/OpenStreetMapViewer/src/org/osmdroid/RotationGestureDetector.java

package org.osmdroid;



import android.view.MotionEvent;



public class RotationGestureDetector {



	public interface RotationListener {

		public void onRotate(float deltaAngle);

	}



	protected float mRotation;

	private RotationListener mListener;



	public RotationGestureDetector(RotationListener listener) {

		mListener = listener;

	}



	private float rotation(MotionEvent event) {

		double delta_x = (event.getX(0) - event.getX(1));

		double delta_y = (event.getY(0) - event.getY(1));

		double radians = Math.atan2(delta_y, delta_x);

		return (float) Math.toDegrees(radians);

	}



	public void onTouch(MotionEvent e) {

		if (e.getPointerCount() != 2)

			return;



		if (e.getActionMasked() == MotionEvent.ACTION_POINTER_DOWN) {

			mRotation = rotation(e);

		}



		float rotation = rotation(e);

		float delta = rotation - mRotation;

		mRotation += delta;

		mListener.onRotate(delta);

	}



}