Android实现在列表List中显示半透明小窗体效果的控件用法详解

import com.hiapk.market.R;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"/>