wicketdnd.IEBackgroundImageCacheFix.java Source code

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Here is the source code for wicketdnd.IEBackgroundImageCacheFix.java

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/*
 * Copyright 2009 Sven Meier
 *
 * 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 wicketdnd;

import org.apache.wicket.Component;
import org.apache.wicket.behavior.Behavior;
import org.apache.wicket.markup.html.IHeaderResponse;
import org.apache.wicket.protocol.http.request.WebClientInfo;
import org.apache.wicket.request.cycle.RequestCycle;

/**
 * Fix for caching of background images in IE.
 * <br>
 * IE 6 fails to cache images if they are used as CSS backgrounds. This
 * javascript enables caching by executing an IE proprietary command.
 * 
 * @author Sven Meier
 */
public class IEBackgroundImageCacheFix extends Behavior {

    private static final long serialVersionUID = 1L;

    @Override
    public void renderHead(Component component, IHeaderResponse response) {
        WebClientInfo info = new WebClientInfo(RequestCycle.get());
        if (info.getProperties().isBrowserInternetExplorer()) {
            String initJS = "try { document.execCommand('BackgroundImageCache', false, true); } catch (e) {};}";
            response.renderOnDomReadyJavaScript(initJS);
        }
    }
}