android PopupWindow 自下往上的弹框

【实例截图】

【核心代码】

package com.example.popwindow;

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

public class MainActivity extends Activity {

	private Button ok ;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		ok = (Button) findViewById(R.id.btn);
		
		ok.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				showPopFormBottom(v);
			}

			private void showPopFormBottom(View v) {
				// TODO Auto-generated method stub
				TakePhotoPopWin takePhotoPopWin = new TakePhotoPopWin(MainActivity.this, onClickListener); 
				  //showAtLocation(View parent, int gravity, int x, int y) 
				  takePhotoPopWin.showAtLocation(findViewById(R.id.btn), Gravity.CENTER, 0, 0);
			}
		});
	}

	private View.OnClickListener onClickListener = new View.OnClickListener() { 
		  @Override
		  public void onClick(View v) { 
		  
		    switch (v.getId()) { 
		      case R.id.btn_take_photo: 
//		        System.out.println("btn_take_photo"); 
		        Toast.makeText(MainActivity.this, "btn_take_photo", Toast.LENGTH_SHORT).show();
		        break; 
		      case R.id.btn_pick_photo: 
//		        System.out.println("btn_pick_photo"); 
		    	Toast.makeText(MainActivity.this, "btn_pick_photo111", Toast.LENGTH_SHORT).show();
		        break; 
		    } 
		  } 
		}; 
}