QLineF Class ReferenceThe QLineF class provides a two-dimensional vector using floating point precision. Далее... #include <QLineF>
Открытые типы
Открытые функции
Статические открытые члены
Связанные нечлены класса
Подробное описаниеThe 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.
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 intersect() function determines the IntersectType for this line and a given line, while the angle() 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. See also QLine, QPolygonF, and QRectF. Описание типов-членовenum QLineF::IntersectTypeDescribes the intersection between two lines.
intersect() will also return this value if the intersect point is within the start and end point of only one of the lines.
Смотрите также intersect(). Описание функций-членовQLineF::QLineF ()Constructs a null line. QLineF::QLineF ( const QPointF & p1, const QPointF & p2 )Constructs a line object that represents the line between p1 and p2. QLineF::QLineF ( qreal x1, qreal y1, qreal x2, qreal y2 )Constructs a line object that represents the line between (x1, y1) and (x2, y2). QLineF::QLineF ( const QLine & line )Construct a QLineF object from the given integer-based line. See also toLine(). QPointF QLineF::p1 () constReturns the line's start point. See also setP1(), x1(), y1(), and p2(). QPointF QLineF::p2 () constReturns the line's end point. See also setP2(), x2(), y2(), and p1(). qreal QLineF::x1 () constReturns the x-coordinate of the line's start point. See also p1(). qreal QLineF::x2 () constReturns the x-coordinate of the line's end point. See also p2(). qreal QLineF::y1 () constReturns the y-coordinate of the line's start point. See also p1(). qreal QLineF::y2 () constReturns the y-coordinate of the line's end point. See also p2(). qreal QLineF::angle () constReturns 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). Эта функция была введена в Qt 4.4. See also setAngle(). qreal QLineF::angleTo ( const QLineF & line ) constReturns the angle (in positive degrees) from this line to the given line, taking the direction of the lines into account. Если линии не пересекаются в своем диапазоне, то это точка пересечения продолженных линий, которая выступает в качестве начала координат (смотрите 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. Эта функция была введена в Qt 4.4. Смотрите также intersect(). qreal QLineF::dx () constReturns the horizontal component of the line's vector. Return value is positive if x2() >= x1() and negative if x2() < x1(). qreal QLineF::dy () constReturns the vertical component of the line's vector. Return value is positive if y2() >= y1() and negative if y2() < y1(). QLineF QLineF::fromPolar ( qreal length, qreal angle ) [static]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. Ноль градусов соответствует 3-часовой отметке. Эта функция была введена в Qt 4.4. IntersectType QLineF::intersect ( const QLineF & line, QPointF * intersectionPoint ) constReturns 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. bool QLineF::isNull () constReturns true if the line is not set up with valid start and end point; otherwise returns false. qreal QLineF::length () constReturns the length of the line. See also setLength(). QLineF QLineF::normalVector () constReturns a line that is perpendicular to this line with the same starting point and length.
See also unitVector(). QPointF QLineF::pointAt ( qreal t ) constReturns 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. void QLineF::setP1 ( const QPointF & p1 )Sets the starting point of this line to p1. Эта функция была введена в Qt 4.4. void QLineF::setP2 ( const QPointF & p2 )Sets the end point of this line to p2. Эта функция была введена в Qt 4.4. 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. Positive values for the angles mean counter-clockwise while negative values mean the clockwise direction. Ноль градусов соответствует 3-часовой отметке. Эта функция была введена в Qt 4.4. See also angle(). void QLineF::setLength ( qreal length )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 given length is negative the angle() is also changed. If the line is a null line, the length will remain zero regardless of the length specified. See also length() and isNull(). 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. Эта функция была введена в Qt 4.4. See also setP1(), setP2(), p1(), and 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. Эта функция была введена в Qt 4.4. See also setP1(), setP2(), p1(), and p2(). QLine QLineF::toLine () constReturns an integer based copy of this line. Note that the returned line's start and end points are rounded to the nearest integer. See also QLineF(). void QLineF::translate ( const QPointF & offset )Translates this line by the given offset. void QLineF::translate ( qreal dx, qreal dy )Это перегруженная функция. Translates this line the distance specified by dx and dy. QLineF QLineF::translated ( const QPointF & offset ) constReturns this line translated by the given offset. Эта функция была введена в Qt 4.4. QLineF QLineF::translated ( qreal dx, qreal dy ) constЭто перегруженная функция. Returns this line translated the distance specified by dx and dy. Эта функция была введена в Qt 4.4. QLineF QLineF::unitVector () constReturns the unit vector for this line, i.e a line starting at the same point as this line with a length of 1.0. See also normalVector(). bool QLineF::operator!= ( const QLineF & line ) constReturns true if the given 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. bool QLineF::operator== ( const QLineF & line ) constReturns true if the given 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. Связанные нечлены классаQDataStream & operator<< ( QDataStream & stream, const QLineF & line )Writes the given line to the given stream and returns a reference to the stream. Смотрите также Преобразование типов данных Qt в последовательный вид. QDataStream & operator>> ( QDataStream & stream, QLineF & line )Reads a line from the given stream into the given line and returns a reference to the stream. Смотрите также Преобразование типов данных Qt в последовательный вид. |
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