Java 如何在android中通过保持左上角位置固定和其他点的更改来扩展视图

当我触摸和移动时，视图的大小正在改变。但我的要求是只改变大小，而不改变左上角的位置

这是xml代码警报窗口。xml

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

    <RelativeLayout
        android:id="@+id/r1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dip"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp" >

        <RelativeLayout
            android:id="@+id/liner"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/ll" >

            <TextView
                android:id="@+id/edit_list_name2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerHorizontal="true"
                android:layout_marginTop="5dip"
                android:gravity="center"
                android:text="--- -"
                android:textAppearance="?android:attr/textAppearanceSmall" />

            <ScrollView 
                android:id="@+id/scroll"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_above="@+id/liner2"
                android:layout_below="@+id/edit_list_name2">

                <RelativeLayout 
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content">

                    <TextView
                        android:id="@+id/defualt_button"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:ellipsize="end"
                        android:layout_marginLeft="2dip"
                        android:layout_marginRight="2dip"
                        android:layout_marginTop="2dp"
                        android:layout_marginBottom="1dp"
                        android:text="Smack that all on the floor \nSmack that give me some more\n"
                        android:textAppearance="?android:attr/textAppearanceSmall"/>
                </RelativeLayout>
            </ScrollView>

            <RelativeLayout
                android:id="@+id/liner2"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_alignParentBottom="true"
                android:layout_marginTop="2dp" >

                <ImageView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_alignParentLeft="true"
                    android:layout_centerVertical="true"
                    android:padding="3dp" />

                <ImageView
                    android:id="@+id/iv_expand"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_alignParentRight="true"
                    android:src="@drawable/popup_expand" 
                    android:layout_centerVertical="true"
                    android:padding="3dp"/>
            </RelativeLayout>
        </RelativeLayout>
    </RelativeLayout>
</RelativeLayout>

public class ResizeService extends Service {

    ImageView iv_expand;

    int height_layout,width,height,height_params;       
    WindowManager windowManager;
    View myView;        

    @Override 
    public IBinder onBind(Intent intent) {

        // Not used
        return null;
    }

    @SuppressLint("NewApi")
    @Override 
    public void onCreate() {

        super.onCreate();

        //470,420  wrap content,500
        windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);   

        DisplayMetrics metrics = ResizeService.this.getResources().getDisplayMetrics();
        width = metrics.widthPixels;
        height = metrics.heightPixels;

        width=(width/100)*100;
        height_params=(height/100)*40;

        //window for the main layout
        final WindowManager.LayoutParams params = new winndowManager.LayoutParams(width,height_params, WindowManager.LayoutParams.TYPE_PHONE, WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE, PixelFormat.TRANSLUCENT);

        params.gravity = Gravity.TOP | Gravity.LEFT;
        LayoutInflater inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
        myView   = inflater.inflate(R.layout.alert_window, null);
        iv_expand   = (ImageView)     myView.findViewById(R.id.iv_expand);
        windowManager.addView(myView, params);

        iv_expand.setOnTouchListener(new OnTouchListener() {

            private int initial_expand_X;
            private int initial_expand_Y;
            private float initialExpandTouchX;
            private float initialExpandTouchY;


            @Override
            public boolean onTouch(View v, MotionEvent event) {

                try {

                    switch (event.getAction()) {

                        case MotionEvent.ACTION_DOWN:
                            initial_expand_X = params.x;
                            initial_expand_Y = params.y;
                            initialExpandTouchX = event.getRawX();
                            initialExpandTouchY = event.getRawY();
                            return true;
                        case MotionEvent.ACTION_UP:
                            return true;

                        case MotionEvent.ACTION_MOVE:                               
                            params.x = initial_expand_X + (int) (event.getRawX() - initialExpandTouchX);
                            params.y = initial_expand_Y + (int) (event.getRawY() - initialExpandTouchY);
                            params.width=(int) event.getRawX();
                            params.height=(int)event.getRawY();
                            windowManager.updateViewLayout(myView, params);
                            return true;
                       }

                } catch (Exception e) {

                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                return false;
            }
        });
    }
}