Fling gesture detection on grid layout

Question

I want to get fling gesture detection working in my Android application.

What I have is a GridLayout that contains 9 ImageView

Answer 1

This is a combined answer of the two answers at top, if anyone wants a working implementation.

package com.yourapplication;

import android.content.Context;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;

public abstract class OnSwipeListener implements View.OnTouchListener {

    private final GestureDetector gestureDetector;

    public OnSwipeListener(Context context){
        gestureDetector = new GestureDetector(context, new OnSwipeGestureListener(context));
        gestureDetector.setIsLongpressEnabled(false);
    }

    @Override
    public boolean onTouch(View view, MotionEvent event) {
        return gestureDetector.onTouchEvent(event);
    }

    private final class OnSwipeGestureListener extends GestureDetector.SimpleOnGestureListener {

        private final int minSwipeDelta;
        private final int minSwipeVelocity;
        private final int maxSwipeVelocity;

        private OnSwipeGestureListener(Context context) {
            ViewConfiguration configuration = ViewConfiguration.get(context);
            // We think a swipe scrolls a full page.
            //minSwipeDelta = configuration.getScaledTouchSlop();
            minSwipeDelta = configuration.getScaledPagingTouchSlop();
            minSwipeVelocity = configuration.getScaledMinimumFlingVelocity();
            maxSwipeVelocity = configuration.getScaledMaximumFlingVelocity();
        }

        @Override
        public boolean onDown(MotionEvent event) {
            // Return true because we want system to report subsequent events to us.
            return true;
        }

        // NOTE: see http://stackoverflow.com/questions/937313/android-basic-gesture-detection
        @Override
        public boolean onFling(MotionEvent event1, MotionEvent event2, float velocityX,
                               float velocityY) {

            boolean result = false;
            try {
                float deltaX = event2.getX() - event1.getX();
                float deltaY = event2.getY() - event1.getY();
                float absVelocityX = Math.abs(velocityX);
                float absVelocityY = Math.abs(velocityY);
                float absDeltaX = Math.abs(deltaX);
                float absDeltaY = Math.abs(deltaY);
                if (absDeltaX > absDeltaY) {
                    if (absDeltaX > minSwipeDelta && absVelocityX > minSwipeVelocity
                            && absVelocityX < maxSwipeVelocity) {
                        if (deltaX < 0) {
                            onSwipeLeft();
                        } else {
                            onSwipeRight();
                        }
                    }
                    result = true;
                } else if (absDeltaY > minSwipeDelta && absVelocityY > minSwipeVelocity
                        && absVelocityY < maxSwipeVelocity) {
                    if (deltaY < 0) {
                        onSwipeTop();
                    } else {
                        onSwipeBottom();
                    }
                }
                result = true;
            } catch (Exception e) {
                e.printStackTrace();
            }
            return result;
        }
    }

    public void onSwipeLeft() {}

    public void onSwipeRight() {}

    public void onSwipeTop() {}

    public void onSwipeBottom() {}
}