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21 
22 
23 
24 #ifndef INCLUDED_SLIDESHOW_NUMBERANIMATION_HXX
25 #define INCLUDED_SLIDESHOW_NUMBERANIMATION_HXX
26 
27 #include <animation.hxx>
28 
29 
30 /* Definition of NumberAnimation interface */
31 
32 namespace slideshow
33 {
34     namespace internal
35     {
36         /** Interface defining a number animation.
37 
38         	This interface is a specialization of the Animation
39         	interface, and is used to animate attributes representable
40         	by a single floating point value.
41          */
42         class NumberAnimation : public Animation
43         {
44         public:
45             typedef double ValueType;
46 
47             /** Set the animation to value x
48 
49                 @param x
50                 Current animation value (must be in an
51                 attribute-specific permissible range). Overflowing
52                 values will be clipped to the permissible range
53                 internally.
54              */
55             virtual bool operator()( ValueType x ) = 0;
56 
57             /** Request the underlying value for this animation.
58 
59             	This is necessary for pure To or By animations, as the
60             	Activity cannot determine a sensible start value
61             	otherwise.
62 
63                 @attention Note that you are only permitted to query
64                 for the underlying value, if the animation has actually
65                 been started (via start() call).
66              */
67             virtual ValueType getUnderlyingValue() const = 0;
68         };
69 
70         typedef ::boost::shared_ptr< NumberAnimation > NumberAnimationSharedPtr;
71 
72     }
73 }
74 
75 #endif /* INCLUDED_SLIDESHOW_NUMBERANIMATION_HXX */
76