Source
Matrix cloneInvert() {
num det = this.det;
num a = this.d / det;
num b = - this.b / det;
num c = - this.c / det;
num d = this.a / det;
num tx = - this.tx * a - this.ty * c;
num ty = - this.tx * b - this.ty * d;
return new Matrix(a, b, c, d, tx, ty);
}