Package eu.webtoolkit.jwt

Class WLayout

java.lang.Object

eu.webtoolkit.jwt.WObject

eu.webtoolkit.jwt.WLayout

All Implemented Interfaces:

WLayoutItem

Direct Known Subclasses:

WBorderLayout, WBoxLayout, WFitLayout, WGridLayout

public abstract class WLayout
extends WObject
implements WLayoutItem

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().

Nested Class Summary

Nested classes/interfaces inherited from class eu.webtoolkit.jwt.WObject

WObject.FormData

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	WLayout()	Create a layout.

Method Summary

Modifier and Type	Method	Description
abstract void	addItem(WLayoutItem item)	Adds a layout item.
void	addWidget(WWidget w)	Adds the given widget to the layout.
WWidgetItem	findWidgetItem(WWidget widget)	Finds the widget item associated with the given widget.
int	getContentsMargin(Side side)	Returns a contents margin.
abstract int	getCount()	Returns the number of items in this layout.
WLayoutImpl	getImpl()
protected LayoutImplementation	getImplementation()
abstract WLayoutItem	getItemAt(int index)	Returns the layout item at a specific index.
WLayout	getLayout()	Returns the layout that implements this WLayoutItem.
WLayout	getParentLayout()	Returns the layout in which this item is contained.
WWidget	getParentWidget()
protected LayoutImplementation	getPreferredImplementation()
WWidget	getWidget()	Returns the widget that is held by this WLayoutItem.
int	indexOf(WLayoutItem item)	Returns the index of a given item.
boolean	isImplementationIsFlexLayout()
protected void	itemAdded(WLayoutItem item)
protected void	itemRemoved(WLayoutItem item)
abstract WLayoutItem	removeItem(WLayoutItem item)	Removes a layout item (widget or nested layout).
WWidget	removeWidget(WWidget w)	Removes the given widget from the layout.
void	setContentsMargins(int left, int top, int right, int bottom)	Set contents margins (in pixels).
static void	setDefaultImplementation(LayoutImplementation implementation)	Sets the preferred layout implementation globally.
protected void	setImpl(WLayoutImpl impl)
void	setParentLayout(WLayout layout)	Internal method.
void	setParentWidget(WWidget parent)	Internal method.
void	setPreferredImplementation(LayoutImplementation implementation)	Set the preferred layout implementation.
protected final void	update()	Update the layout.
protected void	update(WLayoutItem item)	Update the layout.
protected void	updateImplementation()

Methods inherited from class eu.webtoolkit.jwt.WObject

getId, getObjectName, remove, setFormData, setObjectName, tr

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface eu.webtoolkit.jwt.WLayoutItem

iterateWidgets

Constructor Details

WLayout

protected WLayout()

Create a layout.

Method Details

setPreferredImplementation

public void setPreferredImplementation(LayoutImplementation implementation)

Set the preferred layout implementation.

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

See Also:

• setDefaultImplementation(LayoutImplementation implementation)

setDefaultImplementation

public static void setDefaultImplementation(LayoutImplementation implementation)

Sets the preferred layout implementation globally.

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

Because there are cases where LayoutImplementation.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(LayoutImplementation implementation)

addItem

public abstract void addItem(WLayoutItem item)

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 item)

addWidget

public void addWidget(WWidget w)

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 w)

removeItem

public abstract WLayoutItem removeItem(WLayoutItem item)

Removes a layout item (widget or nested layout).

See Also:

• removeWidget(WWidget w)

removeWidget

public WWidget removeWidget(WWidget w)

Removes the given widget from the layout.

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

See Also:

• removeItem(WLayoutItem item)

getCount

public abstract int getCount()

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 getItemAt().

getItemAt

public abstract WLayoutItem getItemAt(int index)

Returns the layout item at a specific index.

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

See Also:

• indexOf(WLayoutItem item)
• getCount()

indexOf

public int indexOf(WLayoutItem item)

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:

• getItemAt(int index)

findWidgetItem

public WWidgetItem findWidgetItem(WWidget widget)

Finds the widget item associated with the given widget.

Specified by:

findWidgetItem in interface WLayoutItem

getWidget

public WWidget getWidget()

Description copied from interface: WLayoutItem

Returns the widget that is held by this WLayoutItem.

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

Specified by:

getWidget in interface WLayoutItem

getLayout

public WLayout getLayout()

Description copied from interface: WLayoutItem

Returns the layout that implements this WLayoutItem.

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

Specified by:

getLayout in interface WLayoutItem

getParentLayout

public WLayout getParentLayout()

Description copied from interface: WLayoutItem

Returns the layout in which this item is contained.

Specified by:

getParentLayout in interface WLayoutItem

getParentWidget

public WWidget getParentWidget()

Specified by:

getParentWidget in interface WLayoutItem

getImpl

public WLayoutImpl getImpl()

Specified by:

getImpl in interface WLayoutItem

setContentsMargins

public void 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(int left, int top, int right, int bottom)

getContentsMargin

public int getContentsMargin(Side side)

Returns a contents margin.

See Also:

• setContentsMargins(int left, int top, int right, int bottom)

isImplementationIsFlexLayout

public boolean isImplementationIsFlexLayout()

update

protected void update(WLayoutItem item)

Update the layout.

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

update

protected final void update()

Update the layout.

Calls update((WLayoutItem)null)

itemAdded

protected void itemAdded(WLayoutItem item)

itemRemoved

protected void itemRemoved(WLayoutItem item)

setParentWidget

public void setParentWidget(WWidget parent)

Description copied from interface: WLayoutItem

Internal method.

Specified by:

setParentWidget in interface WLayoutItem

setImpl

protected void setImpl(WLayoutImpl impl)

getImplementation

protected LayoutImplementation getImplementation()

getPreferredImplementation

protected LayoutImplementation getPreferredImplementation()

updateImplementation

protected void updateImplementation()

setParentLayout

public void setParentLayout(WLayout layout)

Description copied from interface: WLayoutItem

Internal method.

Specified by:

setParentLayout in interface WLayoutItem