com.google.gwt.visualization.client.events.Handler.java Source code

Introduction

Here is the source code for com.google.gwt.visualization.client.events.Handler.java

Source

/*
 * Copyright 2008 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.visualization.client.events;

import com.google.gwt.ajaxloader.client.Properties;
import com.google.gwt.ajaxloader.client.Properties.TypeException;
import com.google.gwt.core.client.GWT;
import com.google.gwt.visualization.client.visualizations.Visualization;

/**
 * The base class for visualization event handlers.
 */
public abstract class Handler {
    /**
     * Add a Handler to a visualization.
     * 
     * @param viz a Visualization supporting the given event.
     * @param eventName The name of the event.
     * @param handler A Handler to add.
     */
    public static native void addHandler(Visualization<?> viz, String eventName, Handler handler) /*-{
                                                                                                  var jso = viz.@com.google.gwt.visualization.client.visualizations.Visualization::getJso()();
                                                                                                  var callback = function(event) {
                                                                                                  @com.google.gwt.visualization.client.events.Handler::onCallback(Lcom/google/gwt/visualization/client/events/Handler;Lcom/google/gwt/ajaxloader/client/Properties;)
                                                                                                  (handler, event);
                                                                                                  };
                                                                                                  $wnd.google.visualization.events.addListener(jso, eventName, callback);
                                                                                                  }-*/;

    @SuppressWarnings("unused")
    private static void onCallback(final Handler handler, final Properties properties) {
        try {
            handler.onEvent(properties);
        } catch (Throwable x) {
            GWT.getUncaughtExceptionHandler().onUncaughtException(x);
        }
    }

    /**
     * This method should be overridden by event-specific Handler subclasses. The
     * subclass should extract the event properties (if any), create a GWT Event
     * bean object, and pass it to the event-specific callback.
     * 
     * @param properties The JavaScriptObject containing data about the event.
     * @throws TypeException If some property of the event has an unexpected type.
     */
    protected abstract void onEvent(Properties properties) throws TypeException;
}