C#图片切割、图片压缩、缩略图生成代码汇总

/// 图片切割函数
 /// </summary>
 /// <param name="sourcefile">原始图片文件</param>
 /// <param name="xnum">在ｘ轴上的切割数量</param>
 /// <param name="ynum">在ｙ轴上的切割数量</param>
 /// <param name="quality">质量压缩比</param>
 /// <param name="outputfile">输出文件名，不带后缀</param>
 /// <returns>成功返回true，失败则返回false</returns>
 public static bool imagecut(string sourcefile, int xnum, int ynum, long quality, string outputfile)
 {
  try
  {
   long imagequality      = quality;
   bitmap sourceimage      = new bitmap(sourcefile);
   imagecodecinfo myimagecodecinfo   = getencoderinfo("image/jpeg");
   encoder myencoder      = encoder.quality;
   encoderparameters myencoderparameters = new encoderparameters(1);
   encoderparameter myencoderparameter  = new encoderparameter(myencoder, imagequality);
   myencoderparameters.param[0]    = myencoderparameter;
   float xwidth        = sourceimage.width / xnum;
   float ywidth        = sourceimage.height / ynum;
   string outputimage      = "";
    
   for (int county = 0; county < ynum; county++)
    for (int countx = 0; countx < xnum; countx++)
    {
 
     rectanglef clonerect    = new rectanglef(countx * xwidth, county * ywidth, xwidth, ywidth);
     bitmap newimage     = sourceimage.clone(clonerect, pixelformat.format24bpprgb);
     outputimage      = outputfile + countx + county + ".jpg";
     newimage.save(outputimage, myimagecodecinfo, myencoderparameters);
 
    }
   return true;
  }
  catch
  {
   return false;
  }
 
 }
 #endregion imagecut
 
 imagecompress
#region
imagecompress
 /**//// <summary>
 /// 图片压缩函数
 /// </summary>
 /// <param name="sourcefile">原始图片文件</param>
 /// <param name="quality">质量压缩比</param>
 /// <param name="ouputfile">输出文件名,请用 .jpg 后缀 </param>
 /// <returns>成功返回true，失败则返回false</returns>
 public static bool imagecompress(string sourcefile,long quality,string outputfile)
 {
  try
  {
   long imagequality      = quality;
   bitmap sourceimage      = new bitmap(sourcefile);
   imagecodecinfo myimagecodecinfo  = getencoderinfo("image/jpeg");
   encoder myencoder      = encoder.quality;
   encoderparameters myencoderparameters = new encoderparameters(1);
   encoderparameter myencoderparameter = new encoderparameter(myencoder, imagequality);
   myencoderparameters.param[0]   = myencoderparameter;
   
   sourceimage.save(outputfile, myimagecodecinfo, myencoderparameters);
   return true;
 
  }
  catch
  {
   return false;
  }
 
 }
 #endregion imagecompress
 
 getthumimage#region getthumimage
 /**//// <summary>
 /// 生成缩略图
 /// </summary>
 /// <param name="sourcefile">原始图片文件</param>
 /// <param name="quality">质量压缩比</param>
 /// <param name="multiple">收缩倍数</param>
 /// <param name="outputfile">输出文件名</param>
 /// <returns>成功返回true,失败则返回false</returns>
 public static bool getthumimage(string sourcefile, long quality, int multiple, string outputfile)
 {
  try
  {
   long imagequality      = quality;
   bitmap sourceimage      = new bitmap(sourcefile);
   imagecodecinfo myimagecodecinfo  = getencoderinfo("image/jpeg");
   encoder myencoder      = encoder.quality;
   encoderparameters myencoderparameters = new encoderparameters(1);
   encoderparameter myencoderparameter = new encoderparameter(myencoder, imagequality);
   myencoderparameters.param[0]   = myencoderparameter;
   float xwidth       = sourceimage.width;
   float ywidth       = sourceimage.height;
   bitmap newimage      = new bitmap((int)(xwidth /multiple), (int)(ywidth /multiple));
   graphics g        = graphics.fromimage(newimage);
    
   g.drawimage(sourceimage, 0, 0, xwidth / multiple, ywidth / multiple);
   g.dispose();
   newimage.save(outputfile,myimagecodecinfo,myencoderparameters);
   return true;
  }
  catch
  {
   return false;
  }
 }
 #endregion getthumimage
 
 imagecodecinfo#region imagecodecinfo
 /**//// <summary>
 /// 获取图片编码信息
 /// </summary>
 private 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;
 }