include/basegfx/tools/keystoplerp.hxx

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  19
  20 #ifndef INCLUDED_BASEGFX_TOOLS_KEYSTOPLERP_HXX
  21 #define INCLUDED_BASEGFX_TOOLS_KEYSTOPLERP_HXX
  22
  23 #include <basegfx/numeric/ftools.hxx>
  24 #include <vector>
  25 #include <basegfx/basegfxdllapi.h>
  26
  27 namespace com{ namespace sun{ namespace star{ namespace uno {
  28     template<typename T> class Sequence;
  29 }}}}
  30
  31 namespace basegfx
  32 {
  33     namespace tools
  34     {
  35         /** Lerp in a vector of key stops
  36
  37             This class holds a key stop vector and provides the
  38             functionality to lerp inside it. Useful e.g. for
  39             multi-stop gradients, or the SMIL key time activity.
  40
  41             For those, given a global [0,1] lerp alpha, one need to
  42             find the suitable bucket index from key stop vector, and
  43             then calculate the relative alpha between the two buckets
  44             found.
  45          */
  46         class BASEGFX_DLLPUBLIC KeyStopLerp
  47         {
  48         public:
  49             typedef std::pair<std::ptrdiff_t,double> ResultType;
  50
  51             /** Create lerper with given vector of stops
  52
  53                 @param rKeyStops
  54
  55                 Vector of stops, must contain at least two elements
  56                 (though preferably more, otherwise you probably don't
  57                 need key stop lerping in the first place). All
  58                 elements must be of monotonically increasing value.
  59              */
  60             explicit KeyStopLerp( const std::vector<double>& rKeyStops );
  61
  62             /** Create lerper with given sequence of stops
  63
  64                 @param rKeyStops
  65
  66                 Sequence of stops, must contain at least two elements
  67                 (though preferably more, otherwise you probably don't
  68                 need key stop lerping in the first place). All
  69                 elements must be of monotonically increasing value.
  70              */
  71             explicit KeyStopLerp( const ::com::sun::star::uno::Sequence<double>& rKeyStops );
  72
  73             /** Find two nearest bucket index & interpolate
  74
  75                 @param fAlpha
  76                 Find bucket index i, with keyStops[i] < fAlpha <=
  77                 keyStops[i+1]. Return new alpha value in [0,1),
  78                 proportional to fAlpha's position between keyStops[i]
  79                 and keyStops[i+1]
  80              */
  81             ResultType lerp(double fAlpha) const;
  82
  83         private:
  84             std::vector<double>    maKeyStops;
  85             mutable std::ptrdiff_t mnLastIndex;
  86         };
  87     }
  88 }
  89
  90 #endif
  91
  92 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */