CalculateOpacityHeroImage

calculate_opacity_hero_image.dart

final _opacityStart = 1.0;
final _opacityEnd = 0.0;

double _calculateOpacity(double currentScrollPosition) {
  final double distance = heroImageHeight / 2;
  final double startPoint = heroImageHeight - topBarHeight;
  final rawOpacity = ((startPoint - currentScrollPosition) / distance);
  return rawOpacity.clamp(_opacityEnd, _opacityStart);
}