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Date Posted: 17:28:20 11/16/01 Fri
Author: Michel
Subject: Re: BMP to Transparent PNG for IE
In reply to: Brett 's message, "Re: BMP to Transparent PNG for IE" on 05:52:33 11/16/01 Fri

Hi Brett,

At first glance I don't see anything odd.

I would replace TBitmap with TBitmapGraphic because the conversion when using
PNG.Assign(Bitmap) will be from a native DibGraphic.

If you still get the AV, could you email me simple project that I could compile
check out the problem.

Best regards,


>I am trying to do a simply image transformation on a
>bmp file and then outputing it as a png file (ideally
>transparent -- but that isn't the issue presently). I
>have the following code associated to a button click:
> Bitmap := TBitmap.Create;
> Bitmap.LoadFromFile( 'c:\BAADFOOD.bmp' );
> Transform := TImageFormatTransform.Create;
> PNG := TPNGGraphic.Create;
> PNG.NewImage(Bitmap.width, Bitmap.height,
>ifColor256, Nil, 0, 0 );
> PNG.Assign( Bitmap );
> PNG.SaveTransparent := True;
> Transform.Quantize := True;
> Transform.ImageFormat := ifColor256;
> Transform.Apply( PNG );
> PNG.TransparentColor := PNG.RGB[0,0]; { Set
>Transparency of graphic }
> DeleteFile( 'c:\ATemp.PNG' );
> If PNG.Palette.palNumEntries <> 256 Then
> Begin
> ShowMessage( IntToStr( PNG.Palette.palNumEntries
> End
> Else
> PNG.SaveToFile( 'c:\ATemp.PNG' );
> PNG.Free;
> Transform.Free;
> Bitmap.Free;
>Everytime it gives an AV on the SaveToFile method in
>TPngGraphic.SaveToStream(Stream: TStream) -->
>RgbToPaletteConverter.GetIndex(Color : TRgb) on line
> for Index := 0 to (pPalette.palNumEntries - 1) do
>as palNumEntries is invalid.
>Any offers?

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