Save the Qpainter with save() and restore()

MélissaQT

Hello all,
I have a problem on my qt project.
I would like to save circles that I have created on an image, because for now I only have a new circle at every mouse click.
Where I can place save() and restore()?

My label is:
@ void paintEvent (QPaintEvent *event)
{
QLabel::paintEvent( event );
QPainter painter(this);
painter.setPen(QPen(Qt::red, 1, Qt::SolidLine, Qt::FlatCap, Qt::BevelJoin));

     RectImage.setX(PixelColumn-10);
     RectImage.setY(PixelRow-10);
     RectImage.setHeight(19);
     RectImage.setWidth(19);
     painter.drawEllipse(RectImage);
     
}@

Thanks,
Mélissa

SGaist

Hi and welcome to devnet,

QPainter's save and restore are not meant for that. What you should do is keep a structure (e.g. a QVector) containing the circles data you want to draw. Each time you create a new circle, push it in the QVector and draw them all in your paintEvent.

Hope it helps

raven-worx

do like SGaist said.
Or if you depend on this mechanismn you can also try QPicture class to save QPainter commands and replay them.

QPainter's save()/restore() methods are just a stack to save the settings of the object.

MélissaQT

Hello,
thanks both for yours answers,
I tried with a QVector of QlineF, now with line and no ellipse, like that:
@
extern std::vector<QLineF> LinesSaves;
extern int NumLine;

void paintEvent (QPaintEvent *event)
{
int CptLine;

     QLabel::paintEvent( event );
     QPainter painter(this);

     painter.setPen(QPen(Qt::red, 1, Qt::SolidLine, Qt::FlatCap, Qt::BevelJoin));

     if (lineCreation)
     {
     Point1.setX(PixelColumn);
     Point1.setY(PixelRow);
     }
     else
     {
     Point2.setX(PixelColumn);
     Point2.setY(PixelRow);

     //problem below
     LinesSaves[NumLine].push_back(Point1,Point2);
     //problem above

     NumLine = NumLine +1;
     }
     for (int CptLine = 0; CptLine < NumLine; ++CptLine) {
        painter.drawLine(LinesSaves[CptLine]);
     }

     lineCreation=!lineCreation;
}@

But, I have a problem where it's noted. It say:
no member named 'push_back' in 'QLineF'
I don't understand because I'm using the vector properties and not QLineF.

raven-worx

but int he line
@
LinesSaves[NumLine].push_back(Point1,Point2)
@
you are retrieving a QLineF object and calling puch_back() on it.

Do this instead:
@
LinesSaves.push_back(Point1,Point2)
@

MélissaQT

[quote author="raven-worx" date="1389260024"]but int he line
@
LinesSaves[NumLine].push_back(Point1,Point2)
@
you are retrieving a QLineF object and calling puch_back() on it.

Do this instead:
@
LinesSaves.push_back(Point1,Point2)
@[/quote]

Yes it's logic, now I understand, thank you raven.