The QPolygon class provides a list of points using integer precision. More...
| Header: | #include <QPolygon> |
| CMake: | find_package(Qt6 COMPONENTS Gui REQUIRED) target_link_libraries(mytarget PRIVATE Qt6::Gui) |
| qmake: | QT += gui |
| Inherits: | QList |
Note: All functions in this class are reentrant.
| QPolygon(const QRect &rectangle, bool closed = false) | |
| QPolygon(const QList<QPoint> &points) | |
| QPolygon() | |
| QRect | boundingRect() const |
| bool | containsPoint(const QPoint &point, Qt::FillRule fillRule) const |
| QPolygon | intersected(const QPolygon &r) const |
| bool | intersects(const QPolygon &p) const |
| void | point(int index, int *x, int *y) const |
| QPoint | point(int index) const |
| void | putPoints(int index, int nPoints, const QPolygon &fromPolygon, int fromIndex = 0) |
| void | putPoints(int index, int nPoints, int firstx, int firsty, ...) |
| void | setPoint(int index, int x, int y) |
| void | setPoint(int index, const QPoint &point) |
| void | setPoints(int nPoints, const int *points) |
| void | setPoints(int nPoints, int firstx, int firsty, ...) |
| QPolygon | subtracted(const QPolygon &r) const |
| void | swap(QPolygon &other) |
| void | translate(int dx, int dy) |
| void | translate(const QPoint &offset) |
| QPolygon | translated(int dx, int dy) const |
| QPolygon | translated(const QPoint &offset) const |
| QPolygon | united(const QPolygon &r) const |
| QVariant | operator QVariant() const |
| QDataStream & | operator<<(QDataStream &stream, const QPolygon &polygon) |
| QDataStream & | operator>>(QDataStream &stream, QPolygon &polygon) |
A QPolygon object is a QList<QPoint>. The easiest way to add points to a QPolygon is to use QList's streaming operator, as illustrated below:
QPolygon polygon; polygon << QPoint(10, 20) << QPoint(20, 30);
In addition to the functions provided by QList, QPolygon provides some point-specific functions.
Each point in a polygon can be retrieved by passing its index to the point() function. To populate the polygon, QPolygon provides the setPoint() function to set the point at a given index, the setPoints() function to set all the points in the polygon (resizing it to the given number of points), and the putPoints() function which copies a number of given points into the polygon from a specified index (resizing the polygon if necessary).
QPolygon provides the boundingRect() and translate() functions for geometry functions. Use the QTransform::map() function for more general transformations of QPolygons.
The QPolygon class is implicitly shared.
See also QList, QPolygonF, and QLine.
Constructs a polygon from the given rectangle. If closed is false, the polygon just contains the four points of the rectangle ordered clockwise, otherwise the polygon's fifth point is set to rectangle.topLeft().
Note that the bottom-right corner of the rectangle is located at (rectangle.x() + rectangle.width(), rectangle.y() + rectangle.height()).
See also setPoints().
Constructs a polygon containing the specified points.
See also setPoints().
Constructs a polygon with no points.
See also QList::isEmpty().
Returns the bounding rectangle of the polygon, or QRect(0, 0, 0, 0) if the polygon is empty.
See also QList::isEmpty().
Returns true if the given point is inside the polygon according to the specified fillRule; otherwise returns false.
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().
[since 5.10] bool QPolygon::intersects(const QPolygon &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.
This function was introduced in Qt 5.10.
See also intersected().
Extracts the coordinates of the point at the given index to *x and *y (if they are valid pointers).
See also setPoint().
This is an overloaded function.
Returns the point at the given index.
This is an overloaded function.
Copies nPoints points from the given fromIndex ( 0 by default) in fromPolygon into this polygon, starting at the specified index. For example:
QPolygon polygon1; polygon1.putPoints(0, 3, 1,2, 0,0, 5,6); // polygon1 is now the three-point polygon(1,2, 0,0, 5,6); QPolygon polygon2; polygon2.putPoints(0, 3, 4,4, 5,5, 6,6); // polygon2 is now (4,4, 5,5, 6,6); polygon1.putPoints(2, 3, polygon2); // polygon1 is now the five-point polygon(1,2, 0,0, 4,4, 5,5, 6,6);
Copies nPoints points from the variable argument list into this polygon from the given index.
The points are given as a sequence of integers, starting with firstx then firsty, and so on. The polygon is resized if index+nPoints exceeds its current size.
The example code creates a polygon with three points (4,5), (6,7) and (8,9), by expanding the polygon from 1 to 3 points:
QPolygon polygon(1); polygon[0] = QPoint(4, 5); polygon.putPoints(1, 2, 6,7, 8,9);
The following code has the same result, but here the putPoints() function overwrites rather than extends:
QPolygon polygon(3); polygon.putPoints(0, 3, 4,5, 0,0, 8,9); polygon.putPoints(1, 1, 6,7);
See also setPoints().
Sets the point at the given index to the point specified by (x, y).
See also point(), putPoints(), and setPoints().
This is an overloaded function.
Sets the point at the given index to the given point.
Resizes the polygon to nPoints and populates it with the given points.
The example code creates a polygon with two points (10, 20) and (30, 40):
static const int points[] = { 10, 20, 30, 40 };
QPolygon polygon;
polygon.setPoints(2, points); See also setPoint() and putPoints().
This is an overloaded function.
Resizes the polygon to nPoints and populates it with the points specified by the variable argument list. The points are given as a sequence of integers, starting with firstx then firsty, and so on.
The example code creates a polygon with two points (10, 20) and (30, 40):
QPolygon polygon; polygon.setPoints(2, 10, 20, 30, 40);
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.
Swaps polygon other with this polygon. This operation is very fast and never fails.
Translates all points in the polygon by (dx, dy).
See also translated().
This is an overloaded function.
Translates all points in the polygon by the given offset.
See also translated().
Returns a copy of the polygon that is translated by (dx, dy).
See also translate().
This is an overloaded function.
Returns a copy of the polygon that is translated by the given offset.
See also translate().
Returns a polygon which is the union of this polygon and r.
Set operations on polygons, will treat the polygons as areas, and implicitly close the polygon.
See also intersected() and subtracted().
Returns the polygon as a QVariant
Writes the given polygon to the given stream, and returns a reference to the stream.
See also Serializing Qt Data Types.
Reads a polygon from the given stream into the given polygon, and returns a reference to the stream.
See also Serializing Qt Data Types.
© The Qt Company Ltd
Licensed under the GNU Free Documentation License, Version 1.3.
https://doc.qt.io/qt-6.2/qpolygon.html