slideshow/source/engine/transitions/parametricpolypolygon.hxx

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  19
  20 #ifndef INCLUDED_SLIDESHOW_SOURCE_ENGINE_TRANSITIONS_PARAMETRICPOLYPOLYGON_HXX
  21 #define INCLUDED_SLIDESHOW_SOURCE_ENGINE_TRANSITIONS_PARAMETRICPOLYPOLYGON_HXX
  22
  23 #include <basegfx/polygon/b2dpolypolygon.hxx>
  24 #include <memory>
  25
  26
  27 /* Definition of ParametricPolyPolygon interface */
  28
  29 namespace slideshow::internal
  30     {
  31         /** Interface defining a parametric poly-polygon.
  32
  33             This interface defines a poly-polygon, whose actual shape
  34             is parameterized by a floating point value. This is
  35             e.g. used to generically access the various clip polygon
  36             generators for transition effects.
  37
  38             Since for every parametric poly-polygon, there is a set of
  39             variations, which can easily be generated by simple
  40             transformations or change in parameter range sweep
  41             direction, objects implementing this interface only
  42             generate <em>one</em> prototypical instance of the
  43             parametric poly-polygon. Generally speaking, the main
  44             effect direction should be horizontal, it should make
  45             increasingly more area visible (transition 'in'), and when
  46             there is a designated direction given, that should be
  47             left-to-right.
  48          */
  49         class ParametricPolyPolygon
  50         {
  51         public:
  52             virtual ~ParametricPolyPolygon() {}
  53
  54             /** Retrieve the poly-polygon for value t.
  55
  56                 @param t
  57                 Current parameter value to retrieve the corresponding
  58                 poly-polygon for. Permissible values for t must be in
  59                 the range [0,1].
  60
  61                 @return a poly-polygon corresponding to the given
  62                 parameter value. The poly-polygon is interpreted as
  63                 living in the unit rectangle (i.e. [0,1]x[0,1]), but
  64                 is not necessarily constrained to completely lie in
  65                 this area (this very much depends on the actual effect
  66                 to be generated). Although, from a performance
  67                 perspective, it currently <em>is</em> advantageous to
  68                 try to keep the poly-polygon within these bounds (at
  69                 least if there are no hard reasons not to do so),
  70                 because then reversion or out transformations are
  71                 potentially faster to compute (see the
  72                 TransitionInfo::meReverseMethod member in
  73                 transitionfactory.cxx). Furthermore, if one of the
  74                 polygon modifications involve subtraction (also see
  75                 TransitionInfo::meReverseMethod), all generated
  76                 polygons should be oriented clock-wise
  77                 (i.e. traversing the polygon vertices with increasing
  78                 vertex index should generate a clock-wise movement).
  79              */
  80             virtual ::basegfx::B2DPolyPolygon operator()( double t ) = 0;
  81         };
  82
  83         typedef ::std::shared_ptr< ParametricPolyPolygon > ParametricPolyPolygonSharedPtr;
  84
  85 }
  86
  87 #endif // INCLUDED_SLIDESHOW_SOURCE_ENGINE_TRANSITIONS_PARAMETRICPOLYPOLYGON_HXX
  88
  89 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */