Here’s how to implement multi-language support in Qt:<\/p>\n\n\n\n
QTranslator *trans = new QTranslator;\nif (curLang == \"us_EN\") {\n trans->load(QCoreApplication::applicationDirPath() + \"\/language\/us_EN.qm\");\n} else if (curLang == \"zh_CN\") {\n trans->load(QCoreApplication::applicationDirPath() + \"\/language\/zh_CN.qm\");\n}\nqApp->installTranslator(trans);\n<\/code><\/code><\/pre>\n\n\n\nThis code snippet should be placed before ui->setupUi(this);<\/code> to ensure that the translation files are loaded before the UI is initialized.<\/p>\n\n\n\n2. Dynamic Multi-language Update for Sub-windows in Qt<\/h3>\n\n\n\n
To dynamically update the text content of sub-windows when switching languages, the retranslateUi()<\/code> method must be called. This method, generated by Qt Designer, sets the translations for all text elements in the UI.<\/p>\n\n\n\nDetailed Steps to Call the retranslateUi()<\/code> Method:<\/strong><\/p>\n\n\n\nDetailed Steps to Call the retranslateUi()<\/code> Method:<\/strong><\/p>\n\n\n\n\n- 1. Ensure the Sub-window Has a
retranslateUi()<\/code> Method<\/strong> If the sub-window is created using Qt Designer, the retranslateUi()<\/code> method will automatically be included in the ui_*.h<\/code> file. For example, if your sub-window class is ChildWindow<\/code>, it typically has a member object like Ui::ChildWindow<\/code>, where retranslateUi()<\/code> is defined.<\/li>\n\n\n\n- 2. Implement
changeEvent(QEvent *event)<\/code> in the Sub-window Class<\/strong> Ensure the sub-window overrides the changeEvent<\/code> method to detect the QEvent::LanguageChange<\/code> event and call retranslateUi()<\/code>.<\/li>\n<\/ol>\n\n\n\n\/\/ ChildWindow.h\n\nifndef CHILDWINDOW_H\n\ndefine CHILDWINDOW_H\n\ninclude\n\nnamespace Ui {\n\nclass ChildWindow;\n\n}\n\nclass ChildWindow : public QWidget\n\n{\n\nQ_OBJECT\n\npublic:\n\nexplicit ChildWindow(QWidget *parent = nullptr);\n\n~ChildWindow();\n\nprotected:\n\nvoid changeEvent(QEvent *event) override; \/\/ Override changeEvent\n\nprivate:\n\nUi::ChildWindow *ui;\n\n};\n\nendif \/\/ CHILDWINDOW_H<\/code><\/pre>\n\n\n\n\n- 3. Call
retranslateUi()<\/code> in the Sub-window Implementation<\/strong> In the changeEvent<\/code> method, detect the language change event and call retranslateUi()<\/code>.<\/li>\n<\/ul>\n\n\n\n\/\/ ChildWindow.cpp\n#include \"ChildWindow.h\"\n#include \"ui_ChildWindow.h\"\n\nChildWindow::ChildWindow(QWidget *parent) :\n QWidget(parent),\n ui(new Ui::ChildWindow)\n{\n ui->setupUi(this);\n}\n\nChildWindow::~ChildWindow()\n{\n delete ui;\n}\n\nvoid ChildWindow::changeEvent(QEvent *event)\n{\n if (event->type() == QEvent::LanguageChange) {\n ui->retranslateUi(this); \/\/ Update the UI text\n }\n QWidget::changeEvent(event); \/\/ Call the base class changeEvent\n}\n<\/code><\/pre>\n\n\n\n\n- 4. Install the Translator and Trigger Events in the Main Window<\/strong> Ensure that when switching languages, the translator is correctly installed, and
changeEvent<\/code> is triggered for both the main and sub-windows.<\/li>\n<\/ul>\n\n\n\n\/\/ MainWindow.cpp\n#include \"MainWindow.h\"\n#include \"ChildWindow.h\"\n#include <QTranslator>\n#include <QApplication>\n\nMainWindow::MainWindow(QWidget *parent) :\n QMainWindow(parent),\n ui(new Ui::MainWindow)\n{\n ui->setupUi(this);\n childWindow = new ChildWindow(this); \/\/ Create sub-window\n}\n\nvoid MainWindow::switchLanguage(const QString &languageFile)\n{\n QTranslator translator;\n if (translator.load(languageFile)) {\n qApp->installTranslator(&translator); \/\/ Install the translator\n QEvent event(QEvent::LanguageChange);\n QApplication::sendEvent(this, &event); \/\/ Trigger language change in main window\n QApplication::sendEvent(childWindow, &event); \/\/ Trigger language change in sub-window\n }\n}\n<\/code><\/pre>\n\n\n\nSummary:<\/strong><\/p>\n\n\n\n\n- Sub-windows need to override
changeEvent<\/code> and call retranslateUi()<\/code> when QEvent::LanguageChange<\/code> occurs.<\/li>\n\n\n\n- Ensure that the language change event is correctly sent to all relevant windows, including sub-windows, when switching languages.<\/li>\n\n\n\n
- This approach ensures that both the main and sub-windows dynamically update their text content during language changes.<\/li>\n<\/ul>\n\n\n\n
3. Refreshing Newly Added tr()<\/code> in Qt Creator and Qt Linguist<\/h3>\n\n\n\nThe tr()<\/code> function in Qt is used for string localization. When new or modified content is added within tr()<\/code>, you need to refresh Qt Linguist to display the latest translations. Here are the steps:<\/p>\n\n\n\n\n- Update Translation Files (.ts):<\/strong>\n
\n- Right-click the
.pro<\/code> file in the project tree and select \u201cRun qmake\u201d or choose \u201cRun qmake\u201d from the \u201cBuild\u201d menu.<\/li>\n\n\n\n- This updates the project files and detects new
tr()<\/code> calls.<\/li>\n<\/ul>\n<\/li>\n\n\n\n- Generate or Update
.ts<\/code> Files:<\/strong>\n\n- Go to \u201cTools\u201d \u2192 \u201cExternal\u201d \u2192 \u201cLinguist\u201d \u2192 \u201cUpdate Translations\u201d in Qt Creator. This automatically runs the
lupdate<\/code> command, updating the .ts<\/code> files with the latest tr()<\/code> strings.<\/li>\n<\/ul>\n<\/li>\n\n\n\n- Refresh Qt Linguist:<\/strong>\n
\n- Open the relevant
.ts<\/code> file to check for new tr()<\/code> strings. If the new strings are not visible, try rerunning lupdate<\/code> or manually editing the .ts<\/code> file.<\/li>\n<\/ul>\n<\/li>\n\n\n\n- Edit and Save Translations:<\/strong>\n
\n- Use Qt Linguist to edit the translations in the
.ts<\/code> file and save your changes.<\/li>\n<\/ul>\n<\/li>\n\n\n\n- Regenerate
.qm<\/code> Files:<\/strong>\n\n- In Qt Creator, go to \u201cExternal\u201d \u2192 \u201cLinguist\u201d \u2192 \u201cCompile Translations\u201d to regenerate the
.qm<\/code> files for use by your application.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\nAfter completing these steps, the new content within tr()<\/code> will be refreshed and displayed correctly in Qt Linguist.<\/p>\n","protected":false},"excerpt":{"rendered":"\u00a01. Implementing Multi-language Support in Qt Here̵ […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-341","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/chaixiangyu.cn\/index.php?rest_route=\/wp\/v2\/posts\/341","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/chaixiangyu.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/chaixiangyu.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/chaixiangyu.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/chaixiangyu.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=341"}],"version-history":[{"count":3,"href":"https:\/\/chaixiangyu.cn\/index.php?rest_route=\/wp\/v2\/posts\/341\/revisions"}],"predecessor-version":[{"id":351,"href":"https:\/\/chaixiangyu.cn\/index.php?rest_route=\/wp\/v2\/posts\/341\/revisions\/351"}],"wp:attachment":[{"href":"https:\/\/chaixiangyu.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=341"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/chaixiangyu.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=341"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/chaixiangyu.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=341"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}