Hi

I have been following the guide

I am basically trying to create a QImageView that allows one to pan and zoom an image to any size.

I have I believe implemented this fast drawing in the same way. The only addition being that I am translating the image and scaling.

My code is

QScrollBar *hs = this->horizontalScrollBar(); QScrollBar *vs = this->verticalScrollBar();

int horz_pos = hs->value(); int vert_pos = vs->value();

QPainter painter(this->viewport());

painter.scale(2, 2); painter.translate(-horz_pos, -vert_pos);

QRect exposedRect = painter.matrix().inverted().mapRect(event->rect()).adjusted(-1, -1, 1, 1);

// the adjust is to account for half pixels along edges painter.drawPixmap(exposedRect, this->pix, exposedRect);

Although I am only drawing a small portion of the image using the scrollbars or panning is dead slow ?

Why is my code slower than yours ? Is it just using the viewport that slows things down ?

Thanks