Android 得到控件在屏幕中的坐標

package xiaosi.location;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;

public class LocationActivity extends Activity {
    /** Called when the activity is first created. */
	private ImageView img = null;
	private Button button = null;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        img = (ImageView)findViewById(R.id.image);
        button = (Button)findViewById(R.id.button);
        button.setOnClickListener(new buttonListener());
    }   
    public class buttonListener implements OnClickListener{

		public void onClick(View v)
		{
			int[] location = new int[2];
	        img.getLocationOnScreen(location);
	        int x = location[0];
	        int y = location[1];
	        System.out.println(x:+x+y:+y);
            System.out.println(Left：+img.getLeft());
			System.out.println(Right：+img.getRight());
			System.out.println(Top：+img.getTop());
			System.out.println(Bottom：+img.getBottom());
		}
    }
}

getLocationOnScreen ，計算該視圖在全局坐標系中的x，y值，（注意這個值是要從屏幕頂端算起，也就是索包括了通知欄的高度）//獲取在當前屏幕內的絕對坐標
getLocationInWindow ，計算該視圖在它所在的widnow的坐標x，y值，//獲取在整個窗口內的絕對坐標 (不是很理解= =、)
getLeft , getTop, getBottom, getRight, 這一組是獲取相對在它父親裡的坐標
如果在Activity的OnCreate()事件輸出那些參數，是全為0，要等UI控件都加載完了才能獲取到這些。