How to disable updatePaintNode on a QQuickItem at will

Roby Brundle

I have a QQuickItem derived class

// Class
class MyQQuickItem : public QQuickItem {
  Q_OBJECT
}

// updatePaintNode in cpp function
QSGNode * MyQQuickItem::updatePaintNode(QSGNode * oldNode, UpdatePaintNodeData * updatePaintNodeData) {

  // draw UI logic
  return node;
}

// QML component
MyQQuickItem {
  id: my_quick
  objectName: "myquickitem"
  width : 500
  height : 500
}

I am doing something on a separate UI which causes the updatePaintNode of MyQQuickItem to be fired. If I have a pointer to MyQQuickItem on cpp side like so,

QQuickItem * my_quick_item_ptr = m_qml_engine->rootObjects()[0]->findChild<QQuickItem*>("myquickitem");

How can disable MyQQuickItem's updatePaintNode from getting called when I don't want it to?
Secondary question: If yes, How to reinstate it back again?

SGaist

Hi,

What about just setting the visible property to false ?

Roby Brundle

@SGaist I am taking MyQQuickItem & rendering it off screen on a QQuickRenderControl to run some algorithms & do other stuff. To render MyQQuickItem I am setting its parent using SetParentitem to my off screen window. For this work properly, I need MyQQuickItem to not update itself & stay visible.

Hence making visible false is not an option for me. Any other way to block the updatePaintNode call?

SGaist

So some kind of boolean property Q_PROPERTY (e.g. renderingEnabled) that you would check at rendering time to know if you should do anything ?

Luan Nguyen

Hi Roby Brundle,
I have the same problem.
I also want to disable seft update for exist QQuickItem.
Did you found the solution yet?