The QGraphicsLayoutItem class can be inherited to allow your custom items to be managed by layouts. More...

#include <qgraphicslayoutitem.h>

Inheritance diagram for QGraphicsLayoutItem:

Collaboration diagram for QGraphicsLayoutItem:

Public Member Functions
	QGraphicsLayoutItem (QGraphicsLayoutItem *parent=nullptr, bool isLayout=false)

virtual	~QGraphicsLayoutItem ()

void	setSizePolicy (const QSizePolicy &policy)

void	setSizePolicy (QSizePolicy::Policy hPolicy, QSizePolicy::Policy vPolicy, QSizePolicy::ControlType controlType=QSizePolicy::DefaultType)

QSizePolicy	sizePolicy () const

void	setMinimumSize (const QSizeF &size)

void	setMinimumSize (qreal w, qreal h)

QSizeF	minimumSize () const

void	setMinimumWidth (qreal width)

qreal	minimumWidth () const

void	setMinimumHeight (qreal height)

qreal	minimumHeight () const

void	setPreferredSize (const QSizeF &size)

void	setPreferredSize (qreal w, qreal h)

QSizeF	preferredSize () const

void	setPreferredWidth (qreal width)

qreal	preferredWidth () const

void	setPreferredHeight (qreal height)

qreal	preferredHeight () const

void	setMaximumSize (const QSizeF &size)

void	setMaximumSize (qreal w, qreal h)

QSizeF	maximumSize () const

void	setMaximumWidth (qreal width)

qreal	maximumWidth () const

void	setMaximumHeight (qreal height)

qreal	maximumHeight () const

virtual void	setGeometry (const QRectF &rect)

QRectF	geometry () const

virtual void	getContentsMargins (qreal left, qreal top, qreal right, qreal bottom) const

QRectF	contentsRect () const

QSizeF	effectiveSizeHint (Qt::SizeHint which, const QSizeF &constraint=QSizeF()) const

virtual void	updateGeometry ()

virtual bool	isEmpty () const

QGraphicsLayoutItem *	parentLayoutItem () const

void	setParentLayoutItem (QGraphicsLayoutItem *parent)

bool	isLayout () const

QGraphicsItem *	graphicsItem () const

bool	ownedByLayout () const

Protected Member Functions
void	setGraphicsItem (QGraphicsItem *item)

void	setOwnedByLayout (bool ownedByLayout)

	QGraphicsLayoutItem (QGraphicsLayoutItemPrivate &dd)

virtual QSizeF	sizeHint (Qt::SizeHint which, const QSizeF &constraint=QSizeF()) const =0

Protected Attributes
QScopedPointer< QGraphicsLayoutItemPrivate >	d_ptr

Friends
class	QGraphicsLayout

Detailed Description

The QGraphicsLayoutItem class can be inherited to allow your custom items to be managed by layouts.

Since: 4.4

\inmodule QtWidgets

QGraphicsLayoutItem is an abstract class that defines a set of virtual functions describing sizes, size policies, and size hints for any object arranged by QGraphicsLayout. The API contains functions relevant for both the item itself and for the user of the item as most of QGraphicsLayoutItem's functions are also part of the subclass' public API.

In most cases, existing layout-aware classes such as QGraphicsWidget and QGraphicsLayout already provide the functionality you require. However, subclassing these classes will enable you to create both graphical elements that work well with layouts (QGraphicsWidget) or custom layouts (QGraphicsLayout).

Definition at line 54 of file qgraphicslayoutitem.h.

Constructor & Destructor Documentation

◆ QGraphicsLayoutItem() [1/2]

QGraphicsLayoutItem::QGraphicsLayoutItem	(	QGraphicsLayoutItem *	parent = `nullptr`,
		bool	isLayout = `false`
	)

Constructs the QGraphicsLayoutItem object. parent becomes the object's parent. If isLayout is true the item is a layout, otherwise isLayout is false.

Definition at line 390 of file qgraphicslayoutitem.cpp.

◆ ~QGraphicsLayoutItem()

QGraphicsLayoutItem::~QGraphicsLayoutItem ( )

virtual

Destroys the QGraphicsLayoutItem object.

Definition at line 413 of file qgraphicslayoutitem.cpp.

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◆ QGraphicsLayoutItem() [2/2]

QGraphicsLayoutItem::QGraphicsLayoutItem ( QGraphicsLayoutItemPrivate & dd )

protected

Definition at line 402 of file qgraphicslayoutitem.cpp.

Member Function Documentation

◆ contentsRect()

QRectF QGraphicsLayoutItem::contentsRect ( ) const

Returns the contents rect in local coordinates.

The contents rect defines the subrectangle used by an associated layout when arranging subitems. This function is a convenience function that adjusts the item's geometry() by its contents margins. Note that getContentsMargins() is a virtual function that you can reimplement to return the item's contents margins.

See also: getContentsMargins(), geometry()

Definition at line 768 of file qgraphicslayoutitem.cpp.

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◆ effectiveSizeHint()

QSizeF QGraphicsLayoutItem::effectiveSizeHint	(	Qt::SizeHint	which,
		const QSizeF &	constraint = `QSizeF()`
	)		const

Returns the effective size hint for this QGraphicsLayoutItem.

which is the size hint in question. constraint is an optional argument that defines a special constrain when calculating the effective size hint. By default, constraint is QSizeF(-1, -1), which means there is no constraint to the size hint.

If you want to specify the widget's size hint for a given width or height, you can provide the fixed dimension in constraint. This is useful for widgets that can grow only either vertically or horizontally, and need to set either their width or their height to a special value.

For example, a text paragraph item fit into a column width of 200 may grow vertically. You can pass QSizeF(200, -1) as a constraint to get a suitable minimum, preferred and maximum height).

You can adjust the effective size hint by reimplementing sizeHint() in a QGraphicsLayoutItem subclass, or by calling one of the following functions: setMinimumSize(), setPreferredSize, or setMaximumSize() (or a combination of both).

This function caches each of the size hints and guarantees that sizeHint() will be called only once for each value of which - unless constraint is not specified and updateGeometry() has been called.

See also: sizeHint()

Definition at line 803 of file qgraphicslayoutitem.cpp.

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◆ geometry()

QRectF QGraphicsLayoutItem::geometry ( ) const

Returns the item's geometry (e.g., position and size) as a QRectF. This function is equivalent to QRectF(pos(), size()).

See also: setGeometry()

Definition at line 731 of file qgraphicslayoutitem.cpp.

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◆ getContentsMargins()

void QGraphicsLayoutItem::getContentsMargins	(	qreal *	left,
		qreal *	top,
		qreal *	right,
		qreal *	bottom
	)		const

virtual

This virtual function provides the left, top, right and bottom contents margins for this QGraphicsLayoutItem. The default implementation assumes all contents margins are 0. The parameters point to values stored in qreals. If any of the pointers is \nullptr, that value will not be updated.

See also: QGraphicsWidget::setContentsMargins()

Reimplemented in QGraphicsWidget, and QGraphicsLayout.

Definition at line 745 of file qgraphicslayoutitem.cpp.

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◆ graphicsItem()

QGraphicsItem * QGraphicsLayoutItem::graphicsItem ( ) const

Returns the QGraphicsItem that this layout item represents. For QGraphicsWidget it will return itself. For custom items it can return an aggregated value.

See also: setGraphicsItem()

Definition at line 931 of file qgraphicslayoutitem.cpp.

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◆ isEmpty()

bool QGraphicsLayoutItem::isEmpty ( ) const

virtual

Since: 6.0

Returns true if this item is empty, i.e whether it has no content and should not occupy any space.

The default implementation returns true true if the item has been hidden, unless its \l{sizePolicy()}{size policy} has retainSizeWhenHidden set to true

See also: sizePolicy()

Reimplemented in LayoutItem.

Definition at line 840 of file qgraphicslayoutitem.cpp.

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◆ isLayout()

bool QGraphicsLayoutItem::isLayout ( ) const

Returns true if this QGraphicsLayoutItem is a layout (e.g., is inherited by an object that arranges other QGraphicsLayoutItem objects); otherwise returns false.

See also: QGraphicsLayout

Definition at line 879 of file qgraphicslayoutitem.cpp.

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◆ maximumHeight()

qreal QGraphicsLayoutItem::maximumHeight ( ) const

inline

Returns the maximum height.

See also: setMaximumHeight(), setMaximumSize(), maximumSize()

Definition at line 143 of file qgraphicslayoutitem.h.

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◆ maximumSize()

QSizeF QGraphicsLayoutItem::maximumSize ( ) const

Returns the maximum size.

See also: setMaximumSize(), minimumSize(), preferredSize(), Qt::MaximumSize, sizeHint()

Definition at line 625 of file qgraphicslayoutitem.cpp.

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◆ maximumWidth()

qreal QGraphicsLayoutItem::maximumWidth ( ) const

inline

Returns the maximum width.

See also: setMaximumWidth(), setMaximumSize(), maximumSize()

Definition at line 141 of file qgraphicslayoutitem.h.

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◆ minimumHeight()

qreal QGraphicsLayoutItem::minimumHeight ( ) const

inline

Returns the minimum height.

See also: setMinimumHeight(), setMinimumSize(), minimumSize()

Definition at line 133 of file qgraphicslayoutitem.h.

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◆ minimumSize()

QSizeF QGraphicsLayoutItem::minimumSize ( ) const

Returns the minimum size.

See also: setMinimumSize(), preferredSize(), maximumSize(), Qt::MinimumSize, sizeHint()

Definition at line 517 of file qgraphicslayoutitem.cpp.

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◆ minimumWidth()

qreal QGraphicsLayoutItem::minimumWidth ( ) const

inline

Returns the minimum width.

See also: setMinimumWidth(), setMinimumSize(), minimumSize()

Definition at line 131 of file qgraphicslayoutitem.h.

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◆ ownedByLayout()

bool QGraphicsLayoutItem::ownedByLayout ( ) const

Since: 4.6

Returns whether a layout should delete this item in its destructor. If its true, then the layout will delete it. If its false, then it is assumed that another object has the ownership of it, and the layout won't delete this item.

If the item inherits both QGraphicsItem and QGraphicsLayoutItem (such as QGraphicsWidget does) the item is really part of two ownership hierarchies. This property informs what the layout should do with its child items when it is destructed. In the case of QGraphicsWidget, it is preferred that when the layout is deleted it won't delete its children (since they are also part of the graphics item hierarchy).

By default this value is initialized to false in QGraphicsLayoutItem, but it is overridden by QGraphicsLayout to return true. This is because QGraphicsLayout is not normally part of the QGraphicsItem hierarchy, so the parent layout should delete it. Subclasses might override this default behaviour by calling setOwnedByLayout(true).

See also: setOwnedByLayout()

Definition at line 908 of file qgraphicslayoutitem.cpp.

◆ parentLayoutItem()

QGraphicsLayoutItem * QGraphicsLayoutItem::parentLayoutItem ( ) const

Returns the parent of this QGraphicsLayoutItem, or \nullptr if there is no parent, or if the parent does not inherit from QGraphicsLayoutItem (QGraphicsLayoutItem is often used through multiple inheritance with QObject-derived classes).

See also: setParentLayoutItem()

Definition at line 857 of file qgraphicslayoutitem.cpp.

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◆ preferredHeight()

qreal QGraphicsLayoutItem::preferredHeight ( ) const

inline

Returns the preferred height.

See also: setPreferredHeight(), setPreferredSize(), preferredSize()

Definition at line 138 of file qgraphicslayoutitem.h.

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◆ preferredSize()

QSizeF QGraphicsLayoutItem::preferredSize ( ) const

Returns the preferred size.

See also: setPreferredSize(), minimumSize(), maximumSize(), Qt::PreferredSize, sizeHint()

Definition at line 571 of file qgraphicslayoutitem.cpp.

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◆ preferredWidth()

qreal QGraphicsLayoutItem::preferredWidth ( ) const

inline

Returns the preferred width.

See also: setPreferredWidth(), setPreferredSize(), preferredSize()

Definition at line 136 of file qgraphicslayoutitem.h.

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◆ setGeometry()

void QGraphicsLayoutItem::setGeometry ( const QRectF & rect )

virtual

This virtual function sets the geometry of the QGraphicsLayoutItem to rect, which is in parent coordinates (e.g., the top-left corner of rect is equivalent to the item's position in parent coordinates).

You must reimplement this function in a subclass of QGraphicsLayoutItem to receive geometry updates. The layout will call this function when it does a rearrangement.

If rect is outside of the bounds of minimumSize and maximumSize, it will be adjusted to its closest size so that it is within the legal bounds.

See also: geometry()

Reimplemented in SubQGraphicsLayoutItem, RectWidget, Layout, TestLayout, TestGraphicsWidget, QGraphicsWidget, QGraphicsProxyWidget, QGraphicsLinearLayout, QGraphicsGridLayout, QGraphicsAnchorLayout, PixmapWidget, SlowWidget, AnimatedLayout, AnimatedLayoutItem, FlowLayout, and LayoutItem.

Definition at line 715 of file qgraphicslayoutitem.cpp.

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◆ setGraphicsItem()

void QGraphicsLayoutItem::setGraphicsItem ( QGraphicsItem * item )

protected

If the QGraphicsLayoutItem represents a QGraphicsItem, and it wants to take advantage of the automatic reparenting capabilities of QGraphicsLayout it should set this value. Note that if you delete item and not delete the layout item, you are responsible of calling setGraphicsItem(\nullptr) in order to avoid having a dangling pointer.

See also: graphicsItem()

Definition at line 946 of file qgraphicslayoutitem.cpp.

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◆ setMaximumHeight()

void QGraphicsLayoutItem::setMaximumHeight ( qreal height )

Sets the maximum height to height.

See also: maximumHeight(), setMaximumSize(), maximumSize()

Definition at line 645 of file qgraphicslayoutitem.cpp.

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◆ setMaximumSize() [1/2]

void QGraphicsLayoutItem::setMaximumSize ( const QSizeF & size )

Sets the maximum size to size. This property overrides sizeHint() for Qt::MaximumSize and ensures that effectiveSizeHint() will never return a size larger than size. In order to unset the maximum size, use an invalid size.

See also: maximumSize(), minimumSize(), preferredSize(), Qt::MaximumSize, sizeHint()

Definition at line 605 of file qgraphicslayoutitem.cpp.

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◆ setMaximumSize() [2/2]

void QGraphicsLayoutItem::setMaximumSize	(	qreal	w,
		qreal	h
	)

inline

This convenience function is equivalent to calling setMaximumSize(QSizeF(w, h)).

See also: maximumSize(), setMinimumSize(), setPreferredSize(), sizeHint()

Definition at line 128 of file qgraphicslayoutitem.h.

◆ setMaximumWidth()

void QGraphicsLayoutItem::setMaximumWidth ( qreal width )

Sets the maximum width to width.

See also: maximumWidth(), setMaximumSize(), maximumSize()

Definition at line 635 of file qgraphicslayoutitem.cpp.

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◆ setMinimumHeight()

void QGraphicsLayoutItem::setMinimumHeight ( qreal height )

Sets the minimum height to height.

See also: minimumHeight(), setMinimumSize(), minimumSize()

Definition at line 537 of file qgraphicslayoutitem.cpp.

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◆ setMinimumSize() [1/2]

void QGraphicsLayoutItem::setMinimumSize ( const QSizeF & size )

Sets the minimum size to size. This property overrides sizeHint() for Qt::MinimumSize and ensures that effectiveSizeHint() will never return a size smaller than size. In order to unset the minimum size, use an invalid size.

See also: minimumSize(), maximumSize(), preferredSize(), Qt::MinimumSize, sizeHint(), setMinimumWidth(), setMinimumHeight()

Definition at line 497 of file qgraphicslayoutitem.cpp.

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◆ setMinimumSize() [2/2]

void QGraphicsLayoutItem::setMinimumSize	(	qreal	w,
		qreal	h
	)

inline

This convenience function is equivalent to calling setMinimumSize(QSizeF(w, h)).

See also: minimumSize(), setMaximumSize(), setPreferredSize(), sizeHint()

Definition at line 124 of file qgraphicslayoutitem.h.

◆ setMinimumWidth()

void QGraphicsLayoutItem::setMinimumWidth ( qreal width )

Sets the minimum width to width.

See also: minimumWidth(), setMinimumSize(), minimumSize()

Definition at line 527 of file qgraphicslayoutitem.cpp.

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◆ setOwnedByLayout()

void QGraphicsLayoutItem::setOwnedByLayout ( bool ownership )

protected

Since: 4.6

Sets whether a layout should delete this item in its destructor or not. ownership must be true to in order for the layout to delete it.

See also: ownedByLayout()

Definition at line 919 of file qgraphicslayoutitem.cpp.

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◆ setParentLayoutItem()

void QGraphicsLayoutItem::setParentLayoutItem ( QGraphicsLayoutItem * parent )

Sets the parent of this QGraphicsLayoutItem to parent.

See also: parentLayoutItem()

Definition at line 867 of file qgraphicslayoutitem.cpp.

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◆ setPreferredHeight()

void QGraphicsLayoutItem::setPreferredHeight ( qreal height )

Sets the preferred height to height.

See also: preferredWidth(), setPreferredSize(), preferredSize()

Definition at line 581 of file qgraphicslayoutitem.cpp.

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◆ setPreferredSize() [1/2]

void QGraphicsLayoutItem::setPreferredSize ( const QSizeF & size )

Sets the preferred size to size. This property overrides sizeHint() for Qt::PreferredSize and provides the default value for effectiveSizeHint(). In order to unset the preferred size, use an invalid size.

See also: preferredSize(), minimumSize(), maximumSize(), Qt::PreferredSize, sizeHint()

Definition at line 551 of file qgraphicslayoutitem.cpp.

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◆ setPreferredSize() [2/2]

void QGraphicsLayoutItem::setPreferredSize	(	qreal	w,
		qreal	h
	)

inline

This convenience function is equivalent to calling setPreferredSize(QSizeF(w, h)).

See also: preferredSize(), setMaximumSize(), setMinimumSize(), sizeHint()

Definition at line 126 of file qgraphicslayoutitem.h.

◆ setPreferredWidth()

void QGraphicsLayoutItem::setPreferredWidth ( qreal width )

Sets the preferred width to width.

See also: preferredHeight(), setPreferredSize(), preferredSize()

Definition at line 591 of file qgraphicslayoutitem.cpp.

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◆ setSizePolicy() [1/2]

void QGraphicsLayoutItem::setSizePolicy ( const QSizePolicy & policy )

Sets the size policy to policy. The size policy describes how the item should grow horizontally and vertically when arranged in a layout.

QGraphicsLayoutItem's default size policy is (QSizePolicy::Fixed, QSizePolicy::Fixed, QSizePolicy::DefaultType), but it is common for subclasses to change the default. For example, QGraphicsWidget defaults to (QSizePolicy::Preferred, QSizePolicy::Preferred, QSizePolicy::DefaultType).

See also: sizePolicy(), QWidget::sizePolicy()

Definition at line 453 of file qgraphicslayoutitem.cpp.

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◆ setSizePolicy() [2/2]

void QGraphicsLayoutItem::setSizePolicy	(	QSizePolicy::Policy	hPolicy,
		QSizePolicy::Policy	vPolicy,
		QSizePolicy::ControlType	controlType = `QSizePolicy::DefaultType`
	)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

This function is equivalent to calling setSizePolicy(QSizePolicy(hPolicy, vPolicy, controlType)).

See also: sizePolicy(), QWidget::sizePolicy()

Definition at line 470 of file qgraphicslayoutitem.cpp.

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◆ sizeHint()

QSizeF QGraphicsLayoutItem::sizeHint	(	Qt::SizeHint	which,
		const QSizeF &	constraint = `QSizeF()`
	)		const

protectedpure virtual

This pure virtual function returns the size hint for which of the QGraphicsLayoutItem, using the width or height of constraint to constrain the output.

Reimplement this function in a subclass of QGraphicsLayoutItem to provide the necessary size hints for your items.

See also: effectiveSizeHint()

Implemented in SubQGraphicsLayoutItem, CustomLayout, MySquareWidget, HFWWidget, SizeHinter, RectWidget, CustomGraphicsWidget, CustomLayoutItem, AnimatedLayoutItem, Layout, RectWidget, TestWidget, QGraphicsWidget, QGraphicsProxyWidget, QGraphicsLinearLayout, QGraphicsGridLayout, QGraphicsAnchorLayout, PixmapWidget, FlowLayout, LayoutItem, and SimpleListView.

◆ sizePolicy()

QSizePolicy QGraphicsLayoutItem::sizePolicy ( ) const

Returns the current size policy.

See also: setSizePolicy(), QWidget::sizePolicy()

Definition at line 482 of file qgraphicslayoutitem.cpp.

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◆ updateGeometry()

void QGraphicsLayoutItem::updateGeometry ( )

virtual

This virtual function discards any cached size hint information. You should always call this function if you change the return value of the sizeHint() function. Subclasses must always call the base implementation when reimplementing this function.

See also: effectiveSizeHint()

Reimplemented in SubQGraphicsLayoutItem, QGraphicsWidget, and QGraphicsLayout.

Definition at line 822 of file qgraphicslayoutitem.cpp.

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Friends And Related Function Documentation

◆ QGraphicsLayout

friend class QGraphicsLayout

friend

Definition at line 117 of file qgraphicslayoutitem.h.

Member Data Documentation

◆ d_ptr

QScopedPointer<QGraphicsLayoutItemPrivate> QGraphicsLayoutItem::d_ptr

protected

Definition at line 111 of file qgraphicslayoutitem.h.

The documentation for this class was generated from the following files:

src/widgets/graphicsview/qgraphicslayoutitem.h
src/widgets/graphicsview/qgraphicslayoutitem.cpp

Public Member Functions

Protected Member Functions

Protected Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

◆ QGraphicsLayoutItem() [1/2]

◆ ~QGraphicsLayoutItem()

◆ QGraphicsLayoutItem() [2/2]

Member Function Documentation

◆ contentsRect()

◆ effectiveSizeHint()

◆ geometry()

◆ getContentsMargins()

◆ graphicsItem()

◆ isEmpty()

◆ isLayout()

◆ maximumHeight()

◆ maximumSize()

◆ maximumWidth()

◆ minimumHeight()

◆ minimumSize()

◆ minimumWidth()

◆ ownedByLayout()

◆ parentLayoutItem()

◆ preferredHeight()

◆ preferredSize()

◆ preferredWidth()

◆ setGeometry()

◆ setGraphicsItem()

◆ setMaximumHeight()

◆ setMaximumSize() [1/2]

◆ setMaximumSize() [2/2]

◆ setMaximumWidth()

◆ setMinimumHeight()

◆ setMinimumSize() [1/2]

◆ setMinimumSize() [2/2]

◆ setMinimumWidth()

◆ setOwnedByLayout()

◆ setParentLayoutItem()

◆ setPreferredHeight()

◆ setPreferredSize() [1/2]

◆ setPreferredSize() [2/2]

◆ setPreferredWidth()

◆ setSizePolicy() [1/2]

◆ setSizePolicy() [2/2]

◆ sizeHint()

◆ sizePolicy()

◆ updateGeometry()

Friends And Related Function Documentation

◆ QGraphicsLayout

Member Data Documentation

◆ d_ptr