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Diffstat (limited to 'basebmp/inc/colortraits.hxx')
-rw-r--r-- | basebmp/inc/colortraits.hxx | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/basebmp/inc/colortraits.hxx b/basebmp/inc/colortraits.hxx new file mode 100644 index 000000000000..5a54645dc05a --- /dev/null +++ b/basebmp/inc/colortraits.hxx @@ -0,0 +1,137 @@ +/* -*- 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_INC_COLORTRAITS_HXX +#define INCLUDED_BASEBMP_INC_COLORTRAITS_HXX + +#include <accessoradapters.hxx> +#include <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; + + static inline component_type toGreyscale( ColorType c ) + { + return c; + } + + static inline ColorType fromGreyscale( component_type c ) + { + return c; + } +}; + +} // namespace basebmp + +#endif /* INCLUDED_BASEBMP_INC_COLORTRAITS_HXX */ + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |