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#ifndef INCLUDED_SLIDESHOW_BOOLANIMATION_HXX
#define INCLUDED_SLIDESHOW_BOOLANIMATION_HXX

#include "animation.hxx"


/* Definition of BoolAnimation interface */

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

        	This interface is a specialization of the Animation
        	interface, and is used to animate attributes that have
        	only two discrete values (on and off, or true and false,
        	for example).
         */
        class BoolAnimation : public Animation
        {
        public:
            typedef bool ValueType;
            
            /** Set the animation to the given value

                @param bValue
                Current animation value.
             */
            virtual bool operator()( ValueType bValue ) = 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< BoolAnimation > BoolAnimationSharedPtr;

    }
}

#endif /* INCLUDED_SLIDESHOW_BOOLANIMATION_HXX */