Android手势识别简单封装类

今天在做一个项目时用到了简单的手势功能(向左，向右滑切屏)，于是简单地封装了下

import android.content.Context;
import android.util.DisplayMetrics;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;

public class GestureHelper implements OnGestureListener {
	private GestureDetector gesture_detector;
	private int screen_width;
	private OnFlingListener listener_onfling;
	
	public static abstract class OnFlingListener {
		public abstract void OnFlingLeft();
		public abstract void OnFlingRight();
	}
	
	public GestureHelper(Context context) {
        DisplayMetrics dm = context.getResources().getDisplayMetrics();
        screen_width = dm.widthPixels;
        
		gesture_detector = new GestureDetector(context, this);
	}
	
	public void setOnFlingListener(OnFlingListener listener) {
		listener_onfling = listener;
	}
	
	public boolean onTouchEvent(MotionEvent event) {
		return gesture_detector.onTouchEvent(event);
	}
	
	@Override
	public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
		// 触发条件 ：
		// X轴的坐标位移大于FLING_MIN_DISTANCE，且移动速度大于FLING_MIN_VELOCITY个像素/秒
		final int FLING_MIN_DISTANCE = (int) (screen_width / 3.0f), FLING_MIN_VELOCITY = 200;
		if (e1.getX() - e2.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) > FLING_MIN_VELOCITY) {
			listener_onfling.OnFlingLeft();
		} else if (e2.getX() - e1.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) > FLING_MIN_VELOCITY) {
			listener_onfling.OnFlingRight();
		}

		return true;
	}
	
	@Override
	public boolean onDown(MotionEvent e) {
		return false;
	}
	
	@Override
	public void onLongPress(MotionEvent e) {
	}
	
	@Override
	public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
			float distanceY) {
		return false;
	}
	
	@Override
	public void onShowPress(MotionEvent e) {
	}
	
	@Override
	public boolean onSingleTapUp(MotionEvent e) {
		return false;
	}
}

使用方法如下：

public class TestActivity extends Activity {
	private GestureHelper gh;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_start);
		
		gh = new GestureHelper(this);
		gh.setOnFlingListener(new OnFlingListener() {
			@Override
			public void OnFlingLeft() {
				//向左滑动
			}
			
			@Override
			public void OnFlingRight() {
				//向右滑动
			}
			
		});
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		return gh.onTouchEvent(event);
	}
	
}

诸如向上向下滑等因为需求不多所以没有加上去，有需求的朋友可以自己加上。