public class

LayoutPanel

extends ComplexPanel
implements AnimatedLayout ProvidesResize RequiresResize

java.lang.Object
↳	com.google.gwt.user.client.ui.UIObject
	↳	com.google.gwt.user.client.ui.Widget
		↳	com.google.gwt.user.client.ui.Panel
			↳	com.google.gwt.user.client.ui.ComplexPanel
				↳	com.google.gwt.user.client.ui.LayoutPanel

Known Direct Subclasses

RootLayoutPanel

Class Overview

A panel that lays its children out in arbitrary layers using the Layout class.

This widget will only work in standards mode, which requires that the HTML page in which it is run have an explicit <!DOCTYPE> declaration.

Example

{@example com.google.gwt.examples.LayoutPanelExample}

Use in UiBinder Templates

LayoutPanel elements in UiBinder templates lay out their children with arbitrary constraints, using <g:layer> elements. Each layer may have any of the following constraint attributes specified as CSS length attributes: left, top, right, bottom, width , and height.

Precisely zero or two constraints are required for each axis (horizontal and vertical). Specifying no constraints implies that the child should fill that axis completely.

The valid sets of horizontal constraints are:

(none): Fill the parent's horizontal axis
left, width: Fixed width, positioned from parent's left edge
right, width: Fixed width, positioned from parent's right edge
left, right: Width implied by fixed distance from parent's left and right edges

The valid sets of vertical constraints are:

(none): Fill the parent's vertical axis
top, height: Fixed height, positioned from parent's top edge
bottom, height: Fixed height, positioned from parent's bottom edge
top, bottom: Height implied by fixed distance from parent's top and bottom edges

The values of constraint attributes can be any valid CSS length, such as 1px, 3em, or 0 (zero lengths require no units).

For example:

 <g:LayoutPanel>
   <!-- No constraints causes the layer to fill the parent -->
   <g:layer>
     <g:Label>Lorem ipsum...</g:Label>
   </g:layer>
   <!-- Position horizontally 25% from each edge;
        Vertically 4px from the top and 10em tall. -->
   <g:layer left='25%' right='25%' top='4px' height='10em'>
     <g:Label>Header</g:Label>
   </g:layer>
 </g:LayoutPanel>

Summary

[Expand]

Inherited Constants

From class com.google.gwt.user.client.ui.UIObject

Public Constructors
	LayoutPanel() Creates an empty layout panel.

Public Methods
void	add(Widget widget) Adds a widget to this panel.
void	animate(int duration) Layout children, animating over the specified period of time.
void	animate(int duration, Layout.AnimationCallback callback) Layout children, animating over the specified period of time.
void	forceLayout() Layout children immediately.
Element	getWidgetContainerElement(Widget child) Gets the container element wrapping the given child widget.
void	insert(Widget widget, int beforeIndex) Inserts a widget before the specified index.
void	onResize() This method must be called whenever the implementor's size has been modified.
boolean	remove(Widget w) Removes a child widget.
void	setWidgetBottomHeight(Widget child, double bottom, Style.Unit bottomUnit, double height, Style.Unit heightUnit) Sets the child widget's bottom and height values.
void	setWidgetHorizontalPosition(Widget child, Layout.Alignment position) Sets the child widget's horizontal position within its layer.
void	setWidgetLeftRight(Widget child, double left, Style.Unit leftUnit, double right, Style.Unit rightUnit) Sets the child widget's left and right values.
void	setWidgetLeftWidth(Widget child, double left, Style.Unit leftUnit, double width, Style.Unit widthUnit) Sets the child widget's left and width values.
void	setWidgetRightWidth(Widget child, double right, Style.Unit rightUnit, double width, Style.Unit widthUnit) Sets the child widget's right and width values.
void	setWidgetTopBottom(Widget child, double top, Style.Unit topUnit, double bottom, Style.Unit bottomUnit) Sets the child widget's top and bottom values.
void	setWidgetTopHeight(Widget child, double top, Style.Unit topUnit, double height, Style.Unit heightUnit) Sets the child widget's top and height values.
void	setWidgetVerticalPosition(Widget child, Layout.Alignment position) Sets the child widget's vertical position within its layer.
void	setWidgetVisible(Widget child, boolean visible) Shows or hides the given widget and its layer.

Protected Methods
void	onLoad() This method is called immediately after a widget becomes attached to the browser's document.
void	onUnload() This method is called immediately before a widget will be detached from the browser's document.

[Expand]

Inherited Methods

From class com.google.gwt.user.client.ui.ComplexPanel

void	add(Widget child, Element container) Adds a new child widget to the panel, attaching its Element to the specified container Element.
int	adjustIndex(Widget child, int beforeIndex) Adjusts beforeIndex to account for the possibility that the given widget is already a child of this panel.
void	checkIndexBoundsForAccess(int index) Checks that `index` is in the range [0, getWidgetCount()), which is the valid range on accessible indexes.
void	checkIndexBoundsForInsertion(int index) Checks that `index` is in the range [0, getWidgetCount()], which is the valid range for indexes on an insertion.
WidgetCollection	getChildren() Gets the list of children contained in this panel.
Widget	getWidget(int index) Gets the child widget at the specified index.
int	getWidgetCount() Gets the number of child widgets in this panel.
int	getWidgetIndex(Widget child) Gets the index of the specified child widget.
int	getWidgetIndex(IsWidget child)
void	insert(Widget child, Element container, int beforeIndex, boolean domInsert) Insert a new child Widget into this Panel at a specified index, attaching its Element to the specified container Element.
void	insert(Widget child, Element container, int beforeIndex) This method is deprecated. Use `insert(Widget, Element, int, boolean)` instead
Iterator<Widget>	iterator()
boolean	remove(Widget w) Removes a child widget.
boolean	remove(int index) Removes the widget at the specified index.

From class com.google.gwt.user.client.ui.Panel

void	add(IsWidget child)
void	add(Widget child) Adds a child widget.
final void	adopt(Widget child) Finalize the attachment of a Widget to this Panel.
void	adopt(Widget w, Element container) This method is deprecated. Use `adopt(Widget)`.
void	clear() Removes all child widgets.
void	disown(Widget w) This method is deprecated. Use `orphan(Widget)`.
void	doAttachChildren() If a widget contains one or more child widgets that are not in the logical widget hierarchy (the child is physically connected only on the DOM level), it must override this method and call `onAttach()` for each of its child widgets.
void	doDetachChildren() If a widget contains one or more child widgets that are not in the logical widget hierarchy (the child is physically connected only on the DOM level), it must override this method and call `onDetach()` for each of its child widgets.
final void	orphan(Widget child) This method must be called as part of the remove method of any Panel.
abstract boolean	remove(Widget child) Removes a child widget.
boolean	remove(IsWidget child)

From class com.google.gwt.user.client.ui.Widget

HandlerRegistration	addAttachHandler(AttachEvent.Handler handler) Adds an `AttachEvent` handler.
final <H extends EventHandler> HandlerRegistration	addDomHandler(H handler, Type<H> type) Adds a native event handler to the widget and sinks the corresponding native event.
final <H extends EventHandler> HandlerRegistration	addHandler(H handler, Type<H> type) Adds this handler to the widget.
Widget	asWidget() Returns the `Widget` aspect of the receiver.
static Widget	asWidgetOrNull(IsWidget w) This convenience method makes a null-safe call to `asWidget()`.
HandlerManager	createHandlerManager() Creates the `HandlerManager` used by this Widget.
void	delegateEvent(Widget target, GwtEvent<?> event) Fires an event on a child widget.
void	doAttachChildren() If a widget contains one or more child widgets that are not in the logical widget hierarchy (the child is physically connected only on the DOM level), it must override this method and call `onAttach()` for each of its child widgets.
void	doDetachChildren() If a widget contains one or more child widgets that are not in the logical widget hierarchy (the child is physically connected only on the DOM level), it must override this method and call `onDetach()` for each of its child widgets.
void	fireEvent(GwtEvent<?> event) Fires the given event to the handlers listening to the event's type.
int	getHandlerCount(Type<?> type) Gets the number of handlers listening to the event type.
Object	getLayoutData() Gets the panel-defined layout data associated with this widget.
Widget	getParent() Gets this widget's parent panel.
boolean	isAttached() Determines whether this widget is currently attached to the browser's document (i.e., there is an unbroken chain of widgets between this widget and the underlying browser document).
final boolean	isOrWasAttached() Has this widget ever been attached?
void	onAttach() This method is called when a widget is attached to the browser's document.
void	onBrowserEvent(Event event) Fired whenever a browser event is received.
void	onDetach() This method is called when a widget is detached from the browser's document.
void	onLoad() This method is called immediately after a widget becomes attached to the browser's document.
void	onUnload() This method is called immediately before a widget will be detached from the browser's document.
void	removeFromParent() Removes this widget from its parent widget, if one exists.
void	setLayoutData(Object layoutData) Sets the panel-defined layout data associated with this widget.
void	sinkEvents(int eventBitsToAdd) Overridden to defer the call to super.sinkEvents until the first time this widget is attached to the dom, as a performance enhancement.

From class com.google.gwt.user.client.ui.UIObject

void	addStyleDependentName(String styleSuffix) Adds a dependent style name by specifying the style name's suffix.
void	addStyleName(String style) Adds a secondary or dependent style name to this object.
static void	ensureDebugId(Element elem, String baseID, String id) Set the debug id of a specific element.
final void	ensureDebugId(String id) Ensure that the main `Element` for this `UIObject` has an ID property set, which allows it to integrate with third-party libraries and test tools.
static void	ensureDebugId(Element elem, String id) Ensure that elem has an ID property set, which allows it to integrate with third-party libraries and test tools.
int	getAbsoluteLeft() Gets the object's absolute left position in pixels, as measured from the browser window's client area.
int	getAbsoluteTop() Gets the object's absolute top position in pixels, as measured from the browser window's client area.
Element	getElement() Gets a handle to the object's underlying DOM element.
int	getOffsetHeight() Gets the object's offset height in pixels.
int	getOffsetWidth() Gets the object's offset width in pixels.
Element	getStyleElement() Template method that returns the element to which style names will be applied.
String	getStyleName() Gets all of the object's style names, as a space-separated list.
static String	getStyleName(Element elem) Gets all of the element's style names, as a space-separated list.
String	getStylePrimaryName() Gets the primary style name associated with the object.
static String	getStylePrimaryName(Element elem) Gets the element's primary style name.
String	getTitle() Gets the title associated with this object.
boolean	isVisible() Determines whether or not this object is visible.
static boolean	isVisible(Element elem)
void	onEnsureDebugId(String baseID) Called when the user sets the id using the `ensureDebugId(String)` method.
void	removeStyleDependentName(String styleSuffix) Removes a dependent style name by specifying the style name's suffix.
void	removeStyleName(String style) Removes a style name.
final void	setElement(Element elem) Sets this object's browser element.
void	setElement(Element elem) Sets this object's browser element.
void	setHeight(String height) Sets the object's height.
void	setPixelSize(int width, int height) Sets the object's size, in pixels, not including decorations such as border, margin, and padding.
void	setSize(String width, String height) Sets the object's size.
void	setStyleDependentName(String styleSuffix, boolean add) Adds or removes a dependent style name by specifying the style name's suffix.
static void	setStyleName(Element elem, String styleName) Clears all of the element's style names and sets it to the given style.
static void	setStyleName(Element elem, String style, boolean add) This convenience method adds or removes a style name for a given element.
void	setStyleName(String style) Clears all of the object's style names and sets it to the given style.
void	setStyleName(String style, boolean add) Adds or removes a style name.
void	setStylePrimaryName(String style) Sets the object's primary style name and updates all dependent style names.
static void	setStylePrimaryName(Element elem, String style) Sets the element's primary style name and updates all dependent style names.
void	setTitle(String title) Sets the title associated with this object.
void	setVisible(boolean visible) Sets whether this object is visible.
static void	setVisible(Element elem, boolean visible)
void	setWidth(String width) Sets the object's width.
void	sinkEvents(int eventBitsToAdd) Adds a set of events to be sunk by this object.
String	toString() This method is overridden so that any object can be viewed in the debugger as an HTML snippet.
void	unsinkEvents(int eventBitsToRemove) Removes a set of events from this object's event list.

From class java.lang.Object

From interface com.google.gwt.event.logical.shared.HasAttachHandlers

From interface com.google.gwt.event.shared.HasHandlers

From interface com.google.gwt.user.client.EventListener

From interface com.google.gwt.user.client.ui.AnimatedLayout

From interface com.google.gwt.user.client.ui.HasWidgets

From interface com.google.gwt.user.client.ui.HasWidgets.ForIsWidget

From interface com.google.gwt.user.client.ui.IndexedPanel

From interface com.google.gwt.user.client.ui.IndexedPanel.ForIsWidget

From interface com.google.gwt.user.client.ui.IsWidget

From interface com.google.gwt.user.client.ui.RequiresResize

From interface java.lang.Iterable

Public Constructors

public LayoutPanel ()

Creates an empty layout panel.

Public Methods

public void add (Widget widget)

Adds a widget to this panel.

By default, each child will fill the panel. To build more interesting layouts, set child widgets' layout constraints using setWidgetLeftRight(Widget, double, Style.Unit, double, Style.Unit) and related methods.

Parameters

widget	the widget to be added

public void animate (int duration)

Layout children, animating over the specified period of time.

Parameters

duration	the animation duration, in milliseconds

public void animate (int duration, Layout.AnimationCallback callback)

Layout children, animating over the specified period of time.

This method provides a callback that will be informed of animation updates. This can be used to create more complex animation effects.

Parameters

duration	the animation duration, in milliseconds
callback	the animation callback

public void forceLayout ()

Layout children immediately.

This is not normally necessary, unless you want to update child widgets' positions explicitly to create a starting point for a subsequent call to animate(int).

public Element getWidgetContainerElement (Widget child)

Gets the container element wrapping the given child widget.

Returns

the widget's container element

public void insert (Widget widget, int beforeIndex)

Inserts a widget before the specified index.

By default, each child will fill the panel. To build more interesting layouts, set child widgets' layout constraints using setWidgetLeftRight(Widget, double, Style.Unit, double, Style.Unit) and related methods.

Inserting a widget in this way has no effect on the DOM structure, but can be useful for other panels that wrap LayoutPanel to maintain insertion order.

Parameters

widget	the widget to be inserted
beforeIndex	the index before which it will be inserted

Throws

IndexOutOfBoundsException	if `beforeIndex` is out of range

public void onResize ()

This method must be called whenever the implementor's size has been modified.

public boolean remove (Widget w)

Removes a child widget.

How to Override this Method

There are several important things that must take place in the correct order to properly remove a Widget from a Panel. Not all of these steps will be relevant to every Panel, but all of the steps must be considered.

Validate: Make sure this Panel is actually the parent of the child Widget; return false if it is not.
Orphan: Call orphan(Widget) first while the child Widget is still attached.
Physical Detach: Adjust the DOM to account for the removal of the child Widget. The Widget's Element must be physically removed from the DOM.
Logical Detach: Update the Panel's state variables to reflect the removal of the child Widget. Example: the Widget is removed from the Panel's WidgetCollection.

Parameters

w	the widget to be removed

Returns

true if the child was present

public void setWidgetBottomHeight (Widget child, double bottom, Style.Unit bottomUnit, double height, Style.Unit heightUnit)

Sets the child widget's bottom and height values.

public void setWidgetHorizontalPosition (Widget child, Layout.Alignment position)

Sets the child widget's horizontal position within its layer.

public void setWidgetLeftRight (Widget child, double left, Style.Unit leftUnit, double right, Style.Unit rightUnit)

Sets the child widget's left and right values.

public void setWidgetLeftWidth (Widget child, double left, Style.Unit leftUnit, double width, Style.Unit widthUnit)

Sets the child widget's left and width values.

public void setWidgetRightWidth (Widget child, double right, Style.Unit rightUnit, double width, Style.Unit widthUnit)

Sets the child widget's right and width values.

public void setWidgetTopBottom (Widget child, double top, Style.Unit topUnit, double bottom, Style.Unit bottomUnit)

Sets the child widget's top and bottom values.

public void setWidgetTopHeight (Widget child, double top, Style.Unit topUnit, double height, Style.Unit heightUnit)

Sets the child widget's top and height values.

public void setWidgetVerticalPosition (Widget child, Layout.Alignment position)

Sets the child widget's vertical position within its layer.

public void setWidgetVisible (Widget child, boolean visible)

Shows or hides the given widget and its layer. This method explicitly calls setVisible(boolean) on the child widget and ensures that its associated layer is shown/hidden.

Protected Methods

protected void onLoad ()

This method is called immediately after a widget becomes attached to the browser's document.

protected void onUnload ()

This method is called immediately before a widget will be detached from the browser's document.

Interfaces

Classes

Annotations

Enums

Exceptions

LayoutPanel

Class Overview

Example

Use in UiBinder Templates

Summary

Public Constructors

public LayoutPanel ()

Public Methods

public void add (Widget widget)

Parameters

public void animate (int duration)

Parameters

public void animate (int duration, Layout.AnimationCallback callback)

Parameters

public void forceLayout ()

public Element getWidgetContainerElement (Widget child)

Returns

public void insert (Widget widget, int beforeIndex)

Parameters

Throws

public void onResize ()

public boolean remove (Widget w)

Parameters

Returns

public void setWidgetBottomHeight (Widget child, double bottom, Style.Unit bottomUnit, double height, Style.Unit heightUnit)

public void setWidgetHorizontalPosition (Widget child, Layout.Alignment position)

public void setWidgetLeftRight (Widget child, double left, Style.Unit leftUnit, double right, Style.Unit rightUnit)

public void setWidgetLeftWidth (Widget child, double left, Style.Unit leftUnit, double width, Style.Unit widthUnit)

public void setWidgetRightWidth (Widget child, double right, Style.Unit rightUnit, double width, Style.Unit widthUnit)

public void setWidgetTopBottom (Widget child, double top, Style.Unit topUnit, double bottom, Style.Unit bottomUnit)

public void setWidgetTopHeight (Widget child, double top, Style.Unit topUnit, double height, Style.Unit heightUnit)

public void setWidgetVerticalPosition (Widget child, Layout.Alignment position)

public void setWidgetVisible (Widget child, boolean visible)

Protected Methods

protected void onLoad ()

protected void onUnload ()