解决.net 2.0以上版本GDI+绘图保存后在Photoshop中无法识别的问题

在VS2008（.net 2.0以上版本）下使用如下代码保存图片：

        private void btnSave_Click(object sender, EventArgs e)
        {
            saveFileDialog1.Filter = "PNG Image|*.png|JPeg Image|*.jpg|Bitmap Image|*.bmp|Gif Image|*.gif";
            saveFileDialog1.Title = "Save";
            saveFileDialog1.FileName = string.Empty;
            saveFileDialog1.ShowDialog();
            if (saveFileDialog1.FileName != "")
            {
                System.IO.FileStream fs = (System.IO.FileStream)saveFileDialog1.OpenFile();
                switch (saveFileDialog1.FilterIndex)
                {
                    case 1:
                        this.picEncode.Image.Save(fs,
                           System.Drawing.Imaging.ImageFormat.Jpeg);
                        break;
                    case 2:
                        ((Bitmap)this.picEncode.Image).Save(fs,
                           System.Drawing.Imaging.ImageFormat.Bmp);
                        break;
                    case 3:
                        ((Bitmap)this.picEncode.Image).Save(fs,
                           System.Drawing.Imaging.ImageFormat.Gif);
                        break;
                    case 4:
                       ((Bitmap)this.picEncode.Image).Save(fs,
                           System.Drawing.Imaging.ImageFormat.Png);
                        break;
                }
                fs.Close();
                fs.Dispose();
            }
        }
注意上面case 1和4略有区别。结果都一样：保存的图片在ACD SEE， Windows图片查看器或自带画图板中均可以打开，但使用Photoshop打开图片时，则报错：

（PNG格式）

（JPG格式）
 
还好，几年前写的一个保存图片的类被翻了出来：
// SavePhoto.cs
using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Windows.Forms;
namespace BrawDraw.Com.PhotoFrame.Net.PublicFunctions
{
 /// <summary>
 /// SavePhotos 的摘要说明。
 /// </summary>
 public class SavePhoto
 {
  private Bitmap _bitmapForSave;
  private string _targetFileName;
  private string _targetFolder;
  public SavePhoto()
  {
   //
   // TODO: 在此处添加构造函数逻辑
   //
  }
  public Bitmap BitmapForSave
  {
   get
   {
    return _bitmapForSave;
   }
   set
   {
    _bitmapForSave = value;
   }
  }
  public string TargetFileName
  {
   get
   {
    return _targetFileName;
   }
   set
   {
    _targetFileName = value;
   }
  }
  public string TargetFolder
  {
   get
   {
    if( _targetFolder == string.Empty || _targetFolder == null )
    {
     _targetFolder = @"c:\";
    }
    return _targetFolder;
   }
   set
   {
    _targetFolder = value;
   }
  }
  public string SaveWithDialog()
  {
   return SaveWithDialog( TargetFolder,string.Empty);
  }
  public string SaveWithDialog(string initDir,string fmt)
  {
   SaveFileDialog saveFileDialog = new SaveFileDialog();
   if(initDir==null || initDir==string.Empty)
   {
    initDir = @"C:\" ;
   }
   saveFileDialog.InitialDirectory = initDir;
   string strFilters;
   string strFiltersBmp="Bitmap files (*.bmp)|*.bmp";
   string strFiltersGif="Gif files (*.gif)|*.gif";
   string strFiltersJpg="Jpeg files (*.jpg,jpeg,jpe)|*.jpg;*.jpeg;*.jpe";
   string strFiltersPng="PNG files (*.png)|*.png";
   string strFiltersTif="Tiff files (*.tif,*tiff)|*.tif;*.tiff";
   string strFiltersAll="All files (*.*)|*.*";
   switch(fmt.ToLower())
   {
    case "bmp":
     strFilters = strFiltersBmp;
     break;
    case ".gif":
     strFilters = strFiltersGif;
     break;
    case ".jpg":
    case ".jpeg":
    case ".jpe":
     strFilters = strFiltersJpg;
     break;
    case ".png":
     strFilters = strFiltersPng;
     break;
    case ".tif":
    case ".tiff":
     strFilters = strFiltersTif;
     break;
    default:
     strFilters = strFiltersJpg +"|"+ strFiltersBmp +"|" + strFiltersGif +"|"+ strFiltersPng +"|"+ strFiltersTif +"|"+ strFiltersAll;
     break;
   }
   saveFileDialog.Filter = strFilters;
   saveFileDialog.FilterIndex = 1 ;
   saveFileDialog.RestoreDirectory = true ;
   saveFileDialog.AddExtension=true;
   string strFileName = string.Empty;
   if(DialogResult.OK == saveFileDialog.ShowDialog())
   {
    strFileName = saveFileDialog.FileName;
    bool resultSave = Save(strFileName);
    if(!resultSave)
    {
     strFileName = string.Empty;
    }
   }
   return strFileName;
  }
  public bool Save(Bitmap bitmapOfSave)
  {
   if( _bitmapForSave == null)
   {
    _bitmapForSave = bitmapOfSave;
   }
   try
   {
    SaveWithDialog( TargetFolder, "All");
   }
   catch(Exception ex)
   {
    MessageBox.Show("出错了！" + ex.Message);
    return false;
   }
   return true;
   //   finally
   //   {
   //    if( m_Bitmap != null)
   //     m_Bitmap.Dispose();
   //   }
  }
  public bool Save(string strFileName)
  {
   return Save(strFileName,string.Empty);
  }
  public bool Save(string strFileName,string addString)
  {  
   string[] arrStrFileName = strFileName.Replace(@"\", @"/").Split(new char[]{'/'});
   if(arrStrFileName.Length <= 1)
   {
    strFileName = TargetFolder + @"\" + strFileName;
   }
   ImageCodecInfo myImageCodecInfo;
   System.Drawing.Imaging.Encoder myEncoder;
   EncoderParameter myEncoderParameter;
   EncoderParameters myEncoderParameters;
   string strFileExt;
   if(strFileName.LastIndexOf(@".")<=0)
   {
    strFileExt=".jpg";
    strFileName += (addString + ".jpg");
   }
   else
   {
    strFileExt = strFileName.Substring(strFileName.LastIndexOf(@"."));
    string strCurrentPhotoPath = strFileName.Substring(0,strFileName.LastIndexOf(@"\")+1);
    strFileName = strCurrentPhotoPath + Path.GetFileNameWithoutExtension(strFileName) + addString + strFileExt;
   }
   try
   {
    switch (strFileExt.ToLower())
    {
     case ".bmp":
      _bitmapForSave.Save(strFileName, System.Drawing.Imaging.ImageFormat.Bmp);
      break;
     case ".gif":
      _bitmapForSave.Save(strFileName, System.Drawing.Imaging.ImageFormat.Gif);
      break;
     case ".jpg":
     case ".jpeg":
     case ".jpe":
      //获取JPEG格式的编码方式
      myImageCodecInfo = GetEncoderInfo("image/jpeg");
      //分别设置JPEG文件的图片质量
      //编码参数种类为Quality
      myEncoder = System.Drawing.Imaging.Encoder.Quality;
      //创建一个EncoderParameters对象，它仅包含一个 EncoderParameter对象
      myEncoderParameters = new EncoderParameters(1);      
      //设置JPEG图片质量为80级
      myEncoderParameter = new EncoderParameter(myEncoder,80L);
      myEncoderParameters.Param[0] = myEncoderParameter;
      _bitmapForSave.Save(strFileName, myImageCodecInfo, myEncoderParameters);
      break;
     case ".png":
      _bitmapForSave.Save(strFileName, System.Drawing.Imaging.ImageFormat.Png);
      break;
     case ".tif":
     case ".tiff":
      //获取JPEG格式的编码方式
      myImageCodecInfo = GetEncoderInfo("image/tiff");
      //创建一个描述压缩方式的参数对象
      myEncoder= System.Drawing.Imaging.Encoder.Compression;
      myEncoderParameters = new EncoderParameters(1);
      
      //设置JPEG图片质量为25级
      myEncoderParameter = new EncoderParameter(
       myEncoder, (long)EncoderValue.CompressionLZW
       );
      myEncoderParameters.Param[0] = myEncoderParameter;
      _bitmapForSave.Save(strFileName, myImageCodecInfo, myEncoderParameters);
      break;
     default:
      _bitmapForSave.Save(strFileName + @".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
      break;
    }
   }
   catch(Exception exc)
   {
    MessageBox.Show("Error:" + exc.Message);
    return false;
   }
   return true;
  }
 
  public static ImageCodecInfo GetEncoderInfo(String mimeType)
  {
   int j;
   ImageCodecInfo[] encoders;
   encoders = ImageCodecInfo.GetImageEncoders();
   for(j = 0; j < encoders.Length; ++j)
   {
    if(encoders[j].MimeType == mimeType)
     return encoders[j];
   }
   return null;
  }
 }
 public enum SavePhotoResult
 {
  Yes,
  No,
  Cancel
 }
}
 
// 具体调用时的示例代码：
using BrawDraw.Com.PhotoFrame.Net.PublicFunctions;

private void btnSave_Click(object sender, EventArgs e)
{
            SavePhoto savePhoto = new SavePhoto();
            savePhoto.BitmapForSave = (Bitmap)this.picEncode.Image;
            savePhoto.TargetFolder = @"c:\";
            savePhoto.SaveWithDialog();
}