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