[Lazarus] TPicture.LoadFromStream error

[Mattias Gaertner]

On Fri, 5 Nov 2010 12:43:42 -0300
Leonardo M. Ramé <l.rame at griensu.com> wrote:

> On 2010-11-05 12:39:28 -0300, Leonardo M. Ramé wrote:
> > On 2010-11-05 11:46:01 -0300, Leonardo M. Ramé wrote:
> > > Hi, I'm loading PGM files to an TImage.Picture using its LoadFromFile or LoadFromStream methods.
> > > 
> > > This works well on small to medium sized images, but I'm getting an
> > > "EReadErrorEReadError" exception if I try to load images of 16mb or more.
> > > 
> > > Does anyone knows how can I workaround this?.
> > > 
> > > -- 
> > > Leonardo M. Ramé
> > > http://leonardorame.blogspot.com
> > > 
> > > --
> > 
> > The problem is in fpreadpnm.pp (fpc/packages/fcl-image), in the method:
> > 
> > procedure TFPReaderPNM.InternalRead(Stream:TStream;Img:TFPCustomImage);
> > var
> >   Row:Integer;
> >   l: Integer;
> > begin
> >   ReadHeader(Stream);
> >   Img.SetSize(FWidth,FHeight);
> >   FScanLineSize:=FBitPP*((FWidth+7)shr 3);
> >   GetMem(FScanLine,FScanLineSize);
> >   try
> >     for Row:=0 to img.Height-1 do
> >       begin
> >       ReadScanLine(Row,Stream);
> >       WriteScanLine(Row,Img);
> >       end;
> >   finally
> >     Row := l;
> >     FreeMem(FScanLine);
> >   end;
> > end;  
> > 
> > The ReadScanLine method uses the FScanLineSize to read from a Stream
> > using Stream.ReadBuffer with a size of FScanLineSize, and it seems like
> > in my image, in a specific row (4734 to be clear) it has a different line size than the
> > expected by FScanLineSize.
> > 
> > Maybe the formula used to calculate the scan line size is wrong?.
> > 
> > I can open my image with many viewers like Eye of Gnome, or Gimp without
> > problems.
> > 
> 
> I attached the problematic image here:
> http://www.tarjeta-salud.com.ar/downloads/salida.pgm

Can you create a bug report with a small example program and this
image attached?

Mattias