Placing a widget at fixed place on top of QAbstractScrollArea (actually QGV)

[Vladimir]

Hello All,

I'm trying to place a widget on top of QAbstractScrollArea but make this widget non-moveable when user moves scroll-bars. I've tried to make in a child widget of QAbstractScrollArea inself and viewport and I've tried to call raise() for my widget - in all cases it appears only for a moment when creating window and then gets covered by viewport. I've event tried to use setViewportMargins() - the same effect.

Are there any suggestions ?
Thanks in advance !

[jpn]

Hi. Is the widget allocated on the stack? This usually leads to what you describe..

QWidget widget(graphicsView); // <-- wrong
// vs.
QWidget* widget = new QWidget(graphicsView); // <-- correct

QWidget widget(graphicsView); // <-- wrong
// vs.
QWidget* widget = new QWidget(graphicsView); // <-- correct

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[Vladimir]

No, the widget is allocated on the heap.

[jpn]

At least this works for me:

#include <QtGui>
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    QGraphicsScene scene;
    QGraphicsItem* item = scene.addRect(QRectF(0,0,25,25));
    item->setFlag(QGraphicsItem::ItemIsMovable);
 
    QGraphicsView view;
    view.setScene(&scene);
    QLabel* label = new QLabel("Test", &view);
    Q_UNUSED(label);
 
    view.show();
    return a.exec();
}

#include <QtGui>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    
    QGraphicsScene scene;
    QGraphicsItem* item = scene.addRect(QRectF(0,0,25,25));
    item->setFlag(QGraphicsItem::ItemIsMovable);
    
    QGraphicsView view;
    view.setScene(&scene);
    QLabel* label = new QLabel("Test", &view);
    Q_UNUSED(label);

    view.show();
    return a.exec();
}

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[Vladimir]

Yes, your code works for me too. It seems that I've found a reason for my problem: I've created a widget from QGraphicsView-derived class constructor and viewport was created after it and after raise() call - so my widget was simply covered by viewport. Sorry for disturbing you.

[jpn]

Ok, great that the problem was solved. And no worries, this was not disturbing at all!