diff options
Diffstat (limited to 'doc/src/internationalization/i18n.qdoc')
| -rw-r--r-- | doc/src/internationalization/i18n.qdoc | 277 |
1 files changed, 272 insertions, 5 deletions
diff --git a/doc/src/internationalization/i18n.qdoc b/doc/src/internationalization/i18n.qdoc index e873f4e..2d1b8cc 100644 --- a/doc/src/internationalization/i18n.qdoc +++ b/doc/src/internationalization/i18n.qdoc @@ -51,6 +51,7 @@ \page internationalization.html \title Internationalization with Qt \brief Information about Qt's support for internationalization and multiple languages. + \nextpage Writing Source Code for Translation \keyword internationalization \keyword i18n @@ -59,11 +60,11 @@ the application usable by people in countries other than one's own. \tableofcontents - + \section1 Relevant Qt Classes and APIs These classes support internationalizing of Qt applications. - + \annotatedlist i18n \section1 Languages and Writing Systems @@ -438,9 +439,13 @@ application language. The default event handler for QWidget subclasses responds to the - QEvent::LanguageChange event, and will call this function when necessary; - other application components can also force widgets to update themselves - by posting the \l{QEvent::LanguageChange}{LanguageChange} event to them. + QEvent::LanguageChange event, and will call this function when necessary. + + \l{QEvent::LanguageChange}{LanguageChange} events are posted when a new + translation is installed using the QCoreApplication::installTranslator() + function. Additionally, other application components can also force + widgets to update themselves by posting LanguageChange events to them. + \section1 Translating Non-Qt Classes @@ -516,3 +521,265 @@ For details on Mac-specific translation, refer to the Qt/Mac Specific Issues document \l{Qt for Mac OS X - Specific Issues#Translating the Application Menu and Native Dialogs}{here}. */ + +/*! + \page i18n-source-translation.html + \title Writing Source Code for Translation + \ingroup i18n + \previouspage Internationalization with Qt + \contentspage Internationalization with Qt + \nextpage Translation Rules for Plurals + \brief How to write source code in a way that makes it possible for user-visible text to be translated. + + \tableofcontents + + \section1 The Basics + + Developers use the \l{QObject::}{tr()} function to obtain translated text + for their classes, typically for display purposes. This function is also + used to indicate which text strings in an application are translatable. + + Qt indexes each translatable string by the \e{translation context} it is + associated with; this is generally the name of the QObject subclass it is + used in. + + Translation contexts are defined for new QObject-based classes by the use + of the Q_OBJECT macro in each new class definition. + + When tr() is called, it looks up the translatable string using a QTranslator + object. For translation to work, one or more of these must have been + installed on the application object in the way described in the + \l{#Enabling Translation}{Enabling Translation} section below. + + \section1 Defining a Translation Context + + The translation context for QObject and each QObject subclass is the + class name itself. Developers subclassing QObject must use the + Q_OBJECT macro in their class definition to override the translation + context. This macro sets the context to the name of the subclass. + + For example, the following class definition includes the Q_OBJECT macro, + implementing a new tr() that uses the \c MainWindow context: + + \snippet mainwindows/sdi/mainwindow.h class definition with macro + \dots + + If Q_OBJECT is not used in a class definition, the context will be + inherited from the base class. For example, since all QObject-based + classes in Qt provide a context, a new QWidget subclass defined without + a Q_OBJECT macro will use the \c QWidget context if its tr() function + is invoked. + + \section1 Using tr() to Obtain a Translation + + The following example shows how a translation is obtained for the + class shown in the previous section: + + \snippet mainwindows/sdi/mainwindow.cpp implicit tr context + \dots + + Here, the translation context is \c MainWindow because it is the + \c MainWindow::tr() function that is invoked. The text returned + by the tr() function is a translation of "&File" obtained from + the \c MainWindow context. + + When Qt's translation tool, \l lupdate, is used to process a set of source + files, the text wrapped in tr() calls is stored in a section of the translation + file that corresponds to its translation context. + + In some situations, it is useful to give a translation context explicitly + by fully qualifying the call to tr(); for example: + + \snippet doc/src/snippets/code/src_corelib_kernel_qobject.cpp explicit tr context + + This call obtains the translated text for "Page up" from the \c QScrollBar + context. Developers can also use the QCoreApplication::translate() function + to obtain a translation for a particular translation context. + + \section1 Translator Comments + + Developers can include information about each translatable string to + help translators with the translation process. These are extracted + when \l lupdate is used to process the source files. The recommended + way to add comments is to annotate the tr() calls in your code with + comments of the form: + + \tt{//: ...} + + or + + \tt{\begincomment: ... \endcomment} + + Examples: + + \snippet doc/src/snippets/code/src_corelib_kernel_qobject.cpp 40 + + In these examples, the comments will be associated with the strings + passed to tr() in the context of each call. + + \section1 Adding Meta-Data to Strings + + Additional data can be attached to each translatable message. These are + extracted when \l lupdate is used to process the source files. The + recommended way to add meta-data is to annotate the tr() calls in your code + with comments of the form: + + \tt{//= <id>} + + This can be used to give the message a unique identifier to support tools + which need it. + + An alternative way to attach meta-data is to use the following syntax: + + \tt{//~ <field name> <field contents>} + + This can be used to attach meta-data to the message. The field name should + consist of a domain prefix (possibly the conventional file extension of the + file format the field is inspired by), a hyphen and the actual field name + in underscore-delimited notation. For storage in TS files, the field name + together with the prefix "extra-" will form an XML element name. The field + contents will be XML-escaped, but otherwise appear verbatim as the + element's contents. Any number of unique fields can be added to each + message. + + Example: + + \snippet doc/src/snippets/code/src_corelib_kernel_qobject.cpp meta data + + Meta-data appearing right in front of a magic TRANSLATOR comment applies to + the whole TS file. + + \section1 Disambiguation + + If the same translatable string is used in different roles within the same + translation context, an additional identifying string may be passed in + the call to \l{QObject::}{tr()}. This optional disambiguation argument + is used to distinguish between otherwise identical strings. + + Example: + + \snippet doc/src/snippets/code/src_corelib_kernel_qobject.cpp 17 + \dots + + In Qt 4.4 and earlier, this disambiguation parameter was the preferred + way to specify comments to translators. + + \section1 Character Encodings + + You can set the encoding for the source text by calling QTextCodec::setCodecForTr(). + By default, the source text is assumed to be in Latin-1 encoding. + + \section1 Handling Plurals + + Some translatable strings contain placeholders for integer values and need + to be translated differently depending on the values in use. + + To help with this problem, developers pass an additional integer argument + to the \l{QObject::}{tr()} function, and typically use a special notation + for plurals in each translatable string. + + If this argument is equal or greater than zero, all occurrences of + \c %n in the resulting string are replaced with a decimal representation + of the value supplied. In addition, the translation used will adapt to the + value according to the rules for each language. + + Example: + + \snippet doc/src/snippets/code/src_corelib_kernel_qobject.cpp 18 + + The table below shows what string is returned depending on the + active translation: + + \table + \header \o \o{3,1} Active Translation + \header \o \a n \o No Translation \o French \o English + \row \o 0 \o "0 message(s) saved" \o "0 message sauvegard\unicode{0xE9}" \o "0 message\bold{s} saved" + \row \o 1 \o "1 message(s) saved" \o "1 message sauvegard\unicode{0xE9}" \o "1 message saved" + \row \o 2 \o "2 message(s) saved" \o "2 message\bold{s} sauvegard\unicode{0xE9}\bold{s}" \o "2 message\bold{s} saved" + \row \o 37 \o "37 message(s) saved" \o "37 message\bold{s} sauvegard\unicode{0xE9}\bold{s}" \o "37 message\bold{s} saved" + \endtable + + This idiom is more flexible than the traditional approach; e.g., + + \snippet doc/src/snippets/code/src_corelib_kernel_qobject.cpp 19 + + because it also works with target languages that have several + plural forms (e.g., Irish has a special "dual" form that should + be used when \c n is 2), and it handles the \e n == 0 case + correctly for languages such as French that require the singular. + See the \l{Qt Linguist Manual} for details. + + Instead of \c %n, you can use \c %Ln to produce a localized + representation of \a n. The conversion uses the default locale, + set using QLocale::setDefault(). (If no default locale was + specified, the "C" locale is used.) + + A summary of the rules used to translate strings containing plurals can be + found in the \l{Translation Rules for Plurals} document. + + \section1 Enabling Translation + + Typically, your application's \c main() function will look like + this: + + \snippet doc/src/snippets/code/doc_src_i18n.qdoc 8 + + Note the use of QLibraryInfo::location() to locate the Qt translations. + Developers should request the path to the translations at run-time by + passing QLibraryInfo::TranslationsPath to this function instead of + using the \c QTDIR environment variable in their applications. + + \section1 Further Reading + + \l{Qt Linguist Manual}, \l{Hello tr Example}, \l{Translation Rules for Plurals} +*/ + +/*! + \page i18n-plural-rules.html + \title Translation Rules for Plurals + \ingroup i18n + \previouspage Writing Source Code for Translation + \contentspage Internationalization with Qt + \brief A summary of the translation rules for plurals produced by Qt's i18n tools. + + The table below shows the specific rules that are produced by Qt Linguist + and \c lrelease for a selection of languages. Cells marked \e otherwise + indicate the form used when none of the other rules are appropriate for a + specific language. + + \table 80% + \header \o Language \o Rule 1 \o Rule 2 \o Rule 3 + \row \o English \o \c{n == 1} + \o \e{otherwise} \o N/A + \row \o French \o \c{n < 2} + \o \e{otherwise} \o N/A + \row \o Czech \o \c{n % 100 == 1} + \o \c{n % 100 >= 2 && n % 100 <= 4} + \o \e{otherwise} + \row \o Irish \o \c{n == 1} + \o \c{n == 2} \o \e{otherwise} + \row \o Latvian \o \c{n % 10 == 1&& n % 100 != 11} + \o \c{n != 0} \o \e{otherwise} + \row \o Lithuanian \o \c{n % 10 == 1&& n % 100 != 11} + \o \c{n % 100 != 12 && n % 10 == 2} + \o \e{otherwise} + \row \o Macedonian \o \c{n % 10 == 1} + \o \c{n % 10 == 2} \o \e{otherwise} + \row \o Polish \o \c{n == 1} + \o \c{n % 10 >= 2 && n % 10 <= 4 + && (n % 100 < 10 || n % 100 > 20)} + \o \e{otherwise} + \row \o Romanian \o \c{n == 1} + \o \c{n == 0|| (n % 100 >= 1 && n % 100 <= 20)} + \o \e{otherwise} + \row \o Russian \o \c{n % 10 == 1&& n % 100 != 11} + \o \c{n % 10 >= 2 && n % 10 <= 4 + && (n % 100 < 10 || n % 100 > 20)} + \o \e{otherwise} + \row \o Slovak \o \c{n == 1} \o \c{n >= 2 && n <= 4} + \o \e{otherwise} + \row \o Japanese \o \e{otherwise} \o N/A \o N/A + \endtable + + The rules themselves are not documented and are internal to Qt Linguist and \c lrelease. +*/ |