nanogui: GrDrawImageToFit fail with PNG image with alpha layer
Subject:
Re: GrDrawImageToFit fail with PNG image with alpha layer
From:
"Aaron J. Grier" ####@####.####
Date:
3 Jun 2010 17:39:39 -0000
Message-Id: <20100603173922.GO1020@arwen.poofy.goof.com>
On Thu, Jun 03, 2010 at 03:00:57PM +0200, Daniel Nyström wrote:
> This:
>
> > GrDrawImageToFit(GrNewPixmap(640, 480, NULL),
> > myGC, 0, 0, 640, 480,
> > GrLoadImageFromFile("/path/to/png_with_alpha_channel.png", 0));
>
> fails with the following error:
>
> > nano-X: /path/to/microwin/src/drivers/fblin24.c: 35: linear24_drawpixel: Assertion `c < psd->ncolors' failed.
>
> The function is defined like this:
>
> > /* Set pixel at x, y, to pixelval c*/
> > static void linear24_drawpixel(PSD psd, MWCOORD x, MWCOORD y, MWPIXELVAL c)
>
> and the assertion looks like:
>
> > assert (c < psd->ncolors);
>
> It seems like the PNG buffer is read as 32 bit values, but the
> function quickly thereafter turn the pixelval into r, g and b:
>
> > r = PIXEL888RED(c);
> > g = PIXEL888GREEN(c);
> > b = PIXEL888BLUE(c);
>
> And the pure 'c' is never used again. How about just remove that
> assertion? What would then fail? What would else be a way to get
> fblin24 handle png's with alpha chan?
the assertion is incorrect for non-palettized video modes. I would just
remove the asserts, or change it to
assert(psd->pixtype != MWPF_PALETTE || c < psd->ncolors)
--
Aaron J. Grier | "Not your ordinary poofy goof." | ####@####.####
