exhibition_ bottom_sheet.dart

const double minHeight = 120;
const double iconStartSize = 44;  //<-- add edge values
const double iconEndSize = 120;  //<-- add edge values
const double iconStartMarginTop = 36;  //<-- add edge values
const double iconEndMarginTop = 80;  //<-- add edge values
const double iconsVerticalSpacing = 24;  //<-- add edge values
const double iconsHorizontalSpacing = 16;  //<-- add edge values

class _ExhibitionBottomSheetState extends State<ExhibitionBottomSheet>
    with SingleTickerProviderStateMixin {

  double get itemBorderRadius => lerp(8, 24); //<-- increase item border radius

  double get iconSize => lerp(iconStartSize, iconEndSize); //<-- increase icon size

  double iconTopMargin(int index) =>
      lerp(iconStartMarginTop,
          iconEndMarginTop + index * (iconsVerticalSpacing + iconEndSize)) +
      headerTopMargin; //<-- calculate top margin based on header margin, and size of all of icons above (from small to big)

  double iconLeftMargin(int index) =>
      lerp(index * (iconsHorizontalSpacing + iconStartSize), 0); //<-- calculate left margin (from big to small)

  double lerp(double min, double max) =>
      lerpDouble(min, max, _controller.value);

  @override
  Widget build(BuildContext context) {
    return ...
      child: Stack(
        children: <Widget>[
          MenuButton(),
          SheetHeader(
            fontSize: headerFontSize,
            topMargin: headerTopMargin,
          ),
          for (Event event in events) _buildIcon(event), //<-- Add icons to the stack
        ],
      ),
    ...
  }

  Widget _buildIcon(Event event) {
    int index = events.indexOf(event); //<-- Get index of the event
    return Positioned(
      height: iconSize, //<-- Specify icon's size
      width: iconSize, //<-- Specify icon's size
      top: iconTopMargin(index), //<-- Specify icon's top margin
      left: iconLeftMargin(index), //<-- Specify icon's left margin
      child: ClipRRect(
        borderRadius: BorderRadius.horizontal(
          left: Radius.circular(itemBorderRadius), //<-- Set the rounded corners
          right: Radius.circular(itemBorderRadius),
        ),
        child: Image.asset(
          'assets/${event.assetName}',
          fit: BoxFit.cover,
          alignment: Alignment(lerp(1, 0), 0), //<-- Play with alignment for extra style points
        ),
      ),
    );
  }
}