[CRD iOS] Fix bugs in FlingTracker

[CRD iOS] Fix bugs in FlingTracker

This CL fixes some issues in FlingTracker:

* The velocity from the OS is in pixel/second so it needs to be converted into
  pixel/ms.
* The displacement equation is missing the time constant multiplier.
* It is safer to decide the fling threshold by calculating the maximum
  displacement rather than just the time it takes.
* Just check whether the time elapsed is greater than the fling duration rather
  than calculating the speed every time the object moves.

Review-Url: https://codereview.chromium.org/2888423003
Cr-Commit-Position: refs/heads/master@{#473707}
Committed: https://chromium.googlesource.com/chromium/src/+/1a66c42636cae8a5bbf57ccbdfb6fd561ea56572

[Yuwei, 2017-05-22 04:54:49]

Description was changed from

==========
[CRD iOS] Fix bugs in FlingTracker
==========

to

==========
[CRD iOS] Fix bugs in FlingTracker

This CL fixes some issues in FlingTracker:

* The velocity from the OS is in pixel/second so it needs to be converted into
  pixel/ms.
* The displacement equation is missing the time constant multiplier.
* It is safer to decide the fling threshold by calculating the maximum
  displacement rather than just the time it takes.
* Just check whether the time elapsed is greater than the fling duration rather
  than calculating the speed every time the object moves.
==========

[Yuwei, 2017-05-22 04:55:07]

yuweih@chromium.org changed reviewers:
+ nicholss@chromium.org

[Yuwei, 2017-05-22 04:55:07]

PTAL thanks!

[nicholss, 2017-05-22 20:17:00]

lgtm with some nits and suggestions.

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/flin...
File remoting/client/ui/fling_tracker.cc (right):

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/flin...
remoting/client/ui/fling_tracker.cc:66: if (GetDisplacement(time_constant_,
initial_speed_rate_, fling_duration_) <
It might be more readable if you assign the result of GetDisplacement and then
compare it with kMinDisplacement. It would also let you look at the result in
the debugger.

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/flin...
File remoting/client/ui/fling_tracker.h (right):

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/flin...
remoting/client/ui/fling_tracker.h:17: //                further the object can
move.
I think the extra whitespace is not needed in chromium codebase

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/flin...
remoting/client/ui/fling_tracker.h:24: // velocity is in pixel per second
This should be a whole sentence.

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/gest...
File remoting/client/ui/gesture_interpreter.cc (right):

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/gest...
remoting/client/ui/gesture_interpreter.cc:142: scroll_animation_.Tick();
It is not really animation, more like virtual scroll momentum.

[Yuwei, 2017-05-22 21:18:25]

Thanks!

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/flin...
File remoting/client/ui/fling_tracker.cc (right):

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/flin...
remoting/client/ui/fling_tracker.cc:66: if (GetDisplacement(time_constant_,
initial_speed_rate_, fling_duration_) <
On 2017/05/22 20:16:59, nicholss wrote:
> It might be more readable if you assign the result of GetDisplacement and then
> compare it with kMinDisplacement. It would also let you look at the result in
> the debugger.

Done.

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/flin...
File remoting/client/ui/fling_tracker.h (right):

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/flin...
remoting/client/ui/fling_tracker.h:17: //                further the object can
move.
On 2017/05/22 20:16:59, nicholss wrote:
> I think the extra whitespace is not needed in chromium codebase

Done. Just tried to align a little bit..

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/flin...
remoting/client/ui/fling_tracker.h:24: // velocity is in pixel per second
On 2017/05/22 20:16:59, nicholss wrote:
> This should be a whole sentence. 

Done.

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/gest...
File remoting/client/ui/gesture_interpreter.cc (right):

https://codereview.chromium.org/2888423003/diff/40001/remoting/client/ui/gest...
remoting/client/ui/gesture_interpreter.cc:142: scroll_animation_.Tick();
On 2017/05/22 20:17:00, nicholss wrote:
> It is not really animation, more like virtual scroll momentum.

Done.

[Yuwei, 2017-05-22 21:18:55]

The CQ bit was checked by yuweih@chromium.org

[Yuwei, 2017-05-22 21:18:55]

The patchset sent to the CQ was uploaded after l-g-t-m from
nicholss@chromium.org
Link to the patchset: https://codereview.chromium.org/2888423003/#ps100001
(title: "Merge branch 'master' into fix-fling-curve")

[commit-bot: I haz the power, 2017-05-22 21:19:28]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-22 21:38:09]

CQ is committing da patch.

Bot data: {"patchset_id": 100001, "attempt_start_ts": 1495487935270850,
"parent_rev": "aa6669dd0b8fd25a346fdd4bf5f934e6a3be57e6", "commit_rev":
"1a66c42636cae8a5bbf57ccbdfb6fd561ea56572"}

[commit-bot: I haz the power, 2017-05-22 21:38:18]

Description was changed from

==========
[CRD iOS] Fix bugs in FlingTracker

This CL fixes some issues in FlingTracker:

* The velocity from the OS is in pixel/second so it needs to be converted into
  pixel/ms.
* The displacement equation is missing the time constant multiplier.
* It is safer to decide the fling threshold by calculating the maximum
  displacement rather than just the time it takes.
* Just check whether the time elapsed is greater than the fling duration rather
  than calculating the speed every time the object moves.
==========

to

==========
[CRD iOS] Fix bugs in FlingTracker

This CL fixes some issues in FlingTracker:

* The velocity from the OS is in pixel/second so it needs to be converted into
  pixel/ms.
* The displacement equation is missing the time constant multiplier.
* It is safer to decide the fling threshold by calculating the maximum
  displacement rather than just the time it takes.
* Just check whether the time elapsed is greater than the fling duration rather
  than calculating the speed every time the object moves.

Review-Url: https://codereview.chromium.org/2888423003
Cr-Commit-Position: refs/heads/master@{#473707}
Committed:
https://chromium.googlesource.com/chromium/src/+/1a66c42636cae8a5bbf57ccbdfb6...
==========

[commit-bot: I haz the power, 2017-05-22 21:38:19]

Committed patchset #6 (id:100001) as
https://chromium.googlesource.com/chromium/src/+/1a66c42636cae8a5bbf57ccbdfb6...