QRectF Class
The QRectF class defines a rectangle in the plane using floating point precision. More...
Header: | #include <QRectF> |
qmake: | QT += core |
Note: All functions in this class are reentrant.
Public Functions
QRectF() | |
QRectF(const QPointF &topleft, const QSizeF &size) | |
QRectF(const QPointF &topleft, const QPointF &bottomRight) | |
QRectF(qreal left, qreal top, qreal width, qreal height) | |
QRectF(const QRect &rect) | |
void | adjust(qreal x1, qreal y1, qreal x2, qreal y2) |
QRectF | adjusted(qreal x1, qreal y1, qreal x2, qreal y2) const |
qreal | bottom() const |
QPointF | bottomLeft() const |
QPointF | bottomRight() const |
QPointF | center() const |
bool | contains(const QRectF &r) const |
bool | contains(const QPointF &p) const |
bool | contains(qreal x, qreal y) const |
void | getCoords(qreal *x1, qreal *y1, qreal *x2, qreal *y2) const |
void | getRect(qreal *x, qreal *y, qreal *w, qreal *h) const |
qreal | height() const |
QRectF | intersect(const QRectF &r) const |
QRectF | intersected(const QRectF &other) const |
bool | intersects(const QRectF &r) const |
bool | isEmpty() const |
bool | isNull() const |
bool | isValid() const |
qreal | left() const |
QRectF | marginsAdded(const QMarginsF &margins) const |
QRectF | marginsRemoved(const QMarginsF &margins) const |
void | moveBottom(qreal pos) |
void | moveBottomLeft(const QPointF &p) |
void | moveBottomRight(const QPointF &p) |
void | moveCenter(const QPointF &p) |
void | moveLeft(qreal pos) |
void | moveRight(qreal pos) |
void | moveTo(qreal x, qreal y) |
void | moveTo(const QPointF &p) |
void | moveTop(qreal pos) |
void | moveTopLeft(const QPointF &p) |
void | moveTopRight(const QPointF &p) |
QRectF | normalized() const |
qreal | right() const |
void | setBottom(qreal pos) |
void | setBottomLeft(const QPointF &p) |
void | setBottomRight(const QPointF &p) |
void | setCoords(qreal x1, qreal y1, qreal x2, qreal y2) |
void | setHeight(qreal h) |
void | setLeft(qreal pos) |
void | setRect(qreal x, qreal y, qreal w, qreal h) |
void | setRight(qreal pos) |
void | setSize(const QSizeF &s) |
void | setTop(qreal pos) |
void | setTopLeft(const QPointF &p) |
void | setTopRight(const QPointF &p) |
void | setWidth(qreal w) |
void | setX(qreal pos) |
void | setY(qreal pos) |
QSizeF | size() const |
QRect | toAlignedRect() const |
CGRect | toCGRect() const |
QRect | toRect() const |
qreal | top() const |
QPointF | topLeft() const |
QPointF | topRight() const |
void | translate(qreal dx, qreal dy) |
void | translate(const QPointF &p) |
QRectF | translated(qreal dx, qreal dy) const |
QRectF | translated(const QPointF &p) const |
QRectF | transposed() const |
QRectF | unite(const QRectF &r) const |
QRectF | united(const QRectF &other) const |
qreal | width() const |
qreal | x() const |
qreal | y() const |
QRectF | operator&(const QRectF &r) const |
QRectF & | operator&=(const QRectF &r) |
QRectF & | operator+=(const QMarginsF &margins) |
QRectF & | operator-=(const QMarginsF &margins) |
QRectF | operator|(const QRectF &r) const |
QRectF & | operator|=(const QRectF &r) |
Static Public Members
QRectF | fromCGRect(CGRect rect) |
Related Non-Members
bool | operator!=(const QRectF &r1, const QRectF &r2) |
QRectF | operator+(const QRectF &lhs, const QMarginsF &rhs) |
QRectF | operator+(const QMarginsF &lhs, const QRectF &rhs) |
QRectF | operator-(const QRectF &lhs, const QMarginsF &rhs) |
QDataStream & | operator<<(QDataStream &stream, const QRectF &rectangle) |
bool | operator==(const QRectF &r1, const QRectF &r2) |
QDataStream & | operator>>(QDataStream &stream, QRectF &rectangle) |
Detailed Description
The QRectF class defines a rectangle in the plane using floating point precision.
A rectangle is normally expressed as a top-left 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 coordinates, or from a QPointF and a QSizeF. The following code creates two identical rectangles.
QRectF r1(100.0, 200.1, 11.2, 16.3); QRectF r2(QPointF(100.0, 200.1), QSizeF(11.2, 16.3));
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 provides 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 QSizeF. 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.
Rendering
When using an anti-aliased 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.
![]() | ![]() |
Logical representation | One pixel wide pen |
![]() | ![]() |
Two pixel wide pen | Three pixel wide pen |
Coordinates
The QRectF class provides a collection of functions that return the various rectangle coordinates, and enable manipulation of these. QRectF also provides functions to move the rectangle relative to the various coordinates.
For example: the bottom(), setBottom() and moveBottom() functions: bottom() returns the y-coordinate 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 top-left and bottom-right corner, and the getRect() function which extracts the rectangle's top-left corner, width and height. Use the setCoords() and setRect() function to manipulate the rectangle's coordinates and dimensions in one go.
Member Function Documentation
QRectF::QRectF()
Default constructs an instance of QRectF.
QRectF::QRectF(const QPointF &topleft, const QSizeF &size)
Default constructs an instance of QRectF.
QRectF::QRectF(const QPointF &topleft, const QPointF &bottomRight)
Default constructs an instance of QRectF.
QRectF::QRectF(qreal left, qreal top, qreal width, qreal height)
Default constructs an instance of QRectF.
QRectF::QRectF(const QRect &rect)
Default constructs an instance of QRectF.
void QRectF::adjust(qreal x1, qreal y1, qreal x2, qreal y2)
QRectF QRectF::adjusted(qreal x1, qreal y1, qreal x2, qreal y2) const
qreal QRectF::bottom() const
See also setBottom().
QPointF QRectF::bottomLeft() const
See also setBottomLeft().
QPointF QRectF::bottomRight() const
See also setBottomRight().
QPointF QRectF::center() const
bool QRectF::contains(const QRectF &r) const
bool QRectF::contains(const QPointF &p) const
bool QRectF::contains(qreal x, qreal y) const
[static]
QRectF QRectF::fromCGRect(CGRect rect)
Creates a QRectF from CGRect rect.
This function was introduced in Qt 5.8.
See also toCGRect().
void QRectF::getCoords(qreal *x1, qreal *y1, qreal *x2, qreal *y2) const
void QRectF::getRect(qreal *x, qreal *y, qreal *w, qreal *h) const
qreal QRectF::height() const
See also setHeight().
QRectF QRectF::intersect(const QRectF &r) const
QRectF QRectF::intersected(const QRectF &other) const
bool QRectF::intersects(const QRectF &r) const
bool QRectF::isEmpty() const
bool QRectF::isNull() const
bool QRectF::isValid() const
qreal QRectF::left() const
See also setLeft().
QRectF QRectF::marginsAdded(const QMarginsF &margins) const
QRectF QRectF::marginsRemoved(const QMarginsF &margins) const
void QRectF::moveBottom(qreal pos)
void QRectF::moveBottomLeft(const QPointF &p)
void QRectF::moveBottomRight(const QPointF &p)
void QRectF::moveCenter(const QPointF &p)
void QRectF::moveLeft(qreal pos)
void QRectF::moveRight(qreal pos)
void QRectF::moveTo(qreal x, qreal y)
void QRectF::moveTo(const QPointF &p)
void QRectF::moveTop(qreal pos)
void QRectF::moveTopLeft(const QPointF &p)
void QRectF::moveTopRight(const QPointF &p)
QRectF QRectF::normalized() const
Returns a normalized rectangle; i.e., a rectangle that has a non-negative 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() const
See also setRight().
void QRectF::setBottom(qreal pos)
See also bottom().
void QRectF::setBottomLeft(const QPointF &p)
See also bottomLeft().
void QRectF::setBottomRight(const QPointF &p)
See also bottomRight().
void QRectF::setCoords(qreal x1, qreal y1, qreal x2, qreal y2)
void QRectF::setHeight(qreal h)
See also height().
void QRectF::setLeft(qreal pos)
See also left().
void QRectF::setRect(qreal x, qreal y, qreal w, qreal h)
void QRectF::setRight(qreal pos)
See also right().
void QRectF::setSize(const QSizeF &s)
See also size().
void QRectF::setTop(qreal pos)
See also top().
void QRectF::setTopLeft(const QPointF &p)
See also topLeft().
void QRectF::setTopRight(const QPointF &p)
See also topRight().
void QRectF::setWidth(qreal w)
See also width().
void QRectF::setX(qreal pos)
See also x().
void QRectF::setY(qreal pos)
See also y().
QSizeF QRectF::size() const
See also setSize().
QRect QRectF::toAlignedRect() const
CGRect QRectF::toCGRect() const
Creates a CGRect from a QRectF.
This function was introduced in Qt 5.8.
See also fromCGRect().
QRect QRectF::toRect() const
qreal QRectF::top() const
See also setTop().
QPointF QRectF::topLeft() const
See also setTopLeft().
QPointF QRectF::topRight() const
See also setTopRight().
void QRectF::translate(qreal dx, qreal dy)
void QRectF::translate(const QPointF &p)
QRectF QRectF::translated(qreal dx, qreal dy) const
QRectF QRectF::translated(const QPointF &p) const
QRectF QRectF::transposed() const
QRectF QRectF::unite(const QRectF &r) const
QRectF QRectF::united(const QRectF &other) const
qreal QRectF::width() const
See also setWidth().
qreal QRectF::x() const
See also setX().
qreal QRectF::y() const
See also setY().
QRectF QRectF::operator&(const QRectF &r) const
QRectF &QRectF::operator&=(const QRectF &r)
QRectF &QRectF::operator+=(const QMarginsF &margins)
QRectF &QRectF::operator-=(const QMarginsF &margins)
QRectF QRectF::operator|(const QRectF &r) const
QRectF &QRectF::operator|=(const QRectF &r)
Related Non-Members
bool operator!=(const QRectF &r1, const QRectF &r2)
Returns true
if the rectangles r1 and r2 are different, otherwise returns false
.
QRectF operator+(const QRectF &lhs, const QMarginsF &rhs)
Returns the lhs rectangle grown by the rhs margins.
This function was introduced in Qt 5.3.
QRectF operator+(const QMarginsF &lhs, const QRectF &rhs)
This is an overloaded function.
Returns the lhs rectangle grown by the rhs margins.
This function was introduced in Qt 5.3.
QRectF operator-(const QRectF &lhs, const QMarginsF &rhs)
Returns the lhs rectangle grown by the rhs margins.
This function was introduced in Qt 5.3.
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.