如何在嵌套的相对布局之间切换触摸事件？

Question

我有一个相对布局包含一个表面视图和另一个相对布局（嵌套）..

1）如果触摸事件超出子相对布局，我想单独为Surface视图接收触摸事件。 ??

2）如果我的触摸事件落在儿童相对布局上，则当前触摸事件不应转到表面视图。

如何实现此切换???

提前致谢..！

以下是我的活动：

public class DragAndDropBasicActivity extends Activity implements  OnTouchListener {
    private RelativeLayout letterView;                      
    private RelativeLayout mainLayout;


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

        mainLayout = (RelativeLayout) findViewById(R.id.mainLayout);
        mainLayout.setOnTouchListener(this);
        letterView = (RelativeLayout) findViewById(R.id.mlKnobView);
        letterView.setOnTouchListener(this);

    }

    private boolean dragging = false;

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        boolean eventConsumed = true;
        int x = (int)event.getX();
        int y = (int)event.getY();

        int action = event.getAction();
        if (action == MotionEvent.ACTION_DOWN) {
            if (v == letterView) {
                dragging = true;
                eventConsumed = false;
            }
        } else if (action == MotionEvent.ACTION_UP) {
            dragging = false;
            eventConsumed = false;

        } else if (action == MotionEvent.ACTION_MOVE) {
            if (v != letterView) {
                if (dragging) {
                    setAbsoluteLocationCentered(letterView, x, y);
                }
            }
        }

        return eventConsumed;

    }

    private void setAbsoluteLocationCentered(View v, int x, int y) {
        setAbsoluteLocation(v, x - v.getWidth() / 2, y - v.getHeight() / 2);
    }


    private void setAbsoluteLocation(View v, int x, int y) {
        RelativeLayout.LayoutParams alp = (RelativeLayout.LayoutParams) v.getLayoutParams();
        alp.leftMargin = x;
        alp.topMargin = y;
        v.setLayoutParams(alp);
    }
}

在我的Xml文件下面：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/mainLayout"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

     <SurfaceView
        android:id="@+id/surfaceView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:visibility="visible" />

     <RelativeLayout
        android:id="@+id/mlKnobView"
        android:layout_width="260dip"
        android:layout_height="260dip"
        android:layout_below="@+id/txtView"
        android:background="@drawable/border" >

        <Button
            android:id="@+id/button_down"
            style="?android:attr/buttonStyle"
            android:layout_width="140dip"
            android:layout_height="60dip"
            android:layout_alignParentBottom="true"
            android:layout_centerHorizontal="true"
            android:layout_marginBottom="25dip"
            android:background="@drawable/button_down"
            android:text="Down" />

        <com.example.RotaryKnob
            android:id="@+id/jogView"
            android:layout_width="100dip"
            android:layout_height="100dip"
            android:layout_above="@id/button_down"
            android:layout_below="@+id/button_up"
            android:layout_centerHorizontal="true" />

        <Button
            android:id="@+id/button_left"
            style="?android:attr/buttonStyle"
            android:layout_width="60dip"
            android:layout_height="80dip"
            android:layout_above="@id/button_down"
            android:layout_centerVertical="true"
            android:layout_toLeftOf="@id/jogView"
            android:background="@drawable/button_left"
            android:text="Left" />

        <Button
            android:id="@+id/button_right"
            style="?android:attr/buttonStyle"
            android:layout_width="60dip"
            android:layout_height="80dip"
            android:layout_above="@id/button_down"
            android:layout_alignBaseline="@id/button_left"
            android:layout_alignBottom="@id/button_left"
            android:layout_centerVertical="true"
            android:layout_toRightOf="@id/jogView"
            android:background="@drawable/button_right"
            android:text="Right" />

        <Button
            android:id="@+id/button_up"
            style="?android:attr/buttonStyleSmall"
            android:layout_width="140dip"
            android:layout_height="60dip"
            android:layout_above="@+id/button_left"
            android:layout_alignLeft="@+id/button_down"
            android:layout_below="@+id/windowHeader"
            android:background="@drawable/button_up"
            android:text=" UP " />

    </RelativeLayout>

     <TextView
          android:id="@+id/txtView"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_alignParentTop="true"
         android:layout_centerHorizontal="true"
         android:text="Hai" />

</RelativeLayout>