PointerMonitor.js

class PointerMonitor
{
    constructor (scene, pointer, swipeThreshold = 100, swipeDuration = 500)
    {
        //  The current Scene
        this.scene = scene;

        //  The Pointer we're monitoring for swipes
        this.pointer = pointer;

        //  They must move this distance on a single axis during the swipe
        this.swipeThreshold = swipeThreshold;

        //  They cannot move more than 80% in the opposite axis during the swipe
        this.swipeAxisThreshold = swipeThreshold * 0.8;

        //  The swipe must complete within this ms value, or less
        this.swipeDuration = swipeDuration;

        this.start();
    }

    start ()
    {
        this.scene.input.on('pointerup', this.onUp, this);
    }

    stop ()
    {
        this.scene.input.off('pointerup', this.onUp, this);
    }

    onUp (pointer)
    {
        if (pointer !== this.pointer)
        {
            return;
        }

        const distanceX = pointer.getDistanceX();
        const distanceY = pointer.getDistanceY();

        const horizontal = (distanceX > distanceY);

        if (pointer.getDuration() < this.swipeDuration)
        {
            if (horizontal && distanceX > this.swipeThreshold && distanceY < this.swipeAxisThreshold)
            {
                //  Horizontal Swipe
                if (pointer.velocity.x < 0)
                {
                    this.scene.input.emit('swipeleft', this.pointer);
                }
                else
                {
                    this.scene.input.emit('swiperight', this.pointer);
                }
            }
            else if (!horizontal && distanceY > this.swipeThreshold && distanceX < this.swipeAxisThreshold)
            {
                //  Vertical Swipe
                if (pointer.velocity.y < 0)
                {
                    this.scene.input.emit('swipeup', this.pointer);
                }
                else
                {
                    this.scene.input.emit('swipedown', this.pointer);
                }
            }
        }
    }
}