If linked lists of Rect s are needed, the LinkedRect primitive can be used. The above rotations or mirrorings with a scale factor of 1 exist as predefined transforms. GeoIdentityTransform is the identity transformation, i.e, no transformation at all, or the first transform listed above. GeoUpsideDownTransform is the next transform, mirroring across the x -axis.
Many procedures exist to manipulate transformations.
Three procedures compose transforms, producing the transform that is equivalent to applying first one, then the second of the two transforms. There are two special-case procedures. Transforms that adhere to one of the eight rotation formats described above are always invertible. Two procedures extract useful information from Transforms. The next collection of procedures manipulate Points and Rects.