moving forward

[wxWidgets.git] / docs / doxygen / overviews / fontencoding.h

/////////////////////////////////////////////////////////////////////////////
// Name:        fontencoding.h
// Purpose:     topic overview
// Author:      wxWidgets team
// RCS-ID:      $Id$
// Licence:     wxWindows license
/////////////////////////////////////////////////////////////////////////////

/*!

 @page overview_fontencoding Font encoding overview

 wxWidgets has support for multiple font encodings.

 By encoding we mean here the mapping between the character codes and the
 letters. Probably the most well-known encoding is (7 bit) ASCII one which is
 used almost universally now to represent the letters of the English alphabet
 and some other common characters. However, it is not enough to represent the
 letters of foreign alphabets and here other encodings come into play. Please
 note that we will only discuss 8-bit fonts here and not #Unicode.

 Font encoding support is ensured by several classes:
 #wxFont itself, but also #wxFontEnumerator and
 #wxFontMapper. wxFont encoding support is reflected by
 a (new) constructor parameter @e encoding which takes one of the following
 values (elements of enumeration type @c wxFontEncoding):

 @beginDefList
 @itemdef{wxFONTENCODING_SYSTEM,
          The default encoding of the underlying
          operating system (notice that this might be a "foreign" encoding for foreign
          versions of Windows 9x/NT).}
 @itemdef{wxFONTENCODING_DEFAULT,
          The applications default encoding as returned by wxFont::GetDefaultEncoding.
          On program startup, the applications default encoding is the same as
          wxFONTENCODING_SYSTEM, but may be changed to make all the fonts created later
          to use it (by default).}
 @itemdef{wxFONTENCODING_ISO8859_1..15,
          ISO8859 family encodings which are
          usually used by all non-Microsoft operating systems.}
 @itemdef{wxFONTENCODING_KOI8,
          Standard Cyrillic encoding for the Internet
          (but see also wxFONTENCODING_ISO8859_5 and wxFONTENCODING_CP1251).}
 @itemdef{wxFONTENCODING_CP1250, Microsoft analogue of ISO8859-2}
 @itemdef{wxFONTENCODING_CP1251, Microsoft analogue of ISO8859-5}
 @itemdef{wxFONTENCODING_CP1252, Microsoft analogue of ISO8859-1}
 @endDefList

 As you may see, Microsoft's encoding partly mirror the standard ISO8859 ones,
 but there are (minor) differences even between ISO8859-1 (Latin1, ISO encoding
 for Western Europe) and CP1251 (WinLatin1, standard code page for English
 versions of Windows) and there are more of them for other encodings.

 The situation is particularly complicated with Cyrillic encodings for which
 (more than) three incompatible encodings exist: KOI8 (the old standard, widely
 used on the Internet), ISO8859-5 (ISO standard for Cyrillic) and CP1251
 (WinCyrillic).

 This abundance of (incompatible) encodings should make it clear that using
 encodings is less easy than it might seem. The problems arise both from the
 fact that the standard encodings for the given language (say Russian, which is
 written in Cyrillic) are different on different platforms and because the
 fonts in the given encoding might just not be installed (this is especially a
 problem with Unix, or, in general, non-Win32 systems).

 To clarify, the #wxFontEnumerator
 class may be used to enumerate both all available encodings and to find the
 facename(s) in which the given encoding exists. If you can find the font in
 the correct encoding with wxFontEnumerator then your troubles are over, but,
 unfortunately, sometimes this is not enough. For example, there is no standard
 way (that I know of, please tell me if you do!) to find a font on a Windows system
 for KOI8 encoding (only for WinCyrillic one which is quite different), so
 #wxFontEnumerator will never return one, even if
 the user has installed a KOI8 font on his system.

 To solve this problem, a #wxFontMapper class is provided.

 This class stores the mapping between the encodings and the font face
 names which support them in #wxConfig object. Of
 course, it would be fairly useless if it tried to determine these mappings by
 itself, so, instead, it (optionally) asks the user and remembers his answers
 so that the next time the program will automatically choose the correct font.
 All these topics are illustrated by the @ref samplefont_overview;
 please refer to it and the documentation of the classes mentioned here for
 further explanations.

*/