class QLineF#

The QLineF class provides a two-dimensional vector using floating point precision. More…

Synopsis#

Methods#

def __init__()
def __reduce__()
def __repr__()
def angle()
def angleTo()
def center()
def dx()
def dy()
def intersects()
def isNull()
def length()
def normalVector()
def __ne__()
def __mul__()
def __eq__()
def p1()
def p2()
def pointAt()
def setAngle()
def setLength()
def setLine()
def setP1()
def setP2()
def setPoints()
def toLine()
def toTuple()
def translate()
def translated()
def unitVector()
def x1()
def x2()
def y1()
def y2()

Static functions#

def fromPolar()

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description#

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() , and y2() functions. The dx() and dy() functions return the horizontal and vertical components of the line, respectively.

The line’s length can be retrieved using the length() function, and altered using the setLength() function. Similarly, angle() and 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() function.

Constraints#

QLine is limited to the minimum and maximum values for the int type. Operations on a QLine that could potentially result in values outside this range will result in undefined behavior.

See also

QLine QRectF

class IntersectionType#

Describes the intersection between two lines.

QLineF::UnboundedIntersection

QLineF::BoundedIntersection

Constant

Description

QLineF.NoIntersection

Indicates that the lines do not intersect; i.e. they are parallel.

QLineF.UnboundedIntersection

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

The two lines intersect with each other within the start and end points of each line.

See also

intersects()

Constant	Description
QLineF.NoIntersection	Indicates that the lines do not intersect; i.e. they are parallel.
QLineF.UnboundedIntersection	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	The two lines intersect with each other within the start and end points of each line.

__init__(line)#

Parameters:: line – QLine

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

See also

toLine() toLineF()

__init__()

Constructs a null line.

__init__(x1, y1, x2, y2)

Parameters:

x1 – float
y1 – float
x2 – float
y2 – float

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

__init__(pt1, pt2)

Parameters:

pt1 – QPointF
pt2 – QPointF

Constructs a line object that represents the line between p1 and p2.

__reduce__()#

Return type:: object

__repr__()#

Return type:: object

angle()#

Return type:: float

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).

See also

setAngle()

angleTo(l)#

Parameters:: l – QLineF
Return type:: float

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 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.

See also

intersects()

center()#

Return type:: QPointF

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

dx()#

Return type:: float

Returns the horizontal component of the line’s vector.

See also

dy() pointAt()

dy()#

Return type:: float

Returns the vertical component of the line’s vector.

See also

dx() pointAt()

static fromPolar(length, angle)#

Parameters:

length – float
angle – float

Return type:

QLineF

Returns a QLineF with the given length and angle.

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

Positive values for the angles mean counter-clockwise while negative values mean the clockwise direction. Zero degrees is at the 3 o’clock position.

intersects(l)#

Parameters:: l – QLineF
Return type:: (intersectType, intersectionPoint)

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.

isNull()#

Return type:: bool

Returns 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.

Note

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