Recently Vine has launched Loops, and one of the fun parts that I took on was building loop animation that shows as Loops and thought I'd share it as part of Vine's open source efforts:

Usage

setKnownCount() where you can give it the current count, the time the current count is obtained, and a velocity that the count should be increasing at.

setExtraCount() where you can give it extra counts independent of the known counts variables.

Animation Modes

The gist version supports three different parameters for AnimationModes:

continuousAnimation: if the increments will be continuous, if this is false animation will run once to the current number and then stop until the next time the count is changed.

pedometerAnimation: if true, the digits will move up 1 by 1, instead of skipping when animation increment is > 1 for that digit.

alphaAnimation: if true, the alpha will be changed as percentage of the animation completion.

The default on the gist: non-continuous, non-pedometer, alpha-on, which is the way it is on Vine for Android as of Version 2.1.0.

Other Customizations

You can of course change and play with the digit spacings, animation durations, typefaces with either the given methods or change the constants. Test with the usual velocities that you wanna give and you will see interesting effects. I had a demo app working with all the different variations but I think I'll leave it to the reader to play with.

How it works

On count invalidation, count will be checked against the current count and adjust the digit sizes. The current count based on the starting count and starting time and extra count will be calculated and produce individual states for each digit. Each digit keeps track of its own animation state. And then onDraw of View will be triggered via view invalidation.

On View invalidation, onDraw will simply draw out each digit one by one using the state it is in, and then post a runnable to calculate the updated states again. Note that frame rate is adjustable as well via a constant as the delay of re-calculating the states.

Comments? Bugs? Suggestions? Feel free to leave it here or on the gist.