code.delx.au - gnu-emacs/blob - src/fontset.h

   1 /* Header for fontset handler.
   2    Ver.1.0
   3    Copyright (C) 1995 Free Software Foundation, Inc.
   4    Copyright (C) 1995 Electrotechnical Laboratory, JAPAN.
   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., 59 Temple Place - Suite 330,
  21 Boston, MA 02111-1307, USA.  */
  22
  23 #ifndef _FONTSET_H
  24 #define _FONTSET_H
  25
  26 /*
  27
  28 #define GENERIC_FONT_PTR void
  29
  30 /* This data type is used for the font_table field of window system
  31    depending data area (e.g. struct x_display_info on X window).  */
  32
  33 struct font_info
  34 {
  35   /* Pointer to window system dependent font structure.  On X window,
  36      this value should be coerced to (XFontStruct *).  */
  37   void *font;
  38
  39   /* Index number of the font.  */
  40   int font_idx;
  41
  42   /* Name to be used to find the font.  */
  43   char *name;
  44
  45   /* Full name of the font given by a window system.  */
  46   char *full_name;
  47
  48   /* Charset of characters displayed by the font.  */
  49   int charset;
  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 same as (font->ascent
  56      + font->descent).  */
  57   int height;
  58
  59   /* Encodings of the font indexed by CHARSET.  The value an integer
  60      0, 1, 2, or 3:
  61         0: code points 0x20..0x7F or 0x2020..0x7F7F are used
  62         1: code points 0xA0..0xFF or 0xA0A0..0xFFFF are used
  63         2: code points 0x20A0..0x7FFF are used
  64         3: code points 0xA020..0xFF7F are used
  65      For instance, ASCII and Latin-1 characters may use the same font
  66      but different code points (ASCII uses 0x20..0x7F and Latin-1 uses
  67      0xA0..0xFF).
  68
  69      If the value can't be decided from information of the font, we
  70      consult `font-encoding-alist' to get of the corresponding charset
  71      whose default value is defined in lisp/fontset.el.  Since there's
  72      no charset whose id is 1, we use encoding[1] to store the
  73      encoding information decided by the font itself.  */
  74   char encoding[MAX_CHARSET + 1];
  75
  76   /* The baseline position of a font is normally `ascent' value of the
  77      font.  However, there exists many fonts which don't set `ascent'
  78      an appropriate value to be used as baseline position.  This is
  79      typical in such ASCII fonts which are designed to be used with
  80      Chinese, Japanese, Korean characters.  When we use mixture of
  81      such fonts and normal fonts (having correct `ascent' value), a
  82      display line gets very ugly.  Since we have no way to fix it
  83      automatically, it is users responsibility to supply well designed
  84      fonts or correct `ascent' value of fonts.  But, the latter
  85      requires heavy work (modifying all bitmap data in BDF files).
  86      So, Emacs accepts a private font property
  87      `_MULE_BASELINE_OFFSET'.  If a font has this property, we
  88      calculate the baseline position by subtracting the value from
  89      `ascent'.  In other words, the value indicates how many bits
  90      higher we should draw a character of the font than normal ASCII
  91      text for a better looking.
  92
  93      We also have to consider the fact that the concept of `baseline'
  94      differs among languages to which each character belongs.  For
  95      instance, baseline should be at the bottom most position of all
  96      glyphs for Chinese, Japanese, and Korean.  But, many of existing
  97      fonts for those characters doesn't have correct `ascent' values
  98      because they are designed to be used with ASCII fonts.  To
  99      display characters of different language on the same line, the
 100      best way will be to arrange them in the middle of the line.  So,
 101      in such a case, again, we utilize the font property
 102      `_MULE_BASELINE_OFFSET'.  If the value is larger than `ascent' we
 103      calculate baseline so that a character is arranged in the middle
 104      of a line.  */
 105
 106   int baseline_offset;
 107
 108   /* Non zero means a character should be composed at a position
 109      relative to the height (or depth) of previous glyphs in the
 110      following cases:
 111         (1) The bottom of the character is higher than this value.  In
 112         this case, the character is drawn above the previous glyphs.
 113         (2) The top of the character is lower than 0 (i.e. baseline
 114         height).  In this case, the character is drawn beneath the
 115         previous glyphs.
 116
 117      This value is taken from a private font property
 118      `_MULE_RELATIVE_COMPOSE' which is introduced by Emacs.  */
 119   int relative_compose;
 120
 121   /* Non zero means an ascent value to be used for a character
 122      registered in char-table `use-default-ascent'.  */
 123   int default_ascent;
 124
 125   /* CCL program to calculate code points of the font.  */
 126   struct ccl_program *font_encoder;
 127 };
 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 /* The following six are window system dependent functions.
 170    Initialization routine of each window system should set appropriate
 171    functions to these variables.  For instance, in case of X window,
 172    x_term_init does this.  */
 173
 174 /* Return a pointer to struct font_info of font FONT_IDX of frame F.  */
 175 extern struct font_info *(*get_font_info_func) (/* FRAME_PTR f;
 176                                                     int font_idx */);
 177
 178 /* Return a list of font names which matches PATTERN.  See the document of
 179    `x-list-fonts' for more detail.  */
 180 extern Lisp_Object (*list_fonts_func) (/* Lisp_Object pattern, face, frame,
 181                                           width */);
 182
 183 /* Load a font named NAME for frame F and return a pointer to the
 184    information of the loaded font.  If loading is failed, return -1.  */
 185 extern struct font_info *(*load_font_func) (/* FRAME_PTR f; char *name */);
 186
 187 /* Return a pointer to struct font_info of a font named NAME for frame F.
 188    If no such font is loaded, return NULL.  */
 189 extern struct font_info *(*query_font_func) (/* FRAME_PTR f; char *name */);
 190
 191 /* Additional function for setting fontset or changing fontset
 192    contents of frame F.  This function may change the coordinate of
 193    the frame.  */
 194 extern void (*set_frame_fontset_func) (/* FRAME_PTR f; Lisp_Object arg, oldval */);
 195
 196 /* Check if any window system is used now.  */
 197 extern void (*check_window_system_func) ();
 198
 199 extern struct fontset_data *alloc_fontset_data ();
 200 extern void free_fontset_data ();
 201 extern struct font_info *fs_load_font ();
 202 extern Lisp_Object list_fontsets ();
 203 extern Lisp_Object Vglobal_fontset_alist;
 204
 205 extern Lisp_Object Qfontset;
 206 extern Lisp_Object Vuse_default_ascent;
 207 extern Lisp_Object Valternative_fontname_alist;
 208 extern Lisp_Object Vhighlight_wrong_size_font;
 209 extern Lisp_Object Vclip_large_size_font;
 210
 211 #endif /* _FONTSET_H */