asp.net產生高品質縮圖通用函數(c#代碼) _asp.net技巧

在網站研發時,產生縮圖是個很常見和實用的功能.以前在asp裡只能藉助com組件實現,現在在.net裡能夠利用架構的強大的類庫輕鬆實現.下面帖出完整的代碼(帶周詳註釋),參考了網上的一些文章及.net sdk相關內容.QQROOM網路家園的圖片上傳用到了任何的4種產生方式.         /// <summary>         /// 產生縮圖         /// </summary>         /// <param name="originalImagePath">源圖路徑（實體路徑）</param>         /// <param name="thumbnailPath">縮圖路徑（實體路徑）</param>         /// <param name="width">縮圖寬度</param>         /// <param name="height">縮圖高度</param>         /// <param name="mode">產生縮圖的方式</param>            public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)         {             Image originalImage = Image.FromFile(originalImagePath);                         int towidth = width;             int toheight = height;                     int x = 0;             int y = 0;             int ow = originalImage.Width;             int oh = originalImage.Height;                    switch (mode)             {                        case "HW"://指定高寬縮放（可能變形）                                    break;                 case "W"://指定寬，高按比例                                        toheight = originalImage.Height * width/originalImage.Width;                     break;                 case "H"://指定高，寬按比例                     towidth = originalImage.Width * height/originalImage.Height;                                        break;                        case "Cut"://指定高寬裁減（不變形）                                    if((double)originalImage.Width/(double)originalImage.Height > (double)towidth/(double)toheight)                     {                         oh = originalImage.Height;                         ow = originalImage.Height*towidth/toheight;                         y = 0;                         x = (originalImage.Width - ow)/2;                     }                     else                     {                         ow = originalImage.Width;                         oh = originalImage.Width*height/towidth;                         x = 0;                         y = (originalImage.Height - oh)/2;                     }                     break;                                    default :                     break;             }                            //建立一個bmp圖片             Image bitmap = new System.Drawing.Bitmap(towidth,toheight);             //建立一個畫板             Graphics g = System.Drawing.Graphics.FromImage(bitmap);             //配置高品質插值法             g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;             //配置高品質,低速度呈現平滑程度             g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;             //清空畫布並以透明背景色填充             g.Clear(Color.Transparent);                    //在指定位置並且按指定大小繪製原圖片的指定部分             g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),                 new Rectangle(x, y, ow,oh),                 GraphicsUnit.Pixel);             try             {                            //以jpg格式儲存縮圖                 bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);             }             catch(System.Exception e)             {                 throw e;             }             finally             {                 originalImage.Dispose();                 bitmap.Dispose();                                        g.Dispose();             }         } 關鍵方法Graphics.DrawImage見ms-help://MS.NETFrameworkSDKv1.1.CHS/cpref/html/frlrfsystemdrawinggraphicsclassdrawimagetopic11.htm http://www.cnblogs.com/jialine/archive/2006/09/15/505459.html