1.174.2 Send methods

transform ->initialise: rotate=[num], scale=[num|tuple], shear=[tuple]

Build from optional rotate (degrees), scale (uniform num or tuple(sx, sy)) and shear (tuple(kx, ky)). The fresh transform starts at identity; the supplied operations are applied in the fixed order scale, rotate, shear. Following the post-multiplication convention this means an input point is transformed shear-first, then rotated, then scaled.

For an arbitrary transform whose six coefficients are known, use

new(T, transform), send(T, set, XX, XY, YX, YY, TX, TY)

transform ->set: xx=num, xy=num, yx=num, yy=num, tx=num, ty=num

Set all six matrix coefficients directly.

transform ->copy: from=transform

Copy the six coefficients from another transform.

transform ->identity:

Reset to the identity transform.

transform ->translate: dx=num, dy=num

Post-multiply by a translation: self := self * translate(dx,dy).

transform ->scale: sx=num, sy=[num]

Post-multiply by a (possibly non-uniform) scale. If sy is omitted the same factor is used for both axes.

transform ->rotate: degrees=num

Post-multiply by a rotation around the origin.

transform ->shear: kx=num, ky=num

Post-multiply by a shear matrix [1 kx; ky 1].

transform ->compose: transform

Post-multiply by the argument: self := self * argument.

transform ->invert:

Invert in place. Fails when the transform is singular (the determinant of the linear part is zero).