ASP.NET中產生圖片以及檢測圖片大小的兩個函數

/// <summary>
  /// 產生縮圖
  /// </summary>
  /// <param name="strSourceFileName">源檔案</param>
  /// <param name="strDesFileName">縮圖檔案</param>
  /// <param name="intWidth">縮圖寬度</param>
  /// <param name="intHeight">縮圖高度</param>
        /// <param name="isScale">是否保證長寬比</param>
        public static void MiniImage(string strSourceFileName, string strDesFileName, int intWidth, int intHeight, bool isScale)
  {
//   int intWidth = 95;
//   int intHeight = 80;
            if(isScale)
            {
                Bitmap bp = new Bitmap(strSourceFileName);
                double douWidth = (double)bp.Width / intWidth;
                double douHeight = (double)bp.Height / intHeight;

                if ((douWidth) > (douHeight))
                {
                    //以Width為標準
                    intHeight = intWidth * bp.Height / bp.Width;
                }
                else
                {
                    //以Height為標準
                    intWidth = intHeight * bp.Width / bp.Height;
                }
            }
   
   Bitmap bpDes = new Bitmap (intWidth,intHeight);
   Bitmap bpSource = new Bitmap (strSourceFileName);

   Graphics myGraphics = Graphics.FromImage (bpDes);

   // ------- 高品質圖片

   myGraphics.InterpolationMode = InterpolationMode.High;
   myGraphics.SmoothingMode = SmoothingMode.HighQuality;

   myGraphics.DrawImage (bpSource, 0,0,intWidth,intHeight);
   bpDes.Save (strDesFileName, ImageFormat.Jpeg);
   bpDes.Dispose ();
   bpSource.Dispose ();

  }

  
  /// <summary>
  ///  驗證圖片大小
  /// </summary>
  /// <param name="strFileName">圖片源檔案</param>
  /// <param name="intWidth"></param>
  /// <param name="intHeight"></param>
  /// <returns></returns>
  public static  bool CheckImageSize (string strFileName,int intWidth,int intHeight)
  {
   
   Bitmap bp = new Bitmap (strFileName);
   if (bp.Height == intHeight && bp.Width == intWidth)
   {
    bp.Dispose ();
    return true;
   }
   else
   {
    bp.Dispose ();
    return false;
   }
  } 

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以下是從另外一個Blog裡面轉載過來的。

在網站開發時,產生縮圖是一個非常常見和實用的功能.以前在asp裡只能藉助com組件實現,現在在.net裡可以利用架構的強大的類庫輕鬆實現.下面帖出完整的代碼(帶詳細注釋),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所有的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);

            //設定高品質插值法
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            //設定高品質,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