Re: [pygame] subsurfaces outside of their parents

[Forest Darling <fdarling@xxxxxxxxx>]

I want a subsurface to be the size/location that you ask it, even if
it overlaps/is outside of the parent surface. Any pixels that are
outside of the surface would be "dummy" pixels and any drawing to them
would be ignored. The idea is to be able to draw to a surface (0,
0)through(10, 10) and on the parent surface have it be drawing (-5,
-5)through(5, 5), and only (5, 5) --> (10, 10), which is (0, 0)
through(5, 5) on the parent surface, would actually be drawing to
non-dummy pixels. This might be really hackish though because what
then if you were to blit this subsurface to another surface, with its
dummy pixels? what would the dummy pixels show up as? I guess it
simply wouldn't copy them... as if you had asked it to blit a smaller
rect. I am mostly thinking about drawing aspect though...

On 11/10/05, Brian Fisher <brian_fisher@xxxxxxx> wrote:
> ------ Original Message ------
> > No, it needs to appear to be 20x20 because the whole idea is to have
> > whether or not its off the surface to be transparent. This makes it so
> > code can draw 0, 0, --> 20, 20 on the subsurface without having to
> > compensate for being off the surface and such... I want this feature,
> > personally, for a widget drawing system involving subsurfaces.
> >
> That sounds wrong - the whole idea of subsurface is that it shares pixels with
> it's parent surface, right? So are you hoping this subsurface call to grow the
> parent? are you hoping it would partially share pixels with the parent and
> have some of it's own pixels? are you hoping it would have all it's own pixels
> and none shared? are you hoping it would just return a false width and height
> and really only have shared pixels on the area that did overlap the parent?
>
> ...Because none of those 4 behaviors are something I'd want pygame to do and I
> can't think of any other way to resolve the surface having the size you asked
> for in the case you describe.
>
> ...I really like the modification Pete described though - I agree that it
> seems to be the right thing, and aside from the fact that nothing would be
> drawn to the area that didn't exist on the parent (which seems like the right
> thing to me), it appears to satisfy your requirement "to have whether or not
> its off the surface to be transparent" in that you can draw from 0,0 to 20,20
> and have the destination be where you said it should be.
>
>
> > On 11/8/05, Peter Shinners <pete@xxxxxxxxxxxx> wrote:
> > > On Tue, 2005-11-08 at 00:46 -0500, Forest Darling wrote:
> > > > I would like to see a feature where you could have a subsurface take a
> > > > rect that covered an area that was partially or completely outside
> > > > parent surface's rect...
> > > >
> > > > s = pygame.Surface((100, 100))
> > > > sub = s.subsurface(Rect(-10, -10, 20, 20)
> > >
> > > This has been suggested before. If it is ok for the returned subsurface
> > > to be smaller than requested, this would be easy to implement. The
> > > surface would still use the right offset so that drawing to it would
> > > appear where you expected.
> > >
> > > sub = s.subsurface(Rect(-10, -10, 20, 20)
> > > print sub.get_size()
> > > (10, 10)
> > >
> > > I'll think about it some more, it can lead to strange cases, but for the
> > > most part I think it would do the right thing.
> > >
> > >
> >
>
>
>
>