C#中把Image无损转换为Icon的实例详解

/// <summary>

/// 转换Image为Icon

/// </summary>

/// <param name="image">要转换为图标的Image对象</param>

/// <param name="nullTonull">当image为null时是否返回null。false则抛空引用异常</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))

    {

      //写图标头部

      bin.Write((short)0);      //0-1保留

      bin.Write((short)1);      //2-3文件类型。1=图标, 2=光标

      bin.Write((short)1);      //4-5图像数量（图标可以包含多个图像）

      bin.Write((byte)image.Width); //6图标宽度

      bin.Write((byte)image.Height); //7图标高度

      bin.Write((byte)0);      //8颜色数（若像素位深>=8，填0。这是显然的，达到8bpp的颜色数最少是256，byte不够表示）

      bin.Write((byte)0);      //9保留。必须为0

      bin.Write((short)0);      //10-11调色板

      bin.Write((short)32);     //12-13位深

      bin.Write((int)msImg.Length); //14-17位图数据大小

      bin.Write(22);         //18-21位图数据起始字节

      //写图像数据

      bin.Write(msImg.ToArray());

      bin.Flush();

      bin.Seek(0, SeekOrigin.Begin);

      return new Icon(msIco);

    }

  }

}