Android 手势滑动事件判断

要做的东西需要判断一下上下左右的滑动，所以就查了一下，发现需要定义一个GestureDetector的变量，然后监听手的动作。

用了两个文件，一个是获取屏幕信息的类ScreenInfo，另外一个就是主类MainActivity了

public class ScreenInfo {

public int widthPixels;
public int heighPixel;

public ScreenInfo(int widthPixels, int heighrPixels) {
this.widthPixels = widthPixels;
this.heighPixel = heighrPixels;
}

public static ScreenInfo getSreenInfo(Context context) {
DisplayMetrics dm = new DisplayMetrics();

WindowManager window = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
window.getDefaultDisplay().getMetrics(dm);

return new ScreenInfo(dm.widthPixels, dm.heightPixels);
}


}

public class MainActivity extends Activity {

public static final int RIGHT = 0;
public static final int LEFT = 1;
public static final int UP = 2;
public static final int DOWN = 3;

private GestureDetector gestureDector;
private ScreenInfo screen; 

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

screen = ScreenInfo.getSreenInfo(this);
gestureDector = new GestureDetector(MainActivity.this, OnGestureListener);
}

private GestureDetector.OnGestureListener OnGestureListener  = 
new GestureDetector.OnGestureListener() {

@Override
public boolean onSingleTapUp(MotionEvent arg0) {
return false;
}

@Override
public void onShowPress(MotionEvent arg0) {

}

@Override
public boolean onScroll(MotionEvent arg0, MotionEvent arg1, float arg2,
float arg3) {
return false;
}

@Override
public void onLongPress(MotionEvent arg0) {

}

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float arg2,
float arg3) {
float x = e2.getX() - e1.getX();
float y = e2.getY() - e1.getY();

//判断为屏幕宽度的1/4
float x_min = screen.widthPixels / 4;
//判断为屏幕高度的1/5
float y_min = screen.heighPixel  / 5;

if (x > x_min || x < -x_min) {
if (x > 0) {
doResult(RIGHT);
} else if (x <= 0) {
doResult(LEFT);
}
}
if (y > y_min || y < -y_min) {
if (y > 0) {
doResult(DOWN);
} else if (y <= 0) {
doResult(UP);
}
}
return true;
}

@Override
public boolean onDown(MotionEvent arg0) {
return false;
}
};

/**
 *判断结果为上下左右的哪种情况
 */
public void doResult(int action) {
switch (action) {
case RIGHT:
show("RIGHT");
break;
case LEFT:
show("LEFT");
break;
case UP:
show("UP");
break;
case DOWN:
show("DOWN");
break;
}
}

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

private void show(String value) {
Toast.makeText(MainActivity.this, value, Toast.LENGTH_SHORT).show();
}

}

只是简单的小Demo，知道是那种手势滑动后就可以进行自己想要做的操作了