com.seanchenxi.gwt.ui.widget.Mask.java Source code

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Here is the source code for com.seanchenxi.gwt.ui.widget.Mask.java

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/*
 * Copyright 2012 Xi CHEN
 *
 * 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.seanchenxi.gwt.ui.widget;

import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.Scheduler;
import com.google.gwt.event.logical.shared.AttachEvent;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.resources.client.ClientBundle;
import com.google.gwt.resources.client.CssResource;
import com.google.gwt.resources.client.ImageResource;
import com.google.gwt.user.client.Command;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.Element;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.Widget;

public class Mask {

    public interface Resources extends ClientBundle {

        public interface Style extends CssResource {
            final static String DEFAULT_CSS = "com/seanchenxi/gwt/ui/widget/Mask.css";

            String mask();

            String loaderIcon();
        }

        @ClientBundle.Source(Style.DEFAULT_CSS)
        Style style();

        @ImageResource.ImageOptions(repeatStyle = ImageResource.RepeatStyle.None, height = 42, width = 42)
        @ClientBundle.Source("com/seanchenxi/gwt/ui/resource/image/mask/ajax-loader.gif")
        ImageResource loaderIcon();
    }

    private static HandlerRegistration handlerRegistration;
    private static final HTML MASK;
    private static final Resources RESOURCES;

    static {
        RESOURCES = GWT.create(Resources.class);
        MASK = new HTML();
        MASK.getElement().setId("Mask");
        MASK.setStyleName(RESOURCES.style().mask());
    }

    public static boolean isShowing() {
        return MASK.isAttached();
    }

    public static void hideMask() {
        RootPanel.get().remove(MASK);
        MASK.setStyleName(RESOURCES.style().mask());
    }

    public static void showMaskFor(final Widget widget) {
        clearHandler();
        if (widget.isAttached()) {
            RESOURCES.style().ensureInjected();
            MASK.addStyleName(RESOURCES.style().loaderIcon());
            Element element = widget.getElement();
            MASK.setPixelSize(element.getOffsetWidth(), element.getOffsetHeight());
            RootPanel.get().add(MASK, DOM.getAbsoluteLeft(element), DOM.getAbsoluteTop(element));
        } else {
            delayHandler(widget);
        }
    }

    private static void delayHandler(final Widget widget) {
        handlerRegistration = widget.addAttachHandler(new AttachEvent.Handler() {
            @Override
            public void onAttachOrDetach(AttachEvent event) {
                Scheduler.get().scheduleDeferred(new Command() {
                    @Override
                    public void execute() {
                        showMaskFor(widget);
                    }
                });
            }
        });
    }

    private static void clearHandler() {
        if (handlerRegistration != null) {
            handlerRegistration.removeHandler();
            handlerRegistration = null;
        }
    }

}