The QSizePolicy class is a layout attribute describing horizontal and vertical resizing policy. More...

Public Typedefs
using	ControlTypes = QFlags< ControlType >

Public Types
enum	ControlType

enum	Policy

enum	PolicyFlag

Public Methods
	QSizePolicy ()

	QSizePolicy (Policy horizontal, Policy vertical, ControlType type=DefaultType)

ControlType	controlType () const

Qt::Orientations	expandingDirections () const

bool	hasHeightForWidth () const

bool	hasWidthForHeight () const

Policy	horizontalPolicy () const

int	horizontalStretch () const

	operator QVariant () const

bool	operator!= (const QSizePolicy &other) const

bool	operator== (const QSizePolicy &other) const

bool	retainSizeWhenHidden () const

void	setControlType (ControlType type)

void	setHeightForWidth (bool isHeightForWidth)

void	setHorizontalPolicy (Policy policy)

void	setHorizontalStretch (int stretchFactor)

void	setRetainSizeWhenHidden (bool retainSize)

void	setVerticalPolicy (Policy policy)

void	setVerticalStretch (int stretchFactor)

void	setWidthForHeight (bool isWidthForHeight)

void	transpose ()

Policy	verticalPolicy () const

int	verticalStretch () const

Friends
QDataStream &	operator<< (QDataStream &stream, const QSizePolicy &policy)

QDataStream &	operator>> (QDataStream &stream, QSizePolicy &policy)

Detailed Description

The QSizePolicy class is a layout attribute describing horizontal and vertical resizing policy.

The size policy of a widget is an expression of its willingness to be resized in various ways, and affects how the widget is treated by the layout management. Each widget returns a QSizePolicy that describes the horizontal and vertical resizing policy it prefers when being laid out. You can change this for a specific widget by changing its QWidget::sizePolicy property.

QSizePolicy contains two independent QSizePolicy::Policy values and two stretch factors; one describes the widget's horizontal size policy, and the other describes its vertical size policy. It also contains a flag to indicate whether the height and width of its preferred size are related.

The horizontal and vertical policies can be set in the constructor, and altered using the setHorizontalPolicy() and setVerticalPolicy() methods. The stretch factors can be set using the setHorizontalStretch() and setVerticalStretch() methods. The flag indicating whether the widget's sizeHint() is width-dependent (such as a menu bar or a word-wrapping label) can be set using the setHeightForWidth() method.

The current size policies and stretch factors be retrieved using the horizontalPolicy(), verticalPolicy(), horizontalStretch() and verticalStretch() methods. Alternatively, use the transpose() method to swap the horizontal and vertical policies and stretches. The hasHeightForWidth() method returns the current status of the flag indicating the size hint dependencies.

Use the expandingDirections() method to determine whether the associated widget can make use of more space than its sizeHint() method indicates, as well as find out in which directions it can expand.

Finally, the QSizePolicy class provides operators comparing this size policy to a given policy, as well as a QVariant operator storing this QSizePolicy as a QVariant object.

See also: QSize, QWidget::sizeHint(), QWidget::sizePolicy, QLayoutItem::sizeHint()

Member Typedef Documentation

QSizePolicy::ControlTypes

Typedef for QFlags<ControlType> which contains an OR combination of ControlType values.

Refer to QSizePolicy::ControlType for the enum documentation.

Member Enumeration Documentation

enum QSizePolicy::ControlType

This enum specifies the different types of widgets in terms of layout interaction.

Constant	Value	Description
QSizePolicy::DefaultType	0x00000001	The default type, when none is specified.
QSizePolicy::ButtonBox	0x00000002	QDialogButtonBox instance.
QSizePolicy::CheckBox	0x00000004	QCheckBox instance.
QSizePolicy::ComboBox	0x00000008	QComboBox instance.
QSizePolicy::Frame	0x00000010	QFrame instance.
QSizePolicy::GroupBox	0x00000020	QGroupBox instance.
QSizePolicy::Label	0x00000040	QLabel instance.
QSizePolicy::Line	0x00000080	QFrame instance with QFrame::HLine or QFrame::VLine.
QSizePolicy::LineEdit	0x00000100	QLineEdit instance.
QSizePolicy::PushButton	0x00000200	QPushButton instance.
QSizePolicy::RadioButton	0x00000400	QRadioButton instance.
QSizePolicy::Slider	0x00000800	QAbstractSlider instance.
QSizePolicy::SpinBox	0x00001000	QAbstractSpinBox instance.
QSizePolicy::TabWidget	0x00002000	QTabWidget instance.
QSizePolicy::ToolButton	0x00004000	QToolButton instance.

See also: setControlType(), controlType()

enum QSizePolicy::Policy

This enum describes the various per-dimension sizing types used when constructing a QSizePolicy.

Constant	Value	Description
`QSizePolicy::Fixed`	`0x0`	The QWidget::sizeHint() is the only acceptable alternative, so the widget can never grow or shrink (e.g. the vertical direction of a push button).
`QSizePolicy::Minimum`	`0x1`	The sizeHint() is minimal, and sufficient. The widget can be expanded, but there is no advantage to it being larger (e.g. the horizontal direction of a push button). It can not be smaller than the size provided by sizeHint().
`QSizePolicy::Maximum`	`0x4`	The sizeHint() is a maximum. The widget can be shrunk any amount without detriment if other widgets need the space (e.g. a separator line). It can not be larger than the size provided by sizeHint().
`QSizePolicy::Preferred`	`0x5`	The sizeHint() is best, but the widget can be shrunk and still be useful. The widget can be expanded, but there is no advantage to it being larger than sizeHint() (the default QWidget policy).
`QSizePolicy::Expanding`	`0x7`	The sizeHint() is a sensible size, but the widget can be shrunk and still be useful. The widget can make use of extra space, so it should get as much space as possible (e.g. the horizontal direction of a horizontal slider).
`QSizePolicy::MinimumExpanding`	`0x3`	The sizeHint() is minimal, and sufficient. The widget can make use of extra space, so it should get as much space as possible (e.g. the horizontal direction of a horizontal slider).
`QSizePolicy::Ignored`	`0xD`	The sizeHint() is ignored. The widget will get as much space as possible.

See also: PolicyFlag, setHorizontalPolicy(), setVerticalPolicy()

enum QSizePolicy::PolicyFlag

These flags are combined together to form the various Policy values:

Constant	Value	Description
`QSizePolicy::GrowFlag`	`0x1`	Can grow beyond its size hint if necessary.
`QSizePolicy::ExpandFlag`	`0x2`	Widget should get as much space as possible.
`QSizePolicy::ShrinkFlag`	`0x4`	Widget can shrink below its size hint if necessary.
`QSizePolicy::IgnoreFlag`	`0x8`	Widget's size hint is ignored. The widget will get as much space as possible.

See also: Policy

Constructor & Destructor Documentation

QSizePolicy::QSizePolicy ( )

inline

Constructs a QSizePolicy object with Fixed as its horizontal and vertical policies.

The policies can be altered using the setHorizontalPolicy() and setVerticalPolicy() functions. Use the setHeightForWidth() function if the preferred height of the widget is dependent on the width of the widget (for example, a QLabel with line wrapping).

See also: setHorizontalStretch(), setVerticalStretch()

QSizePolicy::QSizePolicy	(	Policy	horizontal,
		Policy	vertical,
		ControlType	type = `DefaultType`
	)

inline

Constructs a QSizePolicy object with the given horizontal and vertical policies, and the specified control type.

Use setHeightForWidth() if the preferred height of the widget is dependent on the width of the widget (for example, a QLabel with line wrapping).

See also: setHorizontalStretch(), setVerticalStretch(), controlType()

Method Documentation

ControlType QSizePolicy::controlType ( ) const

Returns the control type associated with the widget for which this size policy applies.

See also: setControlType()

Qt::Orientations QSizePolicy::expandingDirections ( ) const

inline

Returns whether a widget can make use of more space than the QWidget::sizeHint() function indicates.

A value of Qt::Horizontal or Qt::Vertical means that the widget can grow horizontally or vertically (i.e., the horizontal or vertical policy is Expanding or MinimumExpanding), whereas Qt::Horizontal | Qt::Vertical means that it can grow in both dimensions.

See also: horizontalPolicy(), verticalPolicy()

bool QSizePolicy::hasHeightForWidth ( ) const

inline

Returns true if the widget's preferred height depends on its width, otherwise returns false.

See also: setHeightForWidth()

bool QSizePolicy::hasWidthForHeight ( ) const

inline

Returns true if the widget's width depends on its height, otherwise returns false.

See also: setWidthForHeight()

Policy QSizePolicy::horizontalPolicy ( ) const

inline

Returns the horizontal component of the size policy.

See also: setHorizontalPolicy(), verticalPolicy(), horizontalStretch()

int QSizePolicy::horizontalStretch ( ) const

inline

Returns the horizontal stretch factor of the size policy.

See also: setHorizontalStretch(), verticalStretch(), horizontalPolicy()

QSizePolicy::operator QVariant ( ) const

Returns a QVariant storing this QSizePolicy.

bool QSizePolicy::operator!= ( const QSizePolicy & other ) const

inline

Returns true if this policy is different from other, otherwise returns false.

See also: operator==()

bool QSizePolicy::operator== ( const QSizePolicy & other ) const

inline

Returns true if this policy is equal to other, otherwise returns false.

See also: operator!=()

bool QSizePolicy::retainSizeWhenHidden ( ) const

inline

Returns the value of the property.

void QSizePolicy::setControlType ( ControlType type )

Sets the control type associated with the widget for which this size policy applies to type.

The control type specifies the type of the widget for which this size policy applies. It is used by some styles, notably QMacStyle, to insert proper spacing between widgets. For example, the Mac OS X Aqua guidelines specify that push buttons should be separated by 12 pixels, whereas vertically stacked radio buttons only require 6 pixels.

See also: controlType(), QStyle::layoutSpacing()

void QSizePolicy::setHeightForWidth ( bool isHeightForWidth )

inline

Sets isHeightForWidth to indicate whether the widget's preferred height depends on its width.

See also: hasHeightForWidth(), setWidthForHeight()

void QSizePolicy::setHorizontalPolicy ( Policy policy )

inline

Sets the horizontal component to the given policy.

See also: horizontalPolicy(), setVerticalPolicy(), setHorizontalStretch()

void QSizePolicy::setHorizontalStretch ( int stretchFactor )

inline

Sets the horizontal stretch factor of the size policy to the given stretchFactor.

See also: horizontalStretch(), setVerticalStretch(), setHorizontalPolicy()

void QSizePolicy::setRetainSizeWhenHidden ( bool retainSize )

inline

Sets the value of the property to retainSize.

void QSizePolicy::setVerticalPolicy ( Policy policy )

inline

Sets the vertical component to the given policy.

See also: verticalPolicy(), setHorizontalPolicy(), setVerticalStretch()

void QSizePolicy::setVerticalStretch ( int stretchFactor )

inline

Sets the vertical stretch factor of the size policy to the given stretchFactor.

See also: verticalStretch(), setHorizontalStretch(), setVerticalPolicy()

void QSizePolicy::setWidthForHeight ( bool isWidthForHeight )

inline

Sets isWidthForHeigh to indicate whether the widget's preferred width depends on its height.

This is only supported for QGraphicsLayout's subclasses. It is not possible to have a layout with both height-for-width and width-for-height constraints at the same time.

See also: hasWidthForHeight(), setHeightForWidth()

void QSizePolicy::transpose ( )

inline

Swaps the horizontal and vertical policies and stretches.

Policy QSizePolicy::verticalPolicy ( ) const

inline

Returns the vertical component of the size policy.

See also: setVerticalPolicy(), horizontalPolicy(), verticalStretch()

int QSizePolicy::verticalStretch ( ) const

inline

Returns the vertical stretch factor of the size policy.

See also: setVerticalStretch(), horizontalStretch(), verticalPolicy()

Friends And Related Function Documentation

QDataStream & operator<<	(	QDataStream &	stream,
		const QSizePolicy &	policy
	)

friend

Writes the size policy to the data stream and returns a reference to the stream.

Refer to Serializing Data Types for additional information.

QDataStream & operator>>	(	QDataStream &	stream,
		QSizePolicy &	policy
	)

friend

Reads the size policy from the data stream and returns a reference to the stream.

Refer to Serializing Data Types for additional information.

Public Typedefs

Public Types

Public Methods

Friends

Detailed Description

Member Typedef Documentation

Member Enumeration Documentation

Constructor & Destructor Documentation

Method Documentation

Friends And Related Function Documentation