Exemple d'analyse de la façon d'utiliser C# pour personnaliser la barre de progression du lecteur de musique

[DefaultEvent("ProgressClick")]
  [ToolboxBitmap(typeof(TrackBar))]
  public partial class ProcessBar : UserControl
  {
    public ProcessBar()
    {
      //InitializeComponent();
      //this.SetStyle(ControlStyles.UserPaint, true);
      //this.SetStyle(ControlStyles.AllPaintingInWmPaint, true);
      //this.SetStyle(ControlStyles.DoubleBuffer, true);
    }

    private int locationX=0;
    [Description("单击时X的坐标")]
    public int LocationX
    {
      get { return locationX; }
    }
  
    private int current = 0;
    [Description("当前进度")]
    public int Current
    {
      get { return current; }
      set
      {
        if (value > 232 || value < 0)
          return;
        current = value;
        panelCurrent.Size = new Size(value, 1);
        picture.Location = new Point(value - 4, -3);
        Invalidate();
      }
    }

    private bool isPlay = false;
    [Description("是否播放")]
    public bool IsPlay
    {
      get { return isPlay; }
      set { isPlay = value; tmrCurrent.Enabled = isPlay; Invalidate(); }
    }

    public delegate void MouseHandle(object sender,EventArgs e);
    [Description("点下鼠标")]
    public event MouseHandle BarMouseDown;

    int picturetype = 0;
    private void tmrCurrent_Tick(object sender, EventArgs e)
    {
      if (picturetype == 0)
      { picture.Image = Properties.Resources.play_slider_thumb; picturetype = 1; }
      else
      { picture.Image = Properties.Resources.play_slider_thumb_animate; picturetype = 0; }
      GraphicsPath g = subGraphicsPath(picture.Image);
      if (g == null) return;
      picture.Region = new Region(g);
    }

    private unsafe static GraphicsPath subGraphicsPath(Image img)
    {
      if (img == null) return null;
      // 建立GraphicsPath, 给我们的位图路径计算使用  
      GraphicsPath g = new GraphicsPath(FillMode.Alternate);
      Bitmap bitmap = new Bitmap(img);
      int width = bitmap.Width;
      int height = bitmap.Height;
      BitmapData bmData = bitmap.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
      byte* p = (byte*)bmData.Scan0;
      int offset = bmData.Stride - width * 3;
      int p0, p1, p2;     // 记录左上角0，0座标的颜色值 
      p0 = p[0];
      p1 = p[1];
      p2 = p[2];

      int start = -1;
      // 行座标 ( Y col )  
      for (int Y = 0; Y < height; Y++)
      {
        // 列座标 ( X row )  
        for (int X = 0; X < width; X++)
        {
          if (start == -1 && (p[0] != p0 || p[1] != p1 || p[2] != p2))   //如果 之前的点没有不透明 且 不透明  
          {
            start = X;              //记录这个点 
          }
          else if (start > -1 && (p[0] == p0 && p[1] == p1 && p[2] == p2))   //如果 之前的点是不透明 且 透明 
          {
            g.AddRectangle(new Rectangle(start, Y, X - start, 1));  //添加之前的矩形到 
            start = -1;
          }
          if (X == width - 1 && start > -1)    //如果 之前的点是不透明 且 是最后一个点 
          {
            g.AddRectangle(new Rectangle(start, Y, X - start + 1, 1));   //添加之前的矩形到 
            start = -1;
          }
          p += 3;                  //下一个内存地址 
        }
        p += offset;
      } bitmap.UnlockBits(bmData);
      bitmap.Dispose();
      // 返回计算出来的不透明图片路径  
      return g;
    }

    private void panelTotal_MouseDown(object sender, MouseEventArgs e)
    {
      Current = e.Location.X;
      locationX = e.Location.X;
      if (BarMouseDown != null)
      {
        BarMouseDown.Invoke(sender, e);
      }
    }

    private void panelCurrent_MouseDown(object sender, MouseEventArgs e)
    {
      Current = e.Location.X;
      locationX = e.Location.X;
      if (BarMouseDown != null)
      {
        BarMouseDown.Invoke(sender, e);
      }
    }
  }