RenderSliverGap

render_sliver_gap.dart

class RenderSliverGap extends RenderSliver {
  RenderSliverGap({
    double mainAxisExtent,
  }) : _mainAxisExtent = mainAxisExtent;

  double get mainAxisExtent => _mainAxisExtent;
  double _mainAxisExtent;
  set mainAxisExtent(double value) {
    if (_mainAxisExtent != value) {
      _mainAxisExtent = value;
      markNeedsLayout();
    }
  }

  @override
  void performLayout() {
    final double paintExtent = calculatePaintOffset(
      constraints,
      from: 0,
      to: mainAxisExtent,
    );
    final double cacheExtent = calculateCacheOffset(
      constraints,
      from: 0,
      to: mainAxisExtent,
    );

    assert(paintExtent.isFinite);
    assert(paintExtent >= 0.0);
    geometry = SliverGeometry(
      scrollExtent: mainAxisExtent,
      paintExtent: paintExtent,
      cacheExtent: cacheExtent,
      maxPaintExtent: mainAxisExtent,
      hasVisualOverflow: mainAxisExtent > constraints.remainingPaintExtent ||
          constraints.scrollOffset > 0.0,
    );
  }
}