AurumRollingNumber

A number that rolls to its value instead of appearing at it.

On first appearance it lands on easingGlide — nearly all of the distance in the first half of the time, then the last few units crawling to rest — over a duration set by pace, starting from zero or, with landFromFraction, from just below the value so it arrives rather than spins up. Later changes to value roll from the current figure on easingDecelerate, up or down to match the direction of the change, with each digit sliding into place via numericText. When the roll settles it gives a select tick and a 1.5 % scale bump on springFastSpatial. Honours Reduce Motion — it then shows the final value with no roll, no bump and no tick — and reads to VoiceOver as the final figure once.

Aurum never decides how a number is written. format is the caller's: currency symbol, grouping, fraction digits and units come from the same place the surrounding copy does. Mirrors aurum-android's AurumRollingNumber.

Use for the one figure a surface exists to show — a hero amount on a receipt, a locker balance, a total that just changed because of something the user did.