customizeSegment method
Changes the series color, border color, and border width.
Implementation
@override
void customizeSegment(ChartSegment segment) {
final SplineAreaSegment<T, D> splineAreaSegment =
segment as SplineAreaSegment<T, D>;
updateSegmentColor(splineAreaSegment, borderColor, borderWidth);
updateSegmentGradient(splineAreaSegment,
gradientBounds: splineAreaSegment._fillPath.getBounds(),
gradient: gradient,
borderGradient: borderGradient);
}