Module indicator 

The cadence of looping indicators: a spinner, a tab’s busy arc, a sweeping bar.

An indicator only says “still working”; it does not need the display’s full refresh to say it. It moves in steps of INDICATOR_STEP and repaints (damages its own bounds, presents) only when its step changes, so one busy mark on screen costs a few frames a second instead of every refresh. Under reduced motion it stands still (EffectiveMotion::loops).

Constants

INDICATOR_STEP

One step of a looping indicator: 30 a second.

Functions

indicator_elapsed

Time since epoch at the start of the step now falls in: what an indicator draws, so its pose changes once per step.

indicator_phase

Where in a loop period long an indicator stands at now, 0..1, taken at the start of the step now falls in.

indicator_step

The step now falls in, counted from the indicator’s epoch.

next_indicator_step

When the step after the one now falls in begins.