com.google.gwt.sample.expenses.client.place.ProxyListPlacePicker.java Source code

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Here is the source code for com.google.gwt.sample.expenses.client.place.ProxyListPlacePicker.java

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/*
 * Copyright 2010 Google Inc.
 * 
 * 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 com.google.gwt.sample.expenses.client.place;

import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.event.shared.EventBus;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.place.shared.PlaceChangeEvent;
import com.google.gwt.place.shared.PlaceController;
import com.google.gwt.user.client.ui.HasConstrainedValue;

/**
 * <p>
 * <span style="color:red">Experimental API: This class is still under rapid
 * development, and is very likely to be deleted. Use it at your own risk.
 * </span>
 * </p>
 * Drives a {@link ValueChangeHandler} populated with {@link ProxyListPlace}
 * instances, keeping it in sync with the {@link PlaceController}'s notion of
 * the current place, and firing place change events as selections are made.
 */
public class ProxyListPlacePicker implements ValueChangeHandler<ProxyListPlace>, PlaceChangeEvent.Handler {

    private HasConstrainedValue<ProxyListPlace> view;

    private final PlaceController placeController;
    private final ProxyPlaceToListPlace proxyPlaceToListPlace;

    public ProxyListPlacePicker(PlaceController placeController, ProxyPlaceToListPlace proxyPlaceToListPlace) {
        this.placeController = placeController;
        this.proxyPlaceToListPlace = proxyPlaceToListPlace;
    }

    public void onPlaceChange(PlaceChangeEvent event) {
        view.setValue(proxyPlaceToListPlace.proxyListPlaceFor(event.getNewPlace()), false);
    }

    public void onValueChange(ValueChangeEvent<ProxyListPlace> event) {
        placeController.goTo(event.getValue());
    }

    public HandlerRegistration register(EventBus eventBus, HasConstrainedValue<ProxyListPlace> view) {

        this.view = view;

        final HandlerRegistration placeRegistration = eventBus.addHandler(PlaceChangeEvent.TYPE, this);

        final HandlerRegistration viewRegistration = view.addValueChangeHandler(this);

        return new HandlerRegistration() {
            public void removeHandler() {
                placeRegistration.removeHandler();
                viewRegistration.removeHandler();
                ProxyListPlacePicker.this.view = null;
            }
        };
    }
}