sourceContentOpacity static method

double sourceContentOpacity(
  1. double progress, {
  2. double fadeStart = 0.0,
  3. double fadeEnd = 0.4,
})

Opacity of the source/collapsed content.

Fully opaque at fadeStart, fully transparent at fadeEnd.

Implementation

static double sourceContentOpacity(
  double progress, {
  double fadeStart = 0.0,
  double fadeEnd = 0.4,
}) {
  final t = progress.clamp(0.0, 1.0);
  if (t <= fadeStart) return 1.0;
  if (t >= fadeEnd) return 0.0;
  return 1.0 - (t - fadeStart) / (fadeEnd - fadeStart);
}