Android PopupWindow显示位置和显示大小

package com.example.showpop;

import android.app.Activity;
import android.content.Context;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.view.WindowManager;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.PopupWindow;

public class MainActivity extends Activity {
	private LinearLayout layout;
	private ListView listView;
	private PopupWindow popupWindow;
	private String title[] = { "1", "2", "3", "4", "5" };
	private  ImageView imageView;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.activity_main);
		imageView=(ImageView) findViewById(R.id.imageview_above_more);
		imageView.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				showPopupWindow(imageView);
			}
		});
	}
	public void showPopupWindow(View parent) {
		//加载布局
		layout = (LinearLayout) LayoutInflater.from(MainActivity.this).inflate(
				R.layout.dialog, null);
		//找到布局的控件
		listView = (ListView) layout.findViewById(R.id.lv_dialog);
		//设置适配器
		listView.setAdapter(new ArrayAdapter(MainActivity.this,
				R.layout.text, R.id.tv_text, title));
		// 实例化popupWindow
		popupWindow = new PopupWindow(layout, 300,500);
		//控制键盘是否可以获得焦点
		popupWindow.setFocusable(true);
		//设置popupWindow弹出窗体的背景
		popupWindow.setBackgroundDrawable(new BitmapDrawable(null,""));
		WindowManager manager=(WindowManager) getSystemService(Context.WINDOW_SERVICE);
		@SuppressWarnings("deprecation")
		//获取xoff
		int xpos=manager.getDefaultDisplay().getWidth()/2-popupWindow.getWidth()/2;
		//xoff,yoff基于anchor的左下角进行偏移。
		popupWindow.showAsDropDown(parent,xpos, 0);
		//监听
		listView.setOnItemClickListener(new OnItemClickListener() {
			@Override
			public void onItemClick(AdapterView arg0, View arg1, int arg2,
					long arg3) {
				//关闭popupWindow
				popupWindow.dismiss();
				popupWindow = null;
			}
		});
	}
}

源码下载地址