Detect Graphic Dimensions FileSystemObject

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Detect Graphic Type/Dimensions by Daniel Gorroño

Daniel Gorroño Santurtzi [email protected]
Bizkaia - Euskal Herria

This ingenious piece of code demonstrates how to read a file using the file system object and extract bytes that contain the height and width.

<html><head>
<TITLE>dbtable.asp</TITLE>
</head>
<body bgcolor="#FFFFFF">
<%
   graphic="images/learnaspiconmain.gif"
   HW = ReadImg(graphic)
   Response.Write graphic & " Dimensions: " & HW(0) & "x" & HW(1) & "<br>"
   response.write "<img src=""/" & graphic & """"
   response.write height=""" & HW(0) & """
   response.write width=""" & HW(0) & "">"
%>
</body></html>

The library that is included is:

<%
Dim HW

Function AscAt(s, n)
       AscAt = Asc(Mid(s, n, 1))
End Function

Function HexAt(s, n)
       HexAt = Hex(AscAt(s, n))
End Function

Function isJPG(fichero)
       If inStr(uCase(fichero), ".JPG") <> 0 Then
       isJPG = true
       Else
       isJPG = false
       End If
End Function

Function isPNG(fichero)
       If inStr(uCase(fichero), ".PNG") <> 0 Then
       isPNG = true
       Else
       isPNG = false
       End If
End Function

Function isGIF(fichero)
       If inStr(uCase(fichero), ".GIF") <> 0 Then
       isGIF = true
       Else
       isGIF = false
       End If
End Function

Function isBMP(fichero)
       If inStr(uCase(fichero), ".BMP") <> 0 Then
       isBMP = true
       Else
       isBMP = false
       End If
End Function

Function isWMF(fichero)
       If inStr(uCase(fichero), ".WMF") <> 0 Then
       isWMF = true
       Else
       isWMF = false
       End If
End Function

Function isWebImg(f)
       If isGIF(f) Or isJPG(f) Or isPNG(f) Or isBMP(f) Or isWMF(f) Then
       isWebImg = true
       Else
       isWebImg = true
       End If
End Function

Function ReadImg(fichero)
       If isGIF(fichero) Then
       ReadImg = ReadGIF(fichero)
       Else
       If isJPG(fichero) Then
       ReadImg = ReadJPG(fichero)
       Else
       If isPNG(fichero) Then
       ReadImg = ReadPNG(fichero)
       Else
       If isBMP(fichero) Then
       ReadImg = ReadPNG(fichero)
       Else
       If isWMF(fichero) Then
       ReadImg = ReadWMF(fichero)
       Else
       ReadImg = Array(0,0)
       End If
       End If
       End If
       End If
       End If
End Function

Function ReadJPG(fichero)
    Dim fso, ts, s, HW, nbytes
       HW = Array("","")
       Set fso = CreateObject("Scripting.FileSystemObject")
       Set ts = fso.OpenTextFile(Server.MapPath("/" & fichero), 1)
       s = Right(ts.Read(167), 4)
       HW(0) = HexToDec(HexAt(s,3) & HexAt(s,4))
       HW(1) = HexToDec(HexAt(s,1) & HexAt(s,2))
       ts.Close
    ReadJPG = HW
End Function

Function ReadPNG(fichero)
    Dim fso, ts, s, HW, nbytes
       HW = Array("","")
       Set fso = CreateObject("Scripting.FileSystemObject")
       Set ts = fso.OpenTextFile(Server.MapPath("/" & fichero), 1)
       s = Right(ts.Read(24), 8)
       HW(0) = HexToDec(HexAt(s,3) & HexAt(s,4))
       HW(1) = HexToDec(HexAt(s,7) & HexAt(s,8))
       ts.Close
    ReadPNG = HW
End Function

Function ReadGIF(fichero)
    Dim fso, ts, s, HW, nbytes
       HW = Array("","")
       Set fso = CreateObject("Scripting.FileSystemObject")
       Set ts = fso.OpenTextFile(Server.MapPath("/" & fichero), 1)
       s = Right(ts.Read(10), 4)
       HW(0) = HexToDec(HexAt(s,2) & HexAt(s,1))
       HW(1) = HexToDec(HexAt(s,4) & HexAt(s,3))
       ts.Close
    ReadGIF = HW
End Function

Function ReadWMF(fichero)
    Dim fso, ts, s, HW, nbytes
       HW = Array("","")
       Set fso = CreateObject("Scripting.FileSystemObject")
       Set ts = fso.OpenTextFile(Server.MapPath("/" & fichero), 1)
       s = Right(ts.Read(14), 4)
       HW(0) = HexToDec(HexAt(s,2) & HexAt(s,1))
       HW(1) = HexToDec(HexAt(s,4) & HexAt(s,3))
       ts.Close
    ReadWMF = HW
End Function

Function ReadBMP(fichero)
    Dim fso, ts, s, HW, nbytes
       HW = Array("","")
       Set fso = CreateObject("Scripting.FileSystemObject")
       Set ts = fso.OpenTextFile(Server.MapPath("/" & fichero), 1)
       s = Right(ts.Read(24), 8)
       HW(0) = HexToDec(HexAt(s,4) & HexAt(s,3))
       HW(1) = HexToDec(HexAt(s,8) & HexAt(s,7))
       ts.Close
    ReadBMP = HW
End Function

Function isDigit(c)
       If inStr("0123456789", c) <> 0 Then
       isDigit = true
       Else
       isDigit = false
       End If
End Function

Function isHex(c)
       If inStr("0123456789ABCDEFabcdef", c) <> 0 Then
       isHex = true
       Else
       ishex = false
       End If
End Function

Function HexToDec(cadhex)
       Dim n, i, ch, decimal
       decimal = 0
       n = Len(cadhex)
       For i=1 To n
       ch = Mid(cadhex, i, 1)
       If isHex(ch) Then
       decimal = decimal * 16
       If isDigit(c) Then
       decimal = decimal + ch
       Else
       decimal = decimal + Asc(uCase(ch)) - Asc("A")
       End If
       Else
       HexToDec = -1
       End If
       Next
       HexToDec = decimal
End Function
%>

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