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

You can use the droidQuery library to handle flings, clicks, long clicks, and custom events. The implementation is built on my previous answer below, but droidQuery provides a slick, simple syntax:

//global variables    private boolean isSwiping = false;
private SwipeDetector.Direction swipeDirection = null;
private View v;//must be instantiated before next call.

//swipe-handling code
$.with(v).swipe(new Function() {
    @Override
    public void invoke($ droidQuery, Object... params) {
        if (params[0] == SwipeDetector.Direction.START)
            isSwiping = true;
        else if (params[0] == SwipeDetector.Direction.STOP) {
            if (isSwiping) {                    isSwiping = false;
                if (swipeDirection != null) {
                    switch(swipeDirection) {
                        case DOWN :                                //TODO: Down swipe complete, so do something
                            break;
                        case UP :
                            //TODO: Up swipe complete, so do something
                            break;
                        case LEFT :
                            //TODO: Left swipe complete, so do something
                            break;
                        case RIGHT :
                            //TODO: Right swipe complete, so do something
                            break;
                        default :                                break;
                    }
                }                }
        }
        else {
            swipeDirection = (SwipeDetector.Direction) params[0];
        }
    }
});

Original Answer

This answer uses a combination of components from the other answers here. It consists of the SwipeDetector class, which has an inner interface for listening for events. I also provide a RelativeLayout to show how to override a View's onTouch method to allow both swipe events and other detected events (such as clicks or long clicks).

SwipeDetector

package self.philbrown;

import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;

/**
 * Detect Swipes on a per-view basis. Based on original code by Thomas Fankhauser on StackOverflow.com,
 * with adaptations by other authors (see link).
 * @author Phil Brown
 * @see android-basic-gesture-detection
 */
public class SwipeDetector implements View.OnTouchListener
{
    /**
     * The minimum distance a finger must travel in order to register a swipe event.
     */
    private int minSwipeDistance;

    /** Maintains a reference to the first detected down touch event. */
    private float downX, downY;

    /** Maintains a reference to the first detected up touch event. */
    private float upX, upY;

    /** provides access to size and dimension contants */
    private ViewConfiguration config;

    /**
     * provides callbacks to a listener class for various swipe gestures.
     */
    private SwipeListener listener;

    public SwipeDetector(SwipeListener listener)
    {
        this.listener = listener;
    }


    /**
     * {@inheritDoc}
     */
    public boolean onTouch(View v, MotionEvent event)
    {
        if (config == null)
        {
                config = ViewConfiguration.get(v.getContext());
                minSwipeDistance = config.getScaledTouchSlop();
        }

        switch(event.getAction())
        {
        case MotionEvent.ACTION_DOWN:
            downX = event.getX();
            downY = event.getY();
            return true;
        case MotionEvent.ACTION_UP:
            upX = event.getX();
            upY = event.getY();

            float deltaX = downX - upX;
            float deltaY = downY - upY;

            // swipe horizontal?
            if(Math.abs(deltaX) > minSwipeDistance)
            {
                // left or right
                if (deltaX < 0)
                {
                        if (listener != null)
                        {
                                listener.onRightSwipe(v);
                                return true;
                        }
                }
                if (deltaX > 0)
                {
                        if (listener != null)
                        {
                                listener.onLeftSwipe(v);
                                return true;
                        }
                }
            }

            // swipe vertical?
            if(Math.abs(deltaY) > minSwipeDistance)
            {
                // top or down
                if (deltaY < 0)
                {
                        if (listener != null)
                        {
                                listener.onDownSwipe(v);
                                return true;
                        }
                }
                if (deltaY > 0)
                {
                        if (listener != null)
                        {
                                listener.onUpSwipe(v);
                                return true;
                        }
                }
            }
        }
        return false;
    }

    /**
     * Provides callbacks to a registered listener for swipe events in {@link SwipeDetector}
     * @author Phil Brown
     */
    public interface SwipeListener
    {
        /** Callback for registering a new swipe motion from the bottom of the view toward its top. */
        public void onUpSwipe(View v);
        /** Callback for registering a new swipe motion from the left of the view toward its right. */
        public void onRightSwipe(View v);
        /** Callback for registering a new swipe motion from the right of the view toward its left. */
        public void onLeftSwipe(View v);
        /** Callback for registering a new swipe motion from the top of the view toward its bottom. */
        public void onDownSwipe(View v);
    }
}

Swipe Interceptor View

package self.philbrown;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.RelativeLayout;

import com.npeinc.module_NPECore.model.SwipeDetector;
import com.npeinc.module_NPECore.model.SwipeDetector.SwipeListener;

/**
 * View subclass used for handling all touches (swipes and others)
 * @author Phil Brown
 */
public class SwipeInterceptorView extends RelativeLayout
{
    private SwipeDetector swiper = null;

    public void setSwipeListener(SwipeListener listener)
    {
        if (swiper == null)
            swiper = new SwipeDetector(listener);
    }

    public SwipeInterceptorView(Context context) {
        super(context);
    }

    public SwipeInterceptorView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public SwipeInterceptorView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    public boolean onTouchEvent(MotionEvent e)
    {
        boolean swipe = false, touch = false;
        if (swiper != null)
            swipe = swiper.onTouch(this, e);
        touch = super.onTouchEvent(e);
        return swipe || touch;
    }
}