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Qt
Internal/Contributor docs for the Qt SDK. Note: These are NOT official API docs; those are found at https://doc.qt.io/
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Qt
Internal/Contributor docs for the Qt SDK. Note: These are NOT official API docs; those are found at https://doc.qt.io/
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\inmodule QtCore\compares equality \compareswith equality QLine \endcompareswith More...
#include <qline.h>
Public Types | |
| enum | IntersectionType { NoIntersection , BoundedIntersection , UnboundedIntersection } |
| \typealias QLineF::IntersectType More... | |
| using | IntersectType = IntersectionType |
Public Member Functions | |
| constexpr | QLineF () |
| Constructs a null line. | |
| constexpr | QLineF (const QPointF &pt1, const QPointF &pt2) |
| Constructs a line object that represents the line between p1 and p2. | |
| constexpr | QLineF (qreal x1, qreal y1, qreal x2, qreal y2) |
| Constructs a line object that represents the line between (x1, y1) and (x2, y2). | |
| constexpr | QLineF (const QLine &line) |
| Construct a QLineF object from the given integer-based line. | |
| constexpr bool | isNull () const |
Returns true if the line does not have distinct start and end points; otherwise returns false. | |
| constexpr QPointF | p1 () const |
| Returns the line's start point. | |
| constexpr QPointF | p2 () const |
| Returns the line's end point. | |
| constexpr qreal | x1 () const |
| Returns the x-coordinate of the line's start point. | |
| constexpr qreal | y1 () const |
| Returns the y-coordinate of the line's start point. | |
| constexpr qreal | x2 () const |
| Returns the x-coordinate of the line's end point. | |
| constexpr qreal | y2 () const |
| Returns the y-coordinate of the line's end point. | |
| constexpr qreal | dx () const |
| Returns the horizontal component of the line's vector. | |
| constexpr qreal | dy () const |
| Returns the vertical component of the line's vector. | |
| qreal | length () const |
| Returns the length of the line. | |
| void | setLength (qreal len) |
| Sets the length of the line to the given finite length. | |
| qreal | angle () const |
| void | setAngle (qreal angle) |
| qreal | angleTo (const QLineF &l) const |
| 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. | |
| constexpr QLineF | normalVector () const |
| Returns a line that is perpendicular to this line with the same starting point and length. | |
| IntersectionType | intersects (const QLineF &l, QPointF *intersectionPoint=nullptr) const |
| constexpr QPointF | pointAt (qreal t) const |
| Returns the point at the position specified by finite parameter t. | |
| constexpr void | translate (const QPointF &p) |
| Translates this line by the given offset. | |
| constexpr void | translate (qreal dx, qreal dy) |
| This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Translates this line the distance specified by dx and dy. | |
| constexpr QLineF | translated (const QPointF &p) const |
| constexpr QLineF | translated (qreal dx, qreal dy) const |
| This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. | |
| constexpr QPointF | center () const |
| void | setP1 (const QPointF &p1) |
| void | setP2 (const QPointF &p2) |
| void | setPoints (const QPointF &p1, const QPointF &p2) |
| void | setLine (qreal x1, qreal y1, qreal x2, qreal y2) |
| constexpr QLine | toLine () const |
| Returns an integer-based copy of this line. | |
Static Public Member Functions | |
| static QLineF | fromPolar (qreal length, qreal angle) |
Friends | |
| constexpr bool | comparesEqual (const QLineF &lhs, const QLineF &rhs) noexcept |
| constexpr bool | comparesEqual (const QLineF &lhs, const QLine &rhs) noexcept |
| constexpr bool | qFuzzyCompare (const QLineF &lhs, const QLineF &rhs) noexcept |
| constexpr bool | qFuzzyIsNull (const QLineF &line) noexcept |
Related Symbols | |
(Note that these are not member symbols.) | |
| QDataStream & | operator<< (QDataStream &stream, const QLineF &line) |
| Writes the given line to the given stream and returns a reference to the stream. | |
| QDataStream & | operator>> (QDataStream &stream, QLineF &line) |
| Reads a line from the given stream into the given line and returns a reference to the stream. | |
\inmodule QtCore
\compares equality \compareswith equality QLine \endcompareswith
The 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.
\table \row
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.
\typealias QLineF::IntersectType
Describes the intersection between two lines.
\table \row
\value NoIntersection Indicates that the lines do not intersect; i.e. they are parallel.
\value 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.
\value BoundedIntersection The two lines intersect with each other within the start and end points of each line.
Describes the intersection between two lines.
\table \row
\value NoIntersection Indicates that the lines do not intersect; i.e. they are parallel.
\value 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.
\value BoundedIntersection The two lines intersect with each other within the start and end points of each line.
| Enumerator | |
|---|---|
| NoIntersection | |
| BoundedIntersection | |
| UnboundedIntersection | |
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inlineconstexpr |
Construct a QLineF object from the given integer-based line.
| 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).
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 \l{intersects()}{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.
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inlinenodiscardconstexpr |
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inlineconstexpr |
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inlineconstexpr |
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.
| QLineF::IntersectionType QLineF::intersects | ( | const QLineF & | line, |
| QPointF * | intersectionPoint = nullptr ) const |
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inlineconstexpr |
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.
true for lines whose length() is not zero.| qreal QLineF::length | ( | ) | const |
Returns the length of the line.
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inlinenodiscardconstexpr |
Returns a line that is perpendicular to this line with the same starting point and length.
{Diagram showing two vectors with the same starting point: (v_x, v_y) and (vy, -vx).}
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inlineconstexpr |
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inlineconstexpr |
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.
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inlineconstexpr |
Returns an integer-based copy of this line.
Note that the returned line's start and end points are rounded to the nearest integer.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Translates this line the distance specified by dx and dy.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Returns this line translated the distance specified by dx and dy.
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nodiscard |
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.
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inlineconstexpr |
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inlineconstexpr |
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inlineconstexpr |
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inlineconstexpr |
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1.16.1