interpolation.hxx

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#ifndef INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_INTERPOLATION_HXX
#define INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_INTERPOLATION_HXX
 
#include <basegfx/utils/lerp.hxx>
#include <osl/diagnose.h>
#include <rtl/ustring.hxx>
 
#include <rgbcolor.hxx>
#include <hslcolor.hxx>
 
namespace basegfx
{
    namespace utils
    {
        // Interpolator specializations
        // ============================
 
        // NOTE: generic lerp is included from lerp.hxx. Following
        // are some specializations for various
        // not-straight-forward-interpolatable types
 
        template<> ::slideshow::internal::RGBColor lerp< ::slideshow::internal::RGBColor >(
            const ::slideshow::internal::RGBColor& rFrom,
            const ::slideshow::internal::RGBColor& rTo,
            double                                 t     )
        {
            return interpolate( rFrom, rTo, t );
        }
 
        template<> sal_Int16 lerp< sal_Int16 >( const sal_Int16&,
                                                const sal_Int16&    rTo,
                                                double                     )
        {
            OSL_FAIL( "lerp<sal_Int16> called" );
            return rTo;
        }
 
        template<> OUString lerp< OUString >( const OUString&,
                                                            const OUString&  rTo,
                                                            double                       )
        {
            OSL_FAIL( "lerp<OUString> called" );
            return rTo;
        }
 
        template<> bool lerp< bool >( const bool&,
                                      const bool&   rTo,
                                      double             )
        {
            OSL_FAIL( "lerp<bool> called" );
            return rTo;
        }
    }
}
 
namespace slideshow
{
    namespace internal
    {
        template< typename ValueType > struct Interpolator
        {
            ValueType operator()( const ValueType&  rFrom,
                                  const ValueType&  rTo,
                                  double            t ) const
            {
                return basegfx::utils::lerp( rFrom, rTo, t );
            }
        };
 
        template<> struct Interpolator< HSLColor >
        {
            explicit Interpolator( bool bCCW ) :
                mbCCW( bCCW )
            {
            }
 
            HSLColor operator()( const HSLColor&    rFrom,
                                 const HSLColor&    rTo,
                                 double             t ) const
            {
                return interpolate( rFrom, rTo, t, mbCCW );
            }
 
        private:
            const bool mbCCW;
        };
 
 
        template< typename ValueType > ValueType lerp( const Interpolator< ValueType >& rInterpolator,
                                                       const ValueType&                 rFrom,
                                                       const ValueType&                 rTo,
                                                       sal_uInt32                       nFrame,
                                                       ::std::size_t                    nTotalFrames )
        {
            // TODO(P1): There's a nice HAKMEM trick for that
            // nTotalFrames > 1 condition below
 
            // for 1 and 0 frame animations, always take end value
            const double nFraction( nTotalFrames > 1 ? double(nFrame)/(nTotalFrames-1) : 1.0 );
 
            return rInterpolator( rFrom, rTo, nFraction );
        }
 
        template<> sal_Int16 lerp< sal_Int16 >( const Interpolator< sal_Int16 >&    /*rInterpolator*/,
                                                const sal_Int16&                    rFrom,
                                                const sal_Int16&                    rTo,
                                                sal_uInt32                          nFrame,
                                                ::std::size_t                       nTotalFrames )
        {
            // until one half of the total frames are over, take from value.
            // after that, take to value.
            // For nFrames not divisible by 2, we prefer to over from, which
            // also neatly yields to for 1 frame activities
            return nFrame < nTotalFrames/2 ? rFrom : rTo;
        }
 
        template<> OUString lerp< OUString >( const Interpolator< OUString >&  /*rInterpolator*/,
                                                            const OUString&                  rFrom,
                                                            const OUString&                  rTo,
                                                            sal_uInt32                              nFrame,
                                                            ::std::size_t                           nTotalFrames )
        {
            // until one half of the total frames are over, take from value.
            // after that, take to value.
            // For nFrames not divisible by 2, we prefer to over from, which
            // also neatly yields to for 1 frame activities
            return nFrame < nTotalFrames/2 ? rFrom : rTo;
        }
 
        template<> bool lerp< bool >( const Interpolator< bool >&   /*rInterpolator*/,
                                      const bool&                   bFrom,
                                      const bool&                   bTo,
                                      sal_uInt32                    nFrame,
                                      ::std::size_t                 nTotalFrames )
        {
            // until one half of the total frames are over, take from value.
            // after that, take to value.
            // For nFrames not divisible by 2, we prefer to over from, which
            // also neatly yields to for 1 frame activities
            return nFrame < nTotalFrames/2 ? bFrom : bTo;
        }
    }
}
 
#endif // INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_INTERPOLATION_HXX
 
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