Android 在列表List中显示半透明小窗体效果的控

想实现图中这样中间有半透明窗体的效果么？


Android 在列表List中显示半透明小窗体效果的控件，多的不多直接上代码，要说的都在注释里了：

    
import android.content.Context;  
import android.graphics.PixelFormat;  
import android.os.Handler;  
import android.view.LayoutInflater;  
import android.view.View;  
import android.view.WindowManager;  
import android.view.WindowManager.LayoutParams;  
import android.widget.TextView;  
  
/** 
 * 窗口中间显示半透明提示框的小组件 
 * 用法：1. new 2. showPrevLetter(String prevLetter) 
 * @author LL 
 * 
 */  
public class PrevLetterDialog {  
    //窗体消失的延时时间  
    private static final int DELAYED_HIDEN = 500;  
  
    // 实现Runnable接口的类  
    private RemoveWindow mRemoveWindow = new RemoveWindow();  
    //在Handler里能实现对UI线程的修改  
    private Handler mHandler;  
    //窗体管理器  
    private WindowManager mWindowManager;  
    //显示在窗体中间半透明的字体框  
    private TextView mDialogText;  
    //是否正在显示中  
    private boolean mShowing;  
    //是否准备好显示了  
    private boolean mReady;  
    //显示在窗体中的字符  
    private char mPrevLetter = Character.MIN_VALUE;  
      
    /** 
     * 注明：context一定要在可见UI中通过getContext()获得，否则会抛异常。 
     * @param context 
     */  
    public PrevLetterDialog(Context context) {  
        //得到窗体管理器  
        mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);  
  
        //得到布部创建者  
        LayoutInflater inflate = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);  
        //得到TextView  
        mDialogText = (TextView) inflate.inflate(R.layout.list_position, null);  
        //设TextView为可见  
        mDialogText.setVisibility(View.INVISIBLE);  
          
        //通过handler把mDialogText展示出来  
        mHandler = new Handler();  
        //要用post可实现在多线程里调用UI线程并改变  
        mHandler.post(new Runnable() {  
            public void run() {  
                mReady = true;  
                //窗体的布局参数  
                WindowManager.LayoutParams lp = new WindowManager.LayoutParams(LayoutParams.WRAP_CONTENT,  
                        LayoutParams.WRAP_CONTENT, WindowManager.LayoutParams.TYPE_APPLICATION,  
                        WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,  
                        PixelFormat.TRANSLUCENT);  
                //把TextView添加到窗体中去  
                mWindowManager.addView(mDialogText, lp);  
            }  
        });  
          
    }  
      
    //设置可见性  
    public void setmReady(boolean mReady) {  
        this.mReady = mReady;  
    }  
  
    /** 
     * 一般用在onScroll方法中,参数是字符串，不能为空，会取第一个字符显示 
     * @param prevLetter 
     */  
    public void showPrevLetter(String prevLetter) {  
        if (!mReady) {  
            return;  
        }  
        char firstLetter = prevLetter.charAt(0);  
  
        if (!mShowing && firstLetter != mPrevLetter) {  
              
            mShowing = true;  
            mDialogText.setVisibility(View.VISIBLE);  
  
        }  
        //设TextView显示的字体  
        mDialogText.setText(((Character) firstLetter).toString());  
        //移除mRemoveWindow实现的Runnable接口类  
        mHandler.removeCallbacks(mRemoveWindow);  
        //添加mRemoveWindow实现的Runnable接口类，并设延时  
        mHandler.postDelayed(mRemoveWindow, DELAYED_HIDEN);  
        mPrevLetter = firstLetter;  
  
    }  
  
    /** 
     * 实现Runnable接口的类 
     */  
    private final class RemoveWindow implements Runnable {  
        public void run() {  
            removeWindow();  
        }  
    }  
  
    private void removeWindow() {  
        if (mShowing) {  
            mShowing = false;  
            mDialogText.setVisibility(View.INVISIBLE);  
        }  
    }  
  
}  

  

    
<?xml version="1.0" encoding="utf-8"?>  
<TextView xmlns:android="http://schemas.android.com/apk/res/android"  
    android:textSize="50sp"  
    android:textColor="@color/band_common_content"  
    android:background="@drawable/common_list_title"  
    android:minWidth="70dip"  
    android:layout_height="wrap_content"  
    android:padding="5dip"  
    android:gravity="center"  
/>  

  

Android 在列表List中显示半透明小窗体效果的控件