[DUG] XML data to image problem

[Jolyon Smith]

Create a test case that you know should work... i.e. take a known jpeg file,
encode as base 64, embed in an XML and run it thru your code.

If you don't get a valid JPEG file at the end, then you know the code has a
problem - fix it so that you do get a valid JPEG then run it on your real
case again.

If you still don't get a valid JPEG file from your real data then you at
least now know the code is sound and therefore that one or both of your
assumptions about the data is wrong.  Either it isn't a JPEG or it isn't
base64 encoded or it's neither base64 nor a JPEG.


In any event, assumptions are *always* dangerous, but I'm guessing you knew
that already.  :)



-----Original Message-----
From: delphi-bounces at delphi.org.nz [mailto:delphi-bounces at delphi.org.nz] On
Behalf Of Robert Martin
Sent: Thursday, 21 April 2011 10:40
To: NZ Borland Developers Group - Delphi List
Subject: [DUG] XML data to image problem

Hi

I am getting image data from an XML file.  The author has not provided 
information as to encoding or file type but I am assuming base64 and 
Jpg.  I have the following code which does produce a file but it appears 
corrupt.

                 if (aNode <> nil)
                         and (ANode.NodeValue <> Null) then begin
                     //Save file
                     FileName := TempDir + 'Preview.jpg';
                     DeleteFile(FileName);

                     FileStream := TFileStream.Create(FileName, fmCreate);
                     try
                         //Assume node is Base64 encoded binary data
                         base64Decoder := TIdDecoderMIME.Create(Self);
                         try
                             ImageData := 
base64Decoder.DecodeString(ANode.NodeValue)
                         finally
                             base64Decoder.Free;
                         end;

                         FileStream.Position := 0;
                         FileStream.Write(Pointer(ImageData)^, 
Length(ImageData));

                     finally
                         FileStream.Free;
                     end;
                 end


I have tried changing the file extension but it does not open.  I have 
also tried no base 64 decode but that also fails to produce a valid 
file.  Can anyone see anything obviously wrong before I go back to the 
source for further information (they are in the UK so its a day turn 
around AND they are really unhelpful).

Thanks
Rob
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