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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* This file incorporates work covered by the following license notice:
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed
* with this work for additional information regarding copyright
* ownership. The ASF licenses this file to you under the Apache
* License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.apache.org/licenses/LICENSE-2.0 .
*/
#ifndef INCLUDED_BASEBMP_COLORTRAITS_HXX
#define INCLUDED_BASEBMP_COLORTRAITS_HXX
#include <basebmp/accessoradapters.hxx>
#include <basebmp/metafunctions.hxx>
#include <vigra/mathutil.hxx>
namespace basebmp
{
/** Functor template, to calculate alpha blending between two
values. Float case.
@tpl polarity
When true, 0 means fully transparent, and 1 fully opaque. And vice
versa.
*/
template< typename ValueType,
typename AlphaType,
bool polarity > struct BlendFunctor;
template< typename ValueType,
typename AlphaType > struct BlendFunctor<ValueType,AlphaType,true>
: public TernaryFunctorBase<AlphaType,ValueType,ValueType,ValueType>
{
ValueType operator()( AlphaType alpha,
ValueType v1,
ValueType v2 ) const
{
const typename vigra::NumericTraits<AlphaType>::RealPromote fAlpha(
vigra::NumericTraits<AlphaType>::toRealPromote(alpha));
return (vigra::NumericTraits<AlphaType>::one()-fAlpha)*v1 + fAlpha*v2;
}
};
template< typename ValueType,
typename AlphaType > struct BlendFunctor<ValueType,AlphaType,false>
: public TernaryFunctorBase<AlphaType,ValueType,ValueType,ValueType>
{
ValueType operator()( AlphaType alpha,
ValueType v1,
ValueType v2 ) const
{
const typename vigra::NumericTraits<AlphaType>::RealPromote fAlpha(
vigra::NumericTraits<AlphaType>::toRealPromote(alpha));
return fAlpha*v1 + (vigra::NumericTraits<AlphaType>::one()-fAlpha)*v2;
}
};
/** Functor template, to calculate alpha blending between two
values. Integer case.
@tpl polarity
When true, 0 means fully transparent, and 1 fully opaque. And vice
versa.
*/
template< typename ValueType,
typename AlphaType,
bool polarity > struct IntegerBlendFunctor;
template< typename ValueType,
typename AlphaType > struct IntegerBlendFunctor<ValueType,AlphaType,true>
: public TernaryFunctorBase<AlphaType,ValueType,ValueType,ValueType>
{
ValueType operator()( AlphaType alpha,
ValueType v1,
ValueType v2 ) const
{
return (vigra::NumericTraits<AlphaType>::toPromote(
vigra::NumericTraits<AlphaType>::max()-alpha)*v1 + alpha*v2) /
vigra::NumericTraits<AlphaType>::max();
}
};
template< typename ValueType,
typename AlphaType > struct IntegerBlendFunctor<ValueType,AlphaType,false>
: public TernaryFunctorBase<AlphaType,ValueType,ValueType,ValueType>
{
ValueType operator()( AlphaType alpha,
ValueType v1,
ValueType v2 ) const
{
return (alpha*v1 +
vigra::NumericTraits<AlphaType>::toPromote(
vigra::NumericTraits<AlphaType>::max()-alpha)*v2) /
vigra::NumericTraits<AlphaType>::max();
}
};
template< typename ColorType > struct ColorTraits
{
/// Metafunction to select blend functor from color and alpha type
template< typename AlphaType, bool polarity > struct blend_functor : public
ifScalarIntegral< AlphaType,
IntegerBlendFunctor< ColorType, AlphaType, polarity >,
BlendFunctor< ColorType, AlphaType, polarity > > {};
/// @return number of color channels
static int numChannels() { return 1; }
/// Type of a color component (i.e. the type of an individual channel)
typedef ColorType component_type;
/// Calculate normalized distance between color c1 and c2
static inline vigra::NormTraits<ColorType> distance( ColorType c1,
ColorType c2 )
{
return vigra::norm(c1 - c2);
}
static inline component_type toGreyscale( ColorType c )
{
return c;
}
static inline ColorType fromGreyscale( component_type c )
{
return c;
}
};
} // namespace basebmp
#endif /* INCLUDED_BASEBMP_COLORTRAITS_HXX */
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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