Best place to apply a QMatrix transform to paint() event in an app

[Kryzon]

Here's a suggestion: translate that transform to the centre of the viewport. It should look more like a cartesian representation.

QPoint viewportCentre = viewport().rect().center();
QTransform::translate( viewportCentre.x(), viewportCentre.y() );

QPoint viewportCentre = viewport().rect().center();
QTransform::translate( viewportCentre.x(), viewportCentre.y() );

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Make sure you are specifying coordinates in "cartesian" space: +X is to the right, +Y is up.

[Caolan O'Domhnaill]

Here's a suggestion: translate that transform to the centre of the viewport. It should look more like a cartesian representation.

QPoint viewportCentre = viewport().rect().center();
QTransform::translate( viewportCentre.x(), viewportCentre.y() );

QPoint viewportCentre = viewport().rect().center();
QTransform::translate( viewportCentre.x(), viewportCentre.y() );

To copy to clipboard, switch view to plain text mode 

Make sure you are specifying coordinates in "cartesian" space: +X is to the right, +Y is up.

I got it all to work. Thank you very much!