Graphics renderers (exposed through wxGraphicsContext) support arbitrary affine transformations so it is possible to add support for affine transformations in wxGCDC by implementing all wxGCDC::*TransformMatrix() functions with calls to respective wxGraphicsContext functions.
Additionally, this implementation adds support for affine transformations in wxDC under wxGTK3 because in this port wxDC is equivalent to wxGCDC.