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) 2001, 2002
   5      National Institute of Advanced Industrial Science and Technology (AIST)
   6      Registration Number H13PRO009
   7
   8 This file is part of GNU Emacs.
   9
  10 GNU Emacs is free software; you can redistribute it and/or modify
  11 it under the terms of the GNU General Public License as published by
  12 the Free Software Foundation; either version 2, or (at your option)
  13 any later version.
  14
  15 GNU Emacs is distributed in the hope that it will be useful,
  16 but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 GNU General Public License for more details.
  19
  20 You should have received a copy of the GNU General Public License
  21 along with GNU Emacs; see the file COPYING.  If not, write to
  22 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 Boston, MA 02111-1307, USA.  */
  24
  25 #ifndef EMACS_FONTSET_H
  26 #define EMACS_FONTSET_H
  27
  28 /* This data type is used for the font_table field of window system
  29    depending data area (e.g. struct x_display_info on X window).  */
  30
  31 struct font_info
  32 {
  33   /* Pointer to window system dependent font structure.  On X window,
  34      this value should be coerced to (XFontStruct *).  */
  35   void *font;
  36
  37   /* Index number of the font.  */
  38   int font_idx;
  39
  40   /* Name to be used to find the font.  */
  41   char *name;
  42
  43   /* Full name of the font given by a window system.  */
  44   char *full_name;
  45
  46   /* Charset of characters displayed by the font.  */
  47   int charset;
  48
  49 #ifdef WINDOWSNT
  50   /* Codepage of characters that will be displayed by the font.  */
  51   int codepage;
  52 #endif
  53
  54   /* Maximum bound width over all existing characters of the font.  On
  55      X window, this is same as (font->max_bounds.width) */
  56   int size;
  57
  58   /* Height of the font.  On X window, this is the same as
  59      (font->ascent + font->descent).  */
  60   int height;
  61
  62   /* 1 iff `vertical-centering-font-regexp' matches this font name.
  63      In this case, we render characters at vartical center positions
  64      of lines.  */
  65   int vertical_centering;
  66
  67   /* Encoding type of the font.  The value is one of
  68      0, 1, 2, or 3:
  69         0: code points 0x20..0x7F or 0x2020..0x7F7F are used
  70         1: code points 0xA0..0xFF or 0xA0A0..0xFFFF are used
  71         2: code points 0x20A0..0x7FFF are used
  72         3: code points 0xA020..0xFF7F are used
  73      If the member `font_encoder' is not NULL, this member is ignored.
  74   */
  75   unsigned char encoding_type;
  76
  77   /* The baseline position of a font is normally `ascent' value of the
  78      font.  However, there exists many fonts which don't set `ascent'
  79      an appropriate value to be used as baseline position.  This is
  80      typical in such ASCII fonts which are designed to be used with
  81      Chinese, Japanese, Korean characters.  When we use mixture of
  82      such fonts and normal fonts (having correct `ascent' value), a
  83      display line gets very ugly.  Since we have no way to fix it
  84      automatically, it is users responsibility to supply well designed
  85      fonts or correct `ascent' value of fonts.  But, the latter
  86      requires heavy work (modifying all bitmap data in BDF files).
  87      So, Emacs accepts a private font property
  88      `_MULE_BASELINE_OFFSET'.  If a font has this property, we
  89      calculate the baseline position by subtracting the value from
  90      `ascent'.  In other words, the value indicates how many bits
  91      higher we should draw a character of the font than normal ASCII
  92      text for a better looking.
  93
  94      We also have to consider the fact that the concept of `baseline'
  95      differs among languages to which each character belongs.  For
  96      instance, baseline should be at the bottom most position of all
  97      glyphs for Chinese, Japanese, and Korean.  But, many of existing
  98      fonts for those characters doesn't have correct `ascent' values
  99      because they are designed to be used with ASCII fonts.  To
 100      display characters of different language on the same line, the
 101      best way will be to arrange them in the middle of the line.  So,
 102      in such a case, again, we utilize the font property
 103      `_MULE_BASELINE_OFFSET'.  If the value is larger than `ascent' we
 104      calculate baseline so that a character is arranged in the middle
 105      of a line.  */
 106
 107   int baseline_offset;
 108
 109   /* Non zero means a character should be composed at a position
 110      relative to the height (or depth) of previous glyphs in the
 111      following cases:
 112         (1) The bottom of the character is higher than this value.  In
 113         this case, the character is drawn above the previous glyphs.
 114         (2) The top of the character is lower than 0 (i.e. baseline
 115         height).  In this case, the character is drawn beneath the
 116         previous glyphs.
 117
 118      This value is taken from a private font property
 119      `_MULE_RELATIVE_COMPOSE' which is introduced by Emacs.  */
 120   int relative_compose;
 121
 122   /* Non zero means an ascent value to be used for a character
 123      registered in char-table `use-default-ascent'.  */
 124   int default_ascent;
 125
 126   /* CCL program to calculate code points of the font.  */
 127   struct ccl_program *font_encoder;
 128 };
 129
 130 /* A value which may appear in the member `encoding' of struch
 131    font_info indicating that a font itself doesn't tell which encoding
 132    to be used.  */
 133 #define FONT_ENCODING_NOT_DECIDED 255
 134
 135 enum FONT_SPEC_INDEX
 136   {
 137     FONT_SPEC_FAMILY_INDEX,
 138     FONT_SPEC_WEIGHT_INDEX,
 139     FONT_SPEC_SLANT_INDEX,
 140     FONT_SPEC_SWIDTH_INDEX,
 141     FONT_SPEC_ADSTYLE_INDEX,
 142     FONT_SPEC_REGISTRY_INDEX,
 143     FONT_SPEC_MAX_INDEX
 144   };
 145
 146 /* Forward declaration for prototypes.  */
 147 struct frame;
 148
 149 /* The following six are window system dependent functions.
 150    Initialization routine of each window system should set appropriate
 151    functions to these variables.  For instance, in case of X window,
 152    x_term_init does this.  */
 153
 154 /* Return a pointer to struct font_info of font FONT_IDX of frame F.  */
 155 extern struct font_info *(*get_font_info_func) P_ ((struct frame *f,
 156                                                     int font_idx));
 157
 158 /* Return a list of font names which matches PATTERN.  See the document of
 159    `x-list-fonts' for more detail.  */
 160 extern Lisp_Object (*list_fonts_func) P_ ((struct frame *f,
 161                                            Lisp_Object pattern,
 162                                            int size,
 163                                            int maxnames));
 164
 165 /* Load a font named NAME for frame F and return a pointer to the
 166    information of the loaded font.  If loading is failed, return -1.  */
 167 extern struct font_info *(*load_font_func) P_ ((struct frame *f,
 168                                                 char *name, int));
 169
 170 /* Return a pointer to struct font_info of a font named NAME for frame F.
 171    If no such font is loaded, return NULL.  */
 172 extern struct font_info *(*query_font_func) P_ ((struct frame *f, char *name));
 173
 174 /* Additional function for setting fontset or changing fontset
 175    contents of frame F.  This function may change the coordinate of
 176    the frame.  */
 177 extern void (*set_frame_fontset_func) P_ ((struct frame *f, Lisp_Object arg,
 178                                            Lisp_Object oldval));
 179
 180 /* To find a CCL program, fs_load_font calls this function.
 181    The argument is a pointer to the struct font_info.
 182    This function set the memer `encoder' of the structure.  */
 183 extern void (*find_ccl_program_func) P_ ((struct font_info *));
 184
 185 /* Check if any window system is used now.  */
 186 extern void (*check_window_system_func) P_ ((void));
 187
 188 struct face;
 189
 190 extern void free_face_fontset P_ ((FRAME_PTR, struct face *));
 191 extern Lisp_Object fontset_font_pattern P_ ((FRAME_PTR, struct face *, int));
 192 extern int face_suitable_for_char_p P_ ((struct face *, int));
 193 extern int face_for_char P_ ((FRAME_PTR, struct face *, int));
 194 extern int make_fontset_for_ascii_face P_ ((FRAME_PTR, int));
 195 extern struct font_info *fs_load_font P_ ((struct frame *, char *));
 196 extern int fs_query_fontset P_ ((Lisp_Object, int));
 197 EXFUN (Fquery_fontset, 2);
 198 extern Lisp_Object list_fontsets P_ ((struct frame *, Lisp_Object, int));
 199
 200 extern Lisp_Object Qfontset;
 201 extern Lisp_Object Vuse_default_ascent;
 202 extern Lisp_Object Vignore_relative_composition;
 203 extern Lisp_Object Valternate_fontname_alist;
 204 extern Lisp_Object Vfontset_alias_alist;
 205 extern Lisp_Object Vvertical_centering_font_regexp;
 206
 207 /* Load a font named FONTNAME on frame F.  All fonts for frame F is
 208    stored in a table pointed by FONT_TABLE.  Return a pointer to the
 209    struct font_info of the loaded font.  If loading fails, return
 210    NULL.  */
 211
 212 #define FS_LOAD_FONT(f, fontname) fs_load_font (f, fontname)
 213
 214
 215 /* Return an immutable id for font_info FONT_INFO on frame F.  The
 216    reason for this macro is hat one cannot hold pointers to font_info
 217    structures in other data structures, because the table is
 218    reallocated in x_list_fonts.  */
 219
 220 #define FONT_INFO_ID(F, FONT_INFO) \
 221      (FONT_INFO) - (FRAME_X_DISPLAY_INFO ((F))->font_table)
 222
 223 /* Given a font_info id ID, return a pointer to the font_info
 224    structure on frame F.  If ID is invalid, return null.  */
 225
 226 #define FONT_INFO_FROM_ID(F, ID)                                        \
 227      (((ID) >= 0 && (ID) < FRAME_X_DISPLAY_INFO ((F))->font_table_size) \
 228       ? (FRAME_X_DISPLAY_INFO ((F))->font_table + (ID))                 \
 229       : 0)
 230
 231 extern Lisp_Object fontset_name P_ ((int));
 232 extern Lisp_Object fontset_ascii P_ ((int));
 233 extern int fontset_height P_ ((int));
 234
 235 #endif /* EMACS_FONTSET_H */