A layout manager which arranges widgets in a grid. More...

#include <Wt/WGridLayout.h>

Inheritance diagram for Wt::WGridLayout:

Public Member Functions
	WGridLayout ()
	Create a new grid layout. More...

virtual void	addItem (std::unique_ptr< WLayoutItem > item) override
	Adds a layout item. More...

virtual std::unique_ptr< WLayoutItem >	removeItem (WLayoutItem *item) override
	Removes a layout item (widget or nested layout). More...

virtual WLayoutItem *	itemAt (int index) const override
	Returns the layout item at a specific index. More...

virtual int	count () const override
	Returns the number of items in this layout. More...

void	addItem (std::unique_ptr< WLayoutItem > item, int row, int column, int rowSpan=1, int columnSpan=1, WFlags< AlignmentFlag > alignment=None)
	Adds a layout item to the grid. More...

void	addLayout (std::unique_ptr< WLayout > layout, int row, int column, WFlags< AlignmentFlag > alignment=None)
	Adds a nested layout item to the grid. More...

void	addLayout (std::unique_ptr< WLayout > layout, int row, int column, int rowSpan, int columnSpan, WFlags< AlignmentFlag > alignment=None)
	Adds a nested layout item to the grid. More...

void	addWidget (std::unique_ptr< WWidget > widget, int row, int column, WFlags< AlignmentFlag > alignment)
	Adds a widget to the grid. More...

template<typename Widget >
Widget *	addWidget (std::unique_ptr< Widget > widget, int row, int column, WFlags< AlignmentFlag > alignment=None)
	Adds a widget to the grid, returning a raw pointer to the widget. More...

void	addWidget (std::unique_ptr< WWidget > widget, int row, int column, int rowSpan, int columnSpan, WFlags< AlignmentFlag > alignment)
	Adds a widget to the grid. More...

template<typename Widget >
Widget *	addWidget (std::unique_ptr< Widget > widget, int row, int column, int rowSpan, int columnSpan, WFlags< AlignmentFlag > alignment=None)
	Adds a widget to the grid, returning a raw pointer to the widget. More...

void	setHorizontalSpacing (int size)
	Sets the horizontal spacing. More...

int	horizontalSpacing () const
	Returns the horizontal spacing. More...

void	setVerticalSpacing (int size)
	Sets the vertical spacing. More...

int	verticalSpacing () const
	Returns the vertical spacing. More...

int	columnCount () const
	Returns the column count. More...

int	rowCount () const
	Returns the row count. More...

void	setColumnStretch (int column, int stretch)
	Sets the column stretch. More...

int	columnStretch (int column) const
	Returns the column stretch. More...

void	setRowStretch (int row, int stretch)
	Sets the row stretch. More...

int	rowStretch (int row) const
	Returns the column stretch. More...

void	setColumnResizable (int column, bool enabled=true, const WLength &initialSize=WLength::Auto)
	Sets whether the user may drag a particular column border. More...

bool	columnIsResizable (int column) const
	Returns whether the user may drag a particular column border. More...

void	setRowResizable (int row, bool enabled=true, const WLength &initialSize=WLength::Auto)
	Sets whether the user may drag a particular row border. More...

bool	rowIsResizable (int row) const
	Returns whether the user may drag a particular row border. More...

Public Member Functions inherited from Wt::WLayout
virtual	~WLayout ()
	Destructor. More...

void	setPreferredImplementation (LayoutImplementation implementation)
	Set the preferred layout implementation. More...

void	addWidget (std::unique_ptr< WWidget > widget)
	Adds the given widget to the layout. More...

std::unique_ptr< WWidget >	removeWidget (WWidget *widget)
	Removes the given widget from the layout. More...

virtual int	indexOf (WLayoutItem *item) const
	Returns the index of a given item. More...

virtual WWidgetItem *	findWidgetItem (WWidget *widget) override
	Finds the widget item associated with the given widget.

virtual WWidget *	widget () override
	Returns the widget that is held by this WLayoutItem. More...

virtual WLayout *	layout () override
	Returns the layout that implements this WLayoutItem. More...

virtual WLayout *	parentLayout () const override
	Returns the layout in which this item is contained.

void	setContentsMargins (int left, int top, int right, int bottom)
	Set contents margins (in pixels). More...

void	getContentsMargins (int left, int top, int right, int bottom) const
	Returns the contents margins. More...

Public Member Functions inherited from Wt::WLayoutItem
virtual	~WLayoutItem ()
	Destructor.

Public Member Functions inherited from Wt::WObject
void	addChild (std::unique_ptr< WObject > child)
	Add a child WObject whose lifetime is determined by this WObject.

template<typename Child >
Child *	addChild (std::unique_ptr< Child > child)
	Add a child WObject, returning a raw pointer. More...

std::unique_ptr< WObject >	removeChild (WObject *child)
	Remove a child WObject, so its lifetime is no longer determined by this WObject.

template<typename Child >
std::unique_ptr< Child >	removeChild (Child *child)
	Remove a child WObject, so its lifetime is no longer determined by this WObject. More...

virtual const std::string	id () const
	Returns the (unique) identifier for this object. More...

virtual void	setObjectName (const std::string &name)
	Sets an object name. More...

virtual std::string	objectName () const
	Returns the object name. More...

void	resetLearnedSlots ()
	Resets learned stateless slot implementations. More...

template<class T >
void	resetLearnedSlot (void(T::*method)())
	Resets a learned stateless slot implementation. More...

template<class T >
WStatelessSlot *	implementStateless (void(T::*method)())
	Declares a slot to be stateless and learn client-side behaviour on first invocation. More...

template<class T >
WStatelessSlot *	implementStateless (void(T::method)(), void(T::undoMethod)())
	Declares a slot to be stateless and learn client-side behaviour in advance. More...

void	isNotStateless ()
	Marks the current function as not stateless. More...

template<class T >
WStatelessSlot *	implementJavaScript (void(T::*method)(), const std::string &jsCode)
	Provides a JavaScript implementation for a method. More...

Public Member Functions inherited from Wt::Core::observable
	observable () noexcept
	Default constructor.

virtual	~observable ()
	Destructor. More...

template<typename... Args, typename C >
auto	bindSafe (void(C::*method)(Args...)) noexcept
	Protects a method call against object destruction. More...

template<typename... Args, typename C >
auto	bindSafe (void(C::*method)(Args...) const) const noexcept
	Protects a const method call against object destruction. More...

template<typename Function >
auto	bindSafe (const Function &function) noexcept
	Protects a function against object destruction. More...

Private Member Functions
virtual void	setParentWidget (WWidget *parent) override
	Internal method.

Additional Inherited Members
Public Types inherited from Wt::WObject
typedef void(WObject::*	Method) ()
	Typedef for a WObject method without arguments.

Static Public Member Functions inherited from Wt::WLayout
static void	setDefaultImplementation (LayoutImplementation implementation)
	Sets the preferred layout implementation globally. More...

Protected Member Functions inherited from Wt::WLayout
	WLayout ()
	Create a layout.

void	update (WLayoutItem *item=nullptr)
	Update the layout. More...

Protected Member Functions inherited from Wt::WObject
virtual WStatelessSlot *	getStateless (Method method)
	On-demand stateless slot implementation. More...

Detailed Description

A layout manager which arranges widgets in a grid.

This layout manager arranges widgets in a grid.

Each grid cell (row, column) may contain one widget or nested layout. Orientation::Horizontal and vertical space are divided so that each non-stretchable column/row is given its preferred size (if possible) and the remaining space is divided according to stretch factors among the columns/rows. If not all columns/rows can be given their preferred size (there is not enough room), then columns/rows are given a smaller size (down to a minimum size based on widget minimum sizes). If necessary, the container (or parent layout) of this layout is resized to meet minimum size requirements.

The preferred width/height of a column/row is based on the natural size of the widgets, where they present their contents without overflowing. WWidget::resize() or (CSS width, height properties) can be used to adjust the preferred size of a widget.

The minimum width/height of a column/row is based on the minimum dimensions of contained widgets or nested layouts. The default minimum height and width for a widget is 0. It can be specified using WWidget::setMinimumSize() or using CSS min-width and min-height properties.

You should use WContainerWidget::setOverflow(OverflowAuto) to automatically show scrollbars for widgets inserted in the layout to cope with a size set by the layout manager that is smaller than the preferred size.

When the container of a layout manager has a maximum size set using WWidget::setMaximumSize(), then the size of the container will be based on the preferred size of the contents, up to this maximum size, instead of the default behaviour of constraining the size of the children based on the size of the container.

A layout manager may provide resize handles between columns or rows which allow the user to change the automatic layout provided by the layout manager (see setRowResizable() and setColumnResizable()).

Columns and rows are separated using a constant spacing, which defaults to 6 pixels by default, and can be changed using setHorizontalSpacing() and setVerticalSpacing(). In addition, when this layout is a top-level layout (i.e. is not nested inside another layout), a margin is set around the contents. This margin defaults to 9 pixels, and can be changed using setContentsMargins().

For each column or row, a stretch factor may be defined, which controls how remaining horizontal or vertical space is used. Each column and row is stretched using the stretch factor to fill the remaining space. When the stretch factor is 0, the height of the row and its contents is set to the preferred size (if possible). When the stretch factor is 1 or higher, these widgets will be given the remaining size, limited only by their minimum size (their preferred size is ignored).

Usage example:

Wt::WContainerWidget *w = addWidget(std::make_unique<Wt::WContainerWidget>());
w->resize(WLength::Auto, 600);
 
auto layout = std::make_unique<Wt::WGridLayout>();
layout->addWidget(std::make_unique<Wt::WText>("Item 0 0"), 0, 0);
layout->addWidget(std::make_unique<Wt::WText>("Item 0 1"), 0, 1);
layout->addWidget(std::make_unique<Wt::WText>("Item 1 0"), 1, 0);
layout->addWidget(std::make_unique<Wt::WText>("Item 1 1"), 1, 1);
 
w->setLayout(std::move(layout));

Note: When JavaScript support is not available, not all functionality of the layout is available. In particular, vertical size management is not available.; When a layout is used on a first page with progressive bootstrap, then the layout will progress only in a limited way to a full JavaScript-based layout. You can thus not rely on it to behave properly for example when dynamically adding or removing widgets.

Constructor & Destructor Documentation

◆ WGridLayout()

Wt::WGridLayout::WGridLayout ( )

Create a new grid layout.

The grid will grow dynamically as items are added.

Use parent = 0 to create a layout manager that can be nested inside other layout managers or if you use WContainerWidget::setLayout() to add specify the container later.

Member Function Documentation

◆ addItem() [1/2]

void Wt::WGridLayout::addItem ( std::unique_ptr< WLayoutItem > item )

overridevirtual

Adds a layout item.

The item may be a widget or nested layout.

How the item is layed out with respect to siblings is implementation specific to the layout manager. In some cases, a layout manager will overload this method with extra arguments that specify layout options.

See also: removeItem(WLayoutItem *), addWidget(WWidget *)

Implements Wt::WLayout.

◆ addItem() [2/2]

void Wt::WGridLayout::addItem	(	std::unique_ptr< WLayoutItem >	item,
		int	row,
		int	column,
		int	rowSpan = `1`,
		int	columnSpan = `1`,
		WFlags< AlignmentFlag >	alignment = `None`
	)

Adds a layout item to the grid.

Adds the item at (row, column). If an item was already added to that location, it is replaced.

An item may span several more rows or columns, which is controlled by rowSpan and columnSpan.

The alignment specifies the vertical and horizontal alignment of the item. The default value 0 indicates that the item is stretched to fill the entire grid cell. The alignment can be specified as a logical combination of a horizontal alignment (Wt::AlignmentFlag::Left, Wt::AlignmentFlag::Center, or Wt::AlignmentFlag::Right) and a vertical alignment (Wt::AlignmentFlag::Top, Wt::AlignmentFlag::Middle, or Wt::AlignmentFlag::Bottom).

See also: addLayout(), addWidget()

◆ addLayout() [1/2]

void Wt::WGridLayout::addLayout	(	std::unique_ptr< WLayout >	layout,
		int	row,
		int	column,
		int	rowSpan,
		int	columnSpan,
		WFlags< AlignmentFlag >	alignment = `None`
	)

Adds a nested layout item to the grid.

Adds the layout at (row, column). If an item was already added to that location, it is replaced (but not deleted).

An item may span several more rows or columns, which is controlled by rowSpan and columnSpan.

The alignment specifies the vertical and horizontal alignment of the item. The default value 0 indicates that the item is stretched to fill the entire grid cell. The alignment can be specified as a logical combination of a horizontal alignment (Wt::AlignmentFlag::Left, Wt::AlignmentFlag::Center, or Wt::AlignmentFlag::Right) and a vertical alignment (Wt::AlignmentFlag::Top, Wt::AlignmentFlag::Middle, or Wt::AlignmentFlag::Bottom).

See also: addLayout(WLayout *, int, int, WFlags<AlignmentFlag>)

◆ addLayout() [2/2]

void Wt::WGridLayout::addLayout	(	std::unique_ptr< WLayout >	layout,
		int	row,
		int	column,
		WFlags< AlignmentFlag >	alignment = `None`
	)

Adds a nested layout item to the grid.

Adds the layout at (row, column). If an item was already added to that location, it is replaced (but not deleted).

The alignment specifies the vertical and horizontal alignment of the item. The default value 0 indicates that the item is stretched to fill the entire grid cell. The alignment can be specified as a logical combination of a horizontal alignment (Wt::AlignmentFlag::Left, Wt::AlignmentFlag::Center, or Wt::AlignmentFlag::Right) and a vertical alignment (Wt::AlignmentFlag::Top, Wt::AlignmentFlag::Middle, or Wt::AlignmentFlag::Bottom).

See also: addLayout(WLayout *, int, int, int, int, WFlags<AlignmentFlag>)

◆ addWidget() [1/4]

template<typename Widget >

Widget* Wt::WGridLayout::addWidget	(	std::unique_ptr< Widget >	widget,
		int	row,
		int	column,
		int	rowSpan,
		int	columnSpan,
		WFlags< AlignmentFlag >	alignment = `None`
	)

Adds a widget to the grid, returning a raw pointer to the widget.

This is implemented as:

Widget *result = widget.get();
addWidget(std::unique_ptr<WWidget>(std::move(widget)), row, column,
          rowSpan, columnSpan, alignment);
return result;

◆ addWidget() [2/4]

template<typename Widget >

Widget* Wt::WGridLayout::addWidget	(	std::unique_ptr< Widget >	widget,
		int	row,
		int	column,
		WFlags< AlignmentFlag >	alignment = `None`
	)

Adds a widget to the grid, returning a raw pointer to the widget.

This is implemented as:

Widget *result = widget.get();
addWidget(std::unique_ptr<WWidget>(std::move(widget)), row, column, alignment);
return result;

◆ addWidget() [3/4]

void Wt::WGridLayout::addWidget	(	std::unique_ptr< WWidget >	widget,
		int	row,
		int	column,
		int	rowSpan,
		int	columnSpan,
		WFlags< AlignmentFlag >	alignment
	)

Adds a widget to the grid.

Adds the widget at (row, column). If an item was already added to that location, it is replaced (but not deleted).

The widget may span several more rows or columns, which is controlled by rowSpan and columnSpan.

The alignment specifies the vertical and horizontal alignment of the item. The default value 0 indicates that the item is stretched to fill the entire grid cell. The alignment can be specified as a logical combination of a horizontal alignment (Wt::AlignmentFlag::Left, Wt::AlignmentFlag::Center, or Wt::AlignmentFlag::Right) and a vertical alignment (Wt::AlignmentFlag::Top, Wt::AlignmentFlag::Middle, or Wt::AlignmentFlag::Bottom).

See also: addWidget(WWidget *, int, int, WFlags<AlignmentFlag>)

◆ addWidget() [4/4]

void Wt::WGridLayout::addWidget	(	std::unique_ptr< WWidget >	widget,
		int	row,
		int	column,
		WFlags< AlignmentFlag >	alignment
	)

Adds a widget to the grid.

Adds the widget at (row, column). If an item was already added to that location, it is replaced (but not deleted).

The alignment specifies the vertical and horizontal alignment of the item. The default value 0 indicates that the item is stretched to fill the entire grid cell. The alignment can be specified as a logical combination of a horizontal alignment (Wt::AlignmentFlag::Left, Wt::AlignmentFlag::Center, or Wt::AlignmentFlag::Right) and a vertical alignment (Wt::AlignmentFlag::Top, Wt::AlignmentFlag::Middle, or Wt::AlignmentFlag::Bottom).

See also: addWidget(WWidget *, int, int, int, int, WFlags<AlignmentFlag>)

◆ columnCount()

int Wt::WGridLayout::columnCount ( ) const

Returns the column count.

The grid dimensions change dynamically when adding contents to the grid.

See also: rowCount()

◆ columnIsResizable()

bool Wt::WGridLayout::columnIsResizable ( int column ) const

Returns whether the user may drag a particular column border.

This method returns whether the border that separates column column from the next column may be resized by the user.

See also: setColumnResizable()

◆ columnStretch()

int Wt::WGridLayout::columnStretch ( int column ) const

Returns the column stretch.

See also: setColumnStretch(int, int)

◆ count()

int Wt::WGridLayout::count ( ) const

overridevirtual

Returns the number of items in this layout.

This may be a theoretical number, which is greater than the actual number of items. It can be used to iterate over the items in the layout, in conjunction with itemAt().

Implements Wt::WLayout.

◆ horizontalSpacing()

int Wt::WGridLayout::horizontalSpacing ( ) const

Returns the horizontal spacing.

See also: setHorizontalSpacing(int)

◆ itemAt()

WLayoutItem * Wt::WGridLayout::itemAt ( int index ) const

overridevirtual

Returns the layout item at a specific index.

If there is no item at the index, 0 is returned.

See also: indexOf(WLayoutItem *) const, count()

Implements Wt::WLayout.

◆ removeItem()

std::unique_ptr< WLayoutItem > Wt::WGridLayout::removeItem ( WLayoutItem * item )

overridevirtual

Removes a layout item (widget or nested layout).

See also: addItem(WLayoutItem *), removeWidget(WWidget *)

Implements Wt::WLayout.

◆ rowCount()

int Wt::WGridLayout::rowCount ( ) const

Returns the row count.

The grid dimensions change dynamically when adding contents to the grid.

See also: columnCount()

◆ rowIsResizable()

bool Wt::WGridLayout::rowIsResizable ( int row ) const

Returns whether the user may drag a particular row border.

This method returns whether the border that separates row row from the next row may be resized by the user.

See also: setRowResizable()

◆ rowStretch()

int Wt::WGridLayout::rowStretch ( int row ) const

Returns the column stretch.

See also: setRowStretch(int, int)

◆ setColumnResizable()

void Wt::WGridLayout::setColumnResizable	(	int	column,
		bool	enabled = `true`,
		const WLength &	initialSize = `WLength::Auto`
	)

Sets whether the user may drag a particular column border.

This method sets whether the border that separates column column from the next column may be resized by the user, depending on the value of enabled.

The default value is false.

If an initialSize is given (that is not WLength::Auto), then this size is used for the width of the column, overriding the width it would be given by the layout manager.

◆ setColumnStretch()

void Wt::WGridLayout::setColumnStretch	(	int	column,
		int	stretch
	)

Sets the column stretch.

Sets the stretch factor for column column.

See also: columnStretch()

◆ setHorizontalSpacing()

void Wt::WGridLayout::setHorizontalSpacing ( int size )

Sets the horizontal spacing.

The default horizontal spacing is 9 pixels.

See also: setVerticalSpacing(int)

◆ setRowResizable()

void Wt::WGridLayout::setRowResizable	(	int	row,
		bool	enabled = `true`,
		const WLength &	initialSize = `WLength::Auto`
	)

Sets whether the user may drag a particular row border.

This method sets whether the border that separates row row from the next row may be resized by the user, depending on the value of enabled.

The default value is false.

If an initialSize is given (that is not WLength::Auto), then this size is used for the height of the row, overriding the height it would be given by the layout manager.

◆ setRowStretch()

void Wt::WGridLayout::setRowStretch	(	int	row,
		int	stretch
	)

Sets the row stretch.

Sets the stretch factor for row row.

See also: rowStretch()

◆ setVerticalSpacing()

void Wt::WGridLayout::setVerticalSpacing ( int size )

Sets the vertical spacing.

The default vertical spacing is 9 pixels.

See also: setHorizontalSpacing(int)

◆ verticalSpacing()

int Wt::WGridLayout::verticalSpacing ( ) const

Returns the vertical spacing.

See also: setVerticalSpacing(int)

Public Member Functions

Private Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ WGridLayout()

Member Function Documentation

◆ addItem() [1/2]

◆ addItem() [2/2]

◆ addLayout() [1/2]

◆ addLayout() [2/2]

◆ addWidget() [1/4]

◆ addWidget() [2/4]

◆ addWidget() [3/4]

◆ addWidget() [4/4]

◆ columnCount()

◆ columnIsResizable()

◆ columnStretch()

◆ count()

◆ horizontalSpacing()

◆ itemAt()

◆ removeItem()

◆ rowCount()

◆ rowIsResizable()

◆ rowStretch()

◆ setColumnResizable()

◆ setColumnStretch()

◆ setHorizontalSpacing()

◆ setRowResizable()

◆ setRowStretch()

◆ setVerticalSpacing()

◆ verticalSpacing()