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View Full Version : how to ignore graphicsView scale ignore in drawbackground



wagmare
18th June 2013, 11:54
hi friends,

I just drawn grid lines in the QGraphicsView on its


drawbackground(QPainter *painter, const QRectF &rect)
{
QVarLengthArray<QLineF, 100> linesX;
for (qreal x = left; x < sceneRect.right(); x += gridInterval )
{

linesX.append(QLineF(x, sceneRect.top(), x, sceneRect.bottom()));
}

QVarLengthArray<QLineF, 100> linesY;
for (qreal y = top; y < sceneRect.bottom(); y += gridInterval ){

linesY.append(QLineF(sceneRect.left(), y, sceneRect.right(), y));
}

painter->drawLines(linesX.data(), linesX.size());
painter->drawLines(linesY.data(), linesY.size());
}

and im scaling the view by

wheelEvent(QWheelEvent *event)
{
if(event->modifiers().testFlag(Qt::ControlModifier))
{
int numSteps = event->delta() / 15/ 8;

if (numSteps == 0)
{
event->ignore();
return;
}

qreal sc = pow(1.25, numSteps);
QRectF r(0, 0, 1, 1);
qreal factor = transform().scale(scaleFactor, scaleFactor).mapRect(r).width();

if(factor < 1)
return;

this->scale(scaleFactor, scaleFactor);
event->accept();
}
}

now how i can ignore the grid lines not to be scaled .
as u can see even the grid lines also getting scaled every time i zoom .
if it is a graphicsItem i can use ignore transform but for normal painter ..?

i tried QPainter::resetTransform() but in vain ..

Please help me ..