c# 轉換Image為Icon

/// <summary>
/// 轉換Image為Icon
/// </summary>
/// <param name="image">要轉換為圖標的Image對象</param>
/// <param name="nullTonull">當image為null時是否返回null。false則拋空引用異常</param>
/// <exception cref="ArgumentNullException" />
public static Icon ConvertToIcon(Image image, bool nullTonull = false)
{
    if (image == null)
    {
        if (nullTonull) { return null; }
        throw new ArgumentNullException("image");
    }

    using (MemoryStream msImg = new MemoryStream()
                      , msIco = new MemoryStream())
    {
        image.Save(msImg, ImageFormat.Png);

        using (var bin = new BinaryWriter(msIco))
        {
            //寫圖標頭部
            bin.Write((short)0);           //0-1保留
            bin.Write((short)1);           //2-3文件類型。1=圖標, 2=光標
            bin.Write((short)1);           //4-5圖像數量（圖標可以包含多個圖像）

            bin.Write((byte)image.Width);  //6圖標寬度
            bin.Write((byte)image.Height); //7圖標高度
            bin.Write((byte)0);            //8顏色數（若像素位深>=8，填0。這是顯然的，達到8bpp的顏色數最少是256，byte不夠表示）
            bin.Write((byte)0);            //9保留。必須為0
            bin.Write((short)0);           //10-11調色板
            bin.Write((short)32);          //12-13位深
            bin.Write((int)msImg.Length);  //14-17位圖數據大小
            bin.Write(22);                 //18-21位圖數據起始字節

            //寫圖像數據
            bin.Write(msImg.ToArray());

            bin.Flush();
            bin.Seek(0, SeekOrigin.Begin);
            return new Icon(msIco);
        }
    }
}