[Advanced] Qt Script access QObject from C++ code

[bunjee]

Hey guys,

I'm using the Qt script bindings from Qt Labs.

I'm writing the following lines in my script :

function main() {}
 
main.prototype.createPage = function()
{
    box = new QWidget; // I need that QWidget pointer in my C++ code
}

function main() {}

main.prototype.createPage = function()
{
    box = new QWidget; // I need that QWidget pointer in my C++ code
}

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I'm calling this function from C++ code.
Afterward, I need to gather all references to Qt Objects.

How can I do that ?

Thanks.

[wysota]

You can have a function in script that keeps references to all objects created and you can assign a function to the global object of the engine that will return a list of them. Then it's just a matter of calling that function using QScriptEngine::evaluate() and interpreting the resulting QScriptValue as a list of objects.

[bunjee]

You can have a function in script that keeps references to all objects created.

Sounds good, how can I do that ? (I want this to be transparent)

[wysota]

Call it from the function you pasted in your previous post just before returning the object or modify the prototype of each class you want managed directly.

[bunjee]

I did it this way:

Qt script code:

function New(This, object)
{ 
    if (!This.objects) This.objects = new Array;
 
    This.objects.push(object); 
    return object; 
}
 
function objects() { return this.objects; } // Getting objects from C++
 
...
box = New(this, new QWidget);
...

function New(This, object)
{ 
    if (!This.objects) This.objects = new Array;
    
    This.objects.push(object); 
    return object; 
}

function objects() { return this.objects; } // Getting objects from C++

...
box = New(this, new QWidget);
...

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C++ code:

void qkScriptPrivate::updateObjects()
{
    Q_Q(qkScript);
 
    QScriptValue objects = engine->globalObject().property("objects");
    QScriptValue output = objects.call(scriptValue);
 
    QScriptValueIterator it(output);
    while (it.hasNext())
    {
        it.next();
 
        if (it.value().isQObject()) q->declareObject(it.value().toQObject());
        qkPrint("%s : %s", it.name().C_STR, it.value().toString().C_STR);
    }
}

void qkScriptPrivate::updateObjects()
{
    Q_Q(qkScript);

    QScriptValue objects = engine->globalObject().property("objects");
    QScriptValue output = objects.call(scriptValue);

    QScriptValueIterator it(output);
    while (it.hasNext())
    {
        it.next();

        if (it.value().isQObject()) q->declareObject(it.value().toQObject());
        qkPrint("%s : %s", it.name().C_STR, it.value().toString().C_STR);
    }
}

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Note that you can make it fully transparent by parsing every "new myObject" in the script and replace it by "New(this, new myObject)".

[wysota]

Great, that's exactly what I meant