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TheQLineF class provides a two-dimensional vector using floating point precision.More...
| Header: | #include <QLineF> |
| 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 |
| 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) |
TheQLineF class provides a two-dimensional vector using floating point precision.
AQLineF 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 thetoLine() function to retrieve an integer based copy of this line.
 |  |
The positions of the line's start and end points can be retrieved using thep1(),x1(),y1(),p2(),x2(), andy2() functions. Thedx() anddy() functions return the horizontal and vertical components of the line, respectively.
The line's length can be retrieved using thelength() function, and altered using thesetLength() function. Similarly,angle() andsetAngle() are respectively used for retrieving and altering the angle of the line. Use theisNull() function to determine whether theQLineF represents a valid line or a null line.
Theintersect() function determines theIntersectType for this line and a given line, while theangleTo() function returns the angle between the lines. In addition, theunitVector() function returns a line that has the same starting point as this line, but with a length of only 1, while thenormalVector() 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 thetranslate() function, and can be traversed using thepointAt() function.
See alsoQLine,QPolygonF, andQRectF.
Describes the intersection between two lines.
 |  |
| QLineF::UnboundedIntersection | QLineF::BoundedIntersection |
| Constant | Value | Description |
|---|---|---|
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.
| Constant | Value | Description |
|---|---|---|
QLineF::BoundedIntersection | 1 | The two lines intersect with each other within the start and end points of each line. |
See alsointersect().
Constructs a null line.
Constructs a line object that represents the line betweenp1 andp2.
Constructs a line object that represents the line between (x1,y1) and (x2,y2).
Construct aQLineF object from the given integer-basedline.
See alsotoLine().
Returns the line's start point.
See alsosetP1(),x1(),y1(), andp2().
Returns the line's end point.
See alsosetP2(),x2(),y2(), andp1().
Returns the x-coordinate of the line's start point.
See alsop1().
Returns the x-coordinate of the line's end point.
See alsop2().
Returns the y-coordinate of the line's start point.
See alsop1().
Returns the y-coordinate of the line's end point.
See alsop2().
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).
This function was introduced in Qt 4.4.
See alsosetAngle().
Returns the angle (in positive degrees) from this line to the givenline, 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 (seeQLineF::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 givenline, going counter-clockwise.
This function was introduced in Qt 4.4.
See alsointersect().
Returns the horizontal component of the line's vector. Return value is positive ifx2() >=x1() and negative ifx2() <x1().
Returns the vertical component of the line's vector. Return value is positive ify2() >=y1() and negative ify2() <y1().
[static]QLineF QLineF::fromPolar(qreal length,qreal angle)Returns aQLineF with the givenlength andangle.
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.
This function was introduced in Qt 4.4.
Returns a value indicating whether or notthis line intersects with the givenline.
The actual intersection point is extracted tointersectionPoint (if the pointer is valid). If the lines are parallel, the intersection point is undefined.
Returns true if the line is not set up with valid start and end point; otherwise returns false.
Returns the length of the line.
See alsosetLength().
Returns a line that is perpendicular to this line with the same starting point and length.
See alsounitVector().
Returns the point at the parameterized position specified byt. 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 top1.
This function was introduced in Qt 4.4.
Sets the end point of this line top2.
This function was introduced in Qt 4.4.
Sets the angle of the line to the givenangle (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.
This function was introduced in Qt 4.4.
See alsoangle().
Sets the length of the line to the givenlength.QLineF will move the end point -p2() - of the line to give the line its new length. If the givenlength is negative theangle() is also changed.
If the line is a null line, the length will remain zero regardless of the length specified.
Sets this line to the start inx1,y1 and end inx2,y2.
This function was introduced in Qt 4.4.
See alsosetP1(),setP2(),p1(), andp2().
Sets the start point of this line top1 and the end point of this line top2.
This function was introduced in Qt 4.4.
See alsosetP1(),setP2(),p1(), andp2().
Returns an integer based copy of this line.
Note that the returned line's start and end points are rounded to the nearest integer.
See alsoQLineF().
Translates this line by the givenoffset.
This is an overloaded function.
Translates this line the distance specified bydx anddy.
Returns this line translated by the givenoffset.
This function was introduced in Qt 4.4.
This is an overloaded function.
Returns this line translated the distance specified bydx anddy.
This function was introduced in Qt 4.4.
Returns the unit vector for this line, i.e a line starting at the same point asthis line with a length of 1.0.
See alsonormalVector().
Returns true if the givenline is not the same asthis line.
A line is different from another line if their start or end points differ, or the internal order of the points is different.
Returns true if the givenline 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.
Writes the givenline to the givenstream and returns a reference to the stream.
See alsoSerializing Qt Data Types.
Reads a line from the givenstream into the givenline and returns a reference to the stream.
See alsoSerializing Qt Data Types.
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