Add support for QQmlPropertyValueSource

[cbelyaev]

Hi

How can I help with implementing this?
http://doc.qt.io/qt-5/qtqml-cppintegration-definetypes.html#property-value-sources

[pauldotknopf]

That would be an awesome add! I think its implementation should be straightforward as well.

public class QmlProperty
{
    // PInvoke for QQmlProperty: http://doc.qt.io/qt-5/qqmlproperty.html
}


public interface IQmlPropertyValueSource
{
    void setTarget(QmlProperty target);
}

public class MyNetObject : IQmlPropertyValueSource
{
    private QmlProperty _target;

    public MyNetObject()
    {
        // Maybe create a timer to update the "_target" (if not null)
        // at periodic intervals?
    }
    
    public void setTarget(QmlProperty target)
    {
        _target = target;
    }
}

Then, we'd add the QQmlPropertyValueSource base to the existing NetValue (here) type, which will implement the QQmlPropertyValueSource::setTarget(QQmlProperty) method and send it to .NET.

We'd also have to extend the NetTypeInfo (here) to have a bool IsPropertyValueSource that will be used in NetValue to log if someone is trying to use .NET Object as a value source and it doesn't implement the required IQmlPropertyValueSource .NET interface.

[pauldotknopf]

I'm marking this issue as "todo", as I will likely implement it at some point in the future.

However, I'm open to pull requests. I think this would be perfect for new comers. It's not too big of a change and it exposes you to a comfortable amount of the internals.