求助，img显示图像限制问题？

<img alt="缩略图" id="Img1" src="" style="cursor: move;" onload="showImage()"/>


 <script language="javascript" type="text/javascript">
        function showImage()
        {
            var Wmax=document.body.scrollWidth;
            var ImgD=document.getElementById("Img1");
            ImgD.src="<%=ScaleGrid_Load()%>";
            if(typeof(ImgD)== "object")
            {   //判断ImgD装载过后是否为对象，防止异常操作
                var   widthL=0;
                var   heightL=0;
                var   W=ImgD.width;
                var   H=ImgD.height;
                if(W>Wmax)
                {
                    widthL=Wmax;
                    heightL=(H+20)/((W+20)/Wmax); //+20是因为IE方式的默认边距
                }
                else
                {
                    return ;
                }
                if(widthL!=0&&heightL!=0)
                {
                    ImgD.style.width=widthL+"px";
                    ImgD.style.height=heightL+"px";
                }
                else
                {
                    setTimeout( "showImage()", 100);   //   判断图片是否装载完成，只有在装载完成后才能取到宽高值
                }
            }
            else
            {
                return; //alert( "系统错误 ");
            }
        }
</script>

现在有几种方法实现
1> Image imge = Image.FromFile(file.FullName);
  this.imageList1.Images.Add(imge.GetThumbnailImage(32,32,null,IntPtr.Zero))
  item.ImageIndex = this.imageList1.Images.Count - 1;
2>public Image MakeThumbnail(string originalImagePath, int width, int height, string mode)
  {
  System.Drawing.Image originalImage = System.Drawing.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"://指定高宽缩放（可能变形）  
  break;
  case "W"://指定宽，高按比例  
  toheight = originalImage.Height * width / originalImage.Width;
  break;
  case "H"://指定高，宽按比例
  towidth = originalImage.Width * height / originalImage.Height;
  break;
  case "Cut"://指定高宽裁减（不变形）  
  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;
  }

  //新建一个bmp图片
  System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

  //新建一个画板
  System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);

  //设置高质量插值法
  g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

  //设置高质量,低速度呈现平滑程度
  g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

  //清空画布并以透明背景色填充
  g.Clear(System.Drawing.Color.Transparent);

  //在指定位置并且按指定大小绘制原图片的指定部分
  g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight),
  new System.Drawing.Rectangle(x, y, ow, oh),
  System.Drawing.GraphicsUnit.Pixel);

  try
  {
  return (Image)bitmap.Clone();
  }
  catch (System.Exception e)
  {
  throw e;
  }
  finally
  {
  originalImage.Dispose();
  bitmap.Dispose();
  g.Dispose();
  }
  }
3> [DllImport("gdi32.dll", EntryPoint = "FindWindow")]
  private static extern GpStatus GdiplusStartup(long token, string lpWindowName, GdiplusStartupInput inputbuf, ref long outputbuf);


  [DllImport("gdi32.dll", EntryPoint = "FindWindow")]
  private static extern GpStatus GdiplusShutdown(long token);

  [DllImport("gdi32.dll", EntryPoint = "FindWindow")]
  private static extern GpStatus GdipDrawImageRect(long graphics, long image, int X, int Y, int Width, int Height);



  [DllImport("gdi32.dll", EntryPoint = "FindWindow")]
  private static extern GpStatus GdipCreateFromHDC(long hDC, long graphics);

  [DllImport("gdi32.dll", EntryPoint = "FindWindow")]
  private static extern GpStatus GdipDeleteGraphics(long graphics);


  [DllImport("gdi32.dll", EntryPoint = "FindWindow")]
  private static extern GpStatus GdipLoadImageFromFile(string filename, long image);

  [DllImport("gdi32.dll", EntryPoint = "FindWindow")]

1、在aspx文件加上aspcompat=true
<%@ Page language="c#" Codebehind="AddProduct.aspx.cs" AutoEventWireup="false" Inherits="Techsun.XYD.AdminOfXYD.AddProduct" aspcompat=true%>
2、在vs里引用com组件wsImage.dll
3、生成缩略图
wsImage.Resize obj = (wsImage.Resize)Server.CreateObject("wsImage.Resize");

string FilePath = Server.MapPath("25.jpg");
string strOutputPic = Server.MapPath("25_s.jpg");
int w = 125;
int h = 125;
int lngType = 0;

obj.LoadSoucePic(FilePath);
obj.Quality = 100;
obj.OutputSpic(strOutputPic,w,h,lngType);
obj.Free();