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The QPolygon class provides a vector of points using integer precision. More...
#include <QPolygon>
Inherits QVector<QPoint>.
Inherited by Q3PointArray.
Note: All the functions in this class are reentrant.
The QPolygon class provides a vector of points using integer precision.
A QPolygon object is a QVector<QPoint>. The easiest way to add points to a QPolygon is to use QVector's streaming operator, as illustrated below:
QPolygon polygon;
polygon << QPoint(10, 20) << QPoint(20, 30);
In addition to the functions provided by QVector, 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 QMatrix::map() function for more general transformations of QPolygons.
The QPolygon class is implicitly shared.
See also QVector, QPolygonF, and QLine.
Constructs a polygon with no points.
See also QVector::isEmpty().
Constructs a polygon of the given size. Creates an empty polygon if size == 0.
See also QVector::isEmpty().
Constructs a copy of the given polygon.
See also setPoints().
Constructs a polygon containing the specified points.
See also setPoints().
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().
Destroys the polygon.
Returns the bounding rectangle of the polygon, or QRect(0, 0, 0, 0) if the polygon is empty.
See also QVector::isEmpty().
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.
Returns a polygon which is the intersection of this polygon and r.
This function was introduced in Qt 4.3.
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 member function, provided for convenience.
Returns the point at the given index.
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().
This is an overloaded member function, provided for convenience.
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);
Sets the point at the given index to the point specified by (x, y).
See also point(), putPoints(), and setPoints().
This is an overloaded member function, provided for convenience.
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 member function, provided for convenience.
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.
This function was introduced in Qt 4.3.
Translates all points in the polygon by (dx, dy).
This is an overloaded member function, provided for convenience.
Translates all points in the polygon by the given offset.
Returns a polygon which is the union of this polygon and r.
This function was introduced in Qt 4.3.
See also intersected() and subtracted().
Returns the polygon as a QVariant
This is an overloaded member function, provided for convenience.
Writes the given polygon to the given stream, and returns a reference to the stream.
This function was introduced in Qt 4.4.
See also Format of the QDataStream Operators.
This is an overloaded member function, provided for convenience.
Reads a polygon from the given stream into the given polygon, and returns a reference to the stream.
This function was introduced in Qt 4.4.
See also Format of the QDataStream Operators.
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