Re: Animated subviews
Re: Animated subviews
- Subject: Re: Animated subviews
- From: Wyatt Webb <email@hidden>
- Date: Sun, 23 Nov 2008 09:11:31 -0800
I have not done this myself, but I understand that you can find the
"actual" positions of things in the middle of an animation by querying
the [ [ myView layer ] presentationLayer ]. This is a version of the
layer that has all of the current values in the middle of an
animation. As long as you have a chance to check periodically, you
should be able to do your comparisons.
Wyatt
On Nov 23, 2008, at 8:30 AM, DKJ wrote:
I have two subviews sv1 and sv2 that I've animated by setting their
center properties inside of an animation block. This animation code
is in sv1.m and sv2.m. It all works just fine: they both move
smoothly around in the superview by choosing new centre points in a
continuous loop. It looks quite cute, really.
What I want to do now is detect when they come within a certain
distance of one another as they're moving. But when I do this to
move them:
sv1.center = p1;
sv2.center = p2;
their center properties are set immediately to the new values: i.e.
they can't be read to find the intermediate positions. So I can't
use these properties to find out if their centres come within a
given distance of one another.
I've thought of some possible approaches:
1. Having the superview controller calculate whether the lines
between the animation start and finish points intersect, and whether
sv1 and sv2 will be at the intersection at the same time.
2. Breaking up the straight line moves into much smaller segments
and having the center properties set successively to those.
3. Having the superview controller handle the animation and somehow
keep track of the subview's relative distances.
4. Using keyframe animation instead.
#1 seems rather complicated. #2 seems likely to lead to a choppy
animation, and would rule out using the speed-up-then-slow-down
animation mode. #3 would involve throwing out a lot of the code I've
written so far. And I don't yet have a clue whether #4 is plausible,
not having used keyframe animation before.
If there are any other suggestions, I'd be grateful to hear them!
dkj
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