    Return a pointer to the struct font_info of the loaded font.
 233    If loading fails, return 0;
 234    If FONTNAME is NULL, the name is taken from the information of FONTSET.
 235    If FONTSET is given, try to load a font whose size matches that of
 236    FONTSET, and, the font index is stored in the table for FONTSET.  */
 237
 238 #define FS_LOAD_FONT(f, font_table, charset, fontname, fontset)           \
 239   (fontset >= 0 && fontset < FRAME_FONTSET_DATA (f)->n_fontsets           \
 240    && (font_idx_temp = (FRAME_FONTSET_DATA (f)                            \
 241                         ->fontset_table[fontset]->font_indexes[charset]), \
 242        font_idx_temp >= 0)                                                \
 243    ? font_table + font_idx_temp                                           \
 244    : fs_load_font (f, font_table, charset, fontname, fontset))
 245
 246 #endif /* _FONTSET_H */