.net2.0 生成缩略图，与指定比例不等自动补白边的方法

//int_Height int_Width 指定高度和指定宽度 input_Imgfile,out_ImgFile为原图片和缩小后图片的路径。 
public static void Thumbnail (int int_Width, int int_Height, string input_ImgFile, string out_ImgFile)    
        {    
   
            System.Drawing.Image oldimage = System.Drawing.Image.FromFile(input_ImgFile);    
            float New_Width; // 新的宽度    
            float New_Height; // 新的高度    
            float Old_Width,Old_Height; //原始高宽    
            int flat = 0;//标记图片是不是等比    
               
   
            int xPoint = 0;//若果要补白边的话，原图像所在的x，y坐标。    
            int yPoint=0;    
            //判断图片    
   
            Old_Width = (float)oldimage.Width;    
            Old_Height = (float)oldimage.Height;    
   
            if ((Old_Width / Old_Height) > ((float)int_Width / (float)int_Height)) //当图片太宽的时候    
            {    
                New_Height = Old_Height * ((float)int_Width / (float)Old_Width);    
                New_Width = (float)int_Width;    
                 //此时x坐标不用修改    
                yPoint = (int)(((float)int_Height - New_Height) / 2);    
                flat = 1;    
            }    
            else if ((oldimage.Width / oldimage.Height) == ((float)int_Width / (float)int_Height))    
            {    
                New_Width = int_Width;    
                New_Height = int_Height;    
            }    
            else   
            {    
                New_Width = (int)oldimage.Width * ((float)int_Height / (float)oldimage.Height);  //太高的时候   
                New_Height = int_Height;    
                //此时y坐标不用修改    
                xPoint = (int)(((float)int_Width - New_Width) / 2);    
                flat = 1;    
            }    
                
   
                       // ＝＝＝缩小图片＝＝＝    
            System.Drawing.Image thumbnailImage = oldimage.GetThumbnailImage((int)New_Width, (int)New_Height, new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback), IntPtr.Zero);    
            Bitmap bm = new Bitmap(thumbnailImage);    
   
                       if (flat != 0)    
            {    
                Bitmap bmOutput = new Bitmap(int_Width,int_Height);    
                Graphics gc = Graphics.FromImage(bmOutput);    
                SolidBrush tbBg = new SolidBrush(Color.White);    
                gc.FillRectangle(tbBg,0, 0, int_Width, int_Height); //填充为白色    
   
  
                gc.DrawImage(bm,xPoint, yPoint, (int)New_Width, (int)New_Height);    
                bmOutput.Save(out_ImgFile);    
            }    
            else   
            {    
                bm.Save(out_ImgFile);    
            }    
   
        }