// Set our control''s size to be the same as the bitmap
   //设置控件大小为位图大小
   control.Width = bitmap.Width;
   control.Height = bitmap.Height;
   // Check if we are dealing with Form here
   //当控件是form时
   if(control is System.Windows.Forms.Form)
   {
    // Cast to a Form object
    //强制转换为FORM
    Form form = (Form)control;
    // Set our form''s size to be a little larger that the  bitmap just
    // in case the form''s border style is not set to none in the first place
    //当FORM的边界FormBorderStyle不为NONE时，应将FORM的大小设置成比位图大小稍大一点
    form.Width = control.Width;
    form.Height = control.Height;
    // No border
    //没有边界
    form.FormBorderStyle = FormBorderStyle.None;
    // Set bitmap as the background image
    //将位图设置成窗体背景图片
    form.BackgroundImage = bitmap;
    // Calculate the graphics path based on the bitmap supplied
    //计算位图中不透明部分的边界
    GraphicsPath graphicsPath = CalculateControlGraphicsPath(bitmap);
    // Apply new region
    //应用新的区域
    form.Region = new Region(graphicsPath);
   }
    // Check if we are dealing with Button here
    //当控件是button时
   else if(control is System.Windows.Forms.Button)
   {
    // Cast to a button object
    //强制转换为 button
    Button button = (Button)control;
    // Do not show button text
    //不显示button text
    button.Text = "";

    // Change cursor to hand when over button
    //改变 cursor的style
    button.Cursor = Cursors.Hand;
    // Set background image of button
    //设置button的背景图片
    button.BackgroundImage = bitmap;

    // Calculate the graphics path based on the bitmap supplied
    //计算位图中不透明部分的边界
    GraphicsPath graphicsPath = CalculateControlGraphicsPath(bitmap);
    // Apply new region
    //应用新的区域
    button.Region = new Region(graphicsPath);
   }
  }
  /// <summary>
  /// Calculate the graphics path that representing the figure in the bitmap
  /// excluding the transparent color which is the top left pixel.
  /// //计算位图中不透明部分的边界
  /// </summary>
  /// <param name="bitmap">The Bitmap object to calculate our graphics path from</param>
  /// <returns>Calculated graphics path</returns>
  private static GraphicsPath CalculateControlGraphicsPath(Bitmap bitmap)
  {
   // Create GraphicsPath for our bitmap calculation
   //创建 GraphicsPath
   GraphicsPath graphicsPath = new GraphicsPath();
   // Use the top left pixel as our transparent color
   //使用左上角的一点的颜色作为我们透明色
   Color colorTransparent = bitmap.GetPixel(0, 0);
   // This is to store the column value where an opaque pixel is first found.
   // This value will determine where we start scanning for trailing opaque pixels.
   //第一个找到点的X
   int colOpaquePixel = 0;
   // Go through all rows (Y axis)
   // 偏历所有行（Y方向）
   for(int row = 0; row < bitmap.Height; row ++)
   {
    // Reset value
    //重设
    colOpaquePixel = 0;
    // Go through all columns (X axis)
    //偏历所有列（X方向）
    for(int col = 0; col < bitmap.Width; col ++)
    {
     // If this is an opaque pixel, mark it and search for anymore trailing behind
     //如果是不需要透明处理的点则标记，然后继续偏历
     if(bitmap.GetPixel(col, row) != colorTransparent)
     {
      // Opaque pixel found, mark current position
      //记录当前
      colOpaquePixel = col;
      // Create another variable to set the current pixel position
      //建立新变量来记录当前点
      int colNext = col;
      // Starting from current found opaque pixel, search for anymore opaque pixels
         // trailing behind, until a transparent   pixel is found or minimum width is reached
      ///从找到的不透明点开始，继续寻找不透明点,一直到找到或则达到图片宽度
      for(colNext = colOpaquePixel; colNext < bitmap.Width; colNext ++)
      if(bitmap.GetPixel(colNext, row) == colorTransparent)
      break;
      // Form a rectangle for line of opaque   pixels found and add it to our graphics path
      //将不透明点加到graphics path
      graphicsPath.AddRectangle(new Rectangle(colOpaquePixel, row, colNext - colOpaquePixel, 1));
      // No need to scan the line of opaque pixels just found
      col = colNext;
     }
    }
   }
   // Return calculated graphics path
   return graphicsPath;
  }
 }
}