SwipeDetector.java

package net.ggelardi.flucso.comp;

import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;

public class SwipeDetector implements OnTouchListener {
	
	public static enum Action {
		LR, // Left to Right
		RL, // Right to Left
		TB, // Top to bottom
		BT, // Bottom to Top
		None // when no action was detected
	}
	
	private static final String logTag = "SwipeDetector";
	private static final int MIN_DISTANCE = 150;
	private float downX, downY, upX, upY;
	private Action mSwipeDetected = Action.None;
	
	public boolean swipeDetected() {
		return mSwipeDetected != Action.None;
	}
	
	public Action getAction() {
		return mSwipeDetected;
	}
	
	@Override
	public boolean onTouch(View v, MotionEvent event) {
		switch (event.getAction()) {
			case MotionEvent.ACTION_DOWN: {
				downX = event.getX();
				downY = event.getY();
				mSwipeDetected = Action.None;
				return false; // allow other events like Click to be processed
			}
			case MotionEvent.ACTION_MOVE: {
				upX = event.getX();
				upY = event.getY();
				
				float deltaX = downX - upX;
				float deltaY = downY - upY;
				
				// horizontal swipe detection
				if (Math.abs(deltaX) > MIN_DISTANCE) {
					// left or right
					if (deltaX < 0) {
						Log.i(logTag, "Swipe Left to Right");
						mSwipeDetected = Action.LR;
						return true;
					}
					if (deltaX > 0) {
						Log.i(logTag, "Swipe Right to Left");
						mSwipeDetected = Action.RL;
						return true;
					}
				} else
				
				// vertical swipe detection
				if (Math.abs(deltaY) > MIN_DISTANCE) {
					// top or down
					if (deltaY < 0) {
						Log.i(logTag, "Swipe Top to Bottom");
						mSwipeDetected = Action.TB;
						return false;
					}
					if (deltaY > 0) {
						Log.i(logTag, "Swipe Bottom to Top");
						mSwipeDetected = Action.BT;
						return false;
					}
				}
				return true;
			}
		}
		return false;
	}
}