border method
Centers the scaled path's bounds like Compose's toShape adapter.
stretch permits nonuniform scaling; false preserves proportions.
Implementation
BoundsCenteredBorder border({double progress = 1, bool stretch = false}) {
_validateProgress(progress);
final morph = _morph;
return BoundsCenteredBorder(
morph == null
? RoundedPolygonBorder(polygon: to.polygon, squash: stretch ? 1 : 0)
: MorphBorder(
morph: morph,
progress: progress,
squash: stretch ? 1 : 0,
),
alignmentCorrection: _startCorrection * (1 - progress),
);
}