java.lang.Object | ||
↳ | com.google.gwt.user.client.ui.UIObject | |
↳ | com.google.gwt.user.client.ui.Widget |
Known Direct Subclasses
AbstractHasData<T>,
CellWidget<C>,
Composite,
FileUpload,
FocusWidget,
Frame,
Hidden,
Hyperlink,
Image,
LabelBase<T>,
MenuBar,
Panel,
Tree
|
Known Indirect Subclasses
AbsolutePanel,
AbstractCellTree,
AbstractPager,
Anchor,
Audio,
Button,
ButtonBase,
CalendarView,
Canvas,
CaptionPanel,
CellBrowser,
CellList<T>,
CellPanel,
CellTable<T>,
CellTree,
and
79 others.
|
The base class for the majority of user-interface objects. Widget adds
support for receiving events from the browser and being added directly to
panels
.
[Expand]
Inherited Constants | |||||||||||
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From class
com.google.gwt.user.client.ui.UIObject
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Public Constructors | |||||||||||
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Public Methods | |||||||||||
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Adds an
AttachEvent handler. | |||||||||||
Adds a native event handler to the widget and sinks the corresponding
native event.
| |||||||||||
Adds this handler to the widget.
| |||||||||||
Returns the
Widget aspect of the receiver. | |||||||||||
This convenience method makes a null-safe call to
asWidget() . | |||||||||||
Fires the given event to the handlers listening to the event's type.
| |||||||||||
Gets the panel-defined layout data associated with this widget.
| |||||||||||
Gets this widget's parent panel.
| |||||||||||
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).
| |||||||||||
Fired whenever a browser event is received.
| |||||||||||
Removes this widget from its parent widget, if one exists.
| |||||||||||
Sets the panel-defined layout data associated with this widget.
| |||||||||||
Overridden to defer the call to super.sinkEvents until the first time this
widget is attached to the dom, as a performance enhancement.
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Protected Methods | |||||||||||
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Creates the
HandlerManager used by this Widget. | |||||||||||
Fires an event on a child widget.
| |||||||||||
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. | |||||||||||
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. | |||||||||||
Gets the number of handlers listening to the event type.
| |||||||||||
Has this widget ever been attached?
| |||||||||||
This method is called when a widget is attached to the browser's document. | |||||||||||
This method is called when a widget is detached from the browser's document. | |||||||||||
This method is called immediately after a widget becomes attached to the
browser's document.
| |||||||||||
This method is called immediately before a widget will be detached from the
browser's document.
|
[Expand]
Inherited Methods | |||||||||||
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From class
com.google.gwt.user.client.ui.UIObject
| |||||||||||
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.IsWidget
|
Adds a native event handler to the widget and sinks the corresponding native event. If you do not want to sink the native event, use the generic addHandler method instead.
handler | the handler |
---|---|
type | the event key |
HandlerRegistration
used to remove the handler
Adds this handler to the widget.
handler | the handler |
---|---|
type | the event type |
HandlerRegistration
used to remove the handler
This convenience method makes a null-safe call to
asWidget()
.
null
if w is null
Fires the given event to the handlers listening to the event's type.
Any exceptions thrown by handlers will be bundled into a
UmbrellaException
and then re-thrown after all handlers have
completed. An exception thrown by a handler will not prevent other handlers
from executing.
event | the event |
---|
Gets the panel-defined layout data associated with this widget.
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).
true
if the widget is attached
Fired whenever a browser event is received.
event | the event received |
---|
Removes this widget from its parent widget, if one exists.
If it has no parent, this method does nothing. If it is a "root" widget
(meaning it's been added to the detach list via
detachOnWindowClose(Widget)
), it will be removed from the
detached immediately. This makes it possible for Composites and Panels to
adopt root widgets.
IllegalStateException | if this widget's parent does not support
removal (e.g. Composite )
|
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Sets the panel-defined layout data associated with this widget. Only the panel that currently contains a widget should ever set this value. It serves as a place to store layout bookkeeping data associated with a widget.
layoutData | the widget's layout data |
---|
Overridden to defer the call to super.sinkEvents until the first time this
widget is attached to the dom, as a performance enhancement. Subclasses
wishing to customize sinkEvents can preserve this deferred sink behavior by
putting their implementation behind a check of
isOrWasAttached()
:
@Override public void sinkEvents(int eventBitsToAdd) { if (isOrWasAttached()) { /* customized sink code goes here */ } else { super.sinkEvents(eventBitsToAdd); } }
eventBitsToAdd | a bitfield representing the set of events to be added to this element's event set |
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Creates the HandlerManager
used by this Widget. You can override
this method to create a custom HandlerManager
.
HandlerManager
you want to use
Fires an event on a child widget. Used to delegate the handling of an event from one widget to another.
target | fire the event on the given target |
---|---|
event | the event |
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.
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.
Gets the number of handlers listening to the event type.
type | the event type |
---|
Has this widget ever been attached?
This method is called when a widget is attached to the browser's document.
To receive notification after a Widget has been added to the document,
override the onLoad()
method or use addAttachHandler(AttachEvent.Handler)
.
It is strongly recommended that you override onLoad()
or
doAttachChildren()
instead of this method to avoid inconsistencies
between logical and physical attachment states.
Subclasses that override this method must call
super.onAttach()
to ensure that the Widget has been attached
to its underlying Element.
IllegalStateException | if this widget is already attached |
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This method is called when a widget is detached from the browser's
document. To receive notification before a Widget is removed from the
document, override the onUnload()
method or use addAttachHandler(AttachEvent.Handler)
.
It is strongly recommended that you override onUnload()
or
doDetachChildren()
instead of this method to avoid inconsistencies
between logical and physical attachment states.
Subclasses that override this method must call
super.onDetach()
to ensure that the Widget has been detached
from the underlying Element. Failure to do so will result in application
memory leaks due to circular references between DOM Elements and JavaScript
objects.
IllegalStateException | if this widget is already detached |
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This method is called immediately after a widget becomes attached to the browser's document.
This method is called immediately before a widget will be detached from the browser's document.