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 /*
  26
  27 #define GENERIC_FONT_PTR void
  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   /* Maximum bound width over all existing characters of the font.  On
  51      X window, this is same as (font->max_bounds.width) */
  52   int size;
  53
  54   /* Height of the font.  On X window, this is same as (font->ascent
  55      + font->descent).  */
  56   int height;
  57
  58   /* Encodings of the font indexed by CHARSET.  The value an integer
  59      0, 1, 2, or 3:
  60         0: code points 0x20..0x7F or 0x2020..0x7F7F are used
  61         1: code points 0xA0..0xFF or 0xA0A0..0xFFFF are used
  62         2: code points 0x20A0..0x7FFF are used
  63         3: code points 0xA020..0xFF7F are used
  64      For instance, ASCII and Latin-1 characters may use the same font
  65      but different code points (ASCII uses 0x20..0x7F and Latin-1 uses
  66      0xA0..0xFF).
  67
  68      If the value can't be decided from information of the font, we
  69      consult `font-encoding-alist' to get of the corresponding charset
  70      whose default value is defined in lisp/fontset.el.  Since there's
  71      no charset whose id is 1, we use encoding[1] to store the
  72      encoding information decided by the font itself.  */
  73   unsigned char encoding[MAX_CHARSET + 1];
  74
  75   /* The baseline position of a font is normally `ascent' value of the
  76      font.  However, there exists many fonts which don't set `ascent'
  77      an appropriate value to be used as baseline position.  This is
  78      typical in such ASCII fonts which are designed to be used with
  79      Chinese, Japanese, Korean characters.  When we use mixture of
  80      such fonts and normal fonts (having correct `ascent' value), a
  81      display line gets very ugly.  Since we have no way to fix it
  82      automatically, it is users responsibility to supply well designed
  83      fonts or correct `ascent' value of fonts.  But, the latter
  84      requires heavy work (modifying all bitmap data in BDF files).
  85      So, Emacs accepts a private font property
  86      `_MULE_BASELINE_OFFSET'.  If a font has this property, we
  87      calculate the baseline position by subtracting the value from
  88      `ascent'.  In other words, the value indicates how many bits
  89      higher we should draw a character of the font than normal ASCII
  90      text for a better looking.
  91
  92      We also have to consider the fact that the concept of `baseline'
  93      differs among languages to which each character belongs.  For
  94      instance, baseline should be at the bottom most position of all
  95      glyphs for Chinese, Japanese, and Korean.  But, many of existing
  96      fonts for those characters doesn't have correct `ascent' values
  97      because they are designed to be used with ASCII fonts.  To
  98      display characters of different language on the same line, the
  99      best way will be to arrange them in the middle of the line.  So,
 100      in such a case, again, we utilize the font property
 101      `_MULE_BASELINE_OFFSET'.  If the value is larger than `ascent' we
 102      calculate baseline so that a character is arranged in the middle
 103      of a line.  */
 104
 105   int baseline_offset;
 106
 107   /* Non zero means a character should be composed at a position
 108      relative to the height (or depth) of previous glyphs in the
 109      following cases:
 110         (1) The bottom of the character is higher than this value.  In
 111         this case, the character is drawn above the previous glyphs.
 112         (2) The top of the character is lower than 0 (i.e. baseline
 113         height).  In this case, the character is drawn beneath the
 114         previous glyphs.
 115
 116      This value is taken from a private font property
 117      `_MULE_RELATIVE_COMPOSE' which is introduced by Emacs.  */
 118   int relative_compose;
 119
 120   /* Non zero means an ascent value to be used for a character
 121      registered in char-table `use-default-ascent'.  */
 122   int default_ascent;
 123
 124   /* CCL program to calculate code points of the font.  */
 125   struct ccl_program *font_encoder;
 126 };
 127
 128 /* A value which may appear in the member encoding of struch font_info
 129    indicating that a font itself doesn't tell which encoding to be
 130    used.  */
 131 #define FONT_ENCODING_NOT_DECIDED 4
 132
 133 #define FONT_NOT_OPENED -1
 134 #define FONT_NOT_FOUND  -2
 135
 136 struct fontset_info
 137 {
 138   /* Name of the fontset.  */
 139   char *name;
 140
 141   /* Size of the fontset.  This is the same as the size of ASCII font
 142      of this fontset.  */
 143   int size;
 144
 145   /* Height of the tallest font in the fontset.  */
 146   int height;
 147
 148   /* Table of font name for each character set.  */
 149   char *fontname[MAX_CHARSET + 1];
 150
 151   /* Table of index numbers of fonts indexed by charset.  If a font is
 152      not yet loaded, the value is -1 (FONT_NOT_OPENED).  If font
 153      loading is failed, the value is -2 (FONT_NOT_FOUND).  */
 154   int font_indexes[MAX_CHARSET + 1];
 155 };
 156
 157 /* This data type is used for the fontset_data field of struct frame.  */
 158
 159 struct fontset_data
 160 {
 161   /* A table of pointers to all the fontsets.  */
 162   struct fontset_info **fontset_table;
 163
 164   /* The current capacity of fontset_table.  */
 165   int fontset_table_size;
 166
 167   /* The number of fontsets actually stored in fontset_table.
 168      fontset_table[n] is used and valid iff 0 <= n < n_fontsets.
 169      0 <= n_fontsets <= fontset_table_size.  */
 170   int n_fontsets;
 171 };
 172
 173 /* The following six are window system dependent functions.
 174    Initialization routine of each window system should set appropriate
 175    functions to these variables.  For instance, in case of X window,
 176    x_term_init does this.  */
 177
 178 /* Return a pointer to struct font_info of font FONT_IDX of frame F.  */
 179 extern struct font_info *(*get_font_info_func) (/* FRAME_PTR f;
 180                                                     int font_idx */);
 181
 182 /* Return a list of font names which matches PATTERN.  See the document of
 183    `x-list-fonts' for more detail.  */
 184 extern Lisp_Object (*list_fonts_func) (/* Lisp_Object pattern, face, frame,
 185                                           width */);
 186
 187 /* Load a font named NAME for frame F and return a pointer to the
 188    information of the loaded font.  If loading is failed, return -1.  */
 189 extern struct font_info *(*load_font_func) (/* FRAME_PTR f; char *name */);
 190
 191 /* Return a pointer to struct font_info of a font named NAME for frame F.
 192    If no such font is loaded, return NULL.  */
 193 extern struct font_info *(*query_font_func) (/* FRAME_PTR f; char *name */);
 194
 195 /* Additional function for setting fontset or changing fontset
 196    contents of frame F.  This function may change the coordinate of
 197    the frame.  */
 198 extern void (*set_frame_fontset_func) (/* FRAME_PTR f; Lisp_Object arg, oldval */);
 199
 200 /* Check if any window system is used now.  */
 201 extern void (*check_window_system_func) ();
 202
 203 extern struct fontset_data *alloc_fontset_data ();
 204 extern void free_fontset_data ();
 205 extern struct font_info *fs_load_font ();
 206 extern Lisp_Object list_fontsets ();
 207 extern Lisp_Object Vglobal_fontset_alist;
 208
 209 extern Lisp_Object Qfontset;
 210 extern Lisp_Object Vuse_default_ascent;
 211 extern Lisp_Object Vignore_relative_composition;
 212 extern Lisp_Object Valternate_fontname_alist;
 213 extern Lisp_Object Vhighlight_wrong_size_font;
 214 extern Lisp_Object Vclip_large_size_font;
 215
 216 extern int font_idx_temp;
 217
 218 /* Load a font named FONTNAME for displaying CHARSET on frame F.
 219    All fonts for frame F is stored in a table pointed by FONT_TABLE.
 220    Return a pointer to the struct font_info of the loaded font.
 221    If loading fails, return 0;
 222    If FONTNAME is NULL, the name is taken from the information of FONTSET.
 223    If FONTSET is given, try to load a font whose size matches that of
 224    FONTSET, and, the font index is stored in the table for FONTSET.  */
 225
 226 #define FS_LOAD_FONT(f, font_table, charset, fontname, fontset)           \
 227   (fontset >= 0 && fontset < FRAME_FONTSET_DATA (f)->n_fontsets           \
 228    && (font_idx_temp = (FRAME_FONTSET_DATA (f)                            \
 229                         ->fontset_table[fontset]->font_indexes[charset]), \
 230        font_idx_temp >= 0)                                                \
 231    ? font_table + font_idx_temp                                           \
 232    : fs_load_font (f, font_table, charset, fontname, fontset))
 233
 234 #endif /* _FONTSET_H */