docs/doxygen/overviews/nonenglish.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        nonenglish.h
   3 // Purpose:     topic overview
   4 // Author:      wxWidgets team
   5 // Licence:     wxWindows licence
   6 /////////////////////////////////////////////////////////////////////////////
   7
   8 /**
   9
  10 @page overview_nonenglish Writing Non-English Applications
  11
  12 @tableofcontents
  13
  14 This article describes how to write applications that communicate with the user
  15 in a language other than English. Unfortunately many languages use different
  16 charsets under Unix and Windows (and other platforms, to make the situation
  17 even more complicated). These charsets usually differ in so many characters
  18 that it is impossible to use the same texts under all platforms.
  19
  20 The wxWidgets library provides a mechanism that helps you avoid distributing
  21 many identical, only differently encoded, packages with your application (e.g.
  22 help files and menu items in iso8859-13 and windows-1257). Thanks to this
  23 mechanism you can, for example, distribute only iso8859-13 data and it will be
  24 handled transparently under all systems.
  25
  26 Please read the @ref overview_i18n which describes the locales concept.
  27
  28 In the following text, wherever @e iso8859-2 and @e windows-1250 are used, any
  29 encodings are meant and any encodings may be substituted there.
  30
  31
  32
  33 @section overview_nonenglish_locales Locales
  34
  35 The best way to ensure correctly displayed texts in a GUI across platforms is
  36 to use locales. Write your in-code messages in English or without diacritics
  37 and put real messages into the message catalog (see @ref overview_i18n).
  38
  39 A standard .po file begins with a header like this:
  40
  41 @code
  42 # SOME DESCRIPTIVE TITLE.
  43 # Copyright (C) YEAR Free Software Foundation, Inc.
  44 # FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
  45 #
  46 msgid ""
  47 msgstr ""
  48 "Project-Id-Version: PACKAGE VERSION\n"
  49 "POT-Creation-Date: 1999-02-19 16:03+0100\n"
  50 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
  51 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
  52 "Language-Team: LANGUAGE <LL@li.org>\n"
  53 "MIME-Version: 1.0\n"
  54 "Content-Type: text/plain; charset=CHARSET\n"
  55 "Content-Transfer-Encoding: ENCODING\n"
  56 @endcode
  57
  58 Note this particular line:
  59
  60 @code
  61 "Content-Type: text/plain; charset=CHARSET\n"
  62 @endcode
  63
  64 It specifies the charset used by the catalog. All strings in the catalog are
  65 encoded using this charset.
  66
  67 You have to fill in proper charset information. Your .po file may look like
  68 this after doing so:
  69
  70 @code
  71 # SOME DESCRIPTIVE TITLE.
  72 # Copyright (C) YEAR Free Software Foundation, Inc.
  73 # FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
  74 #
  75 msgid ""
  76 msgstr ""
  77 "Project-Id-Version: PACKAGE VERSION\n"
  78 "POT-Creation-Date: 1999-02-19 16:03+0100\n"
  79 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
  80 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
  81 "Language-Team: LANGUAGE <LL@li.org>\n"
  82 "MIME-Version: 1.0\n"
  83 "Content-Type: text/plain; charset=iso8859-2\n"
  84 "Content-Transfer-Encoding: 8bit\n"
  85 @endcode
  86
  87 (Make sure that the header is @b not marked as @e fuzzy.)
  88
  89 wxWidgets is able to use this catalog under any supported platform
  90 (although iso8859-2 is a Unix encoding and is normally not understood by
  91 Windows).
  92
  93 How is this done? When you tell the wxLocale class to load a message catalog
  94 that contains a correct header, it checks the charset. The catalog is then
  95 converted to the charset used (see wxLocale::GetSystemEncoding and
  96 wxLocale::GetSystemEncodingName) by the user's operating system.
  97
  98
  99 @section overview_nonenglish_strings Non-English Strings or 8-bit Characters in Source
 100
 101 By convention, you should only use characters without diacritics (i.e. 7-bit
 102 ASCII strings) for msgids in the source code and write them in English.
 103
 104 If you port software to wxWidgets, you may be confronted with legacy source
 105 code containing non-English string literals. Instead of translating the strings
 106 in the source code to English and putting the original strings into message
 107 catalog, you may configure wxWidgets to use non-English msgids and translate to
 108 English using message catalogs:
 109
 110 @li If you use the program @c xgettext to extract the strings from the source
 111     code, specify the option <tt>--from-code=@<source code charset@></tt>.
 112 @li Specify the source code language and charset as arguments to
 113     wxLocale::AddCatalog. For example:
 114     @code
 115     locale.AddCatalog(wxT("myapp"), wxLANGUAGE_GERMAN, wxT("iso-8859-1"));
 116     @endcode
 117
 118
 119 @section overview_nonenglish_fontmapping Font Mapping
 120
 121 You can use @ref overview_mbconv and wxFontMapper to display text:
 122
 123 @code
 124 if (!wxFontMapper::Get()->IsEncodingAvailable(enc, facename))
 125 {
 126     wxFontEncoding alternative;
 127     if (wxFontMapper::Get()->GetAltForEncoding(enc, &alternative,
 128                                                facename, false))
 129     {
 130         wxCSConv convFrom(wxFontMapper::Get()->GetEncodingName(enc));
 131         wxCSConv convTo(wxFontMapper::Get()->GetEncodingName(alternative));
 132         text = wxString(text.mb_str(convFrom), convTo);
 133     }
 134     else
 135         ...failure (or we may try iso8859-1/7bit ASCII)...
 136 }
 137 ...display text...
 138 @endcode
 139
 140
 141 @section overview_nonenglish_converting Converting Data
 142
 143 You may want to store all program data (created documents etc.) in the same
 144 encoding, let's say @c utf-8. You can use wxCSConv to convert data to the
 145 encoding used by the system your application is running on (see
 146 wxLocale::GetSystemEncoding).
 147
 148
 149 @section overview_nonenglish_help Help Files
 150
 151 If you're using wxHtmlHelpController there is no problem at all. You only need
 152 to make sure that all the HTML files contain the META tag:
 153
 154 @code
 155 <meta http-equiv="Content-Type" content="text/html; charset=iso8859-2">
 156 @endcode
 157
 158 Also, the hhp project file needs one additional line in the @c OPTIONS section:
 159
 160 @code
 161 Charset=iso8859-2
 162 @endcode
 163
 164 This additional entry tells the HTML help controller what encoding is used in
 165 contents and index tables.
 166
 167 */