Break dependency of AnimationPerformance on AnimatedValue

Break dependency of AnimationPerformance on AnimatedValue

This CL decouples the new animation system (based on AnimationPerformance and
AnimatedVariable) from the old animation system (based on AnimatedValue). It
introduces a new Ticker and Timeline class to drive AnimationPerformance and
makes it possible for AnimatedComponent to watch performances directly.

R=eseidel@chromium.org, mpcomplete@chromium.org, mpcomplete@google.com

Committed: https://chromium.googlesource.com/external/mojo/+/88b8e63dc48eff1149dc1dcb30e7f1a9c8bb3454

[eseidel, 2015-07-09 16:55:16]

eseidel@chromium.org changed reviewers:
+ eseidel@chromium.org

[eseidel, 2015-07-09 16:55:17]

lgtm, matt is a better reviewer.

https://codereview.chromium.org/1226263003/diff/1/sky/sdk/lib/animation/timel...
File sky/sdk/lib/animation/timeline.dart (right):

https://codereview.chromium.org/1226263003/diff/1/sky/sdk/lib/animation/timel...
sky/sdk/lib/animation/timeline.dart:16: int _id;
Better name maybe?  Didn't realize this was the cached frame id.

https://codereview.chromium.org/1226263003/diff/1/sky/sdk/lib/animation/timel...
sky/sdk/lib/animation/timeline.dart:146: return _duration - _time;
Wrong.

[abarth-chromium, 2015-07-09 17:27:24]

Addressed Eric's feedback.  Waiting for Matt's feedback.

[Matt Perry, 2015-07-09 17:38:08]

mpcomplete@chromium.org changed reviewers:
+ mpcomplete@chromium.org

[Matt Perry, 2015-07-09 17:38:08]

https://codereview.chromium.org/1226263003/diff/40001/sky/sdk/lib/animation/t...
File sky/sdk/lib/animation/timeline.dart (right):

https://codereview.chromium.org/1226263003/diff/40001/sky/sdk/lib/animation/t...
sky/sdk/lib/animation/timeline.dart:86: Curve _curve;
This class seems overly complicated to me. If it's truly just a Timeline, it
should always animate linearly. All we need for AnimationPerformance is a
stopwatch: start from 0, tick for |duration|, end at 1.0. Methods you need:
start, stop, pause, get/set value, onTick, onDone.

If we need something more complicated, we should use an Animated<Double>.

[abarth-chromium, 2015-07-09 17:48:30]

Done.  PTAL.

https://codereview.chromium.org/1226263003/diff/40001/sky/sdk/lib/animation/t...
File sky/sdk/lib/animation/timeline.dart (right):

https://codereview.chromium.org/1226263003/diff/40001/sky/sdk/lib/animation/t...
sky/sdk/lib/animation/timeline.dart:86: Curve _curve;
On 2015/07/09 at 17:38:08, Matt Perry wrote:
> This class seems overly complicated to me. If it's truly just a Timeline, it
should always animate linearly. All we need for AnimationPerformance is a
stopwatch: start from 0, tick for |duration|, end at 1.0. Methods you need:
start, stop, pause, get/set value, onTick, onDone.
> 
> If we need something more complicated, we should use an Animated<Double>.

Ok.  I'll remove that functionality.

[Matt Perry, 2015-07-09 17:52:57]

https://codereview.chromium.org/1226263003/diff/60001/sky/sdk/lib/animation/t...
File sky/sdk/lib/animation/timeline.dart (right):

https://codereview.chromium.org/1226263003/diff/60001/sky/sdk/lib/animation/t...
sky/sdk/lib/animation/timeline.dart:89: double begin: 0.0,
I don't even think we need a begin/end value. Always use [0, 1]. If the user
needs a different range, they can apply a transform on |value| themselves.

[abarth-chromium, 2015-07-09 17:55:38]

https://codereview.chromium.org/1226263003/diff/60001/sky/sdk/lib/animation/t...
File sky/sdk/lib/animation/timeline.dart (right):

https://codereview.chromium.org/1226263003/diff/60001/sky/sdk/lib/animation/t...
sky/sdk/lib/animation/timeline.dart:89: double begin: 0.0,
On 2015/07/09 at 17:52:57, Matt Perry wrote:
> I don't even think we need a begin/end value. Always use [0, 1]. If the user
needs a different range, they can apply a transform on |value| themselves.

AnimationPerformance uses different begin and end values.  Almost everyone uses
animateTo, which uses |value| as the start value.  Also, 0.0 is as common and
end value as 1.0.  It seems reasonable to be able to run the timeline backwards
and forwards and to start from an arbitrary place.

[Matt Perry, 2015-07-09 18:10:40]

LGTM

https://codereview.chromium.org/1226263003/diff/60001/sky/sdk/lib/animation/t...
File sky/sdk/lib/animation/timeline.dart (right):

https://codereview.chromium.org/1226263003/diff/60001/sky/sdk/lib/animation/t...
sky/sdk/lib/animation/timeline.dart:89: double begin: 0.0,
On 2015/07/09 17:55:37, abarth-chromium wrote:
> On 2015/07/09 at 17:52:57, Matt Perry wrote:
> > I don't even think we need a begin/end value. Always use [0, 1]. If the user
> needs a different range, they can apply a transform on |value| themselves.
> 
> AnimationPerformance uses different begin and end values.  Almost everyone
uses
> animateTo, which uses |value| as the start value.  Also, 0.0 is as common and
> end value as 1.0.  It seems reasonable to be able to run the timeline
backwards
> and forwards and to start from an arbitrary place.

Oh right. Makes sense.

[abarth-chromium, 2015-07-09 19:16:59]

Committed patchset #5 (id:80001) manually as
88b8e63dc48eff1149dc1dcb30e7f1a9c8bb3454 (presubmit successful).