# QPolygonF Class

The QPolygonF class provides a list of points using floating point precision. More...

Header: | #include <QPolygonF> |

CMake: | find_package(Qt6 REQUIRED COMPONENTS Gui) target_link_libraries(mytarget PRIVATE Qt6::Gui) |

qmake: | QT += gui |

Inherits: | QList |

- List of all members, including inherited members
- QPolygonF is part of Painting Classes and Implicitly Shared Classes.

**Note:** All functions in this class are reentrant.

## Public Functions

QPolygonF() | |

QPolygonF(const QList<QPointF> &points) | |

QPolygonF(const QPolygon &polygon) | |

QPolygonF(const QRectF &rectangle) | |

QRectF | boundingRect() const |

bool | containsPoint(const QPointF &point, Qt::FillRule fillRule) const |

QPolygonF | intersected(const QPolygonF &r) const |

bool | intersects(const QPolygonF &p) const |

bool | isClosed() const |

QPolygonF | subtracted(const QPolygonF &r) const |

void | swap(QPolygonF &other) |

QPolygon | toPolygon() const |

void | translate(const QPointF &offset) |

void | translate(qreal dx, qreal dy) |

QPolygonF | translated(const QPointF &offset) const |

QPolygonF | translated(qreal dx, qreal dy) const |

QPolygonF | united(const QPolygonF &r) const |

QVariant | operator QVariant() const |

## Related Non-Members

QDataStream & | operator<<(QDataStream &stream, const QPolygonF &polygon) |

QDataStream & | operator>>(QDataStream &stream, QPolygonF &polygon) |

## Detailed Description

A QPolygonF is a QList<QPointF>. The easiest way to add points to a QPolygonF is to use its streaming operator, as illustrated below:

In addition to the functions provided by QList, QPolygonF provides the boundingRect() and translate() functions for geometry operations. Use the QTransform::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.

**See also **QList, QPolygon, and QLineF.

## Member Function Documentation

`[constexpr noexcept]`

QPolygonF::QPolygonF()

Constructs a polygon with no points.

**See also **QList::isEmpty().

### QPolygonF::QPolygonF(const QList<QPointF> &*points*)

Constructs a polygon containing the specified *points*.

### QPolygonF::QPolygonF(const QPolygon &*polygon*)

Constructs a float based polygon from the specified integer based *polygon*.

**See also **toPolygon().

### 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().

### QRectF QPolygonF::boundingRect() const

Returns the bounding rectangle of the polygon, or QRectF(0,0,0,0) if the polygon is empty.

**See also **QList::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`

.

### 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.

**See also **intersects().

### bool QPolygonF::intersects(const QPolygonF &*p*) const

Returns `true`

if the current polygon intersects at any point the given polygon *p*. Also returns `true`

if the current polygon contains or is contained by any part of *p*.

Set operations on polygons will treat the polygons as areas. Non-closed polygons will be treated as implicitly closed.

**See also **intersected().

### 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 **QList::first() and QList::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.

### void QPolygonF::swap(QPolygonF &*other*)

Swaps polygon *other* with this polygon. This operation is very fast and never fails.

### 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*.

**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*).

**See also **translate().

### QPolygonF QPolygonF::united(const QPolygonF &*r*) const

Returns a polygon which is the union of this polygon and *r*.

**See also **intersected() and subtracted().

### QVariant QPolygonF::operator QVariant() const

Returns the polygon as a QVariant.

## Related Non-Members

### QDataStream &operator<<(QDataStream &*stream*, const QPolygonF &*polygon*)

Writes the given *polygon* to the given *stream*, and returns a reference to the stream.

**See also **Serializing Qt Data Types.

### QDataStream &operator>>(QDataStream &*stream*, QPolygonF &*polygon*)

Reads a polygon from the given *stream* into the given *polygon*, and returns a reference to the stream.

**See also **Serializing Qt Data Types.

© 2024 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.