eu.webtoolkit.jwt
Class WViewWidget

java.lang.Object
  eu.webtoolkit.jwt.WObject
      eu.webtoolkit.jwt.WWidget
          eu.webtoolkit.jwt.WWebWidget
              eu.webtoolkit.jwt.WViewWidget

public abstract class WViewWidget
extends WWebWidget

An abstract base class for an MVC view that is rendered using a widget.

In principle, JWt widgets are self-contained and manage both their content, behavior and layout. From the point of view of a Model-View-Controller (MVC) design pattern, they implement each of these, except for the view widgets that work in conjunction with WAbstractItemModel. As a developer you can chose to keep Model, View and Controller together or separate them as you wish.

This widget facilitates separation of the View from the Model and Controller in a particular way. The View is rendered as a JWt widget. The use of this widget provides two benefits. The classic MVC benefit is a decoupling between view and model, which may allow easier maintainance of code. In addition, this widget enforces the View to be stateless, as it is only created transiently on the server. Therefore the View does not require session resources. This may increase scalability for Internet-deployments.

The rendered View widget returned by getRenderView() should reflect the current model state. Whenever the model changes, rerendering can be triggered by calling update().

Currently, the View cannot enclose WFormWidgets which would allow direct manipulation of the model (but we are working to remove this limitation in the future, and let the Model/Controller handle editing changes) and the View may only be updated by a complete rerendering of the entire view.

The View widget may contain event handling code, but only in one of the following ways:

• event handling implemented directly in JavaScript code
• event handling implemented in pre-learned stateless slot implementations

Thus, currently, event handling code related to the View cannot be implemented at server-side (but we are thinking about a solution for this as well...).

CSS

This widget does not provide styling, and can be styled using inline or external CSS as appropriate.

Constructor Summary

WViewWidget()
Creates a new view widget.

WViewWidget(WContainerWidget parent)
Creates a new view widget.

Method Summary

protected abstract WWidget	getRenderView() Creates a widget that renders the View.
void	load() Loads content just before the widget is used.
void	refresh() Refresh the widget.
void	update() Updates the view.

Methods inherited from class eu.webtoolkit.jwt.WWebWidget

addStyleClass, callJavaScriptMember, childrenChanged, doJavaScript, domCanBeSaved, enableAjax, escapeText, escapeText, escapeText, escapeText, find, getAttributeValue, getChildren, getClearSides, getDecorationStyle, getFloatSide, getHeight, getId, getJavaScriptMember, getLineHeight, getMargin, getMaximumHeight, getMaximumWidth, getMinimumHeight, getMinimumWidth, getOffset, getPositionScheme, getStyleClass, getTabIndex, getToolTip, getVerticalAlignment, getVerticalAlignmentLength, getWidth, isDisabled, isEnabled, isHidden, isHiddenKeepsGeometry, isInline, isLoaded, isPopup, isRendered, isVisible, jsStringLiteral, jsStringLiteral, propagateSetEnabled, remove, removeScript, removeStyleClass, resize, setAttributeValue, setClearSides, setDecorationStyle, setDisabled, setFloatSide, setHidden, setHiddenKeepsGeometry, setId, setInline, setJavaScriptMember, setLineHeight, setLoadLaterWhenInvisible, setMargin, setMaximumSize, setMinimumSize, setOffsets, setPopup, setPositionScheme, setSelectable, setStyleClass, setTabIndex, setToolTip, setVerticalAlignment, updateSignalConnection

Methods inherited from class eu.webtoolkit.jwt.WWidget

acceptDrops, acceptDrops, addCssRule, addCssRule, addStyleClass, animateHide, animateShow, boxBorder, boxPadding, containsExposed, disable, dropEvent, enable, getDrop, getJsRef, getParent, hide, htmlText, isLayoutSizeAware, layoutSizeChanged, positionAt, positionAt, removeStyleClass, resize, setClearSides, setHeight, setHidden, setLayoutSizeAware, setMargin, setMargin, setMargin, setMargin, setMargin, setOffsets, setOffsets, setOffsets, setOffsets, setOffsets, setToolTip, setVerticalAlignment, setWidth, show, stopAcceptDrops, toggleStyleClass, toggleStyleClass, tr

Methods inherited from class eu.webtoolkit.jwt.WObject

getObjectName, setObjectName

Methods inherited from class java.lang.Object

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

Constructor Detail

WViewWidget

public WViewWidget(WContainerWidget parent)

Creates a new view widget.

WViewWidget

public WViewWidget()

Creates a new view widget.

Calls this((WContainerWidget)null)

Method Detail

update

public void update()

Updates the view.

Typically, the model will want to update the view when the model has changed.

This will trigger a call to getRenderView() to ask for a new rendering of the view.

load

public void load()

Description copied from class: WWidget

Loads content just before the widget is used.

When the widget is inserted in the widget hierarchy, this method is called. Widgets that get inserted in the widget hierarchy will be rendered. Visible widgets are rendered immediately, and invisible widgets in the back-ground (or not for a plain HTML session). This method is called when the widget is directly or indirectly inserted into the widget tree.

The default implementation simply propagates the load signal to its children. You may want to override this method to delay loading of resource-intensive contents.

During the life-time of a widget, this method may be called multiple times, so you should make sure that you do a deferred initializiation only once.

Overrides:

load in class WWebWidget

refresh

public void refresh()

Description copied from class: WWidget

Refresh the widget.

The refresh method is invoked when the locale is changed using WApplication#setLocale() or when the user hit the refresh button.

The widget must actualize its contents in response.

Overrides:

refresh in class WWebWidget

getRenderView

protected abstract WWidget getRenderView()

Creates a widget that renders the View.

This method must be reimplemented to return a widget that renders the view. The returned widget will be deleted by WViewWidget.