basegfx/source/tools/keystoplerp.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
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   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #include <basegfx/utils/keystoplerp.hxx>
  21 #include <com/sun/star/uno/Sequence.hxx>
  22 #include <osl/diagnose.h>
  23
  24 #include <algorithm>
  25
  26 static void validateInput(const std::vector<double>& rKeyStops)
  27 {
  28 #ifdef DBG_UTIL
  29     OSL_ENSURE( rKeyStops.size() > 1,
  30                 "KeyStopLerp::KeyStopLerp(): key stop vector must have two entries or more" );
  31
  32     // rKeyStops must be sorted in ascending order
  33     for( std::size_t i=1, len=rKeyStops.size(); i<len; ++i )
  34     {
  35         if( rKeyStops[i-1] > rKeyStops[i] )
  36             OSL_FAIL( "KeyStopLerp::KeyStopLerp(): time vector is not sorted in ascending order!" );
  37     }
  38 #else
  39     (void)rKeyStops;
  40 #endif
  41 }
  42
  43 namespace basegfx
  44 {
  45     namespace utils
  46     {
  47         KeyStopLerp::KeyStopLerp( const std::vector<double>& rKeyStops ) :
  48             maKeyStops(rKeyStops),
  49             mnLastIndex(0)
  50         {
  51             validateInput(maKeyStops);
  52         }
  53
  54         KeyStopLerp::KeyStopLerp( const ::css::uno::Sequence<double>& rKeyStops ) :
  55             maKeyStops(rKeyStops.getLength()),
  56             mnLastIndex(0)
  57         {
  58             std::copy( rKeyStops.begin(), rKeyStops.end(), maKeyStops.begin() );
  59             validateInput(maKeyStops);
  60         }
  61
  62         KeyStopLerp::ResultType KeyStopLerp::lerp(double fAlpha) const
  63         {
  64             // cached value still okay?
  65             if( maKeyStops.at(mnLastIndex) < fAlpha ||
  66                 maKeyStops.at(mnLastIndex+1) >= fAlpha )
  67             {
  68                 // nope, find new index
  69                 mnLastIndex = std::min<std::ptrdiff_t>(
  70                     maKeyStops.size()-2,
  71                     // range is ensured by max below
  72                     std::max<std::ptrdiff_t>(
  73                         0,
  74                         std::distance( maKeyStops.begin(),
  75                                        std::lower_bound( maKeyStops.begin(),
  76                                                          maKeyStops.end(),
  77                                                          fAlpha )) - 1 ));
  78             }
  79
  80             // lerp between stop and stop+1
  81             const double fRawLerp=
  82                 (fAlpha-maKeyStops.at(mnLastIndex)) /
  83                 (maKeyStops.at(mnLastIndex+1) - maKeyStops.at(mnLastIndex));
  84
  85             // clamp to permissible range (input fAlpha might be
  86             // everything)
  87             return ResultType(
  88                 mnLastIndex,
  89                 clamp(fRawLerp,0.0,1.0));
  90         }
  91     }
  92 }
  93
  94 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */