org.apache.wicket.extensions.ajax.markup.html.AjaxIndicatorAppender.java Source code

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Here is the source code for org.apache.wicket.extensions.ajax.markup.html.AjaxIndicatorAppender.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.wicket.extensions.ajax.markup.html;

import org.apache.wicket.Component;
import org.apache.wicket.ajax.AbstractDefaultAjaxBehavior;
import org.apache.wicket.ajax.IAjaxIndicatorAware;
import org.apache.wicket.behavior.Behavior;
import org.apache.wicket.core.request.handler.IPartialPageRequestHandler;
import org.apache.wicket.markup.head.IHeaderResponse;
import org.apache.wicket.request.IRequestHandler;
import org.apache.wicket.request.Response;
import org.apache.wicket.request.cycle.RequestCycle;
import org.apache.wicket.request.handler.resource.ResourceReferenceRequestHandler;
import org.apache.wicket.request.resource.ResourceReference;

/**
 * A behavior that adds a span with wicket's default indicator gif to the end of the component's
 * markup. This span can be used as an ajax busy indicator. For an example usage see
 * {@link IndicatingAjaxLink}
 * <p>
 * Instances of this behavior must not be shared between components.
 * 
 * @see IndicatingAjaxLink
 * @see IAjaxIndicatorAware
 * 
 * @since 1.2
 * 
 * @author Igor Vaynberg (ivaynberg)
 */
public class AjaxIndicatorAppender extends Behavior {
    /**
     * Component instance this behavior is bound to
     */
    private Component component;

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    private final ResourceReference indicator;

    /**
     * Construct.
     */
    public AjaxIndicatorAppender() {
        this(AbstractDefaultAjaxBehavior.INDICATOR);
    }

    /**
     * Build a new instance specifing a custom busy indicator as {@link ResourceReference}.
     * 
     * @param indicator
     *             The {@link ResourceReference} to use as busy indicator.     
     */
    public AjaxIndicatorAppender(ResourceReference indicator) {
        this.indicator = indicator;
    }

    @Override
    public void renderHead(final Component component, final IHeaderResponse response) {
        super.renderHead(component, response);

        component.getRequestCycle().find(IPartialPageRequestHandler.class).ifPresent(target -> {
            final String javascript = "var e = Wicket.$('" + getMarkupId()
                    + "'); if (e != null && typeof(e.parentNode) != 'undefined') e.parentNode.removeChild(e);";

            target.prependJavaScript(javascript);
        });
    }

    @Override
    public void afterRender(final Component component) {
        super.afterRender(component);
        final Response r = component.getResponse();

        r.write("<span style=\"display:none;\" class=\"");
        r.write(getSpanClass());
        r.write("\" ");
        r.write("id=\"");
        r.write(getMarkupId());
        r.write("\">");
        r.write("<img src=\"");
        r.write(getIndicatorUrl());
        r.write("\" alt=\"\"/></span>");

    }

    /**
     * @return url of the animated indicator image
     */
    protected CharSequence getIndicatorUrl() {
        IRequestHandler handler = new ResourceReferenceRequestHandler(indicator);
        return RequestCycle.get().urlFor(handler);
    }

    /**
     * @return css class name of the generated outer span
     */
    protected String getSpanClass() {
        return "wicket-ajax-indicator";
    }

    /**
     * Returns the markup id attribute of the outer most span of this indicator. This is the id of
     * the span that should be hidden or show to hide or show the indicator.
     * 
     * @return markup id of outer most span
     */
    public String getMarkupId() {
        return component.getMarkupId() + "--ajax-indicator";
    }

    /**
     * @see org.apache.wicket.behavior.Behavior#bind(org.apache.wicket.Component)
     */
    @Override
    public final void bind(final Component component) {
        this.component = component;
    }
}