我一直在努力寻找一种方法来获取驻留在我们服务器上的.png文件的图像宽度。我试图读取文件的前24个字节，并从字节17-20解析出宽度。我在网上找到了几个例程但没有成功。奇怪的是，似乎我得到从十六进制到十进制解码的字节21-24的高度就好了。我已经使用十六进制查看器验证了文件内容，文件很好。这是例程的主要部分：
Function ReadPNG(fichero)
Dim fso, ts, s, HW, nbytes
HW = Array("0", "0")
Set fso = CreateObject("Scripting.FileSystemObject")
Set ts = fso.OpenTextFile(Server.MapPath("\forums\attachments/" & 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 HexAt(s, n)
HexAt = Hex(AscAt(s, n))
End Function
Function HexToDec(ByVal HexVal)
Dim i, num, part
num = 0
For I = 1 to Len(HexVal)
part = Mid(StrReverse(UCase(HexVal)), I, 1)
If IsNumeric(part) Then
num = num + (CInt(part) * 16 ^ (I - 1) )
Else
num = num + ( (Asc(part) - 55) * 16^(I - 1) )
End If
Next
HexToDec = num
End Function
例如，我的文件在宽度字节（十进制384）中有十六进制“00 00 01 80” 和高度字节（十进制306）中的十六进制“00 00 01 32”
我得到了高度306但是你的宽度正在返回“0011”（十进制17）。
我完全陷入困境！我也不必使用这个例程。
谢谢， 吉姆
答案 0 :(得分：4)
这是我前一段时间看过的一篇文章，看起来它可能会简化一些事情。我没有测试过，所以让我知道你的结果。
<%
dim iWidth, iheight
sub ImgDimension(img)
dim myImg, fs
Set fs= CreateObject("Scripting.FileSystemObject")
if not fs.fileExists(img) then exit sub
set myImg = loadpicture(img)
iWidth = round(myImg.width / 26.4583)
iheight = round(myImg.height / 26.4583)
set myImg = nothing
end sub
ImgDimension(Server.MapPath("server image file"))
%>
点击此处查看帖子：http://www.haneng.com/asp-forum/ASP---Get-Image-Size_12971.html
更新：看到此方法无法在64位中运行。以下是另一种替代方法的链接：http://www.4guysfromrolla.com/webtech/050300-1.shtml
答案 1 :(得分：2)
我使用这个简单的函数来返回宽度，高度和文件大小（例如640x480 - 200KBytes）：
Function ImgDim(img)
Dim objFSO, objGF, objLP, imgWdt, imgHgt, imgSiz
img = Server.MapPath("/pictures/"& img) 'path to picture
Set objFSO= CreateObject("Scripting.FileSystemObject")
If objFSO.fileExists(img) Then
Set objGF = objFSO.GetFile(img)
imgSiz = objGF.Size
Set objGF = Nothing
Set objLP = loadpicture(img)
imgWdt = round(objLP.width / 26.4583)
imgHgt = round(objLP.height / 26.4583)
Set objLP = Nothing
Set fs = Nothing
ImgDim = imgWdt &"x"& imgHgt &" - "& imgSiz/1024 &"KBytes"
End If
End Function
工作得很漂亮，希望有所帮助。
答案 2 :(得分：0)
这是我在很久以前发现的用于获取图像信息的一组通用函数。我会按照我最后一直使用它的方式。
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::'
'::: :::'
'::: 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
我一直在使用它来为图像库生成随机XML文件。只有在我将新图像上传到库时才会运行脚本。
以下是用法:(或至少我如何使用它）
'collect the image information into an array'
Dim blnGfxSpex, width, height, colors, strType
intCount = 0
For Each objFile In objFS.GetFolder(".\images").Files
If LCase(Right(objFile.Name, 4)) = ".jpg" and intCount <= intNumOfFiles Then
blnGfxSpex = gfxSpex((".\images\" & objFile.Name), width, height, colors, strType)
arrImages(intCount) = "<image>" & vbNewLine & _
"<filename>" & objFile.Name & "</filename>" & vbNewLine & _
"<caption></caption>" & vbNewLine & _
"<width>" & width & "</width>" & vbNewLine & _
"<height>" & height & "</height>" & vbNewLine & _
"</image>" & vbNewLine
intCount = intCount + 1
End If
Next
如您所见，我正在初始化宽度，高度等变量，并且函数会根据需要设置它们。我知道使用像这样的全局变量不是犹太教，但它确实有用。
表现并不像你想象的那么糟糕。在这种特殊情况下，我将图像库过滤为JPG，但这是由于XML所针对的图像库的限制，而不是由于功能的限制。