qline.cpp

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// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qline.h"
 
#include "qdebug.h"
#include "qdatastream.h"
#include "qmath.h"
#include <private/qnumeric_p.h>
 
QT_BEGIN_NAMESPACE
 
#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QLine &p)
{
    QDebugStateSaver saver(dbg);
    dbg.nospace() << "QLine(" << p.p1() << ',' << p.p2() << ')';
    return dbg;
}
#endif
 
#ifndef QT_NO_DATASTREAM
QDataStream &operator<<(QDataStream &stream, const QLine &line)
{
    stream << line.p1() << line.p2();
    return stream;
}
 
QDataStream &operator>>(QDataStream &stream, QLine &line)
{
    QPoint p1, p2;
    stream >> p1;
    stream >> p2;
    line = QLine(p1, p2);
 
    return stream;
}
 
#endif // QT_NO_DATASTREAM
 
qreal QLineF::length() const
{
    return qHypot(dx(), dy());
}
 
qreal QLineF::angle() const
{
    const qreal dx = pt2.x() - pt1.x();
    const qreal dy = pt2.y() - pt1.y();
 
    const qreal theta = qRadiansToDegrees(qAtan2(-dy, dx));
 
    const qreal theta_normalized = theta < 0 ? theta + 360 : theta;
 
    if (qFuzzyCompare(theta_normalized, qreal(360)))
        return qreal(0);
    else
        return theta_normalized;
}
 
void QLineF::setAngle(qreal angle)
{
    const qreal angleR = qDegreesToRadians(angle);
    const qreal l = length();
 
    const qreal dx = qCos(angleR) * l;
    const qreal dy = -qSin(angleR) * l;
 
    pt2.rx() = pt1.x() + dx;
    pt2.ry() = pt1.y() + dy;
}
 
QLineF QLineF::fromPolar(qreal length, qreal angle)
{
    const qreal angleR = qDegreesToRadians(angle);
    return QLineF(0, 0, qCos(angleR) * length, -qSin(angleR) * length);
}
 
QLineF QLineF::unitVector() const
{
    const qreal x = dx();
    const qreal y = dy();
 
    const qreal len = qHypot(x, y);
    QLineF f(p1(), QPointF(pt1.x() + x / len, pt1.y() + y / len));
 
#ifndef QT_NO_DEBUG
    if (qAbs(f.length() - 1) >= 0.001)
        qWarning("QLine::unitVector: New line does not have unit length");
#endif
 
    return f;
}
 
QLineF::IntersectionType QLineF::intersects(const QLineF &l, QPointF *intersectionPoint) const
{
    // ipmlementation is based on Graphics Gems III's "Faster Line Segment Intersection"
    const QPointF a = pt2 - pt1;
    const QPointF b = l.pt1 - l.pt2;
    const QPointF c = pt1 - l.pt1;
 
    const qreal denominator = a.y() * b.x() - a.x() * b.y();
    if (denominator == 0 || !qt_is_finite(denominator))
        return NoIntersection;
 
    const qreal reciprocal = 1 / denominator;
    const qreal na = (b.y() * c.x() - b.x() * c.y()) * reciprocal;
    if (intersectionPoint)
        *intersectionPoint = pt1 + a * na;
 
    if (na < 0 || na > 1)
        return UnboundedIntersection;
 
    const qreal nb = (a.x() * c.y() - a.y() * c.x()) * reciprocal;
    if (nb < 0 || nb > 1)
        return UnboundedIntersection;
 
    return BoundedIntersection;
}
 
qreal QLineF::angleTo(const QLineF &l) const
{
    if (isNull() || l.isNull())
        return 0;
 
    const qreal a1 = angle();
    const qreal a2 = l.angle();
 
    const qreal delta = a2 - a1;
    const qreal delta_normalized = delta < 0 ? delta + 360 : delta;
 
    if (qFuzzyCompare(delta, qreal(360)))
        return 0;
    else
        return delta_normalized;
}
 
#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QLineF &p)
{
    QDebugStateSaver saver(dbg);
    dbg.nospace() << "QLineF(" << p.p1() << ',' << p.p2() << ')';
    return dbg;
}
#endif
 
#ifndef QT_NO_DATASTREAM
QDataStream &operator<<(QDataStream &stream, const QLineF &line)
{
    stream << line.p1() << line.p2();
    return stream;
}
 
QDataStream &operator>>(QDataStream &stream, QLineF &line)
{
    QPointF start, end;
    stream >> start;
    stream >> end;
    line = QLineF(start, end);
 
    return stream;
}
 
#endif // QT_NO_DATASTREAM
 
QT_END_NAMESPACE