/**
* Copyright (C) 2016 Red Hat, Inc. and/or its affiliates.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jboss.errai.common.client.ui;
import com.google.gwt.event.dom.client.ChangeEvent;
import com.google.gwt.event.dom.client.ChangeHandler;
import com.google.gwt.event.logical.shared.HasValueChangeHandlers;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.event.shared.GwtEvent;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.ui.HasValue;
import com.google.gwt.user.client.ui.Widget;
/**
* Utility class for managing widgets implementing {@link HasValue}.
*
* @author Max Barkley <mbarkley@redhat.com>
*/
public class ValueChangeManager<T, W extends Widget & HasValue<T>> implements HasValueChangeHandlers<T> {
private boolean valueChangeHandlerInitialized;
private final W widget;
public ValueChangeManager(final W widget) {
this.widget = widget;
}
@Override
public void fireEvent(final GwtEvent<?> event) {
widget.fireEvent(event);
}
@Override
public HandlerRegistration addValueChangeHandler(final ValueChangeHandler<T> handler) {
if (!valueChangeHandlerInitialized) {
valueChangeHandlerInitialized = true;
widget.addDomHandler(new ChangeHandler() {
@Override
public void onChange(ChangeEvent event) {
ValueChangeEvent.fire(widget, widget.getValue());
}
}, ChangeEvent.getType());
}
return widget.addHandler(handler, ValueChangeEvent.getType());
}
}