slideshow/source/inc/expressionnode.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
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   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
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  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #pragma once
  21
  22 /* Definition of ExpressionNode interface */
  23
  24 namespace slideshow::internal
  25     {
  26         /** Interface describing an abstract animation function.
  27
  28             Use this interface to model time-dependent animation
  29             functions of one variable.
  30          */
  31         class AnimationFunction
  32         {
  33         public:
  34             virtual ~AnimationFunction() {}
  35
  36             /** Operator to calculate function value.
  37
  38                 This method calculates the function value for the
  39                 given time instant t.
  40
  41                 @param t
  42                 Current time instant, must be in the range [0,1]
  43
  44                 @return the function value, typically in relative
  45                 user coordinate space ([0,1] range).
  46              */
  47             virtual double operator()( double t ) const = 0;
  48
  49         };
  50
  51         /** Refinement of AnimationFunction
  52
  53             This interface is used by the SMIL function parser, to
  54             collapse constant values into precalculated, single nodes.
  55         */
  56         class ExpressionNode : public AnimationFunction
  57         {
  58         public:
  59             /** Predicate whether this node is constant.
  60
  61                 This predicate returns true, if this node is
  62                 neither time- nor ViewInfo dependent. This allows
  63                 for certain optimizations, i.e. not the full
  64                 expression tree needs be represented by
  65                 ExpressionNodes.
  66
  67                 @returns true, if this node is neither time- nor
  68                 ViewInfo dependent
  69             */
  70             virtual bool isConstant() const = 0;
  71         };
  72
  73 }
  74
  75 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */