Wt::Layout Class Reference

handles the layout of widgets More...

#include <layout.h>

Inherits Wt::Object, and Wt::LayoutItem.

Inherited by Wt::LayoutStdContainer< Container >, Wt::LayoutStdContainer< std::list< BoxLayoutItemCompound > >, Wt::LayoutStdContainer< std::list< CascadeLayoutItemCompound > >, and Wt::LayoutStdContainer< Wt::Matrix< MatrixLayoutItemCompound > >.

List of all members.

Public Member Functions
	Layout (Widget *parent, int margin=0, int spacing=-1, const std::string &name="Layout::anon")
	Layout (Layout *parentLayout, int margin=0, int spacing=-1, const std::string &name="Layout::anon")
	Layout (int spacing=-1, const std::string &name="Layout::anon")
virtual	~Layout ()
Widget *	mainWidget () const
bool	isTopLevel () const
virtual Size	sizeHint () const
virtual Size	minimumSize () const
virtual void	addItem (LayoutItem *li)
virtual bool	removeItem (LayoutItem *li)
	returns true if a layoutitem is actually removed
virtual bool	eventFilter (Object *, Event *)
virtual void	setGeometry (const Rect &r)
Public Attributes
WVar< int >	margin
WVar< int >	spacing
WVar< bool >	autoAdd
Protected Member Functions
virtual bool	onAboutToChangeAutoAdd (bool auto_add)
virtual int	onSpacingOverride (int spacing)
void	adjustMaximumSize (int margin)
virtual bool	exists (const LayoutItem *li) const =0
void	markDeleted (LayoutItem *li)
bool	isDeleted (LayoutItem *li) const
void	enforce ()
	enforces the layout in the mainWidget() children and layouts
void	postLayoutHintEvent ()
void	setWidthasPrimaryLength (bool width=true)
bool	isWidthPrimaryLength () const
template<typename TYPE>
int	primaryLength (const TYPE &t) const
int	preferredLength (const LayoutItem *li, bool expand) const
template<typename TYPE>
int	secondaryLength (const TYPE &t) const
template<typename TYPE>
int	primaryOffset (const TYPE &t) const
template<typename TYPE>
int	secondaryOffset (const TYPE &t) const
Point	getPoint (int primary_offset, int secondary_offset) const
Size	getSize (int primary, int secondary) const
Rect	getRect (int primary_offset, int secondary_offset, int primary_size, int secondary_size) const
int	primaryStretch (const SizePolicy &sp) const
bool	mayGrowPrimally (const SizePolicy &sp) const
bool	mayShrinkPrimally (const SizePolicy &sp) const
bool	expandingPrimally (const SizePolicy &sp) const

---

Detailed Description

handles the layout of widgets

The Layout class takes ownership of child layouts (Objects), and other layoutitems that are not widgets. Widgets have their own ierarchy and so a Layout absolutely does not delete Widgets, in any way.

Layouts will be deleted when the parent layout dies or when they are explictely deleted. The rest of the layout items (spacer) will be deleted on Layout::remove() and/or ~Layout().

In the mean time however, we keep track of all these pointers into our container layout and layout actively syncronizes the list when a child is deleted.

In short: Layout contains LayoutItems. LayoutItems can be Layouts, Widgets and Spacers. Layouts are also children to parent Layout.

Layout Widgets Spacer Deleted on remove y n y Deleted on ~Layout y n y removed on deletion y y *

don't do that. That objects are now belong to Layout and cannot be deleted safely since they are not Objects. If you want them to be deleted remove them from the Layout via Layout::remove()

---

Constructor & Destructor Documentation

Wt::Layout::Layout	(	Widget *	parent,
		int	margin = 0,
		int	spacing = -1,
		const std::string &	name = "Layout::anon"
	)

Wt::Layout::Layout	(	Layout *	parentLayout,
		int	margin = 0,
		int	spacing = -1,
		const std::string &	name = "Layout::anon"
	)

Wt::Layout::Layout	(	int	spacing = -1,
		const std::string &	name = "Layout::anon"
	)

virtual Wt::Layout::~Layout

(

)

[inline, virtual]

---

Member Function Documentation

void Wt::Layout::addItem

(

LayoutItem *

li

)

[virtual]

Reimplemented in Wt::GridLayout, Wt::LayoutStdContainer< Container >, Wt::BoxLayout, Wt::LayoutStdContainer< Wt::Matrix< MatrixLayoutItemCompound > >, Wt::LayoutStdContainer< std::list< CascadeLayoutItemCompound > >, and Wt::LayoutStdContainer< std::list< BoxLayoutItemCompound > >.

void Wt::Layout::adjustMaximumSize

(

int

margin

)

[protected]

void Wt::Layout::enforce

(

)

[protected]

enforces the layout in the mainWidget() children and layouts

it can be only called if there is a main widget

bool Wt::Layout::eventFilter	(	Object *	obj,
		Event *	e
	)			[virtual]

we get events from the mainWidget only if exists. The type of events are:

• ChildEvent (Inserted or ChildRemoved)
• ResizeEvent
• LayoutHintEvent

The following uses cases has to be covered:

• case 1: A widget w deep in the hierarchy changes something (sizeHint, minimumSize, sizePolicy etc..)
• case 2: insert/remove layout item
• case 3: add remove child in a widget with a tll
• case 4: parent widget gets resized

    // we monitor the managed widgets
    // top level layout grabs it (if tll exists)
    Layout::eventFilter() {
        // on layoutHint event calls
        Layout::enforce();
 
        // on resize calls
        Layout::setGeometry(r);
 
        // on child insert / remove in mainWidget
        // this implies enforce called in the next event processing
            Application::postEvent(mainWidget(), new LayoutHintEvent());
    }

Note:

• if there is no top level layout then layout is not automatically enforced
• use cases 1,2,3,4 are working if we assume the presence of a tll
• we do a lot of invalidateRecursively()
• widgets can only have one layout child (setLayout(), layout()) and no more
• a widget cannot tell if it is managed or not
• Layout::setGeometry() reimplementations must call base class implementation

Reimplemented from Wt::Object.

virtual bool Wt::Layout::exists

(

const LayoutItem *

li

)

const [protected, pure virtual]

Implemented in Wt::LayoutStdContainer< Container >, Wt::LayoutStdContainer< Wt::Matrix< MatrixLayoutItemCompound > >, Wt::LayoutStdContainer< std::list< CascadeLayoutItemCompound > >, and Wt::LayoutStdContainer< std::list< BoxLayoutItemCompound > >.

bool Wt::Layout::expandingPrimally

(

const SizePolicy &

sp

)

const [protected]

Point Wt::Layout::getPoint	(	int	primary_offset,
		int	secondary_offset
	)			const [protected]

Rect Wt::Layout::getRect	(	int	primary_offset,
		int	secondary_offset,
		int	primary_size,
		int	secondary_size
	)			const [protected]

Size Wt::Layout::getSize	(	int	primary,
		int	secondary
	)			const [protected]

bool Wt::Layout::isDeleted

(

LayoutItem *

li

)

const [inline, protected]

bool Wt::Layout::isTopLevel

(

)

const

bool Wt::Layout::isWidthPrimaryLength

(

)

const [inline, protected]

Widget * Wt::Layout::mainWidget

(

)

const

void Wt::Layout::markDeleted

(

LayoutItem *

li

)

[inline, protected]

bool Wt::Layout::mayGrowPrimally

(

const SizePolicy &

sp

)

const [protected]

bool Wt::Layout::mayShrinkPrimally

(

const SizePolicy &

sp

)

const [protected]

Size Wt::Layout::minimumSize

(

)

const [virtual]

Reimplemented from Wt::LayoutItem.

bool Wt::Layout::onAboutToChangeAutoAdd

(

bool

auto_add

)

[protected, virtual]

int Wt::Layout::onSpacingOverride

(

int

spacing

)

[protected, virtual]

void Wt::Layout::postLayoutHintEvent

(

)

[protected]

int Wt::Layout::preferredLength	(	const LayoutItem *	li,
		bool	expand
	)			const [protected]

template<typename TYPE>

int Wt::Layout::primaryLength

(

const TYPE &

t

)

const [inline, protected]

template<typename TYPE>

int Wt::Layout::primaryOffset

(

const TYPE &

t

)

const [protected]

int Wt::Layout::primaryStretch

(

const SizePolicy &

sp

)

const [protected]

bool Wt::Layout::removeItem

(

LayoutItem *

li

)

[virtual]

returns true if a layoutitem is actually removed

Reimplemented in Wt::LayoutStdContainer< Container >, Wt::LayoutStdContainer< Wt::Matrix< MatrixLayoutItemCompound > >, Wt::LayoutStdContainer< std::list< CascadeLayoutItemCompound > >, and Wt::LayoutStdContainer< std::list< BoxLayoutItemCompound > >.

template<typename TYPE>

int Wt::Layout::secondaryLength

(

const TYPE &

t

)

const [protected]

template<typename TYPE>

int Wt::Layout::secondaryOffset

(

const TYPE &

t

)

const [protected]

void Wt::Layout::setGeometry

(

const Rect &

r

)

[virtual]

Reimplemented from Wt::LayoutItem.

Reimplemented in Wt::CascadeLayout, Wt::GridLayout, and Wt::BoxLayout.

void Wt::Layout::setWidthasPrimaryLength

(

bool

width = true

)

[protected]

Size Wt::Layout::sizeHint

(

)

const [virtual]

Reimplemented from Wt::LayoutItem.

---

Member Data Documentation

WVar<bool> Wt::Layout::autoAdd

WVar<int> Wt::Layout::margin

WVar<int> Wt::Layout::spacing

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

• layout.h
• layout.cpp

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Generated Fri Jul 28 19:22:38 2006.
Copyright © 1998-2003 by the respective authors.

This document is licensed under the terms of the GNU Free Documentation License and may be freely distributed under the conditions given by this license.