docs/latex/wx/tfontenc.tex

   1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2 %% Name:        tfontenc.tex
   3 %% Purpose:     font encoding overview
   4 %% Author:      Vadim Zeitlin
   5 %% Modified by:
   6 %% Created:     03.11.99
   7 %% RCS-ID:      $Id$
   8 %% Copyright:   (c) Vadim Zeitlin
   9 %% License:     wxWindows license
  10 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  11
  12 \section{Font encoding overview}\label{wxfontencodingoverview}
  13
  14 wxWindows has support for multiple font encodings starting from release 2.2.
  15 By encoding we mean here the mapping between the character codes and the
  16 letters. Probably the most well-known encoding is (7 bit) ASCII one which is
  17 used almost universally now to represent the letters of the English alphabet
  18 and some other common characters. However, it is not enough to represent the
  19 letters of foreign alphabets and here other encodings come into play. Please
  20 note that we will only discuss 8-bit fonts here and not
  21 \helpref{Unicode}{unicode}.
  22
  23 Font encoding support is assured by several classes:
  24 \helpref{wxFont}{wxfont} itself, but also
  25 \helpref{wxFontEnumerator}{wxfontenumerator} and
  26 \helpref{wxFontMapper}{wxfontmapper}. wxFont encoding support is reflected by
  27 a (new) constructor parameter {\it encoding} which takes one of the following
  28 values (elements of enumeration type {\tt wxFontEncoding}):
  29
  30 \begin{twocollist}
  31 \twocolitem{wxFONTENCODING\_SYSTEM}{The default encoding of the underlying
  32 operating system (notice that this might be a "foreign" encoding for foreign
  33 versions of Windows 9x/NT).}
  34 \twocolitem{wxFONTENCODING\_DEFAULT}{The applications default encoding as
  35 returned by \helpref{wxFont::GetDefaultEncoding}{wxfontgetdefaultencoding}. On
  36 program startup, the applications default encoding is the same as
  37 wxFONTENCODING\_SYSTEM, but may be changed to make all the fonts created later
  38 to use it (by default).}
  39 \twocolitem{wxFONTENCODING\_ISO8859\_1..15}{ISO8859 family encodings which are
  40 usually used by all non-Microsoft operating systems}
  41 \twocolitem{wxFONTENCODING\_KOI8}{Standard Cyrillic encoding for the Internet
  42 (but see also wxFONTENCODING\_ISO8859\_5 and wxFONTENCODING\_CP1251)}
  43 \twocolitem{wxFONTENCODING\_CP1250}{Microsoft analogue of ISO8859-2}
  44 \twocolitem{wxFONTENCODING\_CP1251}{Microsoft analogue of ISO8859-5}
  45 \twocolitem{wxFONTENCODING\_CP1252}{Microsoft analogue of ISO8859-1}
  46 \end{twocollist}
  47
  48 As you may see, Microsoft's encoding partly mirror the standard ISO8859 ones,
  49 but there are (minor) differences even between ISO8859-1 (Latin1, ISO encoding
  50 for Western Europe) and CP1251 (WinLatin1, standard code page for English
  51 versions of Windows) and there are more of them for other encodings.
  52
  53 The situation is particularly complicated with Cyrillic encodings for which
  54 (more than) three incompatible encodings exist: KOI8 (the old standard, widely
  55 used on the Internet), ISO8859-5 (ISO standard for Cyrillic) and CP1251
  56 (WinCyrillic).
  57
  58 This abundance of (incompatible) encodings should make it clear that using
  59 encodings is less easy than it might seem. The problems arise both from the
  60 fact that the standard encodings for the given language (say Russian, which is
  61 written in Cyrillic) are different on different platforms and because the
  62 fonts in the given encoding might just not be installed (this is especially a
  63 problem with Unix, or, in general, non-Win32 systems).
  64
  65 To clarify, the \helpref{wxFontEnumerator}{wxfontenumerator}
  66 class may be used to enumerate both all available encodings and to find the
  67 facename(s) in which the given encoding exists. If you can find the font in
  68 the correct encoding with wxFontEnumerator then your troubles are over, but,
  69 unfortunately, sometimes this is not enough. For example, there is no standard
  70 way (that I know of, please tell me if you do!) to find a font on a Windows system
  71 for KOI8 encoding (only for WinCyrillic one which is quite different), so
  72 \helpref{wxFontEnumerator}{wxfontenumerator} will never return one, even if
  73 the user has installed a KOI8 font on his system.
  74
  75 To solve this problem, a \helpref{wxFontMapper}{wxfontmapper} class is provided.
  76 This class stores the mapping between the encodings and the font face
  77 names which support them in \helpref{wxConfig}{wxconfigoverview} object. Of
  78 course, it would be fairly useless if it tried to determine these mappings by
  79 itself, so, instead, it (optionally) ask the user and remember his answers
  80 so that the next time the program will automatically choose the correct font.
  81
  82 All these topics are illustrated by the \helpref{font sample}{samplefont};
  83 please refer to it and the documentation of the classes mentioned here for
  84 further explanations.
  85