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#ifndef INCLUDED_SLIDESHOW_NUMBERANIMATION_HXX
#define INCLUDED_SLIDESHOW_NUMBERANIMATION_HXX

#include <animation.hxx>


/* Definition of NumberAnimation interface */

namespace slideshow
{
    namespace internal
    {
        /** Interface defining a number animation.

        	This interface is a specialization of the Animation
        	interface, and is used to animate attributes representable
        	by a single floating point value.
         */
        class NumberAnimation : public Animation
        {
        public:
            typedef double ValueType;

            /** Set the animation to value x

                @param x
                Current animation value (must be in an
                attribute-specific permissible range). Overflowing
                values will be clipped to the permissible range
                internally.
             */
            virtual bool operator()( ValueType x ) = 0;

            /** Request the underlying value for this animation.

            	This is necessary for pure To or By animations, as the
            	Activity cannot determine a sensible start value
            	otherwise. 

                @attention Note that you are only permitted to query
                for the underlying value, if the animation has actually
                been started (via start() call).
             */
            virtual ValueType getUnderlyingValue() const = 0;
        };

        typedef ::boost::shared_ptr< NumberAnimation > NumberAnimationSharedPtr;

    }
}

#endif /* INCLUDED_SLIDESHOW_NUMBERANIMATION_HXX */