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/****************************************************************************
**
** Copyright (C) 2018 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the lottie-qt module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:GPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 or (at your option) any later version
** approved by the KDE Free Qt Foundation. The licenses are as published by
** the Free Software Foundation and appearing in the file LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include <beziereasing_p.h>
QT_BEGIN_NAMESPACE
void BezierEasing::addCubicBezierSegment(const QPointF &c1, const QPointF &c2, const QPointF &endPoint)
{
mBezier = QBezier::fromPoints(QPointF(0.0, 0.0), c1, c2, endPoint);
}
qreal BezierEasing::valueForProgress(qreal progress) const
{
qreal res = mBezier.pointAt(tForX(progress)).y();
return qBound(0.0, res, 1.0);
}
qreal BezierEasing::tForX(qreal x) const
{
if (x <= 0.0)
return 0.0;
else if (x >= 1.0)
return 1.0;
qreal t0 = 0.0;
qreal t1 = 1.0;
for (int i = 0; i < 10; i++) { // 10 iterations gives error smaller than 0.001
qreal t = qreal(0.5) * (t0 + t1);
qreal a, b, c, d;
QBezier::coefficients(t, a, b, c, d);
qreal xt = a * mBezier.x1 + b * mBezier.x2 + c * mBezier.x3 + d * mBezier.x4;
if (xt < x)
t0 = t;
else
t1 = t;
}
return t0;
}
QT_END_NAMESPACE
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