ASP no component generation thumbnails (1)

Thumbnails | No components first, we know that displaying a picture in a page is the following code:

SRC is the picture path, border control the edge of the picture, width is the length of the picture, height is the picture. The production of thumbnails is actually scaled on the original size. But generally in order to minimize distortion, we will scale proportionally. Thus, getting the long and wide dimensions of a picture is the key to generating thumbnails.

The following steps are to write a component-free build thumbnail:

1. No component to get picture size

Just learned the ASP before soon saw an article using ASCII code to achieve the size of the picture without components. Later tried, found in the acquisition of JPG image size is always not correct display, check the Internet, there are many sites reproduced this program, but no one pointed out the defects of this program, but also not to solve the defects of the method. Then Google again, and finally found an introduction to the use of ADODB.stream to get picture size of the article, according to its introduction method, modify the code inside tried to try, the effect is really good, now take it out to share with you:

Using ADODB.stream to get the general class of picture size
<%
'////////////gps:get picture Size//////////////
'//////////////use ADODB.stream to get picture size//////////////
'/////////cited by Leon (Heart fine) August 11, 2005//////////

Class GPS
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)
' GPS (2005-8-11)
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)
' GPS (2005-8-11)
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)
' GPS (2002-8-11)
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)
' GPS (2002-8-11)
Dim ret
RET = 0
For i = 1 to LenB (BIN)
RET = ret *256 + ASCB (MidB (bin,i,1))
Next
Binval2=ret
End Function

'///The following is the calling code///
Function getimagesize (filespec)
' GPS (2002-8-11)
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":
Todo
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
%>
Copy the above code to generate the gps.asp file so that the generic class without component to get the picture size is OK.