Calculate pre rotation and replace current matrix.

def preRotate(self, theta):
        """Calculate pre rotation and replace current matrix."""
        while theta < 0: theta += 360
        while theta >= 360: theta -= 360
        epsilon = 1e-5
        if abs(0 - theta) < epsilon:
            pass

        elif abs(90.0 - theta) < epsilon:
            a = self.a
            b = self.b
            self.a = self.c
            self.b = self.d
            self.c = -a
            self.d = -b

        elif abs(180.0 - theta) < epsilon:
            self.a = -self.a
            self.b = -self.b
            self.c = -self.c
            self.d = -self.d

        elif abs(270.0 - theta) < epsilon:
            a = self.a
            b = self.b
            self.a = -self.c
            self.b = -self.d
            self.c = a
            self.d = b

        else:
            rad = math.radians(theta)
            s = round(math.sin(rad), 12)
            c = round(math.cos(rad), 12)
            a = self.a
            b = self.b
            self.a = c * a + s * self.c
            self.b = c * b + s * self.d
            self.c =-s * a + c * self.c
            self.d =-s * b + c * self.d

        return self