- Qt 5.5
- Qt Widgets
- I18N Example
- languagechooser.cpp Example File
- Qt 5.5.1 Reference Documentation

# languagechooser.cpp Example File

tools/i18n/languagechooser.cpp

    /****************************************************************************
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    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
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    ** This file is part of the examples of the Qt Toolkit.
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    ** $QT_BEGIN_LICENSE:BSD$
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    #include <QtWidgets>

    #include "languagechooser.h"
    #include "mainwindow.h"

    #ifdef Q_DEAD_CODE_FROM_QT4_MAC
    extern void qt_mac_set_menubar_merge(bool merge);

    #endif

    LanguageChooser::LanguageChooser(const QString& defaultLang, QWidget *parent)
        : QDialog(parent, Qt::WindowStaysOnTopHint)
    {
        groupBox = new QGroupBox("Languages");

        QGridLayout *groupBoxLayout = new QGridLayout;

        QStringList qmFiles = findQmFiles();
        for (int i = 0; i < qmFiles.size(); ++i) {
            QCheckBox *checkBox = new QCheckBox(languageName(qmFiles[i]));
            qmFileForCheckBoxMap.insert(checkBox, qmFiles[i]);
            connect(checkBox, SIGNAL(toggled(bool)), this, SLOT(checkBoxToggled()));
            if (languageMatch(defaultLang, qmFiles[i]))
                    checkBox->setCheckState(Qt::Checked);
            groupBoxLayout->addWidget(checkBox, i / 2, i % 2);
        }
        groupBox->setLayout(groupBoxLayout);

        buttonBox = new QDialogButtonBox;

        showAllButton = buttonBox->addButton("Show All",
                                             QDialogButtonBox::ActionRole);
        hideAllButton = buttonBox->addButton("Hide All",
                                             QDialogButtonBox::ActionRole);

        connect(showAllButton, SIGNAL(clicked()), this, SLOT(showAll()));
        connect(hideAllButton, SIGNAL(clicked()), this, SLOT(hideAll()));

        QVBoxLayout *mainLayout = new QVBoxLayout;
        mainLayout->addWidget(groupBox);
        mainLayout->addWidget(buttonBox);
        setLayout(mainLayout);

    #ifdef Q_DEAD_CODE_FROM_QT4_MAC
        qt_mac_set_menubar_merge(false);
    #endif

        setWindowTitle("I18N");
    }

    bool LanguageChooser::languageMatch(const QString& lang, const QString& qmFile)
    {
        //qmFile: i18n_xx.qm
        const QString prefix = "i18n_";
        const int langTokenLength = 2; /*FIXME: is checking two chars enough?*/
        return qmFile.midRef(qmFile.indexOf(prefix) + prefix.length(), langTokenLength) == lang.leftRef(langTokenLength);
    }

    bool LanguageChooser::eventFilter(QObject *object, QEvent *event)
    {
        if (event->type() == QEvent::Close) {
            MainWindow *window = qobject_cast<MainWindow *>(object);
            if (window) {
                QCheckBox *checkBox = mainWindowForCheckBoxMap.key(window);
                if (checkBox)
                    checkBox->setChecked(false);
            }
        }
        return QWidget::eventFilter(object, event);
    }

    void LanguageChooser::closeEvent(QCloseEvent * /* event */)
    {
        qApp->quit();
    }

    void LanguageChooser::checkBoxToggled()
    {
        QCheckBox *checkBox = qobject_cast<QCheckBox *>(sender());
        MainWindow *window = mainWindowForCheckBoxMap[checkBox];
        if (!window) {
            QTranslator translator;
            translator.load(qmFileForCheckBoxMap[checkBox]);
            qApp->installTranslator(&translator);

            window = new MainWindow;
            window->setPalette(colorForLanguage(checkBox->text()));

            window->installEventFilter(this);
            mainWindowForCheckBoxMap.insert(checkBox, window);
        }
        window->setVisible(checkBox->isChecked());
    }

    void LanguageChooser::showAll()
    {
        foreach (QCheckBox *checkBox, qmFileForCheckBoxMap.keys())
            checkBox->setChecked(true);
    }

    void LanguageChooser::hideAll()
    {
        foreach (QCheckBox *checkBox, qmFileForCheckBoxMap.keys())
            checkBox->setChecked(false);
    }

    QStringList LanguageChooser::findQmFiles()
    {
        QDir dir(":/translations");
        QStringList fileNames = dir.entryList(QStringList("*.qm"), QDir::Files,
                                              QDir::Name);
        QMutableStringListIterator i(fileNames);
        while (i.hasNext()) {
            i.next();
            i.setValue(dir.filePath(i.value()));
        }
        return fileNames;
    }

    QString LanguageChooser::languageName(const QString &qmFile)
    {
        QTranslator translator;
        translator.load(qmFile);

        return translator.translate("MainWindow", "English");
    }

    QColor LanguageChooser::colorForLanguage(const QString &language)
    {
        uint hashValue = qHash(language);
        int red = 156 + (hashValue & 0x3F);
        int green = 156 + ((hashValue >> 6) & 0x3F);
        int blue = 156 + ((hashValue >> 12) & 0x3F);
        return QColor(red, green, blue);
    }