The 國際化 and 本地化 of an application are the processes of adapting the application to different languages, regional differences, and technical requirements of a target market.
The need for internationalization ranges from spelling changes to enabling the application to operate in different languages and to use different input techniques, character encoding, and presentation conventions.
All input controls and text drawing methods in Qt offer built-in support for all supported languages. The built-in font engine correctly renders text that contains characters from a variety of different writing systems at the same time.
| For more information about | 見 |
|---|---|
| Internationalizing source code | 編寫翻譯源代碼 |
| Configuring and deploying translations, as well as using existing Qt module translations | 本地化應用程序 |
| Using the Qt translation tools | Qt Linguist 手冊 |
The following video shows how to internationalize and localize a simple example application:
The following classes support internationalizing of Qt applications.
| QCollator | 根據本地整理算法比較字符串 |
| QCollatorSortKey | 可以用於加速字符串整理 |
| QLocale | 在數字及其各種語言的字符串錶示之間轉換 |
| QStringConverter | Base class for encoding and decoding text |
| QStringDecoder | State-based decoder for text |
| QStringEncoder | State-based encoder for text |
| QTextCodec | 在文本編碼間轉換 |
| QTextDecoder | 基於狀態的解碼器 |
| QTextEncoder | 基於狀態的編碼器 |
| QTranslator | 用於文本輸齣的國際化支持 |
見 編寫翻譯源代碼 for more information about how to use the classes in applications.
Qt supports most 語言 in use today.
Input controls, such as the Qt Quick TextInput 類型和 QLineEdit , QTextEdit , and derived classes, as well as display controls, such as the Text 類型和 QLabel class handle the following special features of the different writing systems:
Some of the Asian languages are written without spaces between words. Line breaking can occur either after any character (with exceptions) as in Chinese, Japanese and Korean, or after logical word boundaries as in Thai.
阿拉伯語和希伯來語從右嚮左書寫，除數字和嵌入的英文文本是從左嚮右書寫外。準確行為的定義是在 Unicode 技術附錄 #9 .
Some languages, such as Vietnamese, make extensive use of these marks and some characters can have more than one mark at the same time to clarify pronunciation.
In special contexts, some pairs of characters get replaced by a combined glyph forming a ligature. Common examples are the
fl
and
fi
ligatures used in typesetting US and European books.
Qt 文本引擎 supports different writing systems that work on all platforms if the fonts for rendering them are installed.
You do not need to know about the writing system used in a particular language, unless you want to write your own text input controls. In some languages, such as Arabic or languages from the Indian subcontinent, the width and shape of a glyph changes depending on the surrounding characters. To take this into account in C++ code, use QTextLayout 。編寫輸入控件還要求一些腳本知識，將要使用它們。通常，最輕鬆方式是子類化 QLineEdit or QTextEdit .
Encoding is relevant both for application source files and the text files that the application reads or writes.
QML documents are always encoded in UTF-8 format. Since Qt 6, 8-bit UTF-8 is the predominant encoding also in Qt C++.
The
lupdate
tool extracts UI strings from your application. It expects all source code to be encoded in UTF-8 by default.
However, some editors, such as Visual Studio, use a different encoding by default. One way to avoid encoding issues is to limit any source code to ASCII, and use escape sequences for translatable strings with other characters, for example:
label->setText(tr("F\374r \310lise"));
QString::toUtf8
() returns the text in UTF-8 encoding, which preserves
Unicode
information while looking like plain ASCII if the text is wholly ASCII. To convert Unicode to local 8-bit encoding, use
QString::toLocal8Bit
(). On Unix systems, this is equivalent to
toUtf8()
. On Windows, the system's current code page is used.
For converting from UTF-8 and local 8-bit encoding to QString ，使用 QString::fromUtf8 () 和 QString::fromLocal8Bit () convenience functions.
使用 QTextStream::setEncoding () to set common encoding for text streams.
If you need some other legacy encoding, use the QTextCodec class from the Qt5Compat module.
When an application starts, the locale of the machine determines the 8-bit encoding used for external 8-bit data. QTextCodec::codecForLocale () returns a codec that you can use to convert between this locale encoding and Unicode.
The application may occasionally require encoding other than the default local 8-bit encoding. For example, an application in a Cyrillic KOI8-R locale (the de-facto standard locale in Russia) might need to output Cyrillic in the ISO 8859-5 encoding. Code for this would be:
QString string = ...; // some Unicode text QTextCodec *codec = QTextCodec::codecForName("ISO 8859-5"); QByteArray encodedString = codec->fromUnicode(string);
The following code demonstrates the conversion from ISO 8859-5 Cyrillic to Unicode:
QByteArray encodedString = ...; // some ISO 8859-5 encoded text QTextCodec *codec = QTextCodec::codecForName("ISO 8859-5"); QString string = codec->toUnicode(encodedString);
For a complete list of supported encodings see the QTextCodec 文檔編製。
Qt 運行的某些 OS (操作係統) 和窗口係統，僅有限支持 Unicode。可用於底層係統的支持級彆對 Qt 在這些平颱提供的支持有一定影響，盡管一般而言 Qt 應用程序不需要太擔心特定平颱的局限性。
/usr/share/locale/ja_JP.EUC
directory, you cannot display Japanese text unless you install Japanese fonts and the directory is complete. For best results, use complete locales from your system vendor.
| 本地化應用程序 | Localizing Qt and Qt Quick apps into multiple languages. |
| Qt Linguist 範例 | 使用 Qt Linguist 國際化 Qt 應用程序 |
| Qt Linguist 手冊 | Using Qt translation tools: lupdate, lrelease, and Qt Linguist |
| Text ID based translations | 基於文本 ID 的國際化，為具有很多目標區域設置和很多要翻譯文本的大型工程提供支持 |
| Translation Rules for Plural Forms | A summary of the translation rules for plural forms produced by Qt's translation tools. |
| 編寫翻譯源代碼 | Writing source code that enables the localization of applications. |