public abstract class Composite extends Widget implements IsRenderable
The composite is useful for creating a single widget out of an aggregate of multiple other widgets contained in a single panel.
public class CompositeExample implements EntryPoint {
/**
* A composite of a TextBox and a CheckBox that optionally enables it.
*/
private static class OptionalTextBox extends Composite implements
ClickHandler {
private TextBox textBox = new TextBox();
private CheckBox checkBox = new CheckBox();
/**
* Constructs an OptionalTextBox with the given caption on the check.
*
* @param caption the caption to be displayed with the check box
*/
public OptionalTextBox(String caption) {
// Place the check above the text box using a vertical panel.
VerticalPanel panel = new VerticalPanel();
panel.add(checkBox);
panel.add(textBox);
// Set the check box's caption, and check it by default.
checkBox.setText(caption);
checkBox.setChecked(true);
checkBox.addClickHandler(this);
// All composites must call initWidget() in their constructors.
initWidget(panel);
// Give the overall composite a style name.
setStyleName("example-OptionalCheckBox");
}
public void onClick(ClickEvent event) {
if (event.getSource() == checkBox) {
// When the check box is clicked, update the text box's enabled state.
textBox.setEnabled(checkBox.isChecked());
}
}
/**
* Sets the caption associated with the check box.
*
* @param caption the check box's caption
*/
public void setCaption(String caption) {
// Note how we use the use composition of the contained widgets to provide
// only the methods that we want to.
checkBox.setText(caption);
}
/**
* Gets the caption associated with the check box.
*
* @return the check box's caption
*/
public String getCaption() {
return checkBox.getText();
}
}
public void onModuleLoad() {
// Create an optional text box and add it to the root panel.
OptionalTextBox otb = new OptionalTextBox("Check this to enable me");
RootPanel.get().add(otb);
}
}
UIObject.DebugIdImpl, UIObject.DebugIdImplEnabledeventsToSinkDEBUG_ID_PREFIX, MISSING_ELEMENT_ERROR, SETELEMENT_TWICE_ERROR| Constructor and Description |
|---|
Composite() |
| Modifier and Type | Method and Description |
|---|---|
void |
claimElement(Element element)
Replace the previous contents of the receiver with the given element,
presumed to have been created and stamped via a previous call to
IsRenderable.render(com.google.gwt.user.client.ui.RenderableStamper). |
protected Widget |
getWidget()
Provides subclasses access to the topmost widget that defines this
composite.
|
void |
initializeClaimedElement()
Perform any initialization needed when the widget is not attached to
the document.
|
protected void |
initWidget(Widget widget)
Sets the widget to be wrapped by the composite.
|
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).
|
protected 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.
|
protected void |
onDetach()
This method is called when a widget is detached from the browser's
document.
|
SafeHtml |
render(RenderableStamper stamper) |
void |
render(RenderableStamper stamper,
SafeHtmlBuilder builder)
Tells this object to render itself as HTML and append it to the given builder.
|
protected Element |
resolvePotentialElement()
EXPERIMENTAL and subject to change.
|
protected void |
setWidget(Widget widget)
Deprecated.
Use
initWidget(Widget) instead |
addAttachHandler, addBitlessDomHandler, addDomHandler, addHandler, asWidget, asWidgetOrNull, createHandlerManager, delegateEvent, doAttachChildren, doDetachChildren, ensureHandlers, fireEvent, getHandlerCount, getHandlerManager, getLayoutData, getParent, isOrWasAttached, onLoad, onUnload, removeFromParent, replaceElement, setLayoutData, setParent, sinkEvents, unsinkEventsaddStyleDependentName, addStyleName, ensureDebugId, ensureDebugId, ensureDebugId, getAbsoluteLeft, getAbsoluteTop, getElement, getOffsetHeight, getOffsetWidth, getStyleElement, getStyleName, getStyleName, getStylePrimaryName, getStylePrimaryName, getTitle, isVisible, isVisible, onEnsureDebugId, removeStyleDependentName, removeStyleName, setElement, setElement, setHeight, setPixelSize, setSize, setStyleDependentName, setStyleName, setStyleName, setStyleName, setStyleName, setStylePrimaryName, setStylePrimaryName, setTitle, setVisible, setVisible, setWidth, sinkBitlessEvent, toStringpublic void claimElement(Element element)
IsRenderableIsRenderable.render(com.google.gwt.user.client.ui.RenderableStamper).claimElement in interface IsRenderablepublic void initializeClaimedElement()
IsRenderableIsRenderable.claimElement(com.google.gwt.dom.client.Element).initializeClaimedElement in interface IsRenderablepublic boolean isAttached()
WidgetisAttached in interface HasAttachHandlersisAttached in class Widgettrue if the widget is attachedpublic void onBrowserEvent(Event event)
EventListeneronBrowserEvent in interface EventListeneronBrowserEvent in class Widgetevent - the event receivedpublic SafeHtml render(RenderableStamper stamper)
render in interface IsRenderableTODO(rdcastro): Remove this once UiBinder doesn't rely on it anymore.public void render(RenderableStamper stamper, SafeHtmlBuilder builder)
IsRenderablerender in interface IsRenderableprotected Widget getWidget()
protected void initWidget(Widget widget)
Widget methods on this object, or adding it
to a panel. This method may only be called once for a given composite.widget - the widget to be wrappedprotected void onAttach()
Widget
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 Widget.onLoad() method or use Widget.addAttachHandler(com.google.gwt.event.logical.shared.AttachEvent.Handler).
It is strongly recommended that you override Widget.onLoad() or
Widget.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.
onAttach in class WidgetWidget.onLoad(),
Widget.doAttachChildren()protected void onDetach()
Widget
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 Widget.onUnload() method or use Widget.addAttachHandler(com.google.gwt.event.logical.shared.AttachEvent.Handler).
It is strongly recommended that you override Widget.onUnload() or
Widget.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.
onDetach in class WidgetWidget.onUnload(),
Widget.doDetachChildren()protected Element resolvePotentialElement()
UIObject
To be overridden by IsRenderable subclasses that initialize
themselves by by calling
setElement(PotentialElement.build(this)).
The receiver must:
Element to replace its PotentialElement
#setElement() with the new Element
This method is called when the receiver's element is about to be
added to a parent node, as a side effect of DOM.appendChild(com.google.gwt.dom.client.Element, com.google.gwt.dom.client.Element).
Note that this method is normally called only on the top element
of an IsRenderable tree. Children instead will receive IsRenderable.render(com.google.gwt.user.client.ui.RenderableStamper) and IsRenderable.claimElement(Element).
resolvePotentialElement in class UIObjectPotentialElement,
IsRenderable@Deprecated protected void setWidget(Widget widget)
initWidget(Widget) insteadinitWidget(Widget).