QT learning: use non TS files such as json/xml to realize multilingual internationalization

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qt The default internationalization is to use Linguist + .ts, To achieve internationalization . However, there may be language documents in other formats used by the translation department within the company , Or build a translation website by yourself , What you can download is definitely not ts file , It is a common file format , such as xml/json wait .
Now we use JSON File to store the translated key And the translated value value, But the project source code is still used internally qt Provided QObject::tr("key") as well as qml The use of qsTr("key") Method to use translation .

The main method is also relatively simple ：

• 1、 Use one map type , Storage JSON The resolved key-value value
• 2、 Create a new class MyTranslator Inherited from QTranslator, And then reload QTranslator::translate Method
• 3、 Use QApplication::instance()->installTranslator register MyTranslator Example
• 4、 Code internal use QObject::tr("key") Way to achieve internationalization

Say below MyTranslator The implementation of the

analysis Json

Mainly is to JSON In the document key-value, Store it in map In the table , For the back translate Use

void MyTranslator::LoadLocalCachedInfo(QString langCode)
{
    QString fileName = (QApplication::applicationDirPath() +
                        TRANS_DIR  + "/" + LOCAL_TRANS_FILE_NAME).arg(langCode);
    QFile langFile(fileName);
    if(!langFile.exists()) {
        return;
    }

    langFile.open(QIODevice::ReadOnly);
    QByteArray byteInfo = langFile.readAll();
    if (!LoadJsonTransInfo(byteInfo)) {
        return;
    }

    emit LanguageChanged();
}

bool MyTranslator::LoadJsonTransInfo(QByteArray& byteinfo)
{
    QJsonObject jsonObj;
    QJsonParseError error;
    QJsonDocument jsonDoc(QJsonDocument::fromJson(byteinfo, &error));

    if (jsonDoc.isEmpty() || jsonDoc.isNull()) {
        QString errorStr = error.errorString();
        return false;
    }

    m_loadedTransInfo.clear();
    for(auto& transKey : jsonDoc.object().keys()) {
        m_loadedTransInfo[transKey.toStdString()] =
                jsonDoc.object()[transKey].toString().toStdString();
    }

    return true;
}

heavy load translate

according to [virtual] QString QTranslator::translate(const char *context, const char *sourceText, const char *disambiguation = nullptr, int n = -1) const The prototype of the , Just reload one . Mainly through the incoming sourceText, In front of map Find the corresponding in the table value, Translation string , Return to .

QString MyTranslator::translate(const char *context, 
                                const char *sourceText, 
                                const char *disambiguation, int n) const
{
    // if no result return original
    if(m_loadedTransInfo.count(sourceText) <= 0) {
        return sourceText;
    }

    // from loaded value
    return QString::fromStdString(m_loadedTransInfo.at(std::string(sourceText)));
}

register MyTranslator example

Registration instance , Be sure to be on the main thread , The other is to use QObject::tr("key") Previous registration .

QApplication::instance()->installTranslator(&MyTranslator::getInstance());

Running results

chinese JSON file ：

{
    "button_name": " Button name ",
	"window_name": " Main window name "
}

The complete implementation can search official account through wechat ：“ Shangguan Hongzhu ”, Pay attention to and reply to ：“qt_language”, Get resource links . If you have any questions, you can also leave a message in official account .

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