Hi again all
Based on everyone's advice, I chose to go with base64 encoding - and
started coding.
Right now I am quite successfully:
1) Reading the image
2) Encoding it to base64 (using the encodeb64 function from the examples)
3) Storing the result in the database (I THINK it's storing right)
Later I then select it, run it through decodeb64 (my own function
based on the above, code below) and then save this string to a file -
a file that has the right extension (the reason for this is actually
good - remote DB access, and I want to cache the images and only
download if they changed)
Finally - a simple TImage.Picture.LoadFromFile is meant to handle the
last bit... only it doesn't - somewhere along the way my data is
corrupted - the files being dumped differ from the orriginals - yet
oddly they are the exact same size.
I know we're not supposed to include attachments on the list, so for
now I didn't but if I may, I would like to add (assuming anybody says
it would be usefull:
1) An orriginal image
2) A post database process filedump of the same image
3) The (apparently) base64 encoded database entry for said image
I can say that I tested my b64encode/b64decode functions with a simple
program that lets me enter string, encodes it, writes that, decodes
THAT and writes it back (which should match the orriginal input) -
that at least seems to work fine.
Any idea where the corruption is coming from ? All help, as always,
greatly appreciated.
Relevant code snippets:
Function DecodeB64(S : String) : String;
Procedure doNothing;
Begin
end;
var
b64decoder: TBase64DecodingStream;
S1 : TSTringStream;
S2 : String;
InputStream: TStream;
IsEnd: Boolean;
begin
S1 := TStringStream.Create(S);
S2 := '';
b64decoder := TBase64DecodingStream.Create(S1);
While not B64Decoder.EOF do
Begin
try
S2 := S2+(CHR(B64Decoder.ReadByte));
except
doNothing;
end;
end;
Result := S2;
b64decoder.Free;
end;
Image Saving:
Procedure SaveBTNClick(Sender:TObject); //Snipped
Var B64 : String;
S :TStringList;
Begin
S := TStringList.Create;
S.LoadFromFile(ImgFileName);
B64 := EncodeB64(S.Text);
Ad.SaveData(add_desc.text,b64);
end;
Procedure TZC_Advertising.SaveData(Description,Data:String);
Var Q : String;
Begin
Q := 'UPDATE advertising SET data='+QS(Data)+'
timestamp='+QS('NOW')+' WHERE description = '+QS(Description)+' ;';
FResult := ZC_DBQuery(Q);
//Notes: FResult is a PPGResult, ZC_DBQuery is a very well tested
wrapper function
//QS = QuoteString - it wraps the input in ''
end;
Image Loading:
Function TZC_Advertising.GetData(Description:String):String;
Var
S : String;
Begin
FResult := ZC_DBQuery('SELECT data FROM advertising WHERE description
= '+QS(Description)+';');
If PqNTuples(Fresult) >= 0 then
begin
S := PQGetValue(FResult,0,0);
GetData:=DecodeB64(S);
end else
GetData := '';
end;
//In the app:
IName := GetTempDir+Ad.GetTimeStamp(add_desc.text)+Ad.GetExt(add_desc.text);
Data := TStringList.Create;
Data.Add(Ad.GetData(add_desc.text));
Data.SaveToFile(Iname);
ad_Img.Picture.LoadFromFile(Iname);
Data.Free;
--
A.J. Venter
CEO - OutKast Solutions C.C.
http://www.outkastsolutions.co.za
Cell: +27 83 455 9978
Fax: +27 21 413 2800
Office: +27 21 591 6766
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