Io uso questa funzione:
<%Sub AnalyzeImage(img)
Dim strURL, objXmlHTTP, strBinaryData
Dim strAsciiData, iImageWidth, iImageHeight
Dim strColors, strType
strURL = img
If (Not(BeginsWith(strURL, "http://"))) And (Not(BeginsWith(strURL, "https://"))) Then
Exit Sub
End If
Set objXmlHTTP = Server.CreateObject("Microsoft.XMLHTTP")
On Error Resume Next
objXmlHTTP.Open "GET", strURL, False
objXmlHTTP.Send
If Err.Number<>0 Then
Set objXmlHTTP=Nothing
Exit Sub
End If
On Error Goto 0
strBinaryData = objXmlHTTP.ResponseBody
Set objXmlHTTP=Nothing
strAsciiData = RSBinaryToString(strBinaryData)
If gfxSpex(strAsciiData, iImageWidth, iImageHeight, strColors, strType) = True then%>
<%End If
End Sub
Function BeginsWith(strMain, strSub)
BeginsWith = LCase(Left(strMain, Len(strSub)))=LCase(strSub)
End Function
Function RSBinaryToString(xBinary)
'Antonin Foller, http://www.motobit.com
'RSBinaryToString converts binary data (VT_UI1 | VT_ARRAY Or MultiByte string)
'to a string (BSTR) using ADO recordset
Dim Binary
Dim RS, LBinary
Const adLongVarChar = 201
'MultiByte data must be converted To VT_UI1 | VT_ARRAY first.
If vartype(xBinary)=8 Then Binary = MultiByteToBinary(xBinary) Else Binary = xBinary
Set RS = CreateObject("ADODB.Recordset")
LBinary = LenB(Binary)
If LBinary>0 Then
RS.Fields.Append "mBinary", adLongVarChar, LBinary
RS.Open
RS.AddNew
RS("mBinary").AppendChunk Binary
RS.Update
RSBinaryToString = RS("mBinary")
Else
RSBinaryToString = ""
End If
End Function
Function MultiByteToBinary(MultiByte)
'© 2000 Antonin Foller, http://www.motobit.com
' MultiByteToBinary converts multibyte string To real binary data (VT_UI1 | VT_ARRAY)
' Using recordset
Dim RS, LMultiByte, Binary
Const adLongVarBinary = 205
Set RS = CreateObject("ADODB.Recordset")
LMultiByte = LenB(MultiByte)
If LMultiByte>0 Then
RS.Fields.Append "mBinary", adLongVarBinary, LMultiByte
RS.Open
RS.AddNew
RS("mBinary").AppendChunk MultiByte & ChrB(0)
RS.Update
Binary = RS("mBinary").GetChunk(LMultiByte)
End If
MultiByteToBinary = Binary
End Function
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
'::: :::
'::: This routine will attempt to identify any filespec passed :::
'::: as a graphic file (regardless of the extension). This will :::
'::: work with BMP, GIF, JPG and PNG files. :::
'::: :::
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
'::: Based on ideas presented by David Crowell :::
'::: (credit where due) :::
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
'::: blah blah blah blah blah blah blah blah blah blah blah blah :::
'::: blah blah blah blah blah blah blah blah blah blah blah blah :::
'::: blah blah Copyright *c* MM, Mike Shaffer blah blah :::
'::: bh blah ALL RIGHTS RESERVED WORLDWIDE blah blah :::
'::: blah blah Permission is granted to use this code blah blah :::
'::: blah blah in your projects, as long as this blah blah :::
'::: blah blah copyright notice is included blah blah :::
'::: blah blah blah blah blah blah blah blah blah blah blah blah :::
'::: blah blah blah blah blah blah blah blah blah blah blah blah :::
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
'::: :::
'::: This function gets a specified number of bytes from any :::
'::: file, starting at the offset (base 1) :::
'::: :::
'::: Passed: :::
'::: flnm => Filespec of file to read :::
'::: offset => Offset at which to start reading :::
'::: bytes => How many bytes to read :::
'::: :::
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
Private Function GetBytes(flnm, offset, bytes)
Dim startPos
If offset=0 Then
startPos = 1
Else
startPos = offset
End If
if bytes = -1 then ' Get All!
GetBytes = flnm
else
GetBytes = Mid(flnm, startPos, bytes)
end if
End Function
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
'::: :::
'::: Functions to convert two bytes to a numeric value (long) :::
'::: (both little-endian and big-endian) :::
'::: :::
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
Private Function lngConvert(strTemp)
lngConvert = clng(asc(left(strTemp, 1)) + ((asc(right(strTemp, 1)) * 256)))
end function
Private Function lngConvert2(strTemp)
lngConvert2 = clng(asc(right(strTemp, 1)) + ((asc(left(strTemp, 1)) * 256)))
end function
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
'::: :::
'::: This function does most of the real work. It will attempt :::
'::: to read any file, regardless of the extension, and will :::
'::: identify if it is a graphical image. :::
'::: :::
'::: Passed: :::
'::: flnm => Filespec of file to read :::
'::: width => width of image :::
'::: height => height of image :::
'::: depth => color depth (in number of colors) :::
'::: strImageType=> type of image (e.g. GIF, BMP, etc.) :::
'::: :::
'::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::
function gfxSpex(flnm, width, height, depth, strImageType)
dim strPNG
dim strGIF
dim strBMP
dim strType
dim strBuff
dim lngSize
dim flgFound
dim strTarget
dim lngPos
dim ExitLoop
dim lngMarkerSize
strType = ""
strImageType = "(unknown)"
gfxSpex = False
strPNG = chr(137) & chr(80) & chr(78)
strGIF = "GIF"
strBMP = chr(66) & chr(77)
strType = GetBytes(flnm, 0, 3)
if strType = strGIF then ' is GIF
strImageType = "GIF"
Width = lngConvert(GetBytes(flnm, 7, 2))
Height = lngConvert(GetBytes(flnm, 9, 2))
Depth = 2 ^ ((asc(GetBytes(flnm, 11, 1)) and 7) + 1)
gfxSpex = True
elseif left(strType, 2) = strBMP then ' is BMP
strImageType = "BMP"
Width = lngConvert(GetBytes(flnm, 19, 2))
Height = lngConvert(GetBytes(flnm, 23, 2))
Depth = 2 ^ (asc(GetBytes(flnm, 29, 1)))
gfxSpex = True
elseif strType = strPNG then ' Is PNG
strImageType = "PNG"
Width = lngConvert2(GetBytes(flnm, 19, 2))
Height = lngConvert2(GetBytes(flnm, 23, 2))
Depth = getBytes(flnm, 25, 2)
select case asc(right(Depth,1))
case 0
Depth = 2 ^ (asc(left(Depth, 1)))
gfxSpex = True
case 2
Depth = 2 ^ (asc(left(Depth, 1)) * 3)
gfxSpex = True
case 3
Depth = 2 ^ (asc(left(Depth, 1))) '8
gfxSpex = True
case 4
Depth = 2 ^ (asc(left(Depth, 1)) * 2)
gfxSpex = True
case 6
Depth = 2 ^ (asc(left(Depth, 1)) * 4)
gfxSpex = True
case else
Depth = -1
end select
else
strBuff = GetBytes(flnm, 0, -1) ' Get all bytes from file
lngSize = len(strBuff)
flgFound = 0
strTarget = chr(255) & chr(216) & chr(255)
flgFound = instr(strBuff, strTarget)
if flgFound = 0 then
exit function
end if
strImageType = "JPG"
lngPos = flgFound + 2
ExitLoop = false
do while ExitLoop = False and lngPos < lngSize
do while asc(mid(strBuff, lngPos, 1)) = 255 and lngPos < lngSize
lngPos = lngPos + 1
loop
if asc(mid(strBuff, lngPos, 1)) < 192 or asc(mid(strBuff, lngPos, 1)) > 195 then
lngMarkerSize = lngConvert2(mid(strBuff, lngPos + 1, 2))
lngPos = lngPos + lngMarkerSize + 1
else
ExitLoop = True
end if
loop
if ExitLoop = False then
Width = -1
Height = -1
Depth = -1
else
Height = lngConvert2(mid(strBuff, lngPos + 4, 2))
Width = lngConvert2(mid(strBuff, lngPos + 6, 2))
Depth = 2 ^ (asc(mid(strBuff, lngPos + 8, 1)) * 8)
gfxSpex = True
end if
end if
End Function
%>
