com.google.appengine.demos.sticky.client.Main.java Source code

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Here is the source code for com.google.appengine.demos.sticky.client.Main.java

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/* Copyright (c) 2009 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.appengine.demos.sticky.client;

import com.google.appengine.demos.sticky.client.model.Model;
import com.google.appengine.demos.sticky.client.model.RetryTimer;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.google.gwt.dom.client.DivElement;
import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.Element;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.SimplePanel;
import com.google.gwt.user.client.ui.UIObject;

/**
 * The entry point for the Sticky application.
 *
 */
public class Main extends RetryTimer implements EntryPoint, Model.LoadObserver, Model.StatusObserver {

    /**
     * An aggregated image bundle will auto-sprite all the images in the
     * application.
     */
    public interface Images extends HeaderView.Images {
    }

    /**
     * Provides Ui to notify the user of model based events. These include tasks
     * (like loading a surface) and also errors (like lost communication to the
     * server).
     */
    private static class StatusView extends SimplePanel {
        private final DivElement taskStatusElement;

        private final DivElement errorStatusElement;

        public StatusView() {
            final Document document = Document.get();
            final Element element = getElement();
            taskStatusElement = element.appendChild(document.createDivElement());
            errorStatusElement = element.appendChild(document.createDivElement());
            errorStatusElement.setInnerText("No response from server");

            setStyleName("status-view");
            taskStatusElement.setClassName("status-view-task");
            errorStatusElement.setClassName("status-view-error");

            hideErrorStatus();
            hideTaskStatus();
        }

        /**
         * Hides the Ui for server communication lost errors.
         */
        public void hideErrorStatus() {
            UIObject.setVisible(errorStatusElement, false);
        }

        /**
         * Hides the task status Ui.
         */
        public void hideTaskStatus() {
            UIObject.setVisible(taskStatusElement, false);
        }

        /**
         * Displays the Ui for server communication lost errors.
         */
        public void showErrorStatus() {
            UIObject.setVisible(errorStatusElement, true);
        }

        /**
         * Displays the the Ui for a task status.
         *
         * @param text
         *          the text to be displayed
         */
        public void showTaskStatus(String text) {
            taskStatusElement.setInnerText(text);
            UIObject.setVisible(taskStatusElement, true);
        }
    }

    private final StatusView status = new StatusView();

    public void onModelLoaded(Model model) {
        status.hideTaskStatus();
        status.hideErrorStatus();

        final Images images = GWT.create(Images.class);

        Window.enableScrolling(false);

        final RootPanel root = RootPanel.get();
        new HeaderView(images, root, model);
        root.add(new SurfaceView(model));
    }

    public void onModelLoadFailed() {
        retryLater();
        status.showErrorStatus();
    }

    public void onModuleLoad() {
        RootPanel.get().add(status);
        status.showTaskStatus("Loading");
        Model.load(this, this);
    }

    public void onServerCameBack() {
        status.hideErrorStatus();
    }

    public void onServerWentAway() {
        status.showErrorStatus();
    }

    public void onTaskFinished() {
        status.hideTaskStatus();
    }

    public void onTaskStarted(String description) {
        status.showTaskStatus(description);
    }

    @Override
    protected void retry() {
        Model.load(this, this);
    }
}