android 上下左右手势判断 根据别人的改的

package com.gesture;

import android.content.Context;
import android.util.DisplayMetrics;
import android.view.WindowManager;

public class GestureUtils {

//获取屏幕的大小
public static Screen getScreenPix(Context context) {
DisplayMetrics dm = new DisplayMetrics();
WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
windowManager.getDefaultDisplay().getMetrics(dm);
return new Screen(dm.widthPixels,dm.heightPixels);
}

public static class Screen{

public int widthPixels;
public int heightPixels;

public Screen(){

}

public Screen(int widthPixels,int heightPixels){
this.widthPixels=widthPixels;
this.heightPixels=heightPixels;
}

@Override
public String toString() {
return "("+widthPixels+","+heightPixels+")";
}

}

}

package com.gesture;

import com.gesture.GestureUtils.Screen;

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

public class  BuileGestureExt  {
public static final int GESTURE_UP=0;
public static final int GESTURE_DOWN=1;
public static final int GESTURE_LEFT=2;
public static final int GESTURE_RIGHT=3;
private OnGestureResult onGestureResult;
private Context mContext;
public BuileGestureExt(Context c,OnGestureResult onGestureResult) {
this.mContext=c;
this.onGestureResult=onGestureResult;
screen = GestureUtils.getScreenPix(c);
}
public GestureDetector Buile()
{
return new GestureDetector(mContext, onGestureListener);
}

private Screen screen;
private GestureDetector.OnGestureListener onGestureListener = new GestureDetector.SimpleOnGestureListener(){

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
float x = e2.getX() - e1.getX();
float y = e2.getY() - e1.getY();
//限制必须得划过屏幕的1/4才能算划过
float x_limit = screen.widthPixels / 4;
float y_limit = screen.heightPixels / 4;
float x_abs = Math.abs(x);
float y_abs = Math.abs(y);
if(x_abs >= y_abs){
//gesture left or right
if(x > x_limit || x < -x_limit){
if(x>0){
//right
doResult(GESTURE_RIGHT);
}else if(x<=0){
//left
doResult(GESTURE_LEFT);
}
}
}else{
//gesture down or up
if(y > y_limit || y < -y_limit){
if(y>0){
//down                        doResult(GESTURE_DOWN);                     }else if(y<=0){                        //up                        doResult(GESTURE_UP);                     }                }            }            return true;        }            };    public void doResult(int result)    {        if(onGestureResult!=null)        {            onGestureResult.onGestureResult(result);        }    }        public interface OnGestureResult    {        public void onGestureResult(int direction);    }}