QGrahicsItem: problem with ItemIsMovable (dragging rectangle bigger than item itself)

penpen

Hello,

I have a problem with a QGraphicsItem in a QGraphicsScene. What I would like is to be able to move the item with mouse. But the problem is that in my case, the dragging rectangle is bigger than the item itself.

Here is the code that I use:

@
class Test: public QGraphicsView
{
public:
Test();

private:
virtual void resizeEvent (QResizeEvent * event);
QGraphicsScene* m_pScene;
};
 
Test::Test()
{
m_pScene = new QGraphicsScene();
setScene(m_pScene);
 
m_pScene->setSceneRect(0, 0, 100, 100);
 
for (int i = 0 ; i < 10 ; i++)
{
QGraphicsRectItem * pItem = new QGraphicsRectItem();
pItem->setFlag(QGraphicsItem::ItemIsMovable);
pItem->setBrush(QBrush(QColor(190, 100, 100)));
pItem->setRect(QRectF(10*i, 10, 5, 80.f));
pItem->setCursor(Qt::SizeAllCursor);
m_pScene->addItem(pItem);
}
 
 
setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
 
resize(600, 200);
fitInView(scene()->sceneRect());
show();
}
 
void Test::resizeEvent(QResizeEvent * event)
{
QGraphicsView::resizeEvent(event);
fitInView(scene()->sceneRect());
}

@

So when I run my program I have this window, and I can drag items. All seems ok.
!http://img841.imageshack.us/img841/6579/screen1is.jpg()!

But if I look closer the dragging zone is bigger than the item itself. (see the blue rectangle on following screenshot) The blue rectangle means that If I move the mouse in this rectangle, the cursor changes, and I can drag the item.
!http://img842.imageshack.us/img842/8181/screen2pd.jpg()!

I have the feeling that the problem is related to the "fitInView(scene()->sceneRect());" line. If I remove it, then it works.
If I add a 'scale(5,1)' for example, there is the same problem.

Do you have an idea of what the problem could be? Am I doing something wring with coordinates?

bunjee

Reproduced it on my side.

When you scale a very smal sceneRect, you get a strange selection area on your scaled QGraphicsRectItem(s).

Could this be a bug ? Should we file a bug report ?

bunjee

Reported here: http://bugreports.qt.nokia.com/browse/QTBUG-17985

stephenju

It's causing a lot of problem since my scene has really high scale level. I cooked up some patches and submitted a merge request. It doesn't seem to be looked at yet. Graphics view bugs tend to be slow acted on for some reason. Maybe it's a really complicated system?

stephenju

Well. The MR has been submitted for 10 days and nothing happens. What's the expected time for someone to look at it and see if it's worth merging? I see a lot of MRs that are months old without even a comment from developers.

Here's the link if anyone is interested: https://qt.gitorious.org/qt/qt/merge_requests/2591

stephenju

I butchered the MR in response to a Troll's comment. Here's the new one:
https://qt.gitorious.org/qt/qt/merge_requests/2594