Re: [pygame] [BUG] SRCALPHA - unexpected behaviour.

["René Dudfield" <renesd@xxxxxxxxx>]

oh yeah...

I should have put:

import pygame
surf = pygame.Surface((100, 100), pygame.SRCALPHA)
flags = surf.get_flags()
depth = surf.get_bitsize()
if depth == 32:
    assert(flags & pygame.SRCALPHA == pygame.SRCALPHA)
else:
    print "surface default is not 32bit"


On 8/18/07, Lenard Lindstrom <len-l@xxxxxxxxx> wrote:
> Actually in this case the surface depth should be a required argument.
> The surface depth is not guaranteed to be 32 bits. My display is set at
> 24 bits, and so that is the default depth for any new surface on my
> machine. If you want per-pixel alpha then is must be explicitly specified.
>
>
> René Dudfield wrote:
> > After a chat on irc today, this unexpected behaviour popped up again.
> > It's bit me a few times, as well as people in irc.
> >
> >
> > import pygame
> > surf = pygame.Surface((100, 100), pygame.SRCALPHA)
> > flags = surf.get_flags()
> > depth = surf.get_bitsize()
> > assert(depth == 32)
> > assert(flags & pygame.SRCALPHA == pygame.SRCALPHA)
> >
> > You would expect that surface to have the SRCALPHA flag if the surface
> > was 32bit right?
> >
> > It doesn't at the moment.  But is there a good reason why it does not?
> >
> > I can understand that if the surface returned was 16bit, or 8bit that
> > the SRCALPHA flag is not set.  However if it's 32bit, then I think it
> > probably should be set.
> >
> > What do you think?  Is there something we're missing?
> >
> > Can you see something breaking if I change this?  So that if SRCALPHA
> > is specified, and the bitsize is 32, then use the SRCALPHA flag.  If
> > someone specifies the SRCALPHA flag I think they expect it to be used
> > - especially if the surface is 32 bit anyway.
> >
>
>