ASP中取得图片宽度和高度的类（无组件）

sp;   
    Private Function BinVal(Bin)
        Dim Ret,I
        Ret = 0
        For I = LenB(Bin) To 1 Step -1
            Ret = Ret *256 + AscB(MidB(Bin,I,1))
        Next
        BinVal=Ret
    End Function
      
    Private Function BinVal2(Bin)
        Dim Ret,I
        Ret = 0
        For I = 1 To LenB(Bin)
            Ret = Ret *256 + AscB(MidB(Bin,I,1))
        Next
        BinVal2=Ret
    End Function
      
    Private Function GetImageSize(filespec)
        Dim bFlag
        Dim Ret(3)
        ASO.LoadFromFile(filespec)
        bFlag=ASO.Read(3)
        Select Case Hex(binVal(bFlag))
        Case "4E5089":
            ASO.Read(15)
            ret(0)="PNG"
            ret(1)=BinVal2(ASO.Read(2))
            ASO.Read(2)
            ret(2)=BinVal2(ASO.Read(2))
        Case "464947":
            ASO.read(3)
            ret(0)="gif"
            ret(1)=BinVal(ASO.Read(2))
            ret(2)=BinVal(ASO.Read(2))
        Case "535746":
            ASO.read(5)
            binData=ASO.Read(1)
            sConv=Num2Str(ascb(binData),2 ,8)
            nBits=Str2Num(left(sConv,5),2)
          &nb