popupwindow的使用，背景虚化

private void initpopu() {
// TODO Auto-generated method stub
//初始popupwindow
if (mpop==null) {
mpop=new PopupWindow(Popuplayout,LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
}
if (mpop.isShowing()) {
mpop.dismiss();
}
//设置点击popupwindow外的区域可以返回
ColorDrawable cd = new ColorDrawable(0x000000);
      mpop.setBackgroundDrawable(cd); 
      //设置背景的透明度
WindowManager.LayoutParams lp=getActivity().getWindow().getAttributes();
   lp.alpha = 0.4f;
   getActivity().getWindow().setAttributes(lp);
   
   //很重要，让布局获取焦点
   Popuplayout.setFocusable(true);
   Popuplayout.setFocusableInTouchMode(true);


//设置popupwindow外的的区域可点击
mpop.setOutsideTouchable(true);
//设置popupwindow获得焦点
mpop.setFocusable(true);

//设置动画
//mpop.setAnimationStyle(R.style.AnimationFade);

//设置popupwindow的位置，水平垂直居中
mpop.showAtLocation(Popuplayout, Gravity.CENTER_VERTICAL|Gravity.CENTER_HORIZONTAL, 0, 0);


//更新一下，关闭的时候恢复透明度
mpop.update();
   mpop.setOnDismissListener(new OnDismissListener(){
   
   //在dismiss中恢复透明度
   public void onDismiss(){
       WindowManager.LayoutParams lp=getActivity().getWindow().getAttributes();
       lp.alpha = 1f;
       getActivity().getWindow().setAttributes(lp);
     }
    });

}