Gesture Detection
Remarks#
Official Documentation: Detecting Common Gestures
Swipe Detection
public class OnSwipeListener implements View.OnTouchListener {
private final GestureDetector gestureDetector;
public OnSwipeListener(Context context) {
gestureDetector = new GestureDetector(context, new GestureListener());
}
@Override
public boolean onTouch(View v, MotionEvent event) {
return gestureDetector.onTouchEvent(event);
}
private final class GestureListener extends GestureDetector.SimpleOnGestureListener {
private static final int SWIPE_VELOCITY_THRESHOLD = 100;
private static final int SWIPE_THRESHOLD = 100;
@Override
public boolean onDown(MotionEvent e) {
return true;
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
float diffY = e2.getY() - e1.getY();
float diffX = e2.getX() - e1.getX();
if (Math.abs(diffX) > Math.abs(diffY)) {
if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
if (diffX > 0) {
onSwipeRight();
} else {
onSwipeLeft();
}
}
} else if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
if (diffY > 0) {
onSwipeBottom();
} else {
onSwipeTop();
}
}
return true;
}
}
public void onSwipeRight() {
}
public void onSwipeLeft() {
}
public void onSwipeTop() {
}
public void onSwipeBottom() {
}
}
Applied to a view…
view.setOnTouchListener(new OnSwipeListener(context) {
public void onSwipeTop() {
Log.d("OnSwipeListener", "onSwipeTop");
}
public void onSwipeRight() {
Log.d("OnSwipeListener", "onSwipeRight");
}
public void onSwipeLeft() {
Log.d("OnSwipeListener", "onSwipeLeft");
}
public void onSwipeBottom() {
Log.d("OnSwipeListener", "onSwipeBottom");
}
});
Basic Gesture Detection
public class GestureActivity extends Activity implements
GestureDetector.OnDoubleTapListener,
GestureDetector.OnGestureListener {
private GestureDetector mGestureDetector;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mGestureDetector = new GestureDetector(this, this);
mGestureDetector.setOnDoubleTapListener(this);
}
@Override
public boolean onTouchEvent(MotionEvent event){
mGestureDetector.onTouchEvent(event);
return super.onTouchEvent(event);
}
@Override
public boolean onDown(MotionEvent event) {
Log.d("GestureDetector","onDown");
return true;
}
@Override
public boolean onFling(MotionEvent event1, MotionEvent event2, float velocityX, float velocityY) {
Log.d("GestureDetector","onFling");
return true;
}
@Override
public void onLongPress(MotionEvent event) {
Log.d("GestureDetector","onLongPress");
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
Log.d("GestureDetector","onScroll");
return true;
}
@Override
public void onShowPress(MotionEvent event) {
Log.d("GestureDetector","onShowPress");
}
@Override
public boolean onSingleTapUp(MotionEvent event) {
Log.d("GestureDetector","onSingleTapUp");
return true;
}
@Override
public boolean onDoubleTap(MotionEvent event) {
Log.d("GestureDetector","onDoubleTap");
return true;
}
@Override
public boolean onDoubleTapEvent(MotionEvent event) {
Log.d("GestureDetector","onDoubleTapEvent");
return true;
}
@Override
public boolean onSingleTapConfirmed(MotionEvent event) {
Log.d("GestureDetector","onSingleTapConfirmed");
return true;
}
}