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 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
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#include <sal/config.h>

#include <o3tl/safeint.hxx>

#include <controller/SlsAnimationFunction.hxx>

namespace sd::slidesorter::controller {

//===== AnimationBezierFunction ===============================================

AnimationBezierFunction::AnimationBezierFunction (
    const double nX1,
    const double nY1)
    : mnX1(nX1),
      mnY1(nY1),
      mnX2(1-nY1),
      mnY2(1-nX1)
{
}

::basegfx::B2DPoint AnimationBezierFunction::operator() (const double nT)
{
    return ::basegfx::B2DPoint(
        EvaluateComponent(nT, mnX1, mnX2),
        EvaluateComponent(nT, mnY1, mnY2));
}

double AnimationBezierFunction::EvaluateComponent (
    const double nT,
    const double nV1,
    const double nV2)
{
    const double nS (1-nT);

    // While the control point values 1 and 2 are explicitly given the start
    // and end values are implicitly given.
    const double nV0 (0);
    const double nV3 (1);

    const double nV01 (nS*nV0 + nT*nV1);
    const double nV12 (nS*nV1 + nT*nV2);
    const double nV23 (nS*nV2 + nT*nV3);

    const double nV012 (nS*nV01 + nT*nV12);
    const double nV123 (nS*nV12 + nT*nV23);

    const double nV0123 (nS*nV012 + nT*nV123);

    return nV0123;
}

//===== AnimationParametricFunction ===========================================

AnimationParametricFunction::AnimationParametricFunction (const ParametricFunction& rFunction)
{
    const sal_Int32 nSampleCount (64);

    // Sample the given parametric function.
    ::std::vector<basegfx::B2DPoint> aPoints;
    aPoints.reserve(nSampleCount);
    for (sal_Int32 nIndex=0; nIndex<nSampleCount; ++nIndex)
    {
        const double nT (nIndex/double(nSampleCount-1));
        aPoints.emplace_back(rFunction(nT));
    }

    // Interpolate at evenly spaced points.
    maY.clear();
    maY.reserve(nSampleCount);
    double nX0 (aPoints[0].getX());
    double nY0 (aPoints[0].getY());
    double nX1 (aPoints[1].getX());
    double nY1 (aPoints[1].getY());
    sal_Int32 nIndex (1);
    for (sal_Int32 nIndex2=0; nIndex2<nSampleCount; ++nIndex2)
    {
        const double nX (nIndex2 / double(nSampleCount-1));
        while (nX > nX1 && nIndex<nSampleCount)
        {
            nX0 = nX1;
            nY0 = nY1;
            nX1 = aPoints[nIndex].getX();
            nY1 = aPoints[nIndex].getY();
            ++nIndex;
        }
        const double nU ((nX-nX1) / (nX0 - nX1));
        const double nY (nY0*nU + nY1*(1-nU));
        maY.push_back(nY);
    }
}

double AnimationParametricFunction::operator() (const double nX)
{
    const sal_Int32 nIndex0 (static_cast<sal_Int32>(nX * maY.size()));
    const double nX0 (nIndex0 / double(maY.size()-1));
    const sal_uInt32 nIndex1 (nIndex0 + 1);
    const double nX1 (nIndex1 / double(maY.size()-1));

    if (nIndex0<=0)
        return maY[0];
    else if (o3tl::make_unsigned(nIndex0)>=maY.size() || nIndex1>=maY.size())
        return maY[maY.size()-1];

    const double nU ((nX-nX1) / (nX0 - nX1));
    return maY[nIndex0]*nU + maY[nIndex1]*(1-nU);
}

} // end of namespace ::sd::slidesorter::controller

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