Viadeo Twitter Google Bookmarks ! Facebook Digg del.icio.us MySpace Yahoo MyWeb Blinklist Netvouz Reddit Simpy StumbleUpon Bookmarks Windows Live Favorites 
Logo Documentation Qt ·  Page d'accueil  ·  Tous les espaces de nom  ·  Toutes les classes  ·  Classes principales  ·  Annotées  ·  Classes groupées  ·  Modules  ·  Fonctions  · 

QLineF Class Reference
[QtCore module]

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

 #include <QLineF>

Public Types

  • enum IntersectType { NoIntersection, UnboundedIntersection, BoundedIntersection }

Public Functions

  • 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

Static Public Members

  • QLineF fromPolar ( qreal length, qreal angle )

Related Non-Members

  • QDataStream & operator<< ( QDataStream & stream, const QLineF & line )
  • QDataStream & operator>> ( QDataStream & stream, QLineF & line )

Detailed Description

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.

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.


Member Type Documentation

enum QLineF::IntersectType

Describes the intersection between two lines.

QLineF::UnboundedIntersectionQLineF::BoundedIntersection

ConstantValueDescription
QLineF::NoIntersection0Indicates that the lines do not intersect; i.e. they are parallel.
QLineF::UnboundedIntersection2The 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.

ConstantValueDescription
QLineF::BoundedIntersection1The two lines intersect with each other within the start and end points of each line.

See also intersect().


Member Function Documentation

QLineF::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 () const

Returns the line's start point.

See also setP1(), x1(), y1(), and p2().

QPointF QLineF::p2 () const

Returns the line's end point.

See also setP2(), x2(), y2(), and p1().

qreal QLineF::x1 () const

Returns the x-coordinate of the line's start point.

See also p1().

qreal QLineF::x2 () const

Returns the x-coordinate of the line's end point.

See also p2().

qreal QLineF::y1 () const

Returns the y-coordinate of the line's start point.

See also p1().

qreal QLineF::y2 () const

Returns the y-coordinate of the line's end point.

See also p2().

qreal QLineF::angle () const

Returns the angle of the line in degrees.

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 also setAngle().

qreal QLineF::angleTo ( const QLineF & line ) const

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.

This function was introduced in Qt 4.4.

See also intersect().

qreal QLineF::dx () const

Returns the horizontal component of the line's vector.

See also dy() and pointAt().

qreal QLineF::dy () const

Returns the vertical component of the line's vector.

See also dx() and pointAt().

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. Zero degrees is at the 3 o'clock position.

This function was introduced in Qt 4.4.

IntersectType QLineF::intersect ( const QLineF & line, QPointF * intersectionPoint ) const

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.

bool QLineF::isNull () const

Returns true if the line is not set up with valid start and end point; otherwise returns false.

qreal QLineF::length () const

Returns the length of the line.

See also setLength().

QLineF QLineF::normalVector () const

Returns a line that is perpendicular to this line with the same starting point and length.

See also unitVector().

QPointF QLineF::pointAt ( qreal t ) const

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.

See also dx() and dy().

void QLineF::setP1 ( const QPointF & p1 )

Sets the starting point of this line to p1.

This function was introduced in Qt 4.4.

See also setP2() and p1().

void QLineF::setP2 ( const QPointF & p2 )

Sets the end point of this line to p2.

This function was introduced in Qt 4.4.

See also setP1() and p2().

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. Zero degrees is at the 3 o'clock position.

This function was introduced in 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 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.

This function was introduced in 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.

This function was introduced in Qt 4.4.

See also setP1(), setP2(), p1(), and p2().

QLine QLineF::toLine () const

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 also QLineF().

void QLineF::translate ( const QPointF & offset )

Translates this line by the given offset.

void QLineF::translate ( qreal dx, qreal dy )

This is an overloaded member function, provided for convenience.

Translates this line the distance specified by dx and dy.

QLineF QLineF::translated ( const QPointF & offset ) const

Returns this line translated by the given offset.

This function was introduced in Qt 4.4.

QLineF QLineF::translated ( qreal dx, qreal dy ) const

This is an overloaded member function, provided for convenience.

Returns this line translated the distance specified by dx and dy.

This function was introduced in Qt 4.4.

QLineF 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.

See also normalVector().

bool QLineF::operator!= ( const QLineF & line ) const

Returns 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 ) const

Returns 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.


Related Non-Members

QDataStream & operator<< ( QDataStream & stream, const QLineF & line )

This is an overloaded member function, provided for convenience.

Writes the given line to the given stream and returns a reference to the stream.

See also Format of the QDataStream Operators.

QDataStream & operator>> ( QDataStream & stream, QLineF & line )

This is an overloaded member function, provided for convenience.

Reads a line from the given stream into the given line and returns a reference to the stream.

See also Format of the QDataStream Operators.

Publicité

Best Of

Actualités les plus lues

Semaine
Mois
Année
  1. « Quelque chose ne va vraiment pas avec les développeurs "modernes" », un développeur à "l'ancienne" critique la multiplication des bibliothèques 53
  2. Les développeurs ignorent-ils trop les failles découvertes dans leur code ? Prenez-vous en compte les remarques des autres ? 17
  3. Apercevoir la troisième dimension ou l'utilisation multithreadée d'OpenGL dans Qt, un article des Qt Quarterly traduit par Guillaume Belz 0
  4. BlackBerry 10 : premières images du prochain OS de RIM qui devrait intégrer des widgets et des tuiles inspirées de Windows Phone 0
  5. Quelles nouveautés de C++11 Visual C++ doit-il rapidement intégrer ? Donnez-nous votre avis 10
  6. Adieu qmake, bienvenue qbs : Qt Building Suite, un outil déclaratif et extensible pour la compilation de projets Qt 17
  7. La rubrique Qt a besoin de vous ! 1
Page suivante

Le Qt Labs au hasard

Logo

Le coût des commodités

Les Qt Labs sont les laboratoires des développeurs de Qt, où ils peuvent partager des impressions sur le framework, son utilisation, ce que pourrait être son futur. Lire l'article.

Communauté

Ressources

Liens utiles

Contact

  • Vous souhaitez rejoindre la rédaction ou proposer un tutoriel, une traduction, une question... ? Postez dans le forum Contribuez ou contactez-nous par MP ou par email (voir en bas de page).

Qt dans le magazine

Cette page est une traduction d'une page de la documentation de Qt, écrite par Nokia Corporation and/or its subsidiary(-ies). Les éventuels problèmes résultant d'une mauvaise traduction ne sont pas imputables à Nokia. Qt 4.4
Copyright © 2012 Developpez LLC. Tous droits réservés Developpez LLC. Aucune reproduction, même partielle, ne peut être faite de ce site et de l'ensemble de son contenu : textes, documents et images sans l'autorisation expresse de Developpez LLC. Sinon, vous encourez selon la loi jusqu'à 3 ans de prison et jusqu'à 300 000 E de dommages et intérêts. Cette page est déposée à la SACD.
Vous avez déniché une erreur ? Un bug ? Une redirection cassée ? Ou tout autre problème, quel qu'il soit ? Ou bien vous désirez participer à ce projet de traduction ? N'hésitez pas à nous contacter ou par MP !
 
 
 
 
Partenaires

Hébergement Web