fluentSkeletonWaveOffset function

double fluentSkeletonWaveOffset(
  1. double t
)

The wave band's left edge at t, as a multiple of the skeleton's own width.

t is a position along the loop, already eased — not a raw clock fraction.

Transcribed from the five Figma Frame keyframes, which are the animation sampled rather than a widget property: over a 132-wide component the Shimmer layer sits at 0, -132, -264, -396 and +132, i.e. -3W to +W in even steps. The two extremes are exactly the positions at which the 3W-wide band falls entirely outside the clip, which is also where Figma's own keyframes carry a mis-bound highlight colour nobody ever saw.

Upstream states the same sweep as translate(-100%) to translate(100%).

Implementation

double fluentSkeletonWaveOffset(double t) => -3 + 4 * t;