C#生成高清缩略图

 01/// <summary> 
 02   /// 为图片生成缩略图   
 03   /// </summary> 
 04   /// <param name="phyPath">原图片的路径</param> 
 05   /// <param name="width">缩略图宽</param> 
 06   /// <param name="height">缩略图高</param> 
 07   /// <returns></returns> 
 08   public System.Drawing.Image GetThumbnail(System.Drawing.Image image, int width, intheight) 
 09   { 
 10       Bitmap bmp = newBitmap(width, height); 
 11       //从Bitmap创建一个System.Drawing.Graphics 
 12       System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp); 
 13       //设置  
 14       gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; 
 15       //下面这个也设成高质量 
 16       gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; 
 17       //下面这个设成High 
 18       gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; 
 19       //把原始图像绘制成上面所设置宽高的缩小图 
 20       System.Drawing.Rectangle rectDestination = newSystem.Drawing.Rectangle(0, 0, width, height); 
 21    
 22       gr.DrawImage(image, rectDestination, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel); 
 23       returnbmp; 
 24   }

调用方法

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 01HttpPostedFile file = photoFile.PostedFile; 
 02        if(!file.ContentType.Contains("image")) 
 03        { 
 04return"照片格式不合法"; 
 05        } 
 06        stringext = Path.GetExtension(file.FileName).ToLower(); 
 07        if (ext != ".jpg" && ext != ".gif" && ext != ".png"&& ext != ".jpeg") 
 08        { 
 09return"请您上传jpg、gif、png图片"; 
 10        } 
 11        if(file.ContentLength > 5 * 1024 * 1024) 
 12        { 
 13return"请您上传512字节内的图片"; 
 14        } 
 15        stringnewName = Guid.NewGuid().ToString(); 
 16        stringtempPath = "upload/"; 
 17        stringimg = tempPath + newName + ext; 
 18        stringfilePath = Server.MapPath(img); 
 19        if(!Directory.Exists(tempPath)) 
 20        { 
 21            Directory.CreateDirectory(tempPath); 
 22        } 
 23        using(System.Drawing.Image originalImage = System.Drawing.Image.FromStream(file.InputStream)) 
 24        { 
 25            GetThumbnail(originalImage, 504, 374).Save(filePath); 
 26        }