Adodb.Stream取得图像的高宽

上传图片或显示SWF的时候都希望得到它的高度和宽度

基本原理使用Adodb.Stream读二进制文件然后进行解析，然后返回一数组
第一个元素为类型(BMP JPG PNG GIF SWF)
第二个元素为宽度{width}
第三个元素为高度{height}
第四个元素为width={width},height={height}式字符串

Class qswhImg
 dim aso
 Private Sub Class_Initialize
  set aso=CreateObject("Adodb.Stream")
  aso.Mode=3
  aso.Type=1
  aso.Open
 End Sub
 Private Sub Class_Terminate
  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)
  'qiushuiwuhen (2002-8-12)
  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)
  'qiushuiwuhen (2002-8-12)
  dim ret
  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)
  'qiushuiwuhen (2002-8-12)
  dim ret
  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)
  'qiushuiwuhen (2002-8-12)
  dim ret
  ret = 0
  for i = 1 to lenb(bin)
   ret = ret *256 + ascb(midb(bin,i,1))
  next
  BinVal2=ret
 End Function
 
 Function getImageSize(filespec) 
  'qiushuiwuhen (2002-9-3)
  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=sConv&Num2Str(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
    aso.Read(15)
    ret(0)="BMP"
    ret(1)=binval(aso.Read(4))
    ret(2)=binval(aso.Read(4))
   else
    ret(0)=""
   end if
  end select
  ret(3)="width=""" & ret(1) &""" height=""" & ret(2) &""""
  getimagesize=ret
 End Function
End Class

使用范例（读某目录下所有图片的宽度）：
 set qswh=new qswhImg

 Set fso = CreateObject("Scripting.FileSystemObject")
 Set f = fso.GetFolder(server.mappath("."))
 Set fc = f.Files
 For Each f1 in fc
  ext=fso.GetExtensionName(f1.path)
  select case ext
  case "gif","bmp","jpg","png":
   arr=qswh.getImageSize(f1.path)
   response.write "
" & arr(0) & " " & arr(3) & ":" & f1.name & " width:" & arr(1) & " height:" & arr(2)
  case "swf"
   arr=qswh.getimagesize(f1.path)
   response.write "
" & arr(0) & " " & arr(3) & ":" & f1.name & " width:" & arr(1) & " height:" & arr(2)
  end select
  
 Next
 Set fc=nothing
 Set f=nothing
 Set fso=nothing
 Set qswh=nothing