QLineF class provides a two-dimensional vector using floating point precision. 更多...
| 头： | #include <QLineF> |
| qmake: | QT += core |
| enum | IntersectType { NoIntersection, UnboundedIntersection, BoundedIntersection } |
| 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 |
| IntersectType | intersect (const QLineF & line , QPointF * intersectionPoint ) 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 |
| QLineF | fromPolar (qreal length , qreal angle ) |
| QDataStream & | operator<< (QDataStream & stream , const QLineF & line ) |
| QDataStream & | operator>> (QDataStream & stream , QLineF & line ) |
QLineF class provides a two-dimensional vector using floating point precision.
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.
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|
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.
intersect () function determines the IntersectType 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。
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.
另请参阅 QLine , QPolygonF ，和 QRectF .
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.
| 常量 | 值 | 描述 |
|---|---|---|
QLineF::BoundedIntersection
|
1
|
The two lines intersect with each other within the start and end points of each line. |
另请参阅 intersect ().
构造 null 线条。
构造的线条对象表示线条介于 p1 and p2 .
Constructs a line object that represents the line between ( x1 , y1 ) 和 ( x2 , y2 ).
构造 QLineF object from the given integer-based line .
另请参阅 toLine ().
返回线条的起始点。
另请参阅 setP1 (), x1 (), y1 ()，和 p2 ().
返回线条的结束点。
另请参阅 setP2 (), x2 (), y2 ()，和 p1 ().
返回线条起始点的 X 坐标。
另请参阅 p1 ().
返回线条结束点的 X 坐标。
另请参阅 p2 ().
返回线条起始点的 Y 坐标。
另请参阅 p1 ().
返回线条结束点的 Y 坐标。
另请参阅 p2 ().
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).
该函数在 Qt 4.4 引入。
另请参阅 setAngle ().
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.
该函数在 Qt 4.4 引入。
另请参阅 intersect ().
Returns the center point of this line. This is equivalent to 0.5 * p1 () + 0.5 * p2 ().
该函数在 Qt 5.8 引入。
Returns the horizontal component of the line's vector.
Returns the vertical component of the line's vector.
[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.
Positive values for the angles mean counter-clockwise while negative values mean the clockwise direction. Zero degrees is at the 3 o'clock position.
该函数在 Qt 4.4 引入。
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.
返回
true
if the line is not set up with valid start and end point; otherwise returns
false
.
Returns the length of the line.
另请参阅 setLength ().
Returns a line that is perpendicular to this line with the same starting point and length.
另请参阅 unitVector ().
Returns the point at the parameterized position specified by t . The function returns the line's start point if t = 0, and its end point if t = 1.
Sets the starting point of this line to p1 .
该函数在 Qt 4.4 引入。
Sets the end point of this line to p2 .
该函数在 Qt 4.4 引入。
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.
Positive values for the angles mean counter-clockwise while negative values mean the clockwise direction. Zero degrees is at the 3 o'clock position.
该函数在 Qt 4.4 引入。
另请参阅 angle ().
Sets the length of the line to the given length . QLineF will move the end point - p2 () - of the line to give the line its new length.
If the line is a null line, the length will remain zero regardless of the length specified.
Sets this line to the start in x1 , y1 and end in x2 , y2 .
该函数在 Qt 4.4 引入。
另请参阅 setP1 (), setP2 (), p1 ()，和 p2 ().
Sets the start point of this line to p1 and the end point of this line to p2 .
该函数在 Qt 4.4 引入。
另请参阅 setP1 (), setP2 (), p1 ()，和 p2 ().
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 ().
Translates this line by the given offset .
这是重载函数。
Translates this line the distance specified by dx and dy .
Returns this line translated by the given offset .
该函数在 Qt 4.4 引入。
这是重载函数。
Returns this line translated the distance specified by dx and dy .
该函数在 Qt 4.4 引入。
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.
另请参阅 normalVector ().
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.
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.
写入给定 line 到给定 stream 并返回流引用。
另请参阅 序列化 Qt 数据类型 .
Reads a line from the given stream 进给定 line 并返回流引用。
另请参阅 序列化 Qt 数据类型 .