rotate method
Applies a rotation transformation to this matrix object.
Implementation
void rotate(double angle) {
final cos = math.cos(angle);
final sin = math.sin(angle);
var a1 = a * cos - b * sin;
b = a * sin + b * cos;
a = a1;
var c1 = c * cos - d * sin;
d = c * sin + d * cos;
c = c1;
var tx1 = tx * cos - ty * sin;
ty = tx * sin + ty * cos;
tx = tx1;
}