winform下的简易播放器

编写这个播放器，遇到很多问题，比如目前只实现了wav音频文件的播放，而对于这个图中中间所标注的按钮

不能实现让其暂停的功能，同时当点击的时候，让其文本变为"▷",对于这部分功能不知道选定该按钮时的属性是

如何，所以还需继续完善

播放器代码

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows.Forms;
 using System.Media;
 using System.IO;

 namespace WindowsFormsApplication1
 {
     public partial class Form1 : Form
     {
         public Form1()
         {
             InitializeComponent();
         }

         private void Form1_Load(object sender, EventArgs e)
         {

         }
         List<string> listSongs = new List<string>();//定义存储歌名的路径泛型变量
         private void button5_Click(object sender, EventArgs e)
         {
             OpenFileDialog ofd = new OpenFileDialog();
             ofd.Title = "请选择音频文件";
             ofd.InitialDirectory =@"F:\wav_music";
             ofd.Filter="音频文件|*.wav|所有文件|*.*";
             ofd.Multiselect=true;//多选设置
             ofd.ShowDialog();
             string[] path = ofd.FileNames;//获取音频文件的全路径
             for (int i = ; i < path.Length; i++)
             {
                 listBox1.Items.Add(Path.GetFileName(path[i]));//将获取到的文件路径截取文件名并添加到listbox中
                 listSongs.Add(path[i]);//将路径添加到list集合当中

             }

         }
         /// <summary>
         /// 双击播放音乐方法。
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>

         private void listBox1_DoubleClick(object sender, EventArgs e)
         {
             SoundPlayer sp = new SoundPlayer();//
             sp.SoundLocation = listSongs[listBox1.SelectedIndex];
             sp.Play();
         }
         /// <summary>
         /// 播放下一首
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>

         private void button4_Click(object sender, EventArgs e)
         {
             //获取当前所选定的音乐项
             int index = listBox1.SelectedIndex;
             index++;
             SoundPlayer sp = new SoundPlayer();
             if (index ==listSongs.Count)
             {

                 index = ;
             }
             listBox1.SelectedIndex = index;//将索引重新赋值给listbox选定。
             sp.SoundLocation = listSongs[index];
             sp.Play();

         }
         /// <summary>
         /// 播放上一首
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>

         private void button2_Click(object sender, EventArgs e)
         {
             //获取当前所选定的音乐项
             int index = listBox1.SelectedIndex;
             index--;
             SoundPlayer sp = new SoundPlayer();
             if (index == )
             {
                 index = listSongs.Count - ;
             }
             listBox1.SelectedIndex = index;
             sp.SoundLocation = listSongs[index];
             sp.Play();

         }
     }
 }