Android手势（上，下，左和右的判断）

来源：互联网发布：血滴子淘宝网编辑：程序博客网时间：2024/04/30 08:51

Android中提供了判断手势的接口，所有我们可以根据提供的API来实现各种各样的手势功能来提高手机应用的用户体验。

下面是我写的一段小Demo：

GestureActivity.java

public class GestureActivity extends Activity {

    private GestureDetector gestureDetector;
    private Screen screen;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        gestureDetector = new GestureDetector(this,onGestureListener);
        //得到屏幕的大小
        screen = GestureUtils.getScreenPix(this);
    }

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

    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1/3才能算划过
            float x_limit = screen.widthPixels / 3;
            float y_limit = screen.heightPixels / 3;
            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
                        show("right");
                    }else if(x
                        //left
                        show("left");
                    }
                }
            }else{
                //gesture down or up
                if(y > y_limit || y < -y_limit){
                    if(y>0){
                        //down
                        show("down");
                    }else if(y
                        //up
                        show("up");
                    }
                }
            }
            return true;
        }

    };

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

}

GestureUtils.java

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+")";
        }

    }

}

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