basegfx/source/tools/keystoplerp.cxx

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  30
  31 // MARKER(update_precomp.py): autogen include statement, do not remove
  32 #include "precompiled_basegfx.hxx"
  33
  34 #include "basegfx/tools/keystoplerp.hxx"
  35 #include <com/sun/star/uno/Sequence.hxx>
  36
  37 #include <algorithm>
  38
  39 static void validateInput(const std::vector<double>& rKeyStops)
  40 {
  41     (void)rKeyStops;
  42 #ifdef DBG_UTIL
  43     OSL_ENSURE( rKeyStops.size() > 1,
  44                 "KeyStopLerp::KeyStopLerp(): key stop vector must have two entries or more" );
  45
  46     // rKeyStops must be sorted in ascending order
  47     for( ::std::size_t i=1, len=rKeyStops.size(); i<len; ++i )
  48     {
  49         if( rKeyStops[i-1] > rKeyStops[i] )
  50             OSL_ENSURE( false,
  51                         "KeyStopLerp::KeyStopLerp(): time vector is not sorted in ascending order!" );
  52     }
  53 #endif
  54 }
  55
  56 namespace basegfx
  57 {
  58     namespace tools
  59     {
  60         KeyStopLerp::KeyStopLerp( const std::vector<double>& rKeyStops ) :
  61             maKeyStops(rKeyStops),
  62             mnLastIndex(0)
  63         {
  64             validateInput(maKeyStops);
  65         }
  66
  67         KeyStopLerp::KeyStopLerp( const ::com::sun::star::uno::Sequence<double>& rKeyStops ) :
  68             maKeyStops(rKeyStops.getLength()),
  69             mnLastIndex(0)
  70         {
  71             std::copy( rKeyStops.getConstArray(),
  72                        rKeyStops.getConstArray()+rKeyStops.getLength(),
  73                        maKeyStops.begin() );
  74             validateInput(maKeyStops);
  75         }
  76
  77         KeyStopLerp::ResultType KeyStopLerp::lerp(double fAlpha) const
  78         {
  79             // cached value still okay?
  80             if( maKeyStops.at(mnLastIndex) < fAlpha ||
  81                 maKeyStops.at(mnLastIndex+1) >= fAlpha )
  82             {
  83                 // nope, find new index
  84                 mnLastIndex = std::min<std::ptrdiff_t>(
  85                     maKeyStops.size()-2,
  86                     // range is ensured by max below
  87                     std::max<std::ptrdiff_t>(
  88                         0,
  89                         std::distance( maKeyStops.begin(),
  90                                        std::lower_bound( maKeyStops.begin(),
  91                                                          maKeyStops.end(),
  92                                                          fAlpha )) - 1 ));
  93             }
  94
  95             // lerp between stop and stop+1
  96             const double fRawLerp=
  97                 (fAlpha-maKeyStops.at(mnLastIndex)) /
  98                 (maKeyStops.at(mnLastIndex+1) - maKeyStops.at(mnLastIndex));
  99
 100             // clamp to permissible range (input fAlpha might be
 101             // everything)
 102             return ResultType(
 103                 mnLastIndex,
 104                 clamp(fRawLerp,0.0,1.0));
 105         }
 106     }
 107 }