VelocityTrackerActivity.java

package com.google.mcommerce.sample.android.chapter08.motionEvent;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.VelocityTracker;

import com.google.mcommerce.sample.android.R;

public class VelocityTrackerActivity extends Activity {
	private static final String TAG = "VelocityTracker";

	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.c08_touch_velocity_tracker);
	}

	private VelocityTracker vTracker = null;

	public boolean onTouchEvent(MotionEvent event) {
		int action = event.getAction();
		switch (action) {
		case MotionEvent.ACTION_DOWN:
			if (vTracker == null) {
				vTracker = VelocityTracker.obtain();
			} else {
				vTracker.clear();
			}
			vTracker.addMovement(event);
			break;
		case MotionEvent.ACTION_MOVE:
			vTracker.addMovement(event);
			vTracker.computeCurrentVelocity(1000);
			Log.v(TAG, "X velocity is " + vTracker.getXVelocity()
					+ " pixels per second");
			Log.v(TAG, "Y velocity is " + vTracker.getYVelocity()
					+ " pixels per second");
			break;
		case MotionEvent.ACTION_UP:
		case MotionEvent.ACTION_CANCEL:
			vTracker.recycle();
			break;
		}
		return true;
	}
}