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how to convert xml base64 string gif/jpg/png image file using vba

Posted on 2012-09-12
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Last Modified: 2012-09-16
I am not sure why this is not working?

I am using vba:

If have a base64 gif string (here's the excerpt):

R0lGODlhsAQIB/cAAAAAAI  ... <more here> ... u+I1r3rdK1/76te/Ajawgh1jQAAAOw==

I attempted to create a binary file by loading the xml above into a string: base64_string

   dim btArr() As Byte
   dim base64_string as string

   base64_string=<xml from above>
   btArr = base64_string

   Open 'image.gif" For Binary As #1
   Put #1, 1, Base64decode(btArr)
   Close #1

But when I try to see the image by opening the file, it says the image format is invalid.  

What else do I need to do to make the file a  gif file?
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Question by:kperelman
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5 Comments
 
LVL 40

Expert Comment

by:als315
ID: 38398541
Code from this page:
http://www.nonhostile.com/howto-encode-decode-base64-vb6.asp
works for me.
Sub save_gif()
Dim A As String
A = "R0lGODlhEAAOALMAAOazToeHh0tLS/7LZv/0jvb29t/f3//Ub//ge8WSLf/rhf/3kdbW1mxsbP//mf///yH5BAAAAAAALAAAAAAQAA4AAARe8L1Ekyky67QZ1hLnjM5UUde0ECwLJoExKcppV0aCcGCmTIHEIUEqjgaORCMxIC6e0CcguWw6aFjsVMkkIr7g77ZKPJjPZqIyd7sJAgVGoEGv2xsBxqNgYPj/gAwXEQA7"
Open "c:\tmp\image.gif" For Binary As #1
   Put #1, 1, DecodeBase64(A)
Close #1
End Sub


 
Private Function DecodeBase64(ByVal strData As String) As Byte()
 
    Dim objXML As MSXML2.DOMDocument
    Dim objNode As MSXML2.IXMLDOMElement
    
    ' help from MSXML
    Set objXML = New MSXML2.DOMDocument
    Set objNode = objXML.createElement("b64")
    objNode.DataType = "bin.base64"
    objNode.Text = strData
    DecodeBase64 = objNode.nodeTypedValue
    
    ' thanks, bye
    Set objNode = Nothing
    Set objXML = Nothing
 
End Function

Open in new window

You need reference to Microsoft XML library (I've used 6.0)
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Author Comment

by:kperelman
ID: 38400351
Thanks.

The function works fine.  

Is there an algorythm written in a vba function that does the same thing?
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LVL 40

Expert Comment

by:als315
ID: 38401055
You like to have structures from XML library in vba?
0
 

Author Comment

by:kperelman
ID: 38401733
For the project the algorythm is what I was looking for to endcode and decode.
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LVL 40

Accepted Solution

by:
als315 earned 2000 total points
ID: 38401971
I don't know what is Base64decode in your code, but with function from Antonin Foller's site:
http://www.motobit.com/tips/detpg_Base64/
this code also working without problems:
Dim A As String
A = "R0lGODlhEAAOALMAAOazToeHh0tLS/7LZv/0jvb29t/f3//Ub//ge8WSLf/rhf/3kdbW1mxsbP//mf///yH5BAAAAAAALAAAAAAQAA4AAARe8L1Ekyky67QZ1hLnjM5UUde0ECwLJoExKcppV0aCcGCmTIHEIUEqjgaORCMxIC6e0CcguWw6aFjsVMkkIr7g77ZKPJjPZqIyd7sJAgVGoEGv2xsBxqNgYPj/gAwXEQA7"
Open "c:\tmp\image.gif" For Binary As #1
   Put #1, 1, Base64Decode(A) ' Antonin Foller's function http://www.motobit.com/tips/detpg_Base64/
Close #1

Open in new window

And your original code also working. May be your base64 string is wrong or you've used some other function?
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