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 * 
 * Licensed to the Apache Software Foundation (ASF) under one
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 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
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 * 
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#ifndef INCLUDED_SLIDESHOW_VIEWUPDATE_HXX
#define INCLUDED_SLIDESHOW_VIEWUPDATE_HXX

#include "disposable.hxx"
#include "view.hxx"
#include <boost/shared_ptr.hpp>

/* Definition of ViewUpdate interface */

namespace slideshow
{
    namespace internal
    {
        /** Interface for something that can perform view updates.

            Use this interface for objects that perform view updates
            from time to time, e.g. slide content. Availability of
            updates can be queried, and subsequently performed.
         */
        class ViewUpdate : public Disposable
        {
        public:
            /** Perform the update action on all views

                @return true, if the update was performed
                successfully, false otherwise.
             */
            virtual bool update() = 0;

            /** Perform the update action on given view only

                @return true, if the update was performed
                successfully, false otherwise.
             */
            virtual bool update( ViewSharedPtr const& rView ) = 0;

            /** Query whether updates are pending

                @return true, if updates are pending. Calling update()
                subsequently will perform the pending update then.
             */
            virtual bool needsUpdate() const = 0;
        };

        typedef ::boost::shared_ptr< ViewUpdate > ViewUpdateSharedPtr;
    }
}

#endif /* INCLUDED_SLIDESHOW_VIEWUPDATE_HXX */