[Lazarus] TDBImage -AV [SOLVED] for Jpeg images

[Joost van der Sluis]

Your solution only works if you know for sure that the field contains a
jpeg-image. The lazarus-code assumes that the blob-fields start with the
extension from the image, so that it can 'detect' what kind of image it
is.
That means offcourse, that you also have to use a TDBEdit to place the
image into the database. Or else the leading extension won't be there.

But I think I saw something else which is strange.

btw: maybe you could send a patch (diff -u) next time, that's easier to
read for people who are used to it. This is kind of a puzzle, althoug
maneagable.

Op woensdag 03-09-2008 om 14:56 uur [tijdzone -0300], schreef Osvaldo
Filho:
> The problem, perhaps, is in s.readstring. 
> =================================
> //dbimage.inc line 135
> 
> procedure TDBImage.LoadPicture;
> var //s        : TMemory; // ( lazarus team)
>     s        : TMemoryStream; // ( mine )
>     GraphExt : string;
>     gc       : TGraphicClass;
>     AGraphic : TGraphic;
> 
> begin
>   if not FPictureLoaded then
>     begin
>     FUpdatingRecord := True;
>     if not assigned(FDatalink.Field) then
> Picture.Assign(FDatalink.Field)
>     else
>     if FDatalink.field.IsBlob then
>       begin
>       if FDatalink.field is TBlobField then
>         begin
>         if FDatalink.Field.IsNull then
>           begin
>           Picture.Clear;
>           exit;
>           end;
>     //FDataLink.DataSet.CreateBlobStream(FDataLink.Field,bmRead); //
> (lazarus team)

I guess this should be S:=FDatalink.Dataset.CreateBlobstream.....etc
Maybe you also have to add the s.position := 0?

>     s := TMemoryStream.create; // ( mine )
>         (FDataLink.Field as TBlobField).SaveToStream(s); // ( mine )
>         s.Position:= 0; // ( mine )
> 
>         if (S=Nil) or (s.Size = 0) then
>           begin
>           Picture.Clear;
>           exit;
>           end;
>         try
>           //GraphExt :=  s.ReadAnsiString; // (lazarus team)

Add 'gc := nil; AGraphic := nil;' here, as mentioned by someone else.

>           // gc := GetGraphicClassForFileExtension(GraphExt); //
> (lazarus team)
>           //  if assigned(gc) then  // (lazarus team)
>           //  begin   // (lazarus team)
>           
>       Picture.Jpeg.LoadFromStream(s); // ( mine )
>       
>       //AGraphic. := gc.Create;  // (lazarus team)
>       //AGraphic.LoadFromStream(s);  // (lazarus team)
>       //Picture.Assign(AGraphic);
>             //end;
>         finally
>           //if assigned(AGraphic) then AGraphic.Free;  // (lazarus
> team)
>           s.Free;
>         end {try}
> 
>         end
>       else
>         Picture.Assign(FDataLink.FField);        
>       end;
>     FUpdatingRecord := False;
>     end;
> end;          
> =================================
> 
> 2008/9/2 Osvaldo TCF - Listas <arquivostcf at gmail.com>
>         With my image: a .jpg file
>         ---------------------------
>         in dbimage.inc, line 163:
>                try
>                  GraphExt := s.ReadAnsiString;
>         
>                  gc := GetGraphicClassForFileExtension(GraphExt);
>                  if assigned(gc) then
>                    begin
>                    AGraphic := gc.Create;
>                    AGraphic.LoadFromStream(s);
>         
>                    Picture.Assign(AGraphic);
>                    end;
>         -------------------------------------------
>         
>         gc is not assigned, is it correct?
>         ==========================================================
>         
>         The AV ocour here:
>         dbimage.inc line 175
>         ----------------------
>                    Picture.Assign(AGraphic);
>                    end;
>                finally
>         line 175>>  if assigned(AGraphic) then AGraphic.Free;
>                  s.Free;
>                end {try}
>         ----------------------
>         
>         Em Ter, 2008-09-02 às 10:34 +0200, Joost van der Sluis
>         escreveu:
>         
>         
>         > Op maandag 01-09-2008 om 12:05 uur [tijdzone -0300], schreef
>         Osvaldo
>         > Filho:
>         > > I can not use tdbimage, access violation!
>         > >
>         > > loadpicture error?
>         >
>         > Hmm... I had that working with a few hacks. Maybe that it
>         doesn't work
>         > anymore with the latest image changes in Lazarus-svn. So
>         which fpc and
>         > lazarus version are you using?
>         >
>         > Joost
>         >
>         >
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>         
>         
> 
> 
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