admin/notes/font-backend

   1 Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008
   2   Free Software Foundation, Inc.
   3 See the end of the file for license conditions.
   4
   5
   6 New font handling mechanism with font backend method
   7 ----------------------------------------------------
   8
   9 The configure script, if invoked with "--enable-font-backend", checks
  10 if libraries freetype and fontconfig exist.  If they are both
  11 available, macro "USE_FONT_BACKEND" is defined in src/config.h.  In
  12 that case, the existence of Xft library is checked too.
  13
  14 The new files are:
  15         font.h -- header providing font-backend related structures
  16                 (most important ones are "struct font" and "struct
  17                 font_driver"), macros, and etc.
  18         font.c -- main font handling code.
  19         xfont.c -- font-driver on X for X core fonts.
  20         ftfont.c -- generic font-driver for FreeType fonts providing
  21                 device-independent methods of struct font_driver.
  22         xftfont.c -- font-driver on X using Xft for FreeType fonts
  23                 utilizing methods provided by ftfont.c.
  24         ftxfont.c -- font-driver on X directly using FreeType fonts
  25                 utilizing methods provided by ftfont.c.
  26         w32font.c -- font driver on w32 using Windows native fonts,
  27                 corresponding to xfont.c
  28
  29 So we already have codes for X.  For the other systems (w32 and mac),
  30 it seems that we need these files:
  31         atmfont.c -- font-driver on mac using ATM fonts, corresponding
  32                 to xfont.c
  33 As BDF fonts are currently used on w32, we may also implement these:
  34         bdffont.c -- generic font-driver for BDF fonts, corresponding to
  35                 ftfont.c
  36         bdfw32font.c -- font-driver on w32 using BDF fonts,
  37                 corresponding to ftxfont.c
  38 But, as FreeType already supports BDF fonts, if FreeType and
  39 Fontconfig are also available on w32, what we need may be:
  40         ftw32font.c -- font-driver on w32 directly using FreeType fonts
  41                 utilizing methods provided by ftfont.c.
  42
  43 And, for those to work, macterm.c and macfns.c must be changed by the
  44 similar way as xterm.c and xfns.c (the parts "#ifdef USE_FONT_BACKEND"
  45 ... "#endif" should be checked).
  46
  47 It may be interesting if Emacs supports a frame buffer directly and
  48 has these font driver.
  49         ftfbfont.c -- font-driver on FB for FreeType fonts.
  50         bdffbfont.c -- font-driver on FB for BDF fonts.
  51
  52 Note: The fontset related codes are not yet matured to work well with
  53 the font backend method.  So, for instance, even if you start Emacs
  54 as something like this:
  55   % emacs -fn tahoma
  56 Non-ASCII Latin characters will not be displayed by the font "tahoma".
  57 In such a case, please try this:
  58
  59 (set-fontset-font "fontset-default" 'latin '("tahoma" . "unicode-bmp"))
  60
  61 \f
  62 This file is part of GNU Emacs.
  63
  64 GNU Emacs is free software; you can redistribute it and/or modify
  65 it under the terms of the GNU General Public License as published by
  66 the Free Software Foundation; either version 3, or (at your option)
  67 any later version.
  68
  69 GNU Emacs is distributed in the hope that it will be useful,
  70 but WITHOUT ANY WARRANTY; without even the implied warranty of
  71 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  72 GNU General Public License for more details.
  73
  74 You should have received a copy of the GNU General Public License
  75 along with GNU Emacs; see the file COPYING.  If not, write to the
  76 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  77 Boston, MA 02110-1301, USA.