QRectF Class ReferenceThe QRectF class defines a rectangle in the plane using floating point precision. More... #include <QRectF> Public Functions
Related NonMembers
Detailed DescriptionThe QRectF class defines a rectangle in the plane using floating point precision. A rectangle is normally expressed as an upperleft corner and a size. The size (width and height) of a QRectF is always equivalent to the mathematical rectangle that forms the basis for its rendering. A QRectF can be constructed with a set of left, top, width and height integers, or from a QPoint and a QSize. The following code creates two identical rectangles. QRectF r1(100, 200, 11, 16); QRectF r2(QPoint(100, 200), QSize(11, 16)); There is also a third constructor creating a QRectF from a QRect, and a corresponding toRect() function that returns a QRect object based on the values of this rectangle (note that the coordinates in the returned rectangle are rounded to the nearest integer). The QRectF class provides a collection of functions that return the various rectangle coordinates, and enable manipulation of these. QRectF also provide functions to move the rectangle relative to the various coordinates. In addition there is a moveTo() function that moves the rectangle, leaving its top left corner at the given coordinates. Alternatively, the translate() function moves the rectangle the given offset relative to the current position, and the translated() function returns a translated copy of this rectangle. The size() function returns the rectange's dimensions as a QSize. The dimensions can also be retrieved separately using the width() and height() functions. To manipulate the dimensions use the setSize(), setWidth() or setHeight() functions. Alternatively, the size can be changed by applying either of the functions setting the rectangle coordinates, for example, setBottom() or setRight(). The contains() function tells whether a given point is inside the rectangle or not, and the intersects() function returns true if this rectangle intersects with a given rectangle (otherwise false). The QRectF class also provides the intersected() function which returns the intersection rectangle, and the united() function which returns the rectangle that encloses the given rectangle and this:
The isEmpty() function returns true if the rectangle's width or height is less than, or equal to, 0. Note that an empty rectangle is not valid: The isValid() function returns true if both width and height is larger than 0. A null rectangle (isNull() == true) on the other hand, has both width and height set to 0. Note that due to the way QRect and QRectF are defined, an empty QRectF is defined in essentially the same way as QRect. Finally, QRectF objects can be streamed as well as compared. RenderingWhen using an antialiased painter, the boundary line of a QRectF will be rendered symmetrically on both sides of the mathematical rectangle's boundary line. But when using an aliased painter (the default) other rules apply. Then, when rendering with a one pixel wide pen the QRectF's boundary line will be rendered to the right and below the mathematical rectangle's boundary line. When rendering with a two pixels wide pen the boundary line will be split in the middle by the mathematical rectangle. This will be the case whenever the pen is set to an even number of pixels, while rendering with a pen with an odd number of pixels, the spare pixel will be rendered to the right and below the mathematical rectangle as in the one pixel case.
CoordinatesThe QRectF class provides a collection of functions that return the various rectangle coordinates, and enable manipulation of these. QRectF also provide functions to move the rectangle relative to the various coordinates. For example: the bottom(), setBottom() and moveBottom() functions: bottom() returns the ycoordinate of the rectangle's bottom edge, setBottom() sets the bottom edge of the rectangle to the given y coordinate (it may change the height, but will never change the rectangle's top edge) and moveBottom() moves the entire rectangle vertically, leaving the rectangle's bottom edge at the given y coordinate and its size unchanged. It is also possible to add offsets to this rectangle's coordinates using the adjust() function, as well as retrieve a new rectangle based on adjustments of the original one using the adjusted() function. If either of the width and height is negative, use the normalized() function to retrieve a rectangle where the corners are swapped. In addition, QRectF provides the getCoords() function which extracts the position of the rectangle's topleft and bottomright corner, and the getRect() function which extracts the rectangle's topleft corner, width and height. Use the setCoords() and setRect() function to manipulate the rectangle's coordinates and dimensions in one go. Member Function DocumentationQRectF::QRectF ()Constructs a null rectangle. See also isNull(). QRectF::QRectF ( const QPointF & topLeft, const QSizeF & size )Constructs a rectangle with the given topLeft corner and the given size. See also setTopLeft() and setSize(). QRectF::QRectF ( const QPointF & topLeft, const QPointF & bottomRight )Constructs a rectangle with the given topLeft and bottomRight corners. This function was introduced in Qt 4.3. See also setTopLeft() and setBottomRight(). QRectF::QRectF ( qreal x, qreal y, qreal width, qreal height )Constructs a rectangle with (x, y) as its topleft corner and the given width and height. See also setRect(). QRectF::QRectF ( const QRect & rectangle )Constructs a QRectF rectangle from the given QRect rectangle. See also toRect(). void QRectF::adjust ( qreal dx1, qreal dy1, qreal dx2, qreal dy2 )Adds dx1, dy1, dx2 and dy2 respectively to the existing coordinates of the rectangle. See also adjusted() and setRect(). QRectF QRectF::adjusted ( qreal dx1, qreal dy1, qreal dx2, qreal dy2 ) constReturns a new rectangle with dx1, dy1, dx2 and dy2 added respectively to the existing coordinates of this rectangle. See also adjust(). qreal QRectF::bottom () constReturns the ycoordinate of the rectangle's bottom edge. See also setBottom(), bottomLeft(), and bottomRight(). QPointF QRectF::bottomLeft () constReturns the position of the rectangle's bottomleft corner. See also setBottomLeft(), bottom(), and left(). QPointF QRectF::bottomRight () constReturns the position of the rectangle's bottomright corner. See also setBottomRight(), bottom(), and right(). QPointF QRectF::center () constReturns the center point of the rectangle. See also moveCenter(). bool QRectF::contains ( const QPointF & point ) constReturns true if the given point is inside or on the edge of the rectangle; otherwise returns false. See also intersects(). bool QRectF::contains ( qreal x, qreal y ) constThis is an overloaded function. Returns true if the point (x, y) is inside or on the edge of the rectangle; otherwise returns false. bool QRectF::contains ( const QRectF & rectangle ) constThis is an overloaded function. Returns true if the given rectangle is inside this rectangle; otherwise returns false. void QRectF::getCoords ( qreal * x1, qreal * y1, qreal * x2, qreal * y2 ) constExtracts the position of the rectangle's topleft corner to *x1 and *y1, and the position of the bottomright corner to *x2 and *y2. See also setCoords() and getRect(). void QRectF::getRect ( qreal * x, qreal * y, qreal * width, qreal * height ) constExtracts the position of the rectangle's topleft corner to *x and *y, and its dimensions to *width and *height. See also setRect() and getCoords(). qreal QRectF::height () constReturns the height of the rectangle. See also setHeight(), width(), and size(). QRectF QRectF::intersected ( const QRectF & rectangle ) constReturns the intersection of this rectangle and the given rectangle. Note that r.intersected(s) is equivalent to r & s. This function was introduced in Qt 4.2. See also intersects(), united(), and operator&=(). bool QRectF::intersects ( const QRectF & rectangle ) constReturns true if this rectangle intersects with the given rectangle (i.e. there is a nonempty area of overlap between them), otherwise returns false. The intersection rectangle can be retrieved using the intersected() function. See also contains(). bool QRectF::isEmpty () constReturns true if the rectangle is empty, otherwise returns false. An empty rectangle has width() <= 0 or height() <= 0. An empty rectangle is not valid (i.e., isEmpty() == !isValid()). Use the normalized() function to retrieve a rectangle where the corners are swapped. See also isNull(), isValid(), and normalized(). bool QRectF::isNull () constReturns true if the rectangle is a null rectangle, otherwise returns false. A null rectangle has both the width and the height set to 0. A null rectangle is also empty, and hence not valid. See also isEmpty() and isValid(). bool QRectF::isValid () constReturns true if the rectangle is valid, otherwise returns false. A valid rectangle has a width() > 0 and height() > 0. Note that nontrivial operations like intersections are not defined for invalid rectangles. A valid rectangle is not empty (i.e., isValid() == !isEmpty()). See also isNull(), isEmpty(), and normalized(). qreal QRectF::left () constReturns the xcoordinate of the rectangle's left edge. Equivalent to x(). See also setLeft(), topLeft(), and bottomLeft(). void QRectF::moveBottom ( qreal y )Moves the rectangle vertically, leaving the rectangle's bottom edge at the given y coordinate. The rectangle's size is unchanged. See also bottom(), setBottom(), and moveTop(). void QRectF::moveBottomLeft ( const QPointF & position )Moves the rectangle, leaving the bottomleft corner at the given position. The rectangle's size is unchanged. See also setBottomLeft(), moveBottom(), and moveLeft(). void QRectF::moveBottomRight ( const QPointF & position )Moves the rectangle, leaving the bottomright corner at the given position. The rectangle's size is unchanged. See also setBottomRight(), moveBottom(), and moveRight(). void QRectF::moveCenter ( const QPointF & position )Moves the rectangle, leaving the center point at the given position. The rectangle's size is unchanged. See also center(). void QRectF::moveLeft ( qreal x )Moves the rectangle horizontally, leaving the rectangle's left edge at the given x coordinate. The rectangle's size is unchanged. See also left(), setLeft(), and moveRight(). void QRectF::moveRight ( qreal x )Moves the rectangle horizontally, leaving the rectangle's right edge at the given x coordinate. The rectangle's size is unchanged. See also right(), setRight(), and moveLeft(). void QRectF::moveTo ( qreal x, qreal y )Moves the rectangle, leaving the topleft corner at the given position (x, y). The rectangle's size is unchanged. See also translate() and moveTopLeft(). void QRectF::moveTo ( const QPointF & position )This is an overloaded function. Moves the rectangle, leaving the topleft corner at the given position. void QRectF::moveTop ( qreal y )Moves the rectangle vertically, leaving the rectangle's top line at the given y coordinate. The rectangle's size is unchanged. See also top(), setTop(), and moveBottom(). void QRectF::moveTopLeft ( const QPointF & position )Moves the rectangle, leaving the topleft corner at the given position. The rectangle's size is unchanged. See also setTopLeft(), moveTop(), and moveLeft(). void QRectF::moveTopRight ( const QPointF & position )Moves the rectangle, leaving the topright corner at the given position. The rectangle's size is unchanged. See also setTopRight(), moveTop(), and moveRight(). QRectF QRectF::normalized () constReturns a normalized rectangle; i.e., a rectangle that has a nonnegative width and height. If width() < 0 the function swaps the left and right corners, and it swaps the top and bottom corners if height() < 0. See also isValid() and isEmpty(). qreal QRectF::right () constReturns the xcoordinate of the rectangle's right edge. See also setRight(), topRight(), and bottomRight(). void QRectF::setBottom ( qreal y )Sets the bottom edge of the rectangle to the given y coordinate. May change the height, but will never change the top edge of the rectangle. See also bottom() and moveBottom(). void QRectF::setBottomLeft ( const QPointF & position )Set the bottomleft corner of the rectangle to the given position. May change the size, but will never change the topright corner of the rectangle. See also bottomLeft() and moveBottomLeft(). void QRectF::setBottomRight ( const QPointF & position )Set the bottomright corner of the rectangle to the given position. May change the size, but will never change the topleft corner of the rectangle. See also bottomRight() and moveBottomRight(). void QRectF::setCoords ( qreal x1, qreal y1, qreal x2, qreal y2 )Sets the coordinates of the rectangle's topleft corner to (x1, y1), and the coordinates of its bottomright corner to (x2, y2). See also getCoords() and setRect(). void QRectF::setHeight ( qreal height )Sets the height of the rectangle to the given height. The bottom edge is changed, but not the top one. See also height() and setSize(). void QRectF::setLeft ( qreal x )Sets the left edge of the rectangle to the given x coordinate. May change the width, but will never change the right edge of the rectangle. Equivalent to setX(). See also left() and moveLeft(). void QRectF::setRect ( qreal x, qreal y, qreal width, qreal height )Sets the coordinates of the rectangle's topleft corner to (x, y), and its size to the given width and height. See also getRect() and setCoords(). void QRectF::setRight ( qreal x )Sets the right edge of the rectangle to the given x coordinate. May change the width, but will never change the left edge of the rectangle. See also right() and moveRight(). void QRectF::setSize ( const QSizeF & size )Sets the size of the rectangle to the given size. The topleft corner is not moved. See also size(), setWidth(), and setHeight(). void QRectF::setTop ( qreal y )Sets the top edge of the rectangle to the given y coordinate. May change the height, but will never change the bottom edge of the rectangle. Equivalent to setY(). void QRectF::setTopLeft ( const QPointF & position )Set the topleft corner of the rectangle to the given position. May change the size, but will never change the bottomright corner of the rectangle. See also topLeft() and moveTopLeft(). void QRectF::setTopRight ( const QPointF & position )Set the topright corner of the rectangle to the given position. May change the size, but will never change the bottomleft corner of the rectangle. See also topRight() and moveTopRight(). void QRectF::setWidth ( qreal width )Sets the width of the rectangle to the given width. The right edge is changed, but not the left one. See also width() and setSize(). void QRectF::setX ( qreal x )Sets the left edge of the rectangle to the given x coordinate. May change the width, but will never change the right edge of the rectangle. Equivalent to setLeft(). See also x(), setY(), and setTopLeft(). void QRectF::setY ( qreal y )Sets the top edge of the rectangle to the given y coordinate. May change the height, but will never change the bottom edge of the rectangle. Equivalent to setTop(). See also y(), setX(), and setTopLeft(). QSizeF QRectF::size () constReturns the size of the rectangle. See also setSize(), width(), and height(). QRect QRectF::toAlignedRect () constReturns a QRect based on the values of this rectangle that is the smallest possible integer rectangle that completely contains this rectangle. This function was introduced in Qt 4.3. See also toRect(). QRect QRectF::toRect () constReturns a QRect based on the values of this rectangle. Note that the coordinates in the returned rectangle are rounded to the nearest integer. See also QRectF() and toAlignedRect(). qreal QRectF::top () constReturns the ycoordinate of the rectangle's top edge. Equivalent to y(). See also setTop(), topLeft(), and topRight(). QPointF QRectF::topLeft () constReturns the position of the rectangle's topleft corner. See also setTopLeft(), top(), and left(). QPointF QRectF::topRight () constReturns the position of the rectangle's topright corner. See also setTopRight(), top(), and right(). void QRectF::translate ( qreal dx, qreal dy )Moves the rectangle dx along the xaxis and dy along the yaxis, relative to the current position. Positive values move the rectangle to the right and downwards. See also moveTopLeft(), moveTo(), and translated(). void QRectF::translate ( const QPointF & offset )This is an overloaded function. Moves the rectangle offset.x() along the x axis and offset.y() along the y axis, relative to the current position. QRectF QRectF::translated ( qreal dx, qreal dy ) constReturns a copy of the rectangle that is translated dx along the x axis and dy along the y axis, relative to the current position. Positive values move the rectangle to the right and down. See also translate(). QRectF QRectF::translated ( const QPointF & offset ) constThis is an overloaded function. Returns a copy of the rectangle that is translated offset.x() along the x axis and offset.y() along the y axis, relative to the current position. QRectF QRectF::united ( const QRectF & rectangle ) constReturns the bounding rectangle of this rectangle and the given rectangle. This function was introduced in Qt 4.2. See also intersected(). qreal QRectF::width () constReturns the width of the rectangle. See also setWidth(), height(), and size(). qreal QRectF::x () constReturns the xcoordinate of the rectangle's left edge. Equivalent to left(). See also setX(), y(), and topLeft(). qreal QRectF::y () constReturns the ycoordinate of the rectangle's top edge. Equivalent to top(). See also setY(), x(), and topLeft(). QRectF QRectF::operator& ( const QRectF & rectangle ) constReturns the intersection of this rectangle and the given rectangle. Returns an empty rectangle if there is no intersection. See also operator&=() and intersected(). QRectF & QRectF::operator&= ( const QRectF & rectangle )Intersects this rectangle with the given rectangle. See also intersected() and operator=(). QRectF QRectF::operator ( const QRectF & rectangle ) constReturns the bounding rectangle of this rectangle and the given rectangle. See also united() and operator=(). QRectF & QRectF::operator= ( const QRectF & rectangle )Unites this rectangle with the given rectangle. Related NonMembersbool operator!= ( const QRectF & r1, const QRectF & r2 )Returns true if the rectangles r1 and r2 are different, otherwise returns false. QDataStream & operator<< ( QDataStream & stream, const QRectF & rectangle )Writes the rectangle to the stream, and returns a reference to the stream. See also Serializing Qt Data Types. bool operator== ( const QRectF & r1, const QRectF & r2 )Returns true if the rectangles r1 and r2 are equal, otherwise returns false. QDataStream & operator>> ( QDataStream & stream, QRectF & rectangle )Reads a rectangle from the stream, and returns a reference to the stream. See also Serializing Qt Data Types. X

Попытка перевода Qt документации. Если есть желание присоединиться, или если есть замечания или пожелания, то заходите на форум: Перевод Qt документации на русский язык... Люди внесшие вклад в перевод: Команда переводчиков 