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diff --git a/doc/src/unicode.qdoc b/doc/src/unicode.qdoc new file mode 100644 index 0000000..42ac5a4 --- /dev/null +++ b/doc/src/unicode.qdoc @@ -0,0 +1,165 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Qt Software Information (qt-info@nokia.com) +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain +** additional rights. These rights are described in the Nokia Qt LGPL +** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this +** package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3.0 as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU General Public License version 3.0 requirements will be +** met: http://www.gnu.org/copyleft/gpl.html. +** +** If you are unsure which license is appropriate for your use, please +** contact the sales department at qt-sales@nokia.com. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! + \page unicode.html + \title Unicode + \ingroup architecture + \ingroup text-processing + \brief Information about support for Unicode in Qt. + + Unicode is a multi-byte character set, portable across all major + computing platforms and with decent coverage over most of the world. + It is also single-locale; it includes no code pages or other + complexities that make software harder to write and test. There is no + competing character set that's reasonably cross-platform. For these + reasons, Unicode 4.0 is used as the native character set for Qt. + + + \section1 Information about Unicode on the Web + + The \l{http://www.unicode.org/}{Unicode Consortium} has a number + of documents available, including + + \list + + \i \l{http://www.unicode.org/unicode/standard/principles.html}{A + technical introduction to Unicode} + \i \l{http://www.unicode.org/unicode/standard/standard.html}{The + home page for the standard} + + \endlist + + + \section1 The Standard + + The current version of the standard is 4.0.0. + + \list + + \i \link http://www.amazon.com/exec/obidos/ASIN/0321185781/trolltech/t + The Unicode Standard, version 4.0.\endlink See also + \link http://www.unicode.org/unicode/standard/versions/ + its home page.\endlink + \i \link http://www.amazon.com/exec/obidos/ASIN/0201616335/trolltech/t + The Unicode Standard, version 3.2.\endlink + \i \link http://www.amazon.com/exec/obidos/ASIN/0201473459/trolltech/t + The Unicode Standard, version 2.0.\endlink See also the + \link http://www.unicode.org/unicode/reports/tr8.html 2.1 + update\endlink and + \link http://www.unicode.org/unicode/standard/versions/enumeratedversions.html#Unicode 2.1.9 the 2.1.9 data files\endlink at www.unicode.org. + + \endlist + + \section1 Unicode in Qt + + In Qt, and in most applications that use Qt, most or all user-visible + strings are stored using Unicode. Qt provides: + + \list + + \i Translation to/from legacy encodings for file I/O: see + QTextCodec and QTextStream. + \i Translation from Input Methods and 8-bit keyboard input. + \i Translation to legacy character sets for on-screen display. + \i A string class, QString, that stores Unicode characters, with + support for migrating from C strings including fast (cached) + translation to and from US-ASCII, and all the usual string + operations. + \i Unicode-aware widgets where appropriate. + \i Unicode support detection on Windows, so that Qt provides Unicode + even on Windows platforms that do not support it natively. + + \endlist + + To fully benefit from Unicode, we recommend using QString for storing + all user-visible strings, and performing all text file I/O using + QTextStream. Use QKeyEvent::text() for keyboard input in any custom + widgets you write; it does not make much difference for slow typists + in Western Europe or North America, but for fast typists or people + using special input methods using text() is beneficial. + + All the function arguments in Qt that may be user-visible strings, + QLabel::setText() and a many others, take \c{const QString &}s. + QString provides implicit casting from \c{const char *} + so that things like + + \snippet doc/src/snippets/code/doc_src_unicode.qdoc 0 + + will work. There is also a function, QObject::tr(), that provides + translation support, like this: + + \snippet doc/src/snippets/code/doc_src_unicode.qdoc 1 + + QObject::tr() maps from \c{const char *} to a Unicode string, and + uses installable QTranslator objects to do the mapping. + + Qt provides a number of built-in QTextCodec classes, that is, + classes that know how to translate between Unicode and legacy + encodings to support programs that must talk to other programs or + read/write files in legacy file formats. + + By default, conversion to/from \c{const char *} uses a + locale-dependent codec. However, applications can easily find codecs + for other locales, and set any open file or network connection to use + a special codec. It is also possible to install new codecs, for + encodings that the built-in ones do not support. (At the time of + writing, Vietnamese/VISCII is one such example.) + + Since US-ASCII and ISO-8859-1 are so common, there are also especially + fast functions for mapping to and from them. For example, to open an + application's icon one might do this: + + \snippet doc/src/snippets/code/doc_src_unicode.qdoc 2 + + or + + \snippet doc/src/snippets/code/doc_src_unicode.qdoc 3 + + Regarding output, Qt will do a best-effort conversion from + Unicode to whatever encoding the system and fonts provide. + Depending on operating system, locale, font availability, and Qt's + support for the characters used, this conversion may be good or bad. + We will extend this in upcoming versions, with emphasis on the most + common locales first. + + \sa {Internationalization with Qt} +*/ |