Bishop, Michael W. CONTR J9C880 wrote:
transform="translate(x, y) scale(x, y) rotate(t)"
Is there a way to get the value of t?
Here's a method I wrote to do this. Not sure if it's what
you need but perhaps it could be a start (no guarantees :-).
/**
* Compute the rotation angle of an affine transformation.
* Counter-clockwise rotation is considered positive.
*
* @return rotation angle in radians (beween -pi and pi),
* or NaN if the transformation is bogus.
*/
public static double getRotationAngle(AffineTransform transform) {
// Eliminate any post-translation
transform = (AffineTransform)transform.clone();
transform.preConcatenate(AffineTransform.getTranslateInstance(
-transform.getTranslateX(), -transform.getTranslateY()));
// Apply transformation to a vector
Point2D v1 = new Point2D.Double(1, 0);
Point2D v2 = transform.transform(v1, null);
// Compute dot product
double dotProduct = v1.getX() * v2.getX() + v1.getY() * v2.getY();
// Compute positive angle
double angle = Math.acos(dotProduct
/ (v1.distance(0, 0) * v2.distance(0, 0)));
// Negate angle if rotation direction is clockwise
if (v2.getY() < 0)
angle = -angle;
// Done
return angle;
}
-Archie
__________________________________________________________________________
Archie Cobbs * CTO, Awarix * http://www.awarix.com
--
__________________________________________________________________________
Archie Cobbs * CTO, Awarix * http://www.awarix.com
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