Wt  4.0.2
Public Member Functions | Static Public Member Functions | Protected Member Functions | Private Member Functions | List of all members
Wt::WLayout Class Referenceabstract

An abstract base class for layout managers. More...

#include <Wt/WLayout.h>

Inheritance diagram for Wt::WLayout:
Inheritance graph
[legend]

Public Member Functions

virtual ~WLayout ()
 Destructor. More...
 
void setPreferredImplementation (LayoutImplementation implementation)
 Set the preferred layout implementation. More...
 
virtual void addItem (std::unique_ptr< WLayoutItem > item)=0
 Adds a layout item. More...
 
void addWidget (std::unique_ptr< WWidget > widget)
 Adds the given widget to the layout. More...
 
virtual std::unique_ptr< WLayoutItemremoveItem (WLayoutItem *item)=0
 Removes a layout item (widget or nested layout). More...
 
std::unique_ptr< WWidgetremoveWidget (WWidget *widget)
 Removes the given widget from the layout. More...
 
virtual int count () const =0
 Returns the number of items in this layout. More...
 
virtual WLayoutItemitemAt (int index) const =0
 Returns the layout item at a specific index. More...
 
virtual int indexOf (WLayoutItem *item) const
 Returns the index of a given item. More...
 
virtual WWidgetItemfindWidgetItem (WWidget *widget) override
 Finds the widget item associated with the given widget.
 
virtual WWidgetwidget () override
 Returns the widget that is held by this WLayoutItem. More...
 
virtual WLayoutlayout () override
 Returns the layout that implements this WLayoutItem. More...
 
virtual WLayoutparentLayout () 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< WObjectremoveChild (WObject *child)
 Remove a child WObject, so its lifetime is no longer determined by this WObject.
 
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...
 

Static Public Member Functions

static void setDefaultImplementation (LayoutImplementation implementation)
 Sets the preferred layout implementation globally. More...
 

Protected Member Functions

 WLayout ()
 Create a layout.
 
void update (WLayoutItem *item=nullptr)
 Update the layout. More...
 
virtual void setParentWidget (WWidget *parent) override
 Internal method.
 
- Protected Member Functions inherited from Wt::WObject
virtual WStatelessSlot * getStateless (Method method)
 On-demand stateless slot implementation. More...
 

Private Member Functions

virtual void setParentLayout (WLayout *parentLayout) override
 Internal method.
 

Additional Inherited Members

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

Detailed Description

An abstract base class for layout managers.

This class is the abstract base class for any layout manager. A layout manager is associated with a container widget, and manages the layout of children inside the whole space available to the container widget.

The implementation of the layout manager depends on the container widget to which it is set, and is therefore deferred to WLayoutImpl.

Note
When applying a layout manager to a WContainerWidget, you may not define any padding for the container widget. Instead, use setContentsMargins().

Constructor & Destructor Documentation

Wt::WLayout::~WLayout ( )
virtual

Destructor.

This will delete the layout (and nested layouts), but not the contained widgets.

Member Function Documentation

virtual void Wt::WLayout::addItem ( std::unique_ptr< WLayoutItem item)
pure virtual

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 *)

Implemented in Wt::WGridLayout, Wt::WBoxLayout, Wt::WBorderLayout, and Wt::WFitLayout.

void Wt::WLayout::addWidget ( std::unique_ptr< WWidget widget)

Adds the given widget to the layout.

This method wraps the widget in a WWidgetItem and calls addItem(WLayoutItem *).

How the widget 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
removeWidget(WWidget *), addItem(WLayoutItem *)
virtual int Wt::WLayout::count ( ) const
pure virtual

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().

Implemented in Wt::WGridLayout, Wt::WBoxLayout, Wt::WBorderLayout, and Wt::WFitLayout.

void Wt::WLayout::getContentsMargins ( int *  left,
int *  top,
int *  right,
int *  bottom 
) const

Returns the contents margins.

See also
setContentsMargins()
int Wt::WLayout::indexOf ( WLayoutItem item) const
virtual

Returns the index of a given item.

The default implementation loops over all items, and returns the index for which itemAt(index) equals item.

See also
itemAt(int) const

Reimplemented in Wt::WFitLayout.

virtual WLayoutItem* Wt::WLayout::itemAt ( int  index) const
pure virtual

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()

Implemented in Wt::WGridLayout, Wt::WBoxLayout, Wt::WBorderLayout, and Wt::WFitLayout.

virtual WLayout* Wt::WLayout::layout ( )
overridevirtual

Returns the layout that implements this WLayoutItem.

This implements a type-safe upcasting mechanism to a WLayout.

Implements Wt::WLayoutItem.

virtual std::unique_ptr<WLayoutItem> Wt::WLayout::removeItem ( WLayoutItem item)
pure virtual

Removes a layout item (widget or nested layout).

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

Implemented in Wt::WGridLayout, Wt::WBoxLayout, Wt::WBorderLayout, and Wt::WFitLayout.

std::unique_ptr< WWidget > Wt::WLayout::removeWidget ( WWidget widget)

Removes the given widget from the layout.

This method finds the corresponding WWidgetItem and calls removeItem(WLayoutItem *), and returns the widget.

See also
addWidget(WWidget *), removeItem(WLayoutItem *)
void Wt::WLayout::setContentsMargins ( int  left,
int  top,
int  right,
int  bottom 
)

Set contents margins (in pixels).

The default contents margins are 9 pixels in all directions.

Note
Only used when the layout manager is applied to a WContainerWidget.
See also
setContentsMargins()
void Wt::WLayout::setDefaultImplementation ( LayoutImplementation  implementation)
static

Sets the preferred layout implementation globally.

The default implementation for box layouts and fit layouts is Flex (if supported by the browser). Otherwise a fallback to JavaScript is used.

Because there are cases where Flex does not work properly, this method can be used to set the global preferred implementation to LayoutImplementation::JavaScript instead.

Since this is a system-wide setting, and not a per-session setting, you should call this function before any session is created, e.g. in main() before calling WRun().

See also
setPreferredImplementation()
void Wt::WLayout::setPreferredImplementation ( LayoutImplementation  implementation)

Set the preferred layout implementation.

The default implementation for box layouts and fit layouts is Flex (if supported by the browser). Otherwise a fallback to JavaScript is used.

See also
setDefaultImplementation()
void Wt::WLayout::update ( WLayoutItem item = nullptr)
protected

Update the layout.

Must be called whenever some properties of the layout have changed.

virtual WWidget* Wt::WLayout::widget ( )
overridevirtual

Returns the widget that is held by this WLayoutItem.

This implements a type-safe upcasting mechanism to a WWidgetItem.

Implements Wt::WLayoutItem.


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