QLineF 类

QLineF 类提供使用浮点精度的 2D 向量。更多...

头：	#include <QLineF>
CMake:	find_package(Qt6 REQUIRED COMPONENTS Core) target_link_libraries(mytarget PRIVATE Qt6::Core)
qmake:	QT += core

公共类型

enum	IntersectionType { NoIntersection, UnboundedIntersection, BoundedIntersection }

公共函数

	QLineF ()
	QLineF (const QPointF & p1 , const QPointF & p2 )
	QLineF (qreal x1 , qreal y1 , qreal x2 , qreal y2 )
	QLineF (const QLine & line )
QPointF	p1 () const
QPointF	p2 () const
qreal	x1 () const
qreal	x2 () const
qreal	y1 () const
qreal	y2 () const
qreal	angle () const
qreal	angleTo (const QLineF & line ) const
QPointF	center () const
qreal	dx () const
qreal	dy () const
QLineF::IntersectionType	intersects (const QLineF & line , QPointF * intersectionPoint = nullptr) const
bool	isNull () const
qreal	length () const
QLineF	normalVector () const
QPointF	pointAt (qreal t ) const
void	setP1 (const QPointF & p1 )
void	setP2 (const QPointF & p2 )
void	setAngle (qreal angle )
void	setLength (qreal length )
void	setLine (qreal x1 , qreal y1 , qreal x2 , qreal y2 )
void	setPoints (const QPointF & p1 , const QPointF & p2 )
QLine	toLine () const
void	translate (const QPointF & offset )
void	translate (qreal dx , qreal dy )
QLineF	translated (const QPointF & offset ) const
QLineF	translated (qreal dx , qreal dy ) const
QLineF	unitVector () const
bool	operator!= (const QLineF & line ) const
bool	operator== (const QLineF & line ) const

静态公共成员

QLineF

fromPolar (qreal length , qreal angle )

QDataStream &	operator<< (QDataStream & stream , const QLineF & line )
QDataStream &	operator>> (QDataStream & stream , QLineF & line )

详细描述

A QLineF describes a finite length line (or line segment) on a two-dimensional surface. QLineF defines the start and end points of the line using floating point accuracy for coordinates. Use the toLine () function to retrieve an integer-based copy of this line.

The positions of the line's start and end points can be retrieved using the p1 (), x1 (), y1 (), p2 (), x2 ()，和 y2 () 函数。 dx () 和 dy () functions return the horizontal and vertical components of the line, respectively.

The line's length can be retrieved using the length () 函数，和变更使用 setLength () function. Similarly, angle () 和 setAngle () are respectively used for retrieving and altering the angle of the line. Use the isNull () function to determine whether the QLineF represents a valid line or a null line.

The intersects () function determines the IntersectionType for this line and a given line, while the angleTo () function returns the angle between the lines. In addition, the unitVector () function returns a line that has the same starting point as this line, but with a length of only 1, while the normalVector () function returns a line that is perpendicular to this line with the same starting point and length.

Finally, the line can be translated a given offset using the translate () function, and can be traversed using the pointAt () 函数。

约束

QLine 被限制到最小和最大值是由于 int 类型。操作 QLine 潜在可能导致值超出此范围，会产生未定义行为。

另请参阅 QLine , QPolygonF ，和 QRectF .

成员类型文档编制

enum QLineF:: IntersectionType

Describes the intersection between two lines.


QLineF::UnboundedIntersection	QLineF::BoundedIntersection

常量	值	描述
`QLineF::NoIntersection`	`0`	Indicates that the lines do not intersect; i.e. they are parallel.
`QLineF::UnboundedIntersection`	`2`	The two lines intersect, but not within the range defined by their lengths. This will be the case if the lines are not parallel. intersect() will also return this value if the intersect point is within the start and end point of only one of the lines.
`QLineF::BoundedIntersection`	`1`	The two lines intersect with each other within the start and end points of each line.

另请参阅 intersects ().

成员函数文档编制

`[constexpr]` QLineF:: QLineF ()

构造 null 线条。

`[constexpr]` QLineF:: QLineF (const QPointF & p1 , const QPointF & p2 )

构造的线条对象表示线条介于 p1 and p2 .

`[constexpr]` QLineF:: QLineF ( qreal x1 , qreal y1 , qreal x2 , qreal y2 )

Constructs a line object that represents the line between ( x1 , y1 ) 和 ( x2 , y2 ).

`[constexpr]` QLineF:: QLineF (const QLine & line )

Construct a QLineF object from the given integer-based line .

另请参阅 toLine () 和 QLine::toLineF ().

`[constexpr]` QPointF QLineF:: p1 () const

返回线条的起始点。

另请参阅 setP1 (), x1 (), y1 ()，和 p2 ().

`[constexpr]` QPointF QLineF:: p2 () const

返回线的终点。

另请参阅 setP2 (), x2 (), y2 ()，和 p1 ().

`[constexpr]` qreal QLineF:: x1 () const

返回线条起始点的 X 坐标。

另请参阅 p1 ().

`[constexpr]` qreal QLineF:: x2 () const

返回线终点的 X 坐标。

另请参阅 p2 ().

`[constexpr]` qreal QLineF:: y1 () const

返回线条起始点的 Y 坐标。

另请参阅 p1 ().

`[constexpr]` qreal QLineF:: y2 () const

返回线终点的 Y 坐标。

另请参阅 p2 ().

qreal QLineF:: angle () const

Returns the angle of the line in degrees.

The return value will be in the range of values from 0.0 up to but not including 360.0. The angles are measured counter-clockwise from a point on the x-axis to the right of the origin (x > 0).

另请参阅 setAngle ().

qreal QLineF:: angleTo (const QLineF & line ) const

Returns the angle (in degrees) from this line to the given line , taking the direction of the lines into account. If the lines do not intersect within their range, it is the intersection point of the extended lines that serves as origin (see QLineF::UnboundedIntersection ).

The returned value represents the number of degrees you need to add to this line to make it have the same angle as the given line , going counter-clockwise.

另请参阅 intersects ().

`[constexpr]` QPointF QLineF:: center () const

Returns the center point of this line. This is equivalent to 0.5 * p1 () + 0.5 * p2 ().

`[constexpr]` qreal QLineF:: dx () const

Returns the horizontal component of the line's vector.

另请参阅 dy () 和 pointAt ().

`[constexpr]` qreal QLineF:: dy () const

Returns the vertical component of the line's vector.

另请参阅 dx () 和 pointAt ().

`[static]` QLineF QLineF:: fromPolar ( qreal length , qreal angle )

返回 QLineF 采用给定 length and angle .

The first point of the line will be on the origin.

正值角度意味着逆时针方向，而负值意味着顺时针方向。0 度位于 3 点钟位置。

QLineF::IntersectionType QLineF:: intersects (const QLineF & line , QPointF * intersectionPoint = nullptr) const

Returns a value indicating whether or not this line intersects with the given line .

The actual intersection point is extracted to intersectionPoint (if the pointer is valid). If the lines are parallel, the intersection point is undefined.

`[constexpr]` bool QLineF:: isNull () const

返回 true if the line does not have distinct start and end points; otherwise returns false . The start and end points are considered distinct if qFuzzyCompare () can distinguish them in at least one coordinate.

注意： Due to the use of fuzzy comparison, isNull() may return true for lines whose length () is not zero.

另请参阅 qFuzzyCompare () 和 length ().

qreal QLineF:: length () const

Returns the length of the line.

另请参阅 setLength () 和 isNull ().

`[constexpr]` QLineF QLineF:: normalVector () const

Returns a line that is perpendicular to this line with the same starting point and length.

另请参阅 unitVector ().

`[constexpr]` QPointF QLineF:: pointAt ( qreal t ) const

Returns the point at the position specified by finite parameter t . The function returns the line's start point if t = 0, and its end point if t = 1.

另请参阅 dx () 和 dy ().

void QLineF:: setP1 (const QPointF & p1 )

Sets the starting point of this line to p1 .

另请参阅 setP2 () 和 p1 ().

void QLineF:: setP2 (const QPointF & p2 )

Sets the end point of this line to p2 .

另请参阅 setP1 () 和 p2 ().

void QLineF:: setAngle ( qreal angle )

Sets the angle of the line to the given angle (in degrees). This will change the position of the second point of the line such that the line has the given angle.

正值角度意味着逆时针方向，而负值意味着顺时针方向。0 度位于 3 点钟位置。

另请参阅 angle ().

void QLineF:: setLength ( qreal length )

Sets the length of the line to the given finite length . QLineF will move the end point - p2 () - of the line to give the line its new length, unless length () was previously zero, in which case no scaling is attempted.

另请参阅 length () 和 unitVector ().

void QLineF:: setLine ( qreal x1 , qreal y1 , qreal x2 , qreal y2 )

Sets this line to the start in x1 , y1 and end in x2 , y2 .

另请参阅 setP1 (), setP2 (), p1 ()，和 p2 ().

void QLineF:: setPoints (const QPointF & p1 , const QPointF & p2 )

Sets the start point of this line to p1 and the end point of this line to p2 .

另请参阅 setP1 (), setP2 (), p1 ()，和 p2 ().

`[constexpr]` QLine QLineF:: toLine () const

Returns an integer-based copy of this line.

Note that the returned line's start and end points are rounded to the nearest integer.

另请参阅 QLineF () 和 QLine::toLineF ().

void QLineF:: translate (const QPointF & offset )

Translates this line by the given offset .

void QLineF:: translate ( qreal dx , qreal dy )

这是重载函数。

Translates this line the distance specified by dx and dy .

`[constexpr]` QLineF QLineF:: translated (const QPointF & offset ) const

Returns this line translated by the given offset .

`[constexpr]` QLineF QLineF:: translated ( qreal dx , qreal dy ) const

这是重载函数。

Returns this line translated the distance specified by dx and dy .

QLineF QLineF:: unitVector () const

Returns the unit vector for this line, i.e a line starting at the same point as this line with a length of 1.0, provided the line is non-null.

另请参阅 normalVector () 和 setLength ().

`[constexpr]` bool QLineF:: operator!= (const QLineF & line ) const

返回 true 若给定 line is not the same as this line.

A line is different from another line if their start or end points differ, or the internal order of the points is different.

`[constexpr]` bool QLineF:: operator== (const QLineF & line ) const

返回 true 若给定 line is the same as this line.

A line is identical to another line if the start and end points are identical, and the internal order of the points is the same.

QLineF 类

公共类型

公共函数

静态公共成员

相关非成员

详细描述

约束

成员类型文档编制

enum QLineF:: IntersectionType

成员函数文档编制

[constexpr] QLineF:: QLineF ()

[constexpr] QLineF:: QLineF (const QPointF & p1 , const QPointF & p2 )

[constexpr] QLineF:: QLineF ( qreal x1 , qreal y1 , qreal x2 , qreal y2 )

[constexpr] QLineF:: QLineF (const QLine & line )

[constexpr] QPointF QLineF:: p1 () const

[constexpr] QPointF QLineF:: p2 () const

[constexpr] qreal QLineF:: x1 () const

[constexpr] qreal QLineF:: x2 () const

[constexpr] qreal QLineF:: y1 () const

[constexpr] qreal QLineF:: y2 () const