How to reset anchors?

franziss

I read in http://doc.qt.nokia.com/4.7-snapshot/qml-mousearea.html#drag.active-prop that in order to drag an object which is anchored to its parent, we can undefined the anchors in the onPressed signal. I tried it but I have the compile error

@
Expected token `;'
anchors.bottom: undefined
@

Below is my code, icon is under a rectangle
@
Image {
id: icon
width: 64
height: 64
source: "icon.gif"
anchors.bottom: parent.bottom

       MouseArea {
           id: iconMouseArea
           anchors.fill: parent
           width: 64
           height: 64

           drag.target: parent
           drag.axis: Drag.XandYAxis

           onPressed: {
               anchors.bottom: undefined
           }

       }
   }

@

Can someone help me out? Thanks!

ZapB

I think you need to explicitly state which item you are changing anchors on with something like this in a state.

@
AnchorChanges {
target: icon
anchors.bottom: undefined
}
@

You onPressed: handler can then simply change to that state. Does that work for you?

franziss

Thank you very much for your help ZapB, I implemented a state and use AnchorChanges, it works now.

Is it possible to do anchor changes in c++, instead of qml?

ZapB

Hmmm, good question. I'm not sure. It's not something I have ever tried. In theory I would think yes as the anchors are just properties like everything else. Have a play around with it and see if it is possible. I would be interested to hear the outcome of your experiments.

franziss

I tried the following slot, which is called when I move an object (e.g. icon) into a slide (e.g. rectangle). Once the object is in the slide, I want to set the object as a child of the slide, so that when I drag the slide, the object will move with it.

In this function, both slide and object are cast as QGraphicsWidgets and then I try to use QGraphicsAnchorLayout to anchor the object inside slide, but it does not work.

@
void cc::putObjectIntoSlide(QGraphicsObject * slide, QGraphicsObject * object)
{
if (object != NULL)
{
qDebug("got object in slide");
object->setParent(slide);
QGraphicsWidget *a = new QGraphicsWidget(slide);
QGraphicsWidget *b = new QGraphicsWidget(object);
QGraphicsAnchorLayout *la = new QGraphicsAnchorLayout;
QGraphicsAnchorLayout *lb = new QGraphicsAnchorLayout;
a->setLayout(la);
b->setLayout(lb);
la->addAnchor(la, Qt::AnchorBottom, lb, Qt::AnchorBottom);
}
else
{
qDebug("no object");
}
}
@

ZapB

QGraphicsAnchorLayout has nothing to do with anchors in QML. I'm not sure if the QML anchors are exported in any useable way in C++ other than perhaps by way of the setProperty() and property() functions of QObject.

franziss

Ok, I tried using setProperty as follows, but it doesn't work

@
object->setProperty("anchors.bottom","parent.bottom");
@

andre

I'd think that anchors is actually an object (or some other collection of properties) of its own, so I am not surprised that that doesn't work. No idea how it would work though.

franziss

If I drag an object A into object B, and make object A a child of object B, how do I anchor A to B?

Hit Tiger Tonight

@franziss said in How to reset anchors?:

Thank you very much for your help ZapB, I implemented a state and use AnchorChanges, it works now.

Is it possible to do anchor changes in c++, instead of qml?

Yes, you can. Please refer to: https://forum.qt.io/topic/143222/how-to-pass-an-object-ref-from-c-to-qml

Hit Tiger Tonight

@franziss said in How to reset anchors?:

Thank you very much for your help ZapB, I implemented a state and use AnchorChanges, it works now.

Is it possible to do anchor changes in c++, instead of qml?

Yes, you can. Please refer to: https://forum.qt.io/topic/143222/how-to-pass-an-object-ref-from-c-to-qml