slideshow/source/engine/transitions/parametricpolypolygon.hxx

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  30
  31 #ifndef INCLUDED_SLIDESHOW_PARAMETRICPOLYPOLYGON_HXX
  32 #define INCLUDED_SLIDESHOW_PARAMETRICPOLYPOLYGON_HXX
  33
  34 #include <basegfx/polygon/b2dpolypolygon.hxx>
  35 #include <boost/shared_ptr.hpp>
  36
  37
  38 /* Definition of ParametricPolyPolygon interface */
  39
  40 namespace slideshow
  41 {
  42     namespace internal
  43     {
  44         /** Interface defining a parametric poly-polygon.
  45
  46             This interface defines a poly-polygon, whose actual shape
  47             is parameterized by a floating point value. This is
  48             e.g. used to generically access the various clip polygon
  49             generators for transition effects.
  50
  51             Since for every parametric poly-polygon, there is a set of
  52             variations, which can easily be generated by simple
  53             transformations or change in parameter range sweep
  54             direction, objects implementing this interface only
  55             generate <em>one</em> prototypical instance of the
  56             parametric poly-polygon. Generally speaking, the main
  57             effect direction should be horizontal, it should make
  58             increasingly more area visible (transition 'in'), and when
  59             there is a designated direction given, that should be
  60             left-to-right.
  61          */
  62         class ParametricPolyPolygon
  63         {
  64         public:
  65             virtual ~ParametricPolyPolygon() {}
  66
  67             /** Retrieve the poly-polygon for value t.
  68
  69                 @param t
  70                 Current parameter value to retrieve the corresponding
  71                 poly-polygon for. Permissible values for t must be in
  72                 the range [0,1].
  73
  74                 @return a poly-polygon corresponding to the given
  75                 parameter value. The poly-polygon is interpreted as
  76                 living in the unit rectangle (i.e. [0,1]x[0,1]), but
  77                 is not necessarily constrained to completely lie in
  78                 this area (this very much depends on the actual effect
  79                 to be generated). Although, from a performance
  80                 perspective, it currently <em>is</em> advantageous to
  81                 try to keep the poly-polygon within these bounds (at
  82                 least if there are no hard reasons not to do so),
  83                 because then reversion or out transformations are
  84                 potentially faster to compute (see the
  85                 TransitionInfo::meReverseMethod member in
  86                 transitionfactory.cxx). Furthermore, if one of the
  87                 polygon modifications involve subtraction (also see
  88                 TransitionInfo::meReverseMethod), all generated
  89                 polygons should be oriented clock-wise
  90                 (i.e. traversing the polygon vertices with increasing
  91                 vertex index should generate a clock-wise movement).
  92              */
  93             virtual ::basegfx::B2DPolyPolygon operator()( double t ) = 0;
  94         };
  95
  96         typedef ::boost::shared_ptr< ParametricPolyPolygon > ParametricPolyPolygonSharedPtr;
  97
  98     }
  99 }
 100
 101 #endif /* INCLUDED_SLIDESHOW_PARAMETRICPOLYPOLYGON_HXX */