C#byte数组与Image的相互转换实例代码

c#byte数组与image的相互转换实例代码

功能需求：

1、把一张图片（png bmp jpeg bmp gif）转换为byte数组存放到数据库。

2、把从数据库读取的byte数组转换为image对象，赋值给相应的控件显示。

3、从图片byte数组得到对应图片的格式，生成一张图片保存到磁盘上。

这里的image是system.drawing.image。

  //get an image from file
    image image = image.fromfile("d:\\test.jpg");
    bitmap bitmap = new bitmap("d:\\test.jpg");

以下三个函数分别实现了上述三个需求：

using system;
using system.collections.generic;
using system.drawing;
using system.drawing.imaging;
using system.io;
using system.linq;
using system.text;

namespace netutilitylib
{
  public static class imagehelper
  {
    /// <summary>
    /// convert image to byte[]
    /// </summary>
    /// <param name="image"></param>
    /// <returns></returns>
    public static byte[] imagetobytes(image image)
    {
      imageformat format = image.rawformat;
      using (memorystream ms = new memorystream())
      {
        if (format.equals(imageformat.jpeg))
        {
          image.save(ms, imageformat.jpeg);
        }
        else if (format.equals(imageformat.png))
        {
          image.save(ms, imageformat.png);
        }
        else if (format.equals(imageformat.bmp))
        {
          image.save(ms, imageformat.bmp);
        }
        else if (format.equals(imageformat.gif))
        {
          image.save(ms, imageformat.gif);
        }
        else if (format.equals(imageformat.icon))
        {
          image.save(ms, imageformat.icon);
        }
        byte[] buffer = new byte[ms.length];
        //image.save()会改变memorystream的position，需要重新seek到begin
        ms.seek(0, seekorigin.begin);
        ms.read(buffer, 0, buffer.length);
        return buffer;
      }
    }

    /// <summary>
    /// convert byte[] to image
    /// </summary>
    /// <param name="buffer"></param>
    /// <returns></returns>
    public static image bytestoimage(byte[] buffer)
    {
      memorystream ms = new memorystream(buffer);
      image image = system.drawing.image.fromstream(ms);
      return image;
    }

    /// <summary>
    /// convert byte[] to a picture and store it in file
    /// </summary>
    /// <param name="filename"></param>
    /// <param name="buffer"></param>
    /// <returns></returns>
    public static string createimagefrombytes(string filename, byte[] buffer)
    {
      string file = filename;
      image image = bytestoimage(buffer);
      imageformat format = image.rawformat;
      if (format.equals(imageformat.jpeg))
      {
        file += ".jpeg";
      }
      else if (format.equals(imageformat.png))
      {
        file += ".png";
      }
      else if (format.equals(imageformat.bmp))
      {
        file += ".bmp";
      }
      else if (format.equals(imageformat.gif))
      {
        file += ".gif";
      }
      else if (format.equals(imageformat.icon))
      {
        file += ".icon";
      }
      system.io.fileinfo info = new system.io.fileinfo(file);
      system.io.directory.createdirectory(info.directory.fullname);
      file.writeallbytes(file, buffer);
      return file;
    }
  }
}

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