The function `untransform-distance`

transforms the distance (`
dx dy`
) by the rotation and scale of the effective inverse of `
transform`
. The translation in the inverse transform is ignored. The transformed distance (`
dx dy`
) is returned as two values.

See graphics-state for details of how a transform is used.

*CAPI User Guide and Reference Manual (Macintosh version) - 25 Feb 2015*