1  　　　　 /// 
  2          /// 生成缩略图  3          /// 
  4          /// 源图路径（物理路径）  5          /// 缩略图路径（物理路径）  6          /// 缩略图宽度  7          /// 缩略图高度  8          /// 生成缩略图的方式      9          public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode) 10          { 11              originalImagePath = string.Format(@"{0}{1}\{2}", StrHelp.GetPhysicalPath(), 　　　　　　　　　　　　ConfigurationManager.AppSettings["UploadPath"], 　　　　　　　　　　　　originalImagePath); 12              thumbnailPath = string.Format(@"{0}{1}\{2}", StrHelp.GetPhysicalPath(), ConfigurationManager.AppSettings["UploadPath"], thumbnailPath); 13              System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath); 14   15              int towidth = width; 16              int toheight = height; 17   18              int x = 0; 19              int y = 0; 20              int ow = originalImage.Width; 21              int oh = originalImage.Height; 22   23              switch (mode) 24              { 25                  case "HW"://指定高宽缩放（可能变形）                 26                      break; 27                  case "W"://指定宽，高按比例 28                      if (originalImage.Width < width) 29                      { 30                          towidth = originalImage.Width; 31                          toheight = originalImage.Height; 32                      } 33                      else 34                      { 35                          toheight = originalImage.Height * width / originalImage.Width; 36                      } 37                      break; 38                  case "H"://指定高，宽按比例 39                      if (originalImage.Height < height) 40                      { 41                          toheight = originalImage.Height; 42                          towidth = originalImage.Width; 43                      } 44                      else 45                      { 46                          towidth = originalImage.Width * height / originalImage.Height; 47                      } 48                      break; 49                  case "Cut"://指定高宽裁减（不变形）                 50                      if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight) 51                      { 52                          oh = originalImage.Height; 53                          ow = originalImage.Height * towidth / toheight; 54                          y = 0; 55                          x = (originalImage.Width - ow) / 2; 56                      } 57                      else 58                      { 59                          ow = originalImage.Width; 60                          oh = originalImage.Width * height / towidth; 61                          x = 0; 62                          y = (originalImage.Height - oh) / 2; 63                      } 64                      break; 65                  default: 66                      break; 67              } 68   69              //新建一个bmp图片 70              System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight); 71   72              //新建一个画板 73              System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap); 74   75              //设置高质量插值法 76              g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; 77   78              //设置高质量,低速度呈现平滑程度 79              g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; 80   81              //清空画布并以透明背景色填充 82              g.Clear(System.Drawing.Color.Transparent); 83   84              //在指定位置并且按指定大小绘制原图片的指定部分 85              g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight), 86                  new System.Drawing.Rectangle(x, y, ow, oh), 87                  System.Drawing.GraphicsUnit.Pixel); 88   89              try 90              { 91                  string Path = thumbnailPath.Substring(0, thumbnailPath.LastIndexOf('\\')); 92                  if (!Directory.Exists(Path)) 93                  { 94                      Directory.CreateDirectory(Path); 95                  } 96   97                  //以jpg格式保存缩略图 98                  bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg); 99              }100              catch (System.Exception e)101              {102                  throw e;103              }104              finally105              {106                  originalImage.Dispose();107                  bitmap.Dispose();108                  g.Dispose();109              }110          }