QGraphicsPathItem Doubt

[arjunasd]

Hi all

I am having a QGraphicsPathItem which is selectable. I am able to select the item by clicking the area defined by its path. But I would like it to be selectable by clicking any point within its bounding rectangle.

For example, if my shape is circle, I want it to be selected if I click on any point its bounding rectangle.

Any suggestion for how to do this?

Thanks
Arjun

[Gopala Krishna]

Reimplement the contains function by deriving a class from QGraphicsPathItem like this


class MyPathItem : public QGraphicsPathItem
{
public:
MyPathItem(const QPainterPath & path, QGraphicsItem * parent = 0 ) : QGraphicsPathItem(path,parent)
{}

bool contains( const QPointF & point ) const
{
return boundingRect().contains(point);
}
};

[arjunasd]

One more doubt.

I have the QGraphicsPathItem and its bounding rectangle. I want to change the Pen that draws the bounding rectangle when the item is selected. I dont have the paint function. I just use the default implementation as of now.

How to set the pen for drawing the bounding rectangle when the item is selected. Is there a way to use the default implementation and still achieve this?

Thanks
Arjun

[Gopala Krishna]

Oh you mean the bounding rect is part of the painterpath ? If thats the case you can't achieve what you wanted. You can draw the bounding rect separately. Then you can control its pen like this


MyPathItem::paint(QPainter *p, QStyleOptionGraphicsItem *o, QWidget *w)
{
QGraphicsPathItem::paint(p,o,w);
if(o->State & QStyle::State_Selected)
p->setPen(selectedPen);
else
p->setPen(unselectedPen);
p->drawRect(boundingRect());
}

[arjunasd]

Oh you mean the bounding rect is part of the painterpath ?

No. The bouding rectangle is not part of the painterpath. Its just the QRectF returned by the boudingRect fucntion.

The default paint implemnetation draws it with black pen and dotted lines. I want to chnage this behaviour. So, can I just draw the bounding rect with the new pen over the old one? or can I do it differently?

Thanks a lot
Arjun

[Gopala Krishna]

In this case , the solution above involving paint event is what you need :)

[Gopala Krishna]

BTW i had a look at the source code of QPainterPathItem and actually that draws the bounding rect. So the above solution will be drawing the bounding rect twice :)
You can use this hack instead


MyPathItem::paint(QPainter *p, QStyleOptionGraphicsItem *o, QWidget *w)
{
QStyle::State back = o->state;
o->state &= ~QStyle::State_Selected;//Removes selection flag
QGraphicsPathItem::paint(p,o,w);
o->state = back;
if(o->state & QStyle::State_Selected)
p->setPen(selectedPen);
else
p->setPen(unselectedPen);
p->drawRect(boundingRect());
}

[arjunasd]

This is what I wanted. About how to avoid painting the bouding rect twice. Thanks man.

Arjun