64 bit integers in QML

Question

How do I deal with 64 bit integers in QML? I know that useless Javascript can't handle them normally as it uses doubles for everything, and if I try to use them in a signal, everything gets set to undefined. Is there a way around this? Perhaps I have to use a QVariant or something?

Answer 1

Create your own Integer64 class derived from QObject and give it the functions you need, like

class Integer64 : public QObject
{
    Q_OBJECT

public:
    // ...
    Q_PROPERTY(QString value READ value WRITE setValue NOTIFY valueChanged)
    QString value() const;
    void setValue(QString value);

    Q_INVOKABLE void add(Integer64 * other);
    Q_INVOKABLE void subtract(Integer64 * other);
    Q_INVOKABLE void multiply(Integer64 * other);
    Q_INVOKABLE void divide(Integer64 * other);
    // ...

where you use value() to get a string representation in QML and setValue() to set a value from a string representation.

An additional constructor can be used to efficiently create Integer64 from C++

public:
    explicit Integer64(QObject *parent = 0);
    explicit Integer64(qint64 value, QObject *parent);
    // ...

Then register the type to QML

qmlRegisterType<Integer64>("MyModules", 1, 0, "Integer64");