get qgraphicsitem size

[rogerholmes]

after changing the size of an item, how can i get the new size ?

trackItem is a QGrapicsItem.

if (ui->heightButton->isChecked()==false)
    {scene->trackItem->scale(1 ,1.1);}
    else
    {scene->trackItem->scale(1,.90);}
    newSize = scene->trackItem->sceneBoundingRect(); <- this is where i am trying to get the new size of the item. 
 
//  boundingrect does not  change even after rescaling.

if (ui->heightButton->isChecked()==false)
    {scene->trackItem->scale(1 ,1.1);}
    else
    {scene->trackItem->scale(1,.90);}
    newSize = scene->trackItem->sceneBoundingRect(); <- this is where i am trying to get the new size of the item. 

//  boundingrect does not  change even after rescaling.

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[aamer4yu]

How do you change the size of the item ? The size is always mentioned in boundingRect() or shape().
If you are using some variable to change the size, then you must have the size with you. Hope am getting it correct

[rogerholmes]

I am changing it with

if (ui->heightButton->isChecked()==false)
{scene->trackItem->scale(1 ,1.1);}
else
{scene->trackItem->scale(1,.90);}

[aamer4yu]

The bounding rect will be same. What happens is the transform of the item is changed, and the item is drawn accordingly.
May be if you tell what you want to achieve, we can tell more clearly.

For now it seems you have a look at transform() function of the QGraphicsItem

[rogerholmes]

after i change the size of the item, i want to know the new size

[Lykurg]

Just calculate the new size:

#include <QtGui>
 
int main(int argc, char **argv)
{
    QApplication app(argc, argv);
 
    QGraphicsView view;
    QGraphicsScene scene;
    QGraphicsTextItem *item = scene.addText("foo");
    view.setScene(&scene);
    view.show();
 
    qWarning() << item->boundingRect().size() << item->scale() << item->boundingRect().size() * item->scale();
    item->setScale(11.91);
    qWarning() << item->boundingRect().size() << item->scale() << item->boundingRect().size() * item->scale();
 
    return app.exec();
}

#include <QtGui>

int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    QGraphicsView view;
    QGraphicsScene scene;
    QGraphicsTextItem *item = scene.addText("foo");
    view.setScene(&scene);
    view.show();

    qWarning() << item->boundingRect().size() << item->scale() << item->boundingRect().size() * item->scale();
    item->setScale(11.91);
    qWarning() << item->boundingRect().size() << item->scale() << item->boundingRect().size() * item->scale();

    return app.exec();
}

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[aamer4yu]

I dont think there is a function QGraphicsItem::scale(void) . It simple scales the item but doesnt return anything.
You will need to use QGraphicsItem::transform() and use the matrix variables m11,m22 to multiply with the boundingRect.
Read Basic Matrix Operations

[Lykurg]

I dont think there is a function QGraphicsItem::scale(void)

QGraphicsItem::scale()? (added in 4.6)

Returns

QSizeF(30, 25) 1 QSizeF(30, 25) 
QSizeF(30, 25) 1.91 QSizeF(57.3, 47.75)

QSizeF(30, 25) 1 QSizeF(30, 25) 
QSizeF(30, 25) 1.91 QSizeF(57.3, 47.75)

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[rogerholmes]

Thank You for your help
I will try this tonite.

[rogerholmes]

aamer4yu
lykurg
Thank You guys !

QGraphicsItem::transform() m11,m22 works !

[aamer4yu]

QGraphicsItem::scale()? (added in 4.6)

Yeah, u right. Usually at office I have 4.5 assistant open