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

[Kryzon]

QTransform is a type of matrix that supports perspective transformations (including affine).
QMatrix only supports affine transformations (translation, rotation, shear and scale).

You can create a QTransform and use QTransform::scale( 1.0, -1.0 ) (to flip the vertical axis) and then assign it to the graphics view using setTransform.

Then consider your graphics scene as in cartesian coordinates: treat all coordinates as in a cartesian space. When displayed through the graphics view, the transform of the graphics view will convert from cartesian to device coordinates.