On Mon, 2009-05-25 at 14:46 +0200, Jonas Bonn wrote:
> Hi,
>
> I had a short discussion with ebassi on #clutter... we decided I would send
> an
> email detailing what I feel are some weaknesses in the Animation
> API/implementation. Thanks for considering this; my thoughts follow:
>
> ----
>
> An Animation currently keeps track of:
>
> timeline
> mode
> duration
> loop
I agree that the Animation properties should not go out of sync with the
underlying objects.
personally, my take is that the Animation should:
- cache the values in case the Alpha and/or the Timeline instances
are not present, or if they are being replaced
- proxy the values otherwise
which is basically what are you proposing, except that I wouldn't remove
the loop, duration and mode variables from AnimationPrivate.
the behaviour of the Animation class would then match these invariants:
- set_mode()
+ no alpha set: create an alpha (without a timeline)
+ alpha set: set the mode
- set_duration():
+ no alpha set: create an alpha, then a timeline
+ alpha set: get the timeline of the alpha, set duration
- set_loop()
+ same as set_duration()
- get_mode()
- get_duration()
- get_loop()
+ no alpha or no timeline are set: return the cached values
+ alpha or timeline set: return the alpha or timeline values
for the set_alpha() and set_timeline() we need some more hand-holding,
because we depend on instances to make the animation machinery work:
- set_alpha():
+ no alpha set and passed NULL, create alpha (without a timeline)
+ no alpha set and passed !NULL, own the alpha and use its timeline
+ alpha set and passed NULL, create alpha and reuse the timeline
from the old alpha
+ alpha set and passed !NULL, own the alpha and use its timeline
- set_timeline()
+ no alpha set and passed NULL: create alpha and timeline using
stored values, and assign the timeline to the alpha
+ no alpha set and passed !NULL: create alpha and assign passed
timeline to the alpha
+ alpha set and passed NULL: create timeline using stored values
and assign it to the alpha
+ alpha set and passed !NULL: assign timeline to the alpha
- get_alpha()
+ no alpha set: create an alpha using the stored values, with
no timeline
+ alpha set: return alpha
- get_timeline()
+ return the timeline assigned to the alpha
in short: the Alpha should be available as soon as:
- :mode, :duration or :loop are set
- get_alpha() or get_timeline() are called
while the Timeline will be available as soon as:
- :duration or :loop are set
I'll document this properly before the 1.0 release.
> I hope this makes some sense and I look forward to your comments. I'm happy
> to
> provide clarification where things are less than clear.
thanks for your feedback!
ciao,
Emmanuele.
--
Emmanuele Bassi, Senior Engineer | emmanuele.ba...@intel.com
Intel Open Source Technology Center | http://oss.intel.com
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