在屏幕上移动许多布局

Question

我一直试图在Touch上移动屏幕上的布局，当沿着屏幕的右侧和底部移动时，布局会消失，如何解决这个问题。

这是我的代码：

    public class MainActivity extends Activity {
int windowwidth;
int windowheight;
ImageView ima1, ima2;
RelativeLayout rely1, rely2;
private android.widget.RelativeLayout.LayoutParams layoutParams1,
        layoutParams;

// private android.widget.RelativeLayout.LayoutParams layoutParams ;
// private android.widget.RelativeLayout.LayoutParams layoutParams ;

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

    windowwidth = getWindowManager().getDefaultDisplay().getWidth();
    windowheight = getWindowManager().getDefaultDisplay().getHeight();

    System.out.println("width" + windowwidth);
    System.out.println("height" + windowheight);

    rely1 = (RelativeLayout) findViewById(R.id.rel1);
    rely1.setOnTouchListener(new View.OnTouchListener() {

        public boolean onTouch(View v, MotionEvent event) {
            layoutParams = (RelativeLayout.LayoutParams) rely1
                    .getLayoutParams();

            switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                break;

            case MotionEvent.ACTION_MOVE:
                int x_cord = (int) event.getRawX();
                int y_cord = (int) event.getRawY();

                System.out.println("value of x" + x_cord);
                System.out.println("value of y" + y_cord);
                if (x_cord < windowwidth - rely1.getWidth()) {
                    layoutParams.leftMargin = x_cord;
                }
                if (y_cord < windowheight - rely1.getHeight()) {
                    layoutParams.topMargin = y_cord;
                }

                rely1.setLayoutParams(layoutParams);
                break;
            default:
                break;
            }
            return true;
        }
    });

    rely2 = (RelativeLayout) findViewById(R.id.rel2);
    rely2.setOnTouchListener(new View.OnTouchListener() {

        public boolean onTouch(View v, MotionEvent event) {
            layoutParams1 = (RelativeLayout.LayoutParams) rely2
                    .getLayoutParams();

            switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                break;

            case MotionEvent.ACTION_MOVE:
                int x_cord = (int) event.getRawX();
                int y_cord = (int) event.getRawY();

                System.out.println("value of x" + x_cord);
                System.out.println("value of y" + y_cord);

                if (x_cord < windowwidth - rely2.getWidth()) {
                    layoutParams1.leftMargin = x_cord;
                }
                if (y_cord < windowheight - rely2.getHeight()) {
                    layoutParams1.topMargin = y_cord;
                }
                // layoutParams1.leftMargin = x_cord-25;
                // layoutParams1.topMargin = y_cord-25;
                // layoutParams1.rightMargin = x_cord-25;
                // layoutParams1.bottomMargin = y_cord-25;
                rely2.setLayoutParams(layoutParams1);
                break;
            default:
                break;
            }
            return true;
        }
    });
}

}

这是我的xml：      

<RelativeLayout
    android:id="@+id/rel1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >
 <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_launcher" />
</RelativeLayout>

<RelativeLayout
    android:id="@+id/rel2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >

    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_launcher" />
</RelativeLayout>



   </RelativeLayout>