C#图片压缩类winform

using System;
using System.Collections.Generic;
using
System.Text;
using System.Drawing;
using System.Drawing.Imaging;
using
System.IO;
using System.Windows.Forms;

namespace EU.EUClass
{

class ImgGDI
  {
      public
ImgGDI()
      {
       
//构造函数
      }

///
      /// Bitmap转换byte[]数组
 
  ///
      ///
   
///
      public byte[] Bmptobyte(Bitmap
bmp)
      {
       
MemoryStream ms = new MemoryStream();
     
  bmp.Save(ms, ImageFormat.Jpeg);
     
  ms.Flush();
          byte[]
buffer = ms.GetBuffer();
         
ms.Close();
          return
buffer;
      }

///
      /// byte[]数组转换Bitmap
   
///
      ///
     
///
      public Bitmap bytetobmp(byte[]
buffer)
      {
       
MemoryStream ms = new MemoryStream();
     
  ms.Write(buffer, 0, buffer.Length);
     
  Bitmap bmp = new Bitmap(ms);
       
ms.Close();
          return
bmp;
      }

///
      /// 返回默认图片
     
///
      ///
      public
Bitmap getInstance()
      {
   
    Bitmap bmp = DefaultPic();
     
  return bmp;
      }

///
      /// 选取本地图片
 
  ///
      ///
   
///
      public Bitmap LocalIMG(string
IMG)
      {
       
FileStream fs = new FileStream(IMG, FileMode.Open);
 
      Bitmap bmp = new Bitmap(fs);
   
    fs.Close();
         
return bmp;
      }

///
      /// 返回流状态图片
     
///
      ///
     
///
      public Bitmap ImgFromBase64(string
Img)
      {
       
Bitmap bmp;
          byte[] buffer =
Convert.FromBase64String(Img);
          if
(buffer.Length > 0)
          {

MemoryStream ms = new
MemoryStream();
             
ms.Write(buffer, 0, buffer.Length);
         
  bmp = new Bitmap(ms);
         
  ms.Close();
           
return bmp;
          }

else
       
{
              bmp =
DefaultPic() ;
              return
bmp;
          }
   
}

///
     
/// 默认图片
      ///
     
///
      private Bitmap DefaultPic()
 
  {
          FileStream fs = new
FileStream(Application.StartupPath + @"\Goodr.jpg", FileMode.Open);

Bitmap bmp = new Bitmap(fs);
 
      fs.Close();
       
return bmp;
      }

///
      /// GDI压缩图片
   
///
      /// 传入参数Bitmap
   
///
      public byte[] ImageGdi(Bitmap
bmp)
      {
       
Bitmap xbmp = new Bitmap(bmp);
       
MemoryStream ms = new MemoryStream();
     
  xbmp.Save(ms, ImageFormat.Jpeg);
     
  byte[] buffer;
         
ms.Flush();
          if (ms.Length >
95000)
          {
   
        //buffer = ms.GetBuffer();
 
          double new_width = 0;
 
          double new_height = 0;

Image m_src_image = Image.FromStream(ms);
   
        if (m_src_image.Width >=
m_src_image.Height)
             
{
                 
new_width = 1024;
             
  new_height = new_width * m_src_image.Height /
(double)m_src_image.Width;
           
}
              else if
(m_src_image.Height >= m_src_image.Width)
     
      {
         
      new_height = 768;
     
          new_width = new_height *
m_src_image.Width / (double)m_src_image.Height;
     
      }

Bitmap bbmp = new Bitmap((int)new_width, (int)new_height,
m_src_image.PixelFormat);
           
Graphics m_graphics = Graphics.FromImage(bbmp);
   
        m_graphics.SmoothingMode =
System.Drawing.Drawing2D.SmoothingMode.HighQuality;
   
        m_graphics.InterpolationMode =
System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
 
          m_graphics.DrawImage(m_src_image, 0,
0, bbmp.Width, bbmp.Height);

ms = new MemoryStream();

bbmp.Save(ms, ImageFormat.Jpeg);
   
        buffer = ms.GetBuffer();
 
          ms.Close();

return buffer;
   
    }
         
else
          {
   
        buffer = ms.GetBuffer();
 
          ms.Close();
   
        return buffer;
     
  }
      }
  }
}