C#生成缩略图 (通用模式)

  1 用数据库保存图片的路径和文件名称，把文件保存在文件夹中.
  2 //保存在数据库中的文件路径
  3 ArrayList arrFilePath=new ArrayList();
  4 arrFilePath=myCommonMethod.UploadPic(Files,"/UpLoads/UpPicture/");
  5 //获取文件名称
  6 string fileName=arrFilePath[0].SubString(arrFilePath[0].LastIndexOf("/")+1);
  7 //源图路径（物理路径）
  8 originalImagePath=Request.PhysicalApplicationPath+"/UpLoads/UpPicture/"+fileName;
  9 //缩略图路径（物理路径）
 10 thumbnailPath     =Request.PhysicalApplicationPath+"/UpLoads/UpPicture/"+"thumb_"+fileName;
 11 //调用生成缩略图方法
 12 this.MakeThumbnail(originalImagePath,thumbnailPath,120,150, strMode out outthumbnailPath);
 13 
 14 #region  生成缩略图 
 15   ///<summary> 
 16   /// 生成缩略图 
 17   /// </summary> 
 18   /// <param name="originalImagePath">源图路径（物理路径）</param> 
 19   /// <param name="thumbnailPath">缩略图路径（物理路径）</param> 
 20   /// <param name="width">缩略图宽度</param> 
 21   /// <param name="height">缩略图高度</param> 
 22   /// <param name="mode">生成缩略图的方式</param>     
 23   public  void MakeThumbnail(string originalImagePath,  string thumbnailPath, int width, int height, string mode out string outthumbnailPath) 
 24   { 
 25    System.Drawing.Image originalImage =System.Drawing.Image.FromFile(originalImagePath); 
 26             
 27    int towidth = width; 
 28    int toheight = height; 
 29         
 30    int x = 0; 
 31    int y = 0; 
 32    int ow = originalImage.Width; 
 33    int oh = originalImage.Height;        
 34 
 35    switch (mode) 
 36    {         
 37     case "HW"://指定高宽缩放（可能变形）                 
 38      break; 
 39     case "W"://指定宽，高按比例                     
 40      toheight = originalImage.Height * width/originalImage.Width; 
 41      break; 
 42     case "H"://指定高，宽按比例 
 43      towidth = originalImage.Width * height/originalImage.Height;                     
 44      break;         
 45     case "Cut"://指定高宽裁减（不变形）                 
 46      if((double)originalImage.Width/(double)originalImage.Height > (double)towidth/(double)toheight) 
 47      { 
 48       oh = originalImage.Height; 
 49       ow = originalImage.Height*towidth/toheight; 
 50       y = 0; 
 51       x = (originalImage.Width - ow)/2; 
 52      } 
 53      else 
 54      { 
 55       ow = originalImage.Width; 
 56       oh = originalImage.Width*height/towidth; 
 57       x = 0; 
 58       y = (originalImage.Height - oh)/2; 
 59      } 
 60      break;                     
 61     default : 
 62      break; 
 63    }     
 64             
 65    //新建一个bmp图片 
 66    System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth,toheight);
 67 
 68    //新建一个画板 
 69    Graphics g = System.Drawing.Graphics.FromImage(bitmap);
 70 
 71    //设置高质量插值法 
 72    g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
 73 
 74    //设置高质量,低速度呈现平滑程度 
 75    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
 76 
 77    //清空画布并以透明背景色填充 
 78    g.Clear(Color.Transparent);        
 79 
 80    //在指定位置并且按指定大小绘制原图片的指定部分 
 81    g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight), 
 82     new Rectangle(x, y, ow,oh), 
 83     GraphicsUnit.Pixel);
 84 
 85    try 
 86    {             
 87     //以jpg格式保存缩略图 
 88     bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg); 
 89     outthumbnailPath=thumbnailPath;
 90    } 
 91    catch(System.Exception e) 
 92    { 
 93     throw e; 
 94    } 
 95    finally 
 96    { 
 97     originalImage.Dispose(); 
 98     bitmap.Dispose();                         
 99     g.Dispose(); 
100    } 
101   }