/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* C E D A R
* S O L U T I O N S "Software done right."
* S O F T W A R E
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* Copyright (c) 2013-2014 Kenneth J. Pronovici.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the Apache License, Version 2.0.
* See LICENSE for more information about the licensing terms.
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* Author : Kenneth J. Pronovici <pronovic@ieee.org>
* Language : Java 6
* Project : Common Java Functionality
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
package com.cedarsolutions.client.gwt.event;
import static com.cedarsolutions.client.gwt.event.UnifiedEventType.CLICK_EVENT;
import com.flipthebird.gwthashcodeequals.EqualsBuilder;
import com.flipthebird.gwthashcodeequals.HashCodeBuilder;
import com.google.gwt.event.dom.client.ClickEvent;
/**
* Unified event that can be handled by ViewEventHandler.
*
* <p>
* There are a variety of different events that a view might need to handle.
* The usual strategy is to delegate event handling back to the presenter.
* However, if the presenter knows exactly what kind of event to handle, this
* makes for a tight coupling between view and presenter. For instance, what
* if the view wants to change a button to a menu item? It's a different kind
* of event handler, so the presenter would also need to change, even if all it
* cares about is that the item was clicked on. That seems wrong, since the main
* reason to separate the view and presenter is to give us some flexibility in
* how to implement the UI.
* </p>
*
* <p>
* This class allows the view interface to be structured in terms of a generic
* event handler. If the presenter is just handling the fact that an event
* occurred (i.e. that something was clicked), then it won't have to be
* reimplemented just because the UI element changed. Of course, if the
* presenter needs to do special handling based on the contents of the event
* itself, the presenter will still have to change... but in that case we
* haven't really lost anything.
* </p>
*
* @author Kenneth J. Pronovici <pronovic@ieee.org>
*/
public class UnifiedEvent {
/** Type of the event. */
private UnifiedEventType eventType;
/** Underlying click event, if any. */
private ClickEvent clickEvent;
/** Create a unified event when no extra event type information is needed. */
public UnifiedEvent() {
this(UnifiedEventType.DEFAULT_EVENT);
}
/** Create a unified event of a particular type. */
public UnifiedEvent(UnifiedEventType eventType) {
this.eventType = eventType;
}
/** Create a unified event based on a ClickEvent. */
public UnifiedEvent(ClickEvent clickEvent) {
this(CLICK_EVENT);
this.clickEvent = clickEvent;
}
/** Get the event type. */
public UnifiedEventType getEventType() {
return this.eventType;
}
/** Get the underlying click event, if any. */
public ClickEvent getClickEvent() {
return this.clickEvent;
}
/** Compare this object to another object. */
@Override
public boolean equals(Object obj) {
UnifiedEvent other = (UnifiedEvent) obj;
return new EqualsBuilder()
.append(this.eventType, other.eventType)
.append(this.clickEvent, other.clickEvent)
.isEquals();
}
/** Generate a hash code for this object. */
@Override
public int hashCode() {
return new HashCodeBuilder()
.append(this.eventType)
.append(this.clickEvent)
.toHashCode();
}
}