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Fix QEasingCurve possible imprecision at endpoints

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Both the spline curves and (most of) the predefines curves are defined
as having start value 0.0 and end value 1.0. The spline and In/OutBack
functions would sometimes not produce that result precisely, so code
could not reliably depend on expressions like (easedValue < 1.0)
becoming false. Fix by explicitly handling endpoints.

Fixes: QTBUG-76781
Fixes: QTBUG-72630
Change-Id: I21be43af469a76c090154bffef8406a9baf2d0b1
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
This commit is contained in:
Eirik Aavitsland 2019-10-09 10:29:00 +02:00
parent eaf4911db2
commit c54083ff93
2 changed files with 23 additions and 0 deletions
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12
src/corelib/tools/qeasingcurve.cpp
View File

@ -583,6 +583,13 @@ struct BezierEase : public QEasingCurveFunction
qWarning("QEasingCurve: Invalid bezier curve");
return x;
}
// The bezier computation is not always precise on the endpoints, so handle explicitly
if (!(x > 0))
return 0;
if (!(x < 1))
return 1;
SingleCubicBezier *singleCubicBezier = 0;
getBezierSegment(singleCubicBezier, x);
@ -998,6 +1005,11 @@ struct BackEase : public QEasingCurveFunction
qreal value(qreal t) override
{
// The *Back() functions are not always precise on the endpoints, so handle explicitly
if (!(t > 0))
return 0;
if (!(t < 1))
return 1;
qreal o = (_o < 0) ? qreal(1.70158) : _o;
switch(_t) {
case QEasingCurve::InBack:

11
tests/auto/corelib/tools/qeasingcurve/tst_qeasingcurve.cpp
View File

@ -404,6 +404,11 @@ void tst_QEasingCurve::valueForProgress()
const qreal error = qAbs(ex - curve.valueForProgress(at.at(i)/qreal(100)));
QVERIFY(error <= errorBound);
}
if (type != QEasingCurve::SineCurve && type != QEasingCurve::CosineCurve) {
QVERIFY( !(curve.valueForProgress(0) > 0) );
QVERIFY( !(curve.valueForProgress(1) < 1) );
}
#endif
}
@ -632,6 +637,9 @@ void tst_QEasingCurve::bezierSpline()
QCOMPARE(value, ex);
QVERIFY(error <= errorBound);
}
QVERIFY( !(bezierEasingCurve.valueForProgress(0) > 0) );
QVERIFY( !(bezierEasingCurve.valueForProgress(1) < 1) );
}
void tst_QEasingCurve::tcbSpline_data()
@ -691,6 +699,9 @@ void tst_QEasingCurve::tcbSpline()
QCOMPARE(value, ex);
QVERIFY(error <= errorBound);
}
QVERIFY( !(tcbEasingCurve.valueForProgress(0) > 0) );
QVERIFY( !(tcbEasingCurve.valueForProgress(1) < 1) );
}
/*This is single precision code for a cubic root used inside the spline easing curve.