ASP中取得图片宽度和高度的类

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Class ImgWHInfo 获取图片宽度和高度的类，支持JPG，GIF，PNG，BMP
Dim ASO
Private Sub Class_Initialize
Set ASO=Server.CreateObject(ADODB.Stream)
ASO.Mode=3
ASO.Type=1
ASO.Open
End Sub
Private Sub Class_Terminate
Err.Clear
Set ASO=Nothing
End Sub

Private Function Bin2Str(Bin)
Dim I, Str
For I=1 To LenB(Bin)
clow=MidB(Bin,I,1)
If ASCB(clow)<128 Then
Str = Str Chr(ASCB(clow))
Else
I=I+1
If I <= LenB(Bin) Then Str = Str Chr(ASCW(MidB(Bin,I,1)clow))
End If
Next
Bin2Str = Str
End Function

Private Function Num2Str(Num,Base,Lens)
Dim Ret
Ret =
While(Num>=Base)
Ret = (Num Mod Base) Ret
Num = (Num - Num Mod Base)/Base
Wend
Num2Str = Right(String(Lens,0) Num Ret,Lens)
End Function

Private Function Str2Num(Str,Base)
Dim Ret,I
Ret = 0
For I=1 To Len(Str)
Ret = Ret *base + Cint(Mid(Str,I,1))
Next
Str2Num=Ret
End Function

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)
sConv=mid(sConv,6)
While(len(sConv)<nBits*4)
binData=ASO.Read(1)
sConv=sConvNum2Str(AscB(binData),2 ,8)
Wend
ret(0)=SWF
ret(1)=Int(Abs(Str2Num(Mid(sConv,1*nBits+1,nBits),2)-Str2Num(Mid(sConv,0*nBits+1,nBits),2))/20)
ret(2)=Int(Abs(Str2Num(Mid(sConv,3*nBits+1,nBits),2)-Str2Num(Mid(sConv,2*nBits+1,nBits),2))/20)
Case FFD8FF:
Do
Do: p1=binVal(ASO.Read(1)): Loop While p1=255 And Not ASO.EOS
If p1>191 And p1<196 Then Exit Do Else ASO.read(binval2(ASO.Read(2))-2)
Do:p1=binVal(ASO.Read(1)):Loop While p1<255 And Not ASO.EOS
Loop While True
ASO.Read(3)
ret(0)=JPG
ret(2)=binval2(ASO.Read(2))
ret(1)=binval2(ASO.Read(2))
Case Else:
If left(Bin2Str(bFlag),2)=BM Then
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