2c84f37054
Don't mention Windows 95, OS/2 and SGI. Closes https://github.com/wxWidgets/wxWidgets/pull/135
85 lines
4.2 KiB
C
85 lines
4.2 KiB
C
/////////////////////////////////////////////////////////////////////////////
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// Name: fontencoding.h
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// Purpose: topic overview
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// Author: wxWidgets team
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// Licence: wxWindows licence
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/////////////////////////////////////////////////////////////////////////////
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/**
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@page overview_fontencoding Font Encodings
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@tableofcontents
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wxWidgets has support for multiple font encodings.
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By encoding we mean here the mapping between the character codes and the
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letters. Probably the most well-known encoding is (7 bit) ASCII one which is
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used almost universally now to represent the letters of the English alphabet
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and some other common characters. However, it is not enough to represent the
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letters of foreign alphabets and here other encodings come into play. Please
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note that we will only discuss 8-bit fonts here and not Unicode
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(see @ref overview_unicode).
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Font encoding support is ensured by several classes: wxFont itself, but also
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wxFontEnumerator and wxFontMapper. wxFont encoding support is reflected by a
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(new) constructor parameter @e encoding which takes one of the following values
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(elements of enumeration type @c wxFontEncoding):
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@beginDefList
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@itemdef{wxFONTENCODING_SYSTEM,
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The default encoding of the underlying operating system.}
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@itemdef{wxFONTENCODING_DEFAULT,
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The applications default encoding as returned by wxFont::GetDefaultEncoding.
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On program startup, the applications default encoding is the same as
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wxFONTENCODING_SYSTEM, but may be changed to make all the fonts created later
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to use it (by default).}
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@itemdef{wxFONTENCODING_ISO8859_1..15,
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ISO8859 family encodings which are
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usually used by all non-Microsoft operating systems.}
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@itemdef{wxFONTENCODING_KOI8,
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Standard Cyrillic encoding for the Internet
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(but see also wxFONTENCODING_ISO8859_5 and wxFONTENCODING_CP1251).}
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@itemdef{wxFONTENCODING_CP1250, Microsoft analogue of ISO8859-2}
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@itemdef{wxFONTENCODING_CP1251, Microsoft analogue of ISO8859-5}
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@itemdef{wxFONTENCODING_CP1252, Microsoft analogue of ISO8859-1}
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@endDefList
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As you may see, Microsoft's encoding partly mirror the standard ISO8859 ones,
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but there are (minor) differences even between ISO8859-1 (Latin1, ISO encoding
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for Western Europe) and CP1251 (WinLatin1, standard code page for English
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versions of Windows) and there are more of them for other encodings.
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The situation is particularly complicated with Cyrillic encodings for which
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(more than) three incompatible encodings exist: KOI8 (the old standard, widely
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used on the Internet), ISO8859-5 (ISO standard for Cyrillic) and CP1251
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(WinCyrillic).
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This abundance of (incompatible) encodings should make it clear that using
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encodings is less easy than it might seem. The problems arise both from the
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fact that the standard encodings for the given language (say Russian, which is
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written in Cyrillic) are different on different platforms and because the
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fonts in the given encoding might just not be installed (this is especially a
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problem with Unix, or, in general, non-Win32 systems).
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To clarify, the wxFontEnumerator class may be used to enumerate both all
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available encodings and to find the facename(s) in which the given encoding
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exists. If you can find the font in the correct encoding with wxFontEnumerator
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then your troubles are over, but, unfortunately, sometimes this is not enough.
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For example, there is no standard way (that I know of, please tell me if you
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do!) to find a font on a Windows system for KOI8 encoding (only for WinCyrillic
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one which is quite different), so wxFontEnumerator will never return one, even
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if the user has installed a KOI8 font on his system.
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To solve this problem, a wxFontMapper class is provided.
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This class stores the mapping between the encodings and the font face names
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which support them in wxConfigBase object. Of course, it would be fairly
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useless if it tried to determine these mappings by itself, so, instead, it
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(optionally) asks the user and remembers his answers so that the next time the
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program will automatically choose the correct font. All these topics are
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illustrated by the @ref page_samples_font; please refer to it and the
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documentation of the classes mentioned here for further explanations.
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*/
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