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fix Curves.bounceInOut math (#22825)

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* fix Curves.bounceInOut

* assert maximum slope
This commit is contained in:
Max Bittker 2018-10-16 13:49:18 -07:00 committed by Dan Field
parent 0fb84e96c7
commit 25e40ba599
2 changed files with 24 additions and 1 deletions
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2
packages/flutter/lib/src/animation/curves.dart
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@ -369,7 +369,7 @@ class _BounceInOutCurve extends Curve {
double transform(double t) {
assert(t >= 0.0 && t <= 1.0);
if (t < 0.5)
return (1.0 - _bounce(1.0 - t)) * 0.5;
return (1.0 - _bounce(1.0 - t * 2.0)) * 0.5;
else
return _bounce(t * 2.0 - 1.0) * 0.5 + 0.5;
}

23
packages/flutter/test/animation/curves_test.dart
View File

@ -34,6 +34,29 @@ void main() {
expect(step.transform(1.0), 1.0);
});
void assertMaximumSlope(Curve curve, double maximumSlope) {
const double delta = 0.005;
for (double x = 0.0; x < 1.0 - delta; x += delta) {
final double deltaY = curve.transform(x) - curve.transform(x + delta);
assert(deltaY.abs() < delta * maximumSlope, '${curve.toString()} discontinuous at $x');
}
}
test('Curve is continuous', () {
assertMaximumSlope(Curves.linear, 20.0);
assertMaximumSlope(Curves.decelerate, 20.0);
assertMaximumSlope(Curves.bounceIn, 20.0);
assertMaximumSlope(Curves.bounceOut, 20.0);
assertMaximumSlope(Curves.bounceInOut, 20.0);
assertMaximumSlope(Curves.elasticOut, 20.0);
assertMaximumSlope(Curves.elasticInOut, 20.0);
assertMaximumSlope(Curves.ease, 20.0);
assertMaximumSlope(Curves.easeIn, 20.0);
assertMaximumSlope(Curves.easeOut, 20.0);
assertMaximumSlope(Curves.easeInOut, 20.0);
assertMaximumSlope(Curves.fastOutSlowIn, 20.0);
});
void expectStaysInBounds(Curve curve) {
expect(curve.transform(0.0), inInclusiveRange(0.0, 1.0));
expect(curve.transform(0.1), inInclusiveRange(0.0, 1.0));