Detailed Description
The QPolygonF class provides a vector of points using floating point precision.
A QPolygonF is a QVector<QPointF>. The easiest way to add points to a QPolygonF is to use its streaming operator, as illustrated below:
QPolygonF polygon;
polygon << QPointF(10.4, 20.5) << QPointF(20.2, 30.2);
In addition to the functions provided by QVector, QPolygonF provides the boundingRect() and translate() functions for geometry operations. Use the QMatrix::map() function for more general transformations of QPolygonFs.
QPolygonF also provides the isClosed() function to determine whether a polygon's start and end points are the same, and the toPolygon() function returning an integer precision copy of this polygon.
The QPolygonF class is implicitly shared.
Member Function Documentation
QPolygonF::QPolygonF()
Constructs a polygon with no points.
See also QVector::isEmpty().
QPolygonF::QPolygonF(int size)
Constructs a polygon of the given size. Creates an empty polygon if size == 0.
See also QVector::isEmpty().
QPolygonF::QPolygonF(const QPolygonF & polygon)
Constructs a copy of the given polygon.
QPolygonF::QPolygonF(const QVector<QPointF> & points)
Constructs a polygon containing the specified points.
QPolygonF::QPolygonF(const QRectF & rectangle)
Constructs a closed polygon from the specified rectangle.
The polygon contains the four vertices of the rectangle in clockwise order starting and ending with the top-left vertex.
See also isClosed().
QPolygonF::QPolygonF(const QPolygon & polygon)
Constructs a float based polygon from the specified integer based polygon.
See also toPolygon().
QPolygonF::~QPolygonF()
Destroys the polygon.
QRectF QPolygonF::boundingRect() const
Returns the bounding rectangle of the polygon, or QRectF(0,0,0,0) if the polygon is empty.
See also QVector::isEmpty().
bool QPolygonF::containsPoint(const QPointF & point, Qt::FillRule fillRule) const
Returns true if the given point is inside the polygon according to the specified fillRule; otherwise returns false.
This function was introduced in Qt 4.3.
QPolygonF QPolygonF::intersected(const QPolygonF & r) const
Returns a polygon which is the intersection of this polygon and r.
Set operations on polygons will treat the polygons as areas. Non-closed polygons will be treated as implicitly closed.
This function was introduced in Qt 4.3.
bool QPolygonF::isClosed() const
Returns true if the polygon is closed; otherwise returns false.
A polygon is said to be closed if its start point and end point are equal.
See also QVector::first() and QVector::last().
QPolygonF QPolygonF::subtracted(const QPolygonF & r) const
Returns a polygon which is r subtracted from this polygon.
Set operations on polygons will treat the polygons as areas. Non-closed polygons will be treated as implicitly closed.
This function was introduced in Qt 4.3.
void QPolygonF::swap(QPolygonF & other)
Swaps polygon other with this polygon. This operation is very fast and never fails.
This function was introduced in Qt 4.8.
QPolygon QPolygonF::toPolygon() const
Creates and returns a QPolygon by converting each QPointF to a QPoint.
See also QPointF::toPoint().
void QPolygonF::translate(const QPointF & offset)
Translate all points in the polygon by the given offset.
See also translated().
void QPolygonF::translate(qreal dx, qreal dy)
This is an overloaded function.
Translates all points in the polygon by (dx, dy).
See also translated().
QPolygonF QPolygonF::translated(const QPointF & offset) const
Returns a copy of the polygon that is translated by the given offset.
This function was introduced in Qt 4.6.
See also translate().
QPolygonF QPolygonF::translated(qreal dx, qreal dy) const
This is an overloaded function.
Returns a copy of the polygon that is translated by (dx, dy).
This function was introduced in Qt 4.6.
See also translate().
QPolygonF QPolygonF::united(const QPolygonF & r) const
Returns a polygon which is the union of this polygon and r.
Set operations on polygons will treat the polygons as areas. Non-closed polygons will be treated as implicitly closed.
This function was introduced in Qt 4.3.
See also intersected() and subtracted().
