GraphicsView Zoomout scale Issue - c++

Question

My work Environment : Qt 5.8 MSVC2015 64bit, QT GraphicsView, Windows 7 64 bit
When GraphicsView vertical scroll bar is goes away, zoom out should stop.
So I tried with below code, but it failed to work :
void GraphicsView::scale(qreal scaleFactor)
{
QRectF r(0, 0, 1, 1); // A reference
int pos_x = this->horizontalScrollBar()->value();
int pos_y = this->verticalScrollBar()->value();
qreal factor = transform().scale(scaleFactor, scaleFactor).mapRect(r).width(); // absolute zoom factor
if ( factor > 7) { // Check zoom out limit
return;
}
//Failed, this code failed If zoom out again.**
if(pos_x <= 0 && pos_y <= 0 )
{
return;
}
Any suggestion How I can do to fix the above code ?

Answer 1

No reply for my question. Here is work around solution from me,
Check from wheelEvent are we doing zoom in or zoom out. I scale check vertical & horizontal scroll bar.
here _steps is private data member of my class GraphicsView. GraphicsView derived from QGraphicsView.
void GraphicsView::wheelEvent(QWheelEvent * event)
{
// Typical Calculations (Ref Qt Doc)
const int degrees = event->delta() / 8;
_steps = degrees / 15; // _steps = 1 for Zoom in, _steps = -1 for Zoom out.
}
void GraphicsView::scale(qreal scaleFactor)
{
QRectF r(0, 0, 1, 1); // A reference
int pos_x = this->horizontalScrollBar()->value();
int pos_y = this->verticalScrollBar()->value();
qreal factor = transform().scale(scaleFactor, scaleFactor).mapRect(r).width(); // absolute zoom factor
if ( factor > 7) { // Calculate your zoom in limit from factor
return;
}
//When there is no scroll bar, am I still I am zooming, stop it using _steps
if(pos_x <= 0 && pos_y <= 0 && _steps == -1)
{
return;
}
QGraphicsView::scale(scaleFactor, scaleFactor);
}
I know there is better solution then this, But I found this only :(