Visualization of dynamic c++ list with positions as set of Items in QML-app at corresponding positions.

[ilyaik]

@p3c0 This is an idea!
List is a QList<struct {int x; int y}>

But as it always happens... after 1 day of searching solution appears only after asking a question on forum =)

I did as you said: a C++ class myList with QList inside. I made this class as a context property. Class has Q_PROPERTY (int count READ count NOTIFY countChanged) that is the size of QList.
In QML part i've placed

Repeater { 
   model: myList.count;
   Rectangle {
      // black rectangle
        ...
        x: myList.xPosition(index)
        y: myList.yPosition(index)
   }
}

myList has xPosition(index) and yPosition(index) slots recpectively.

And it works.
Thank you for help!

[p3c0]

@ilyaik You're Welcome :)
Using Repeater is also a good idea. You can mark the post as solved if done.

[ilyaik]

I've faces a new problem.

If QList inside myClass changed it's values, but count myList.count didn't, Repeater doesn't updates. That's ok... strictly speaking the Repeater's model myList.count didn't change.
I made a signal from myClass updateSignal. updateSignal emits when data inside list in myClass is updated. In QML this signal is exposed in Connections part.

Connections {
        target: myClass
        onUpdateSignal {
            repeater.model = 0
            repeater.model = myClass.count
        }
}

// And Repeater part

Repeater { 
    id: repeater
    model: 0
    Rectangle {
      // black rectangle
        ...
        x: myList.xPosition(index)
        y: myList.yPosition(index)
    }
}

It renewsrepeater.
But it seams that it's like a crutch.
Is there any proper way to renew Repeater?

P.S. repeater.update() didn't help.

[p3c0]

@ilyaik That is a valid way. Bindings are meant for that.
Also it should work even without first assigning model to 0 in Connections.

[ilyaik]

No. Repeater doesn't renew without assigning model to 0 in Connections. It seems like nothing changes for Repeater if myClass.count stays unchanged.

[p3c0]

@ilyaik That means the count didnot change

repeater.model = myClass.count

the Repeater will update only when the property changes. That is how Binding works.

[ilyaik]

So that's why i use assigning model to 0 in Connections to force Repeater to renew itself when count stays unchanged.

[p3c0]

@ilyaik Ok. So is it that you only want to update x and y positions even if no new item is added ?

[ilyaik]

Yes. If myClass's QList changes inside

[p3c0]

@ilyaik then I think my first post could be the possible way.