Re: GdkPixbuf pixel data weirdness



Thanks Evan!

It was a rowstride problem. I did not realise that the width of each row was not equal to the number of pixels * 3 (in 8bpp mode) or 4 if an alpha channel was added.

Why is this? What are the padding pixels used for at the end of each row? - is it so that the start of the next row is word aligned? I could not find anything in the docs apart from the gdk_pixbuf_get_rowstride() function call, which simply defines rowstride without an explanation.

Best regards,

Chris.




From: Evan Martin <martine cs washington edu>
To: Chris Garrett <garrett91 hotmail com>
CC: gtk-app-devel-list gnome org
Subject: Re: GdkPixbuf pixel data weirdness
Date: Sun, 9 Mar 2003 19:04:43 -0800

On Sun, Mar 09, 2003 at 09:31:38PM +0000, Chris Garrett wrote:
> I changed the size of the pixbuf and things went pearshaped.  When the
> width of the pixbuf is a multiple of 4, it works (20, 24, 28...). With any
> other width, its as though I have offset the data somehow - the pixbuf
> appears striped and the border comes in diagonally.

Looks like a rowstride problem.  Look for "rowstride" in the docs.

--
      Evan Martin
martine cs washington edu
  http://neugierig.org
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