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         /** Refinement of AnimationFunction
  57
  58             This interface is used by the SMIL function parser, to
  59             collapse constant values into precalculated, single nodes.
  60         */
  61         class ExpressionNode : public AnimationFunction
  62         {
  63         public:
  64             /** Predicate whether this node is constant.
  65
  66                 This predicate returns true, if this node is
  67                 neither time- nor ViewInfo dependent. This allows
  68                 for certain optimizations, i.e. not the full
  69                 expression tree needs be represented by
  70                 ExpressionNodes.
  71
  72                 @returns true, if this node is neither time- nor
  73                 ViewInfo dependent
  74             */
  75             virtual bool isConstant() const = 0;
  76         };
  77     }
  78 }
  79
  80 #endif // INCLUDED_SLIDESHOW_SOURCE_INC_EXPRESSIONNODE_HXX
  81
  82 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */