slideshow/source/inc/expressionnode.hxx

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  19
  20 #ifndef INCLUDED_SLIDESHOW_SOURCE_INC_EXPRESSIONNODE_HXX
  21 #define INCLUDED_SLIDESHOW_SOURCE_INC_EXPRESSIONNODE_HXX
  22
  23 #include <memory>
  24
  25 /* Definition of ExpressionNode interface */
  26
  27 namespace slideshow
  28 {
  29     namespace internal
  30     {
  31         /** Interface describing an abstract animation function.
  32
  33             Use this interface to model time-dependent animation
  34             functions of one variable.
  35          */
  36         class AnimationFunction
  37         {
  38         public:
  39             virtual ~AnimationFunction() {}
  40
  41             /** Operator to calculate function value.
  42
  43                 This method calculates the function value for the
  44                 given time instant t.
  45
  46                 @param t
  47                 Current time instant, must be in the range [0,1]
  48
  49                 @return the function value, typically in relative
  50                 user coordinate space ([0,1] range).
  51              */
  52             virtual double operator()( double t ) const = 0;
  53
  54         };
  55
  56         typedef ::std::shared_ptr< AnimationFunction > AnimationFunctionSharedPtr;
  57
  58         /** Refinement of AnimationFunction
  59
  60             This interface is used by the SMIL function parser, to
  61             collapse constant values into precalculated, single nodes.
  62         */
  63         class ExpressionNode : public AnimationFunction
  64         {
  65         public:
  66             /** Predicate whether this node is constant.
  67
  68                 This predicate returns true, if this node is
  69                 neither time- nor ViewInfo dependent. This allows
  70                 for certain obtimizations, i.e. not the full
  71                 expression tree needs be represented by
  72                 ExpressionNodes.
  73
  74                 @returns true, if this node is neither time- nor
  75                 ViewInfo dependent
  76             */
  77             virtual bool isConstant() const = 0;
  78         };
  79     }
  80 }
  81
  82 #endif // INCLUDED_SLIDESHOW_SOURCE_INC_EXPRESSIONNODE_HXX
  83
  84 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */