Re: [pygame] Color, unpacking to r,g,b and r,g,b,a - ValueError: too many values to unpack

On Wed, Jun 17, 2009 at 2:02 PM, Lenard Lindstrom <len-l@xxxxxxxxx> wrote:

Hi Tyler (and Ian),

In most cases colors are length 4. But in Pygame 1.8.1 and earlier the Surface palette methods get_palette and get_palette_at return 3-tuples. Pygame 1.9 will return color instances instead. For compatibility the se color instances must also be length 3. As for a default alpha, that is 255, which is now consistent throughout Pygame.

Lenard

Tyler Laing wrote:

Hi Lenard,

But are there any situations where one MUST have 3 elements colors only? If not, then just fill in a reasonable default value for times when there isn't an alpha value for the picture.

-Tyler

On Wed, Jun 17, 2009 at 9:31 AM, Lenard Lindstrom <len-l@xxxxxxxxx <mailto:len-l@xxxxxxxxx>> wrote:

Hi Tyler,

Well, one wants 4 element colors when working with per-pixel-alpha
surfaces.

Lenard

Tyler Laing wrote:

Why don't we just fill in a full value of 255 for all the
cases where it returns 3 values? If we make every call return
four values, and warn about this in the documentation, it
becomes very consistent.

-Tyler

On Tue, Jun 16, 2009 at 11:52 PM, Lenard Lindstrom
<len-l@xxxxxxxxx <mailto:len-l@xxxxxxxxx>
<mailto:len-l@xxxxxxxxx <mailto:len-l@xxxxxxxxx>>> wrote:

René Dudfield wrote:

On Wed, Jun 17, 2009 at 4:29 PM, Lenard
Lindstrom<len-l@xxxxxxxxx <mailto:len-l@xxxxxxxxx>
<mailto:len-l@xxxxxxxxx <mailto:len-l@xxxxxxxxx>>> wrote:
René Dudfield wrote:
Hi,

one issue with the new Color type is unpacking to
r,g,b or r,g,b,a.

In some places Color is assumed to return
(r,g,b) and
others
(r,g,b,a), and now many things return a Color
rather
than a tuple.

So I want to change Color to unpack to r,g,b,a
or r,g,b.

r,g,b = pygame.Color(1,2,3,4)
r,g,b,a = pygame.Color(1,2,3,4)

Anyone have an idea how this can work? Either
in C or
python?

This is to keep backwards compatibility.

cheers,

Hi René,

Are there cases where this is breaking code? For
the most
part I believe
Pygame functions returned 4-tuples. So Color is just
pretty much a drop-in
replacement. If a program is using tuples to
declare color
values then the
size is already known and unpacking is not a
problem. It is
Surface.get_palette and get_palette_at, which
originally
returned 3-tuples,
where we run into problems. So here are the choices
I see.
One, just accept
that the new get_palette and get_palette_at will break
things, just as any
program that tries to use a color return value as a
dictionary key will now
break. How many programs actually use color palettes
anyway? Two, give Color
a size property. If alpha is set None it becomes
length 3.
But then how does
one represent this internally without adding
another field
to the Color C
structure? Declare the color component values as C
ints?
Three, create a new
Color subtype of length 3 having a fixed alpha of
255. I'm
not happy with
any of the choices but prefer three. Any other ideas?

Lenard

hi,

yeah for example in solarwolf:
File "solarwolf-1.5/code/gamemenu.py", line 70, in
load_game_resources
pal = [(g,g,b) for (r,g,b) in origpal]

File "solarwolf-1.5/code/objshot.py", line 28, in
load_game_resources
for (r,g,b) in origpal]

hrmm. I think a 3 element Color subtype might be the
way to go.
Maybe we don't even need a subtype, but just a length
property
that
can be 1,2,3, or 4? As you say get_palette(_at) could
return
len 3
Colors.

If it could unpack to 3, or 4 depending on the number of
elements on
the left, I think I'd prefer that though.

Hi,

Well yes, but now you are have something that is basically an
integer array, including the additional overhead.