docs/latex/wx/tnoneng.tex

   1 \section{Writing non-English applications}\label{nonenglishoverview}
   2
   3 This article describes how to write applications that communicate with
   4 user in language other than English. Unfortunately many languages use
   5 different charsets under Unix and Windows (and other platforms, to make
   6 situation even more complicated). These charsets usually differ in so
   7 many characters it is impossible to use same texts under all platforms.
   8
   9 wxWindows library provides mechanism that helps you avoid distributing many
  10 identical, only differently encoded, packages with your application
  11 (e.g. help files and menu items in iso8859-13 and windows-1257). Thanks
  12 to this mechanism you can, for example, distribute only iso8859-13 data
  13 and it will be handled transparently under all systems.
  14
  15 Please read \helpref{Internationalization}{internationalization} which
  16 describes the locales concept.
  17
  18 In the following text, wherever {\it iso8859-2} and {\it windows-1250} are
  19 used, any encodings are meant and any encodings may be substituted there.
  20
  21 \wxheading{Locales}
  22
  23 The best way to ensure correctly displayed texts in a GUI across platforms
  24 is to use locales. Write your in-code messages in English or without
  25 diacritics and put real messages into the message catalog (see
  26 \helpref{Internationalization}{internationalization}).
  27
  28 A standard .po file begins with a header like this:
  29
  30 \begin{verbatim}
  31 # SOME DESCRIPTIVE TITLE.
  32 # Copyright (C) YEAR Free Software Foundation, Inc.
  33 # FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
  34 #
  35 msgid ""
  36 msgstr ""
  37 "Project-Id-Version: PACKAGE VERSION\n"
  38 "POT-Creation-Date: 1999-02-19 16:03+0100\n"
  39 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
  40 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
  41 "Language-Team: LANGUAGE <LL@li.org>\n"
  42 "MIME-Version: 1.0\n"
  43 "Content-Type: text/plain; charset=CHARSET\n"
  44 "Content-Transfer-Encoding: ENCODING\n"
  45 \end{verbatim}
  46
  47 Note this particular line:
  48
  49 \begin{verbatim}
  50 "Content-Type: text/plain; charset=CHARSET\n"
  51 \end{verbatim}
  52
  53 It specifies the charset used by the catalog. All strings in the catalog
  54 are encoded using this charset.
  55
  56 You have to fill in proper charset information. Your .po file may look like this
  57 after doing so:
  58
  59 \begin{verbatim}
  60 # SOME DESCRIPTIVE TITLE.
  61 # Copyright (C) YEAR Free Software Foundation, Inc.
  62 # FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
  63 #
  64 msgid ""
  65 msgstr ""
  66 "Project-Id-Version: PACKAGE VERSION\n"
  67 "POT-Creation-Date: 1999-02-19 16:03+0100\n"
  68 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
  69 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
  70 "Language-Team: LANGUAGE <LL@li.org>\n"
  71 "MIME-Version: 1.0\n"
  72 "Content-Type: text/plain; charset=iso8859-2\n"
  73 "Content-Transfer-Encoding: 8bit\n"
  74 \end{verbatim}
  75
  76 (Make sure that the header is {\bf not} marked as {\it fuzzy}.)
  77
  78 wxWindows is able to use this catalog under any supported platform
  79 (although iso8859-2 is a Unix encoding and is normally not understood by
  80 Windows).
  81
  82 How is this done? When you tell the wxLocale class to load a message catalog that
  83 contains correct header, it checks the charset. The catalog is then converted
  84 to the charset used (see
  85 \helpref{wxLocale::GetSystemEncoding}{wxlocalegetsystemencoding} and
  86 \helpref{wxLocale::GetSystemEncodingName}{wxlocalegetsystemencodingname}) by
  87 user's operating system. This is default behaviour of the
  88 \helpref{wxLocale}{wxlocale} class; you can disable it by {\bf not} passing
  89 {\tt wxLOCALE\_CONV\_ENCODING} to \helpref{wxLocale::Init}{wxlocaleinit}.
  90
  91 \wxheading{Font mapping}
  92
  93 You can use \helpref{wxEncodingConverter}{wxencodingconverter} and
  94 \helpref{wxFontMapper}{wxfontmapper} to display text:
  95
  96 \begin{verbatim}
  97 if (!wxFontMapper::Get()->IsEncodingAvailable(enc, facename))
  98 {
  99    wxFontEncoding alternative;
 100    if (wxTheFontMapper->GetAltForEncoding(enc, &alternative,
 101                                           facename, FALSE))
 102    {
 103        wxEncodingConverted encconv;
 104        if (!encconv.Init(enc, alternative))
 105            ...failure...
 106        else
 107            text = encconv.Convert(text);
 108    }
 109    else
 110        ...failure...
 111 }
 112 ...display text...
 113 \end{verbatim}
 114
 115 \wxheading{Converting data}
 116
 117 You may want to store all program data (created documents etc.) in
 118 the same encoding, let's say windows1250. Obviously, the best way would
 119 be to use \helpref{wxEncodingConverter}{wxencodingconverter}.
 120
 121 \wxheading{Help files}
 122
 123 If you're using \helpref{wxHtmlHelpController}{wxhtmlhelpcontroller} there is
 124 no problem at all. You must only make sure that all the HTML files contain
 125 the META tag, e.g.
 126
 127 \begin{verbatim}
 128 <meta http-equiv="Content-Type" content="text/html; charset=iso8859-2">
 129 \end{verbatim}
 130
 131 and that the hhp project file contains one additional line in the {\tt OPTIONS}
 132 section:
 133
 134 \begin{verbatim}
 135 Charset=iso8859-2
 136 \end{verbatim}
 137
 138 This additional entry tells the HTML help controller what encoding is used
 139 in contents and index tables.
 140