org.apache.myfaces.custom.autoscroll.AutoscrollPageTagHandler Maven / Gradle / Ivy

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JSF components and utilities that can be used with any JSF implementation. This library is based on the JSF1.1 version of Tomahawk, but with minor source code and build changes to take advantage of JSF2.1 features. A JSF2.1 implementation is required to use this version of the Tomahawk library.
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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.myfaces.custom.autoscroll;

import java.io.IOException;
import java.util.List;

import javax.faces.component.StateHolder;
import javax.faces.component.UICommand;
import javax.faces.component.UIComponent;
import javax.faces.component.UIViewRoot;
import javax.faces.component.behavior.ClientBehavior;
import javax.faces.component.behavior.ClientBehaviorHolder;
import javax.faces.context.FacesContext;
import javax.faces.event.ComponentSystemEvent;
import javax.faces.event.ComponentSystemEventListener;
import javax.faces.event.PostAddToViewEvent;
import javax.faces.event.PostRestoreStateEvent;
import javax.faces.event.SystemEvent;
import javax.faces.event.SystemEventListener;
import javax.faces.view.facelets.FaceletContext;
import javax.faces.view.facelets.TagAttribute;
import javax.faces.view.facelets.TagConfig;
import javax.faces.view.facelets.TagHandler;

import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFFaceletAttribute;
import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFFaceletTag;

/**
 * Adds to UICommand components that implements ClientBehaviorHolder interface an
 * AutoscrollBehavior.
 * 
 * Use it in this way to ensure proper operation:
 * 
 * 
 * <f:metadata>
 *   <t:autoScrollPage/>
 * </f:metadata>
 * 
 * 
 * Or in this way:
 * 
 * 
 * <h:body>
 *   <t:autoScrollPage/>
 * 
 * 
 * It is possible to use it at start of the page too, but note this tag attach a listener to
 * PostAddToViewEvent, so previous components added to the view before apply this TagHandler
 * will not be taken into account.
 * 
 * 
 * @since 1.1.10
 * @author Leonardo Uribe (latest modification by $Author: lu4242 $)
 * @version $Revision: 691856 $ $Date: 2008-09-03 21:40:30 -0500 (mié, 03 sep 2008) $
 */
@JSFFaceletTag(name="t:autoScrollPage")
public class AutoscrollPageTagHandler extends TagHandler
{

    /**
     * 
     */
    @JSFFaceletAttribute(name="event",
            className="javax.el.ValueExpression",
            deferredValueType="java.lang.String")
    private TagAttribute _event;
    
    public AutoscrollPageTagHandler(TagConfig config)
    {
        super(config);
        _event = this.getAttribute("event");
    }

    public void apply(FaceletContext ctx, UIComponent parent)
            throws IOException
    {
        UIViewRoot root = getViewRoot(ctx, parent);
        
        if (!root.getAttributes().containsKey(AutoscrollBehaviorTagHandler.AUTOSCROLL_TAG_ON_PAGE))
        {
            root.getAttributes().put(AutoscrollBehaviorTagHandler.AUTOSCROLL_TAG_ON_PAGE, Boolean.TRUE);
        }
        
        String eventName = (_event == null) ? null : _event.getValue(ctx);
        
        root.subscribeToViewEvent(PostAddToViewEvent.class, 
                new RegisterAutoscrollBehaviorOnCommandListener(eventName));
        root.subscribeToEvent(PostRestoreStateEvent.class, new RegisterAutoscrollListener(eventName));
    }
    
    private UIViewRoot getViewRoot(FaceletContext ctx, UIComponent parent)
    {
        UIComponent c = parent;
        do
        {
            if (c instanceof UIViewRoot)
            {
                return (UIViewRoot) c;
            }
            else
            {
                c = c.getParent();
            }
        } while (c != null);

        return ctx.getFacesContext().getViewRoot();
    }

    public static class RegisterAutoscrollListener implements ComponentSystemEventListener, StateHolder
    {
        private String eventName;
        
        public RegisterAutoscrollListener()
        {
            super();
        }

        public RegisterAutoscrollListener(String event)
        {
            super();
            eventName = event;
        }

        public void processEvent(ComponentSystemEvent event)
        {
            FacesContext.getCurrentInstance().getViewRoot().subscribeToViewEvent(PostAddToViewEvent.class, 
                    new RegisterAutoscrollBehaviorOnCommandListener(eventName));
        }

        public boolean isTransient()
        {
            return false;
        }
        
        public void setTransient(boolean newTransientValue)
        {
        }

        public void restoreState(FacesContext context, Object state)
        {
            eventName = (String)state;
        }

        public Object saveState(FacesContext context)
        {
            return eventName;
        }
    }
    
    public static class RegisterAutoscrollBehaviorOnCommandListener implements SystemEventListener
    {
        private String _eventName;

        public RegisterAutoscrollBehaviorOnCommandListener(String eventName)
        {
            super();
            _eventName = eventName;
        }

        public boolean isListenerForSource(Object source)
        {
            return (source instanceof UICommand && source instanceof ClientBehaviorHolder);
        }        
        
        public void processEvent(SystemEvent event)
        {
            ClientBehaviorHolder component = (ClientBehaviorHolder) event.getSource();
            
            String eventName = (_eventName == null) ? component.getDefaultEventName() : _eventName;
            
            boolean found = false;
            List list = component.getClientBehaviors().get(eventName);
            if (list != null)
            {
                for (ClientBehavior cb : list)
                {
                    if (cb instanceof AutoscrollBehavior)
                    {
                        found = true;
                        break;
                    }
                }
            }
            
            if (!found)
            {
                ClientBehavior behavior = (ClientBehavior) FacesContext.getCurrentInstance().getApplication().createBehavior(AutoscrollBehavior.BEHAVIOR_ID);
                component.addClientBehavior(eventName, behavior);
            }
        }
    }
}