QPointF Class

  QPointF p;

  p.setX(p.x() + 1.0);
  p += QPointF(1.0, 0.0);
  p.rx()++;

成员函数

QPointF::QPointF()

Constructs a null point, i.e. with coordinates (0.0, 0.0)

参见 isNull().

QPointF::QPointF(const QPoint &point)

Constructs a copy of the given point.

参见 toPoint().

QPointF::QPointF(qreal xpos, qreal ypos)

Constructs a point with the given coordinates (xpos, ypos).

参见 setX() and setY().

[static] qreal QPointF::dotProduct(const QPointF &p1, const QPointF &p2)

  QPointF p( 3.1, 7.1);
  QPointF q(-1.0, 4.1);
  int lengthSquared = QPointF::dotProduct(p, q);   // lengthSquared becomes 26.01

Returns the dot product of p1 and p2.

This function was introduced in Qt 5.1.

[static] QPointF QPointF::fromCGPoint(CGPoint point)

Creates a QRectF from CGPoint point.

This function was introduced in Qt 5.8.

参见 toCGPoint().

bool QPointF::isNull() const

Returns true if both the x and y coordinates are set to 0.0 (ignoring the sign); otherwise returns false.

qreal QPointF::manhattanLength() const

Returns the sum of the absolute values of x() and y(), traditionally known as the "Manhattan length" of the vector from the origin to the point.

This function was introduced in Qt 4.6.

参见 QPoint::manhattanLength().

qreal &QPointF::rx()

Returns a reference to the x coordinate of this point.

Using a reference makes it possible to directly manipulate x. For example:

   QPointF p(1.1, 2.5);
   p.rx()--;   // p becomes (0.1, 2.5)

参见 x() and setX().

qreal &QPointF::ry()

Returns a reference to the y coordinate of this point.

Using a reference makes it possible to directly manipulate y. For example:

  QPointF p(1.1, 2.5);
  p.ry()++;   // p becomes (1.1, 3.5)

参见 y() and setY().

void QPointF::setX(qreal x)

Sets the x coordinate of this point to the given x coordinate.

参见 x() and setY().

void QPointF::setY(qreal y)

Sets the y coordinate of this point to the given y coordinate.

参见 y() and setX().

CGPoint QPointF::toCGPoint() const

Creates a CGPoint from a QPointF.

This function was introduced in Qt 5.8.

参见 fromCGPoint().

QPoint QPointF::toPoint() const

Rounds the coordinates of this point to the nearest integer, and returns a QPoint object with the rounded coordinates.

参见 QPointF().

qreal QPointF::x() const

Returns the x coordinate of this point.

参见 setX() and rx().

qreal QPointF::y() const

Returns the y coordinate of this point.

参见 setY() and ry().

QPointF &QPointF::operator*=(qreal factor)

Multiplies this point's coordinates by the given factor, and returns a reference to this point. For example:

  QPointF p(-1.1, 4.1);
  p *= 2.5;    // p becomes (-2.75, 10.25)

参见 operator/=().

QPointF &QPointF::operator+=(const QPointF &point)

Adds the given point to this point and returns a reference to this point. For example:

  QPointF p( 3.1, 7.1);
  QPointF q(-1.0, 4.1);
  p += q;    // p becomes (2.1, 11.2)

参见 operator-=().

QPointF &QPointF::operator-=(const QPointF &point)

Subtracts the given point from this point and returns a reference to this point. For example:

  QPointF p( 3.1, 7.1);
  QPointF q(-1.0, 4.1);
  p -= q;    // p becomes (4.1, 3.0)

参见 operator+=().

QPointF &QPointF::operator/=(qreal divisor)

Divides both x and y by the given divisor, and returns a reference to this point. For example:

  QPointF p(-2.75, 10.25);
  p /= 2.5;           // p becomes (-1.1, 4.1)

参见 operator*=().