[Lazarus] Scanline on certain size images seems to be failing : Access Violation...

[dominique at savagesoftwaresolutions.com]

I didn't know there was an LCL define hence why I used FPC. I'll use that
from now on.

Thanks for the heads up.


Dominique.

On Sat, 15 Aug 2009 17:33:10 +0200, Mattias Gaertner
<nc-gaertnma at netcologne.de> wrote:
> On Sat, 15 Aug 2009 09:26:59 -0400
> <dominique at savagesoftwaresolutions.com> wrote:
> 
>> Please ignore,
>>   I just realised that ScanLineImage.Free was being called before the
>> Color_RGBtoColor funcation. Which caused the AV.
>> Hence why the code works under Delphi, but was AVing with FreePascal.
> 
> Note:
> The ScanLine differences have nothing to do with FPC, but with the LCL.
> You can use:
> 
> {$IFDEF LCL}
> 
> Mattias
> 
> 
>> 
>> Dominique.
>> 
>> On Sat, 15 Aug 2009 08:28:53 -0400,
>> <dominique at savagesoftwaresolutions.com> wrote:
>> > I have the following 2 functions to determine the transparency
>> > colour of
>> a
>> > bitmap...
>> > 
>> > // Returns the transparent color for the bitmap
>> > function Bitmap24_TransparentColor(bitmap:TBitmap):TColor;
>> > var
>> >   row : PRGBArray;
>> >   {$IFDEF FPC}
>> >   ScanLineImage : TLazIntfImage;
>> >   {$ENDIF}
>> > begin
>> >   Result := clBlack;
>> > 
>> >   if not IsValidBitmap( bitmap, 'Bitmap24_TransparentColor' ) then
>> >   begin
>> >     Exit;
>> >   end;
>> > 
>> >   {$IFDEF FPC}
>> >   ScanLineImage := bitmap.CreateIntfImage;
>> >   {$ENDIF}
>> > 
>> >   {$IFDEF FPC}
>> >   row := ScanLineImage.GetDataLineStart( bitmap.Height - 1 );
>> >   {$ELSE}
>> >   row := bitmap.ScanLine[ bitmap.Height - 1 ];
>> >   {$ENDIF}
>> > 
>> >   {$IFDEF FPC}
>> >   ScanLineImage.Free;
>> >   {$ENDIF}
>> > 
>> >   Result := Color_RGBtoColor(row[0]); 
>> > end;
>> > 
>> > // Transforms a RGB color into a standard color
>> > function Color_RGBToColor(col : TRGB) : TColor;
>> > begin
>> >   Result := $10000 *  col.b + $100 * col.g + col.r; // ACCESS
>> > VIOLATION HERE if Image greater than 640x480
>> > end;
>> > 
>> > I'm getting an Access violation when passing the row[0] to the
>> RGBtoColor.
>> > Can anyone see what I might be doing wrong?
>> > The only thing I noticed is that it seems to fail when I use images
>> greater
>> > than 640x480, but I'm willing to concede it may be a bit depth
>> > issue. Smaller image sizes seem to work fine.
>> > 
>> > Would I be right in thinking that row[0] is the bottom right corner
>> > of
>> the
>> > image?
>> > 
>> > Thanks,
>> > 
>> > Dominique.
>> > 
>> > --
>> > _______________________________________________
>> > Lazarus mailing list
>> > Lazarus at lists.lazarus.freepascal.org
>> > http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
>> 
>> --
>> _______________________________________________
>> Lazarus mailing list
>> Lazarus at lists.lazarus.freepascal.org
>> http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
> 
> --
> _______________________________________________
> Lazarus mailing list
> Lazarus at lists.lazarus.freepascal.org
> http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus