picformat.asp

asp

<%
function checkImageFormat(checkdata)
'--return: A,B,C (A is image format; B is height pixels; C is width pixels; D is color depth)

  flag=0

'0 is not jpg/gif/png image; 1 is jpg/gif/png

'-------------------------------------------------------check jpg----------------
if flag=0 then
  tempstr=leftB(checkdata,10)
  tstr=chrb(255)&chrb(216)&chrb(255)&chrb(224)&chrb(0)&chrb(16)&chrb(74)&chrb(70)&chrb(73)&chrb(70)

  if strcomp(tempstr,tstr,0)=0 then
    msgstr01="jpg"
    lngSize = len(checkdata)
    flgFound = 0

    strTarget = chrb(255) & chrb(216) & chrb(255)
    flgFound = instrb(checkdata, strTarget)

    lngPos = flgFound + 2
    ExitLoop = false

    do while ExitLoop = False and lngPos < lngSize

      do while ascb(midb(checkdata, lngPos, 1)) = 255 and lngPos < lngSize
        lngPos = lngPos + 1
      loop

      if ascb(midb(checkdata, lngPos, 1)) < 192 or ascb(midb(checkdata, lngPos, 1)) > 195 then
        lngMarkerSize = lngConvert2(midb(checkdata, lngPos + 1, 2))
        lngPos = lngPos + lngMarkerSize + 1
      else
        ExitLoop = True
      end if

    loop

    i_Height = lngConvert2(midb(checkdata, lngPos +4, 2))
    i_Width  = lngConvert2(midb(checkdata, lngPos +6, 2))
    i_Depth  = 2 ^ (ascb(midb(checkdata, lngPos + 8, 1)) * 8)
   
    msgstr02=","& i_height & "," & i_width
    flag=2
  else
    flag=0
  end if
end if
  '--------------------------------------------------check gif--------------------------------
if flag=0 then
  tempstr=leftB(checkdata,6)
  tstr=chrb(71)&chrb(73)&chrb(70)&chrb(56)&chrb(57)&chrb(97)
  tstr2=chrb(71)&chrb(73)&chrb(70)&chrb(56)&chrb(55)&chrb(97)
  if strcomp(tempstr,tstr,0)=0 or strcomp(tempstr,tstr2)=0 then
    msgstr03="gif"

    i_width=lngConvert(midb(checkdata,7,2))
    i_height=lngConvert(midb(checkdata,9,2))
    i_Depth = 2 ^ ((ascb(midb(checkdata, 11, 1)) and 7) + 1)
    msgstr04=","& i_height & ","& i_width 

    flag=2
  else
    flag=0
  end if
end if
  '---------------------------------------------------check png------------------------------
if flag=0 then
  tempstr=leftB(checkdata,4)
  tstr=chrb(137)&chrb(80)&chrb(78)&chrb(71)
  if strcomp(tempstr,tstr,0)=0 then
    msgstr05="png"

    i_Width  = lngConvert2(midb(checkdata, 19, 2))
    i_Height = lngConvert2(midb(checkdata, 23, 2))
    i_Depth  = lngConvert(midb(checkdata, 25, 2))

    select case ascb(right(i_Depth,1))
        case 0
          i_Depth   = 2 ^ (asc(left(i_Depth, 1)))
          gfxSpex = True
        case 2
          i_Depth   = 2 ^ (asc(left(i_Depth, 1)) * 3)
          gfxSpex = True
        case 3
          i_Depth   = 2 ^ (asc(left(i_Depth, 1))) '8
          gfxSpex = True
        case 4
          i_Depth   = 2 ^ (asc(left(i_Depth, 1)) * 2)
          gfxSpex = True
        case 6
          i_Depth   = 2 ^ (asc(left(i_Depth, 1)) * 4)
          gfxSpex = True
        case else
          i_Depth   = -1
    end select
    msgstr06=","& i_height & ","& i_width

    flag=2
  else 
    flag=0
  end if
end if
if flag=0 then
  msgstr07="no image"
end if
  msgstr=msgstr01 & msgstr02 & msgstr03 & msgstr04 & msgstr05 & msgstr06 & msgstr07

  checkImageFormat=msgstr
end function


function lngConvert2(strTemp)
  str1=leftB(strTemp,1)
  str2=rightb(strTemp,1)
  lngConvert2 = clng(ascb(str2) + ((ascb(str1) * 256)))
end function

function lngConvert(strTemp)
  str1=leftB(strTemp,1)
  str2=rightb(strTemp,1)
  len1=ascb(str1)
  len2=ascb(str2)
  lngConvert = clng(ascb(str1) + ascb(str2) * 256)
end function
%>