The QGraphicsAnchorLayout class provides a layout where one can anchor widgets together in Graphics View. More...

#include <qgraphicsanchorlayout.h>

Inheritance diagram for QGraphicsAnchorLayout:

Collaboration diagram for QGraphicsAnchorLayout:

Public Member Functions
	QGraphicsAnchorLayout (QGraphicsLayoutItem *parent=nullptr)
	Constructs a QGraphicsAnchorLayout instance.

virtual	~QGraphicsAnchorLayout ()
	Destroys the QGraphicsAnchorLayout object.

QGraphicsAnchor *	addAnchor (QGraphicsLayoutItem firstItem, Qt::AnchorPoint firstEdge, QGraphicsLayoutItem secondItem, Qt::AnchorPoint secondEdge)
	Creates an anchor between the edge firstEdge of item firstItem and the edge secondEdge of item secondItem.

QGraphicsAnchor *	anchor (QGraphicsLayoutItem firstItem, Qt::AnchorPoint firstEdge, QGraphicsLayoutItem secondItem, Qt::AnchorPoint secondEdge)
	Returns the anchor between the anchor points defined by firstItem and firstEdge and secondItem and secondEdge.

void	addCornerAnchors (QGraphicsLayoutItem firstItem, Qt::Corner firstCorner, QGraphicsLayoutItem secondItem, Qt::Corner secondCorner)
	Creates two anchors between firstItem and secondItem specified by the corners, firstCorner and secondCorner, where one is for the horizontal edge and another one for the vertical edge.

void	addAnchors (QGraphicsLayoutItem firstItem, QGraphicsLayoutItem secondItem, Qt::Orientations orientations=Qt::Horizontal\|Qt::Vertical)
	Anchors two or four edges of firstItem with the corresponding edges of secondItem, so that firstItem has the same size as secondItem in the dimensions specified by orientations.

void	setHorizontalSpacing (qreal spacing)
	Sets the default horizontal spacing for the anchor layout to spacing.

void	setVerticalSpacing (qreal spacing)
	Sets the default vertical spacing for the anchor layout to spacing.

void	setSpacing (qreal spacing)
	Sets the default horizontal and the default vertical spacing for the anchor layout to spacing.

qreal	horizontalSpacing () const
	Returns the default horizontal spacing for the anchor layout.

qreal	verticalSpacing () const
	Returns the default vertical spacing for the anchor layout.

void	removeAt (int index) override
	Removes the layout item at index without destroying it.

void	setGeometry (const QRectF &rect) override
	\reimp

int	count () const override
	\reimp

QGraphicsLayoutItem *	itemAt (int index) const override
	\reimp

void	invalidate () override
	\reimp

Public Member Functions inherited from QGraphicsLayout
	QGraphicsLayout (QGraphicsLayoutItem *parent=nullptr)
	Constructs a QGraphicsLayout object.

	~QGraphicsLayout ()
	Destroys the QGraphicsLayout object.

void	setContentsMargins (qreal left, qreal top, qreal right, qreal bottom)
	Sets the contents margins to left, top, right and bottom.

void	getContentsMargins (qreal left, qreal top, qreal right, qreal bottom) const override
	\reimp

void	activate ()
	Activates the layout, causing all items in the layout to be immediately rearranged.

bool	isActivated () const
	Returns `true` if the layout is currently being activated; otherwise, returns `false`.

virtual void	updateGeometry () override
	\reimp

virtual void	widgetEvent (QEvent *e)
	This virtual event handler receives all events for the managed widget.

Public Member Functions inherited from QGraphicsLayoutItem
	QGraphicsLayoutItem (QGraphicsLayoutItem *parent=nullptr, bool isLayout=false)
	Constructs the QGraphicsLayoutItem object.

virtual	~QGraphicsLayoutItem ()
	Destroys the QGraphicsLayoutItem object.

void	setSizePolicy (const QSizePolicy &policy)
	Sets the size policy to policy.

void	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)).

QSizePolicy	sizePolicy () const
	Returns the current size policy.

void	setMinimumSize (const QSizeF &size)
	Sets the minimum size to size.

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

QSizeF	minimumSize () const
	Returns the minimum size.

void	setMinimumWidth (qreal width)
	Sets the minimum width to width.

qreal	minimumWidth () const
	Returns the minimum width.

void	setMinimumHeight (qreal height)
	Sets the minimum height to height.

qreal	minimumHeight () const
	Returns the minimum height.

void	setPreferredSize (const QSizeF &size)
	Sets the preferred size to size.

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

QSizeF	preferredSize () const
	Returns the preferred size.

void	setPreferredWidth (qreal width)
	Sets the preferred width to width.

qreal	preferredWidth () const
	Returns the preferred width.

void	setPreferredHeight (qreal height)
	Sets the preferred height to height.

qreal	preferredHeight () const
	Returns the preferred height.

void	setMaximumSize (const QSizeF &size)
	Sets the maximum size to size.

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

QSizeF	maximumSize () const
	Returns the maximum size.

void	setMaximumWidth (qreal width)
	Sets the maximum width to width.

qreal	maximumWidth () const
	Returns the maximum width.

void	setMaximumHeight (qreal height)
	Sets the maximum height to height.

qreal	maximumHeight () const
	Returns the maximum height.

QRectF	geometry () const
	Returns the item's geometry (e.g., position and size) as a QRectF.

QRectF	contentsRect () const
	Returns the contents rect in local coordinates.

QSizeF	effectiveSizeHint (Qt::SizeHint which, const QSizeF &constraint=QSizeF()) const
	Returns the effective size hint for this QGraphicsLayoutItem.

virtual bool	isEmpty () const

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).

void	setParentLayoutItem (QGraphicsLayoutItem *parent)
	Sets the parent of this QGraphicsLayoutItem to parent.

bool	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`.

QGraphicsItem *	graphicsItem () const
	Returns the QGraphicsItem that this layout item represents.

bool	ownedByLayout () const

Protected Member Functions
QSizeF	sizeHint (Qt::SizeHint which, const QSizeF &constraint=QSizeF()) const override
	\reimp

Protected Member Functions inherited from QGraphicsLayout
	QGraphicsLayout (QGraphicsLayoutPrivate &, QGraphicsLayoutItem *)

void	addChildLayoutItem (QGraphicsLayoutItem *layoutItem)

Protected Member Functions inherited from QGraphicsLayoutItem
void	setGraphicsItem (QGraphicsItem *item)
	If the QGraphicsLayoutItem represents a QGraphicsItem, and it wants to take advantage of the automatic reparenting capabilities of QGraphicsLayout it should set this value.

void	setOwnedByLayout (bool ownedByLayout)

	QGraphicsLayoutItem (QGraphicsLayoutItemPrivate &dd)

Friends
class	QGraphicsAnchor

Additional Inherited Members
Static Public Member Functions inherited from QGraphicsLayout
static void	setInstantInvalidatePropagation (bool enable)

static bool	instantInvalidatePropagation ()

Protected Attributes inherited from QGraphicsLayoutItem
QScopedPointer< QGraphicsLayoutItemPrivate >	d_ptr

Detailed Description

The QGraphicsAnchorLayout class provides a layout where one can anchor widgets together in Graphics View.

Since: 4.6

\inmodule QtWidgets

The anchor layout allows developers to specify how widgets should be placed relative to each other, and to the layout itself. The specification is made by adding anchors to the layout by calling addAnchor(), addAnchors() or addCornerAnchors().

Existing anchors in the layout can be accessed with the anchor() function. Items that are anchored are automatically added to the layout, and if items are removed, all their anchors will be automatically removed.

\div {class="float-left"} \inlineimage simpleanchorlayout-example.png Using an anchor layout to align simple colored widgets. \enddiv

Anchors are always set up between edges of an item, where the "center" is also considered to be an edge. Consider the following example:

Here, the right edge of item a is anchored to the left edge of item b and the bottom edge of item a is anchored to the top edge of item b, with the result that item b will be placed diagonally to the right and below item b.

The addCornerAnchors() function provides a simpler way of anchoring the corners of two widgets than the two individual calls to addAnchor() shown in the code above. Here, we see how a widget can be anchored to the top-left corner of the enclosing layout:

In cases where anchors are used to match the widths or heights of widgets, it is convenient to use the addAnchors() function. As with the other functions for specifying anchors, it can also be used to anchor a widget to a layout.

Definition at line 39 of file qgraphicsanchorlayout.h.

Constructor & Destructor Documentation

◆ QGraphicsAnchorLayout()

QGraphicsAnchorLayout::QGraphicsAnchorLayout ( QGraphicsLayoutItem * parent = nullptr )

Constructs a QGraphicsAnchorLayout instance.

parent is passed to QGraphicsLayout's constructor.

Definition at line 178 of file qgraphicsanchorlayout.cpp.

References d.

◆ ~QGraphicsAnchorLayout()

QGraphicsAnchorLayout::~QGraphicsAnchorLayout ( )

virtual

Destroys the QGraphicsAnchorLayout object.

Definition at line 188 of file qgraphicsanchorlayout.cpp.

References count(), d, Qt::Horizontal, i, item, Q_ASSERT, removeAt(), and Qt::Vertical.

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Member Function Documentation

◆ addAnchor()

QGraphicsAnchor * QGraphicsAnchorLayout::addAnchor	(	QGraphicsLayoutItem *	firstItem,
		Qt::AnchorPoint	firstEdge,
		QGraphicsLayoutItem *	secondItem,
		Qt::AnchorPoint	secondEdge )

Creates an anchor between the edge firstEdge of item firstItem and the edge secondEdge of item secondItem.

The spacing of the anchor is picked up from the style. Anchors between a layout edge and an item edge will have a size of 0. If there is already an anchor between the edges, the new anchor will replace the old one.

firstItem and secondItem are automatically added to the layout if they are not part of the layout. This means that count() can increase by up to 2.

The spacing an anchor will get depends on the type of anchor. For instance, anchors from the Right edge of one item to the Left edge of another (or vice versa) will use the default horizontal spacing. The same behaviour applies to Bottom to Top anchors, (but they will use the default vertical spacing). For all other anchor combinations, the spacing will be 0. All anchoring functions will follow this rule.

The spacing can also be set manually by using QGraphicsAnchor::setSpacing() method.

Calling this function where firstItem or secondItem are ancestors of the layout have undefined behaviour.

See also: addAnchors(), addCornerAnchors()

Definition at line 234 of file qgraphicsanchorlayout.cpp.

References d, and invalidate().

Referenced by addAnchors().

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◆ addAnchors()

void QGraphicsAnchorLayout::addAnchors	(	QGraphicsLayoutItem *	firstItem,
		QGraphicsLayoutItem *	secondItem,
		Qt::Orientations	orientations = Qt::Horizontal \| Qt::Vertical )

Anchors two or four edges of firstItem with the corresponding edges of secondItem, so that firstItem has the same size as secondItem in the dimensions specified by orientations.

For example, the following example anchors the left and right edges of two items to match their widths:

This can also be achieved using the following line of code:

See also: addAnchor(), addCornerAnchors()

Definition at line 313 of file qgraphicsanchorlayout.cpp.

References addAnchor(), Qt::AnchorBottom, Qt::AnchorLeft, Qt::AnchorRight, Qt::AnchorTop, Qt::Horizontal, ok, and Qt::Vertical.

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◆ addCornerAnchors()

void QGraphicsAnchorLayout::addCornerAnchors	(	QGraphicsLayoutItem *	firstItem,
		Qt::Corner	firstCorner,
		QGraphicsLayoutItem *	secondItem,
		Qt::Corner	secondCorner )

Creates two anchors between firstItem and secondItem specified by the corners, firstCorner and secondCorner, where one is for the horizontal edge and another one for the vertical edge.

This is a convenience function, since anchoring corners can be expressed as anchoring two edges. For instance:

This can also be achieved with the following line of code:

If there is already an anchor between the edge pairs, it will be replaced by the anchors that this function specifies.

firstItem and secondItem are automatically added to the layout if they are not part of the layout. This means that count() can increase by up to 2.

See also: addAnchor(), addAnchors()

Definition at line 277 of file qgraphicsanchorlayout.cpp.

References Qt::AnchorBottom, Qt::AnchorLeft, Qt::AnchorRight, Qt::AnchorTop, d, and invalidate().

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◆ anchor()

QGraphicsAnchor * QGraphicsAnchorLayout::anchor	(	QGraphicsLayoutItem *	firstItem,
		Qt::AnchorPoint	firstEdge,
		QGraphicsLayoutItem *	secondItem,
		Qt::AnchorPoint	secondEdge )

Returns the anchor between the anchor points defined by firstItem and firstEdge and secondItem and secondEdge.

If there is no such anchor, the function will return 0.

Definition at line 248 of file qgraphicsanchorlayout.cpp.

References d.

◆ count()

int QGraphicsAnchorLayout::count ( ) const

overridevirtual

\reimp

Implements QGraphicsLayout.

Definition at line 439 of file qgraphicsanchorlayout.cpp.

References d.

Referenced by ~QGraphicsAnchorLayout().

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◆ horizontalSpacing()

qreal QGraphicsAnchorLayout::horizontalSpacing ( ) const

Returns the default horizontal spacing for the anchor layout.

See also: verticalSpacing(), setHorizontalSpacing()

Definition at line 380 of file qgraphicsanchorlayout.cpp.

References d, and Qt::Horizontal.

◆ invalidate()

void QGraphicsAnchorLayout::invalidate ( )

overridevirtual

\reimp

Reimplemented from QGraphicsLayout.

Definition at line 457 of file qgraphicsanchorlayout.cpp.

References d, and QGraphicsLayout::invalidate().

Referenced by addAnchor(), addCornerAnchors(), removeAt(), setHorizontalSpacing(), setSpacing(), and setVerticalSpacing().

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◆ itemAt()

QGraphicsLayoutItem * QGraphicsAnchorLayout::itemAt ( int index ) const

overridevirtual

\reimp

Implements QGraphicsLayout.

Definition at line 448 of file qgraphicsanchorlayout.cpp.

References d.

◆ removeAt()

void QGraphicsAnchorLayout::removeAt ( int index )

overridevirtual

Removes the layout item at index without destroying it.

Ownership of the item is transferred to the caller.

Removing an item will also remove any of the anchors associated with it.

See also: itemAt(), count()

Implements QGraphicsLayout.

Definition at line 418 of file qgraphicsanchorlayout.cpp.

References d, Qt::Horizontal, invalidate(), item, and Qt::Vertical.

Referenced by ~QGraphicsAnchorLayout().

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◆ setGeometry()

void QGraphicsAnchorLayout::setGeometry ( const QRectF & rect )

overridevirtual

\reimp

Reimplemented from QGraphicsLayoutItem.

Definition at line 400 of file qgraphicsanchorlayout.cpp.

References d, Qt::Horizontal, QGraphicsLayoutItem::setGeometry(), and Qt::Vertical.

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◆ setHorizontalSpacing()

void QGraphicsAnchorLayout::setHorizontalSpacing ( qreal spacing )

Sets the default horizontal spacing for the anchor layout to spacing.

See also: horizontalSpacing(), setVerticalSpacing(), setSpacing()

Definition at line 335 of file qgraphicsanchorlayout.cpp.

References d, Qt::Horizontal, invalidate(), and spacing.

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◆ setSpacing()

void QGraphicsAnchorLayout::setSpacing ( qreal spacing )

Sets the default horizontal and the default vertical spacing for the anchor layout to spacing.

If an item is anchored with no spacing associated with the anchor, it will use the default spacing.

QGraphicsAnchorLayout does not support negative spacings. Setting a negative value will unset the previous spacing and make the layout use the spacing provided by the current widget style.