Camera moves after releasing

[puckey]

On mobile, when you pinch to zoom into the globe, it often moves after you release the pinch.

In this screen recording I am pinching to zoom in multiple times. As you can see the globe moves every time I release the pinch:

https://www.dropbox.com/s/y4zqsrqb1c4rhkq/ScreenRecording_04-21-2018%2014-37-15.MP4?dl=0

[emackey]

What you're seeing is camera inertia. You can "fling" the globe with one finger ("pan"), and if you let go of it while still moving fast, it will slow down gradually rather than abruptly stop.

In this video, it looks like one finger of the pinch-zoom is letting go just prior to the other. When one finger lets go, the other re-enters pan mode. That second finger then lets go while moving fast, and you get inertia off the pan rather than inertia off the pinch.

One thing we might want to consider: If a pinch is in progress, and one finger lets go, we could just end the whole gesture, rather than re-entering pan mode. This would prevent any pan inertia from showing up on the end of a pinch, but would mean you need to let go both fingers of pinch before starting a new pan.

[puckey]

I just put up a pr where a pinch only ends when both fingers have released and a TOUCH_DOWN will only be triggered when not pinching: #6479

I will try to write a test for this behaviour next week.

[puckey]

I added pinch release tests: 293aeeb

[puckey]

My new code was causing PINCH_START to be called too often. Tests and fix here: edc8294