QSize Class

The QSize class defines the size of a two-dimensional object using integer point precision. More...

Header:	#include <QSize>
CMake:	find_package(Qt6 COMPONENTS Core REQUIRED) target_link_libraries(mytarget PRIVATE Qt6::Core)
qmake:	QT += core

• List of all members, including inherited members

Public Functions

	QSize(int width, int height)
	QSize()
QSize	boundedTo(const QSize &otherSize) const
QSize	expandedTo(const QSize &otherSize) const
QSize	grownBy(QMargins margins) const
int	height() const
bool	isEmpty() const
bool	isNull() const
bool	isValid() const
int &	rheight()
int &	rwidth()
void	scale(int width, int height, Qt::AspectRatioMode mode)
void	scale(const QSize &size, Qt::AspectRatioMode mode)
QSize	scaled(int width, int height, Qt::AspectRatioMode mode) const
QSize	scaled(const QSize &s, Qt::AspectRatioMode mode) const
void	setHeight(int height)
void	setWidth(int width)
QSize	shrunkBy(QMargins margins) const
CGSize	toCGSize() const
void	transpose()
QSize	transposed() const
int	width() const
QSize &	operator*=(qreal factor)
QSize &	operator+=(const QSize &size)
QSize &	operator-=(const QSize &size)
QSize &	operator/=(qreal divisor)

Related Non-Members

bool	operator!=(const QSize &s1, const QSize &s2)
QSize	operator*(const QSize &size, qreal factor)
QSize	operator*(qreal factor, const QSize &size)
QSize	operator+(const QSize &s1, const QSize &s2)
QSize	operator-(const QSize &s1, const QSize &s2)
QSize	operator/(const QSize &size, qreal divisor)
QDataStream &	operator<<(QDataStream &stream, const QSize &size)
bool	operator==(const QSize &s1, const QSize &s2)
QDataStream &	operator>>(QDataStream &stream, QSize &size)

Detailed Description

A size is specified by a width() and a height(). It can be set in the constructor and changed using the setWidth(), setHeight(), or scale() functions, or using arithmetic operators. A size can also be manipulated directly by retrieving references to the width and height using the rwidth() and rheight() functions. Finally, the width and height can be swapped using the transpose() function.

The isValid() function determines if a size is valid (a valid size has both width and height greater than or equal to zero). The isEmpty() function returns true if either of the width and height is less than, or equal to, zero, while the isNull() function returns true only if both the width and the height is zero.

Use the expandedTo() function to retrieve a size which holds the maximum height and width of this size and a given size. Similarly, the boundedTo() function returns a size which holds the minimum height and width of this size and a given size.

QSize objects can be streamed as well as compared.

See also QSizeF, QPoint, and QRect.

Member Function Documentation

[since 5.14] QSize QSize::shrunkBy(QMargins margins) const

Returns the size that results from shrinking this size by margins.

This function was introduced in Qt 5.14.

See also grownBy().

[since 5.14] QSize QSize::grownBy(QMargins margins) const

Returns the size that results from growing this size by margins.

This function was introduced in Qt 5.14.

See also shrunkBy().

QSize::QSize(int width, int height)

Constructs a size with the given width and height.

See also setWidth() and setHeight().

QSize::QSize()

Constructs a size with an invalid width and height (i.e., isValid() returns false).

See also isValid().

QSize QSize::boundedTo(const QSize &otherSize) const

Returns a size holding the minimum width and height of this size and the given otherSize.

See also expandedTo() and scale().

QSize QSize::expandedTo(const QSize &otherSize) const

Returns a size holding the maximum width and height of this size and the given otherSize.

See also boundedTo() and scale().

int QSize::height() const

Returns the height.

See also width() and setHeight().

bool QSize::isEmpty() const

Returns true if either of the width and height is less than or equal to 0; otherwise returns false.

See also isNull() and isValid().

bool QSize::isNull() const

Returns true if both the width and height is 0; otherwise returns false.

See also isValid() and isEmpty().

bool QSize::isValid() const

Returns true if both the width and height is equal to or greater than 0; otherwise returns false.

See also isNull() and isEmpty().

int &QSize::rheight()

Returns a reference to the height.

Using a reference makes it possible to manipulate the height directly. For example:

QSize size(100, 10);
size.rheight() += 5;

// size becomes (100,15)

See also rwidth() and setHeight().

int &QSize::rwidth()

Returns a reference to the width.

Using a reference makes it possible to manipulate the width directly. For example:

QSize size(100, 10);
size.rwidth() += 20;

// size becomes (120,10)

See also rheight() and setWidth().

void QSize::scale(int width, int height, Qt::AspectRatioMode mode)

Scales the size to a rectangle with the given width and height, according to the specified mode:

• If mode is Qt::IgnoreAspectRatio, the size is set to (width, height).
• If mode is Qt::KeepAspectRatio, the current size is scaled to a rectangle as large as possible inside (width, height), preserving the aspect ratio.
• If mode is Qt::KeepAspectRatioByExpanding, the current size is scaled to a rectangle as small as possible outside (width, height), preserving the aspect ratio.

Example:

QSize t1(10, 12);
t1.scale(60, 60, Qt::IgnoreAspectRatio);
// t1 is (60, 60)

QSize t2(10, 12);
t2.scale(60, 60, Qt::KeepAspectRatio);
// t2 is (50, 60)

QSize t3(10, 12);
t3.scale(60, 60, Qt::KeepAspectRatioByExpanding);
// t3 is (60, 72)

See also setWidth(), setHeight(), and scaled().

void QSize::scale(const QSize &size, Qt::AspectRatioMode mode)

This is an overloaded function.

Scales the size to a rectangle with the given size, according to the specified mode.

[since 5.0] QSize QSize::scaled(int width, int height, Qt::AspectRatioMode mode) const

Return a size scaled to a rectangle with the given width and height, according to the specified mode.

This function was introduced in Qt 5.0.

See also scale().

[since 5.0] QSize QSize::scaled(const QSize &s, Qt::AspectRatioMode mode) const

This is an overloaded function.

Return a size scaled to a rectangle with the given size s, according to the specified mode.

This function was introduced in Qt 5.0.

void QSize::setHeight(int height)

Sets the height to the given height.

See also rheight(), height(), and setWidth().

void QSize::setWidth(int width)

Sets the width to the given width.

See also rwidth(), width(), and setHeight().

[since 5.8] CGSize QSize::toCGSize() const

Creates a CGSize from a QSize.

This function was introduced in Qt 5.8.

See also QSizeF::fromCGSize().

void QSize::transpose()

Swaps the width and height values.

See also setWidth(), setHeight(), and transposed().

[since 5.0] QSize QSize::transposed() const

Returns a QSize with width and height swapped.

This function was introduced in Qt 5.0.

See also transpose().

int QSize::width() const

Returns the width.

See also height() and setWidth().

QSize &QSize::operator*=(qreal factor)

This is an overloaded function.

Multiplies both the width and height by the given factor, and returns a reference to the size.

Note that the result is rounded to the nearest integer.

See also scale().

QSize &QSize::operator+=(const QSize &size)

Adds the given size to this size, and returns a reference to this size. For example:

QSize s( 3, 7);
QSize r(-1, 4);
s += r;

// s becomes (2,11)

QSize &QSize::operator-=(const QSize &size)

Subtracts the given size from this size, and returns a reference to this size. For example:

QSize s( 3, 7);
QSize r(-1, 4);
s -= r;

// s becomes (4,3)

QSize &QSize::operator/=(qreal divisor)

This is an overloaded function.

Divides both the width and height by the given divisor, and returns a reference to the size.

Note that the result is rounded to the nearest integer.

See also QSize::scale().