morph method
Morph: apply a matrix about a given fixpoint.
Implementation
Rect morph(Point fixpoint, List<double> matrix) {
final p = Point(x0 - fixpoint.x, y0 - fixpoint.y).transform(matrix);
final q = Point(x1 - fixpoint.x, y1 - fixpoint.y).transform(matrix);
return Rect(
p.x + fixpoint.x,
p.y + fixpoint.y,
q.x + fixpoint.x,
q.y + fixpoint.y,
).normalized;
}