如何编制纯asp程序读写图形文件的尺寸大小

作者：整理

<%
‘’:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
‘’::: :::
‘’::: 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 :::
‘’::: blah 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 :::
‘’::: :::
‘’:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
function GetBytes(flnm, offset, bytes)

Dim objFSO
Dim objFTemp
Dim objTextStream
Dim lngSize

on error resume next

Set objFSO = CreateObject("Scripting.FileSystemObject")

‘’ First, we get the filesize
Set objFTemp = objFSO.GetFile(flnm)
lngSize = objFTemp.Size
set objFTemp = nothing

fsoForReading = 1
Set objTextStream = objFSO.OpenTextFile(flnm, fsoForReading)

if offset > 0 then
strBuff = objTextStream.Read(offset - 1)
end if

if bytes = -1 then ‘’ Get All!

GetBytes = objTextStream.Read(lngSize) ‘’ReadAll

else

GetBytes = objTextStream.Read(bytes)

end if

objTextStream.Close
set objTextStream = nothing
set objFSO = nothing

end function

‘’:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
‘’::: :::
‘’::: Functions to convert two bytes to a numeric value (long) :::
‘’::: (both little-endian and big-endian) :::
‘’::: :::
‘’:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
function lngConvert(strTemp)
lngConvert = clng(asc(left(strTemp, 1)) + ((asc(right(strTemp, 1)) *
256)))
end function

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
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

‘’:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
‘’::: Test Harness :::
‘’:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

‘’ To test, we‘’ll just try to show all files with a .GIF extension in
the root of C:

Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objF = objFSO.GetFolder("c:\")
Set objFC = objF.Files

response.write "<table border=""0"" cellpadding=""5"">"

For Each f1 in objFC
if instr(ucase(f1.Name), ".GIF") then
response.write "<tr><td>" & f1.name & "</td><td>" & f1.DateCreated
& "</td><td>" & f1.Size & "</td><td>"

if gfxSpex(f1.name, w, h, c, strType) = true then
response.write w & " x " & h & " " & c & " colors"
else
response.write " "
end if

response.write "</td></tr>"

end if

Next

response.write "</table>"

set objFC = nothing
set objF = nothing
set objFSO = nothing

%>

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