code.delx.au - gnu-emacs/blob - admin/notes/font-backend

   1 Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
   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         w32uniscribe.c -- font driver on w32, using the uniscribe API
  29                 to provide complex script support for opentype fonts on
  30                 Windows 2000 and later, or earlier versions of Windows
  31                 with uniscribe installed as an add-on.
  32
  33 So we already have codes for X and w32.  For Mac it seems that we need
  34 these files:
  35         atmfont.c -- font-driver on mac using ATM fonts, corresponding
  36                 to xfont.c
  37 As BDF fonts are currently used on w32, we may also implement these:
  38         bdffont.c -- generic font-driver for BDF fonts, corresponding to
  39                 ftfont.c
  40         bdfw32font.c -- font-driver on w32 using BDF fonts,
  41                 corresponding to ftxfont.c
  42 But, as FreeType already supports BDF fonts, if FreeType and
  43 Fontconfig are also available on w32, what we need may be:
  44         ftw32font.c -- font-driver on w32 directly using FreeType fonts
  45                 utilizing methods provided by ftfont.c.
  46
  47 And, for those to work, macterm.c and macfns.c must be changed by the
  48 similar way as xterm.c and xfns.c (the parts "#ifdef USE_FONT_BACKEND"
  49 ... "#endif" should be checked).
  50
  51 It may be interesting if Emacs supports a frame buffer directly and
  52 has these font driver.
  53         ftfbfont.c -- font-driver on FB for FreeType fonts.
  54         bdffbfont.c -- font-driver on FB for BDF fonts.
  55
  56 Note: The fontset related codes are not yet matured to work well with
  57 the font backend method.  So, for instance, even if you start Emacs
  58 as something like this:
  59   % emacs -fn tahoma
  60 Non-ASCII Latin characters will not be displayed by the font "tahoma".
  61 In such a case, please try this:
  62
  63 (set-fontset-font "fontset-default" 'latin '("tahoma" . "unicode-bmp"))
  64
  65 \f
  66 This file is part of GNU Emacs.
  67
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  70 the Free Software Foundation, either version 3 of the License, or
  71 (at your option) any later version.
  72
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