diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/corelib/tools/qline.cpp | 39 | ||||
| -rw-r--r-- | src/corelib/tools/qline.h | 13 |
2 files changed, 29 insertions, 23 deletions
diff --git a/src/corelib/tools/qline.cpp b/src/corelib/tools/qline.cpp index d284883dcc..ebcbba0195 100644 --- a/src/corelib/tools/qline.cpp +++ b/src/corelib/tools/qline.cpp @@ -38,8 +38,10 @@ ****************************************************************************/ #include "qline.h" + #include "qdebug.h" #include "qdatastream.h" +#include "qmath.h" #include <private/qnumeric_p.h> QT_BEGIN_NAMESPACE @@ -98,7 +100,7 @@ QT_BEGIN_NAMESPACE /*! \fn bool QLine::isNull() const - Returns \c true if the line is not set up with valid start and end point; + Returns \c true if the line does not have distinct start and end points; otherwise returns \c false. */ @@ -427,8 +429,14 @@ QDataStream &operator>>(QDataStream &stream, QLine &line) /*! \fn bool QLineF::isNull() const - Returns \c true if the line is not set up with valid start and end point; - otherwise returns \c false. + Returns \c true if the line does not have distinct start and end points; + otherwise returns \c false. The start and end points are considered distinct + if qFuzzyCompare() can distinguish them in at least one coordinate. + + \note Due to the use of fuzzy comparison, isNull() may return \c true for + lines whose length() is not zero. + + \sa qFuzzyCompare(), length() */ /*! @@ -511,10 +519,10 @@ QDataStream &operator>>(QDataStream &stream, QLine &line) Sets the length of the line to the given \a length. QLineF will move the end point - p2() - of the line to give the line its new length. - If the line is a null line, the length will remain zero regardless - of the length specified. + A null line will not be rescaled. For non-null lines with very short lengths + (represented by denormal floating-point values), results may be imprecise. - \sa length(), isNull() + \sa length(), isNull(), unitVector() */ /*! @@ -559,13 +567,12 @@ QDataStream &operator>>(QDataStream &stream, QLine &line) /*! Returns the length of the line. - \sa setLength() + \sa setLength(), isNull() */ qreal QLineF::length() const { - qreal x = pt2.x() - pt1.x(); - qreal y = pt2.y() - pt1.y(); - return qSqrt(x*x + y*y); + using std::hypot; + return hypot(dx(), dy()); } /*! @@ -636,16 +643,18 @@ QLineF QLineF::fromPolar(qreal length, qreal angle) /*! Returns the unit vector for this line, i.e a line starting at the - same point as \e this line with a length of 1.0. + same point as \e this line with a length of 1.0, provided the line + is non-null. - \sa normalVector() + \sa normalVector(), setLength() */ QLineF QLineF::unitVector() const { - qreal x = pt2.x() - pt1.x(); - qreal y = pt2.y() - pt1.y(); + qreal x = dx(); + qreal y = dy(); + using std::hypot; + qreal len = hypot(x, y); - qreal len = qSqrt(x*x + y*y); QLineF f(p1(), QPointF(pt1.x() + x/len, pt1.y() + y/len)); #ifndef QT_NO_DEBUG diff --git a/src/corelib/tools/qline.h b/src/corelib/tools/qline.h index adef545d86..8d57e09c4a 100644 --- a/src/corelib/tools/qline.h +++ b/src/corelib/tools/qline.h @@ -40,8 +40,6 @@ #ifndef QLINE_H #define QLINE_H -#include <QtCore/qmath.h> - #include <QtCore/qpoint.h> QT_BEGIN_NAMESPACE @@ -372,15 +370,14 @@ constexpr inline QPointF QLineF::center() const return QPointF(0.5 * pt1.x() + 0.5 * pt2.x(), 0.5 * pt1.y() + 0.5 * pt2.y()); } -QT_WARNING_DISABLE_FLOAT_COMPARE - inline void QLineF::setLength(qreal len) { - const qreal oldlength = qSqrt(dx() * dx() + dy() * dy()); - if (!oldlength) + if (isNull()) return; - const qreal factor = len / oldlength; - pt2 = QPointF(pt1.x() + dx() * factor, pt1.y() + dy() * factor); + Q_ASSERT(length() > 0); + const QLineF v = unitVector(); + len /= v.length(); // In case it's not quite exactly 1. + pt2 = QPointF(pt1.x() + len * v.dx(), pt1.y() + len * v.dy()); } constexpr inline QPointF QLineF::pointAt(qreal t) const |