include/basebmp/paletteimageaccessor.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
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   9  * This file incorporates work covered by the following license notice:
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  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #ifndef INCLUDED_BASEBMP_PALETTEIMAGEACCESSOR_HXX
  21 #define INCLUDED_BASEBMP_PALETTEIMAGEACCESSOR_HXX
  22
  23 #include <basebmp/colortraits.hxx>
  24 #include <basebmp/accessortraits.hxx>
  25
  26 #include <vigra/numerictraits.hxx>
  27 #include <vigra/metaprogramming.hxx>
  28
  29 #include <algorithm>
  30 #include <functional>
  31
  32 namespace basebmp
  33 {
  34
  35 /** Access pixel data via palette indirection
  36
  37     @tpl Accessor
  38     Raw accessor, to be used to actually access the pixel values
  39
  40     @tpl ColorType
  41     The color value type to use - e.g. the palette is an array of that
  42     type
  43  */
  44 template< class Accessor, typename ColorType > class PaletteImageAccessor
  45 {
  46 public:
  47     typedef typename Accessor::value_type  data_type;
  48     typedef ColorType                      value_type;
  49
  50 #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
  51 // making all members public, if no member template friends
  52 private:
  53     template<class A, typename C> friend class PaletteImageAccessor;
  54 #endif
  55
  56     Accessor          maAccessor;
  57     const value_type* mpPalette;
  58     std::size_t       mnNumEntries;
  59
  60 public:
  61     PaletteImageAccessor() :
  62         maAccessor(),
  63         mpPalette(0),
  64         mnNumEntries(0)
  65     {}
  66
  67     template< class A > explicit
  68     PaletteImageAccessor( PaletteImageAccessor<A,ColorType> const& rSrc ) :
  69         maAccessor( rSrc.maAccessor ),
  70         mpPalette( rSrc.mpPalette ),
  71         mnNumEntries( rSrc.mnNumEntries )
  72     {}
  73
  74     PaletteImageAccessor( const value_type* pPalette,
  75                           std::size_t       numEntries ) :
  76         maAccessor(),
  77         mpPalette(pPalette),
  78         mnNumEntries(numEntries)
  79     {}
  80
  81     template< class T > PaletteImageAccessor( T                 accessor,
  82                                               const value_type* pPalette,
  83                                               std::size_t       numEntries ) :
  84         maAccessor(accessor),
  85         mpPalette(pPalette),
  86         mnNumEntries(numEntries)
  87     {}
  88
  89     // -------------------------------------------------------
  90
  91     Accessor const& getWrappedAccessor() const { return maAccessor; }
  92     Accessor&       getWrappedAccessor() { return maAccessor; }
  93
  94     // -------------------------------------------------------
  95
  96     data_type lookup(value_type const& v) const
  97     {
  98         // TODO(P3): use table-based/octree approach here!
  99         const value_type* best_entry;
 100         const value_type* palette_end( mpPalette+mnNumEntries );
 101         if( (best_entry=std::find( mpPalette, palette_end, v)) != palette_end )
 102             return best_entry-mpPalette;
 103
 104         const value_type* curr_entry( mpPalette );
 105         best_entry = curr_entry;
 106         while( curr_entry != palette_end )
 107         {
 108             if( ColorTraits<value_type>::distance(*curr_entry,
 109                                                   *best_entry)
 110                 > ColorTraits<value_type>::distance(*curr_entry,
 111                                                     v) )
 112             {
 113                 best_entry = curr_entry;
 114             }
 115
 116             ++curr_entry;
 117         }
 118
 119         return best_entry-mpPalette;
 120     }
 121
 122     // -------------------------------------------------------
 123
 124     template< class Iterator >
 125     value_type operator()(Iterator const& i) const
 126     {
 127         return mpPalette[ maAccessor(i) ];
 128     }
 129
 130     template< class Iterator, class Difference >
 131     value_type operator()(Iterator const& i, Difference const& diff) const
 132     {
 133         return mpPalette[ maAccessor(i,diff) ];
 134     }
 135
 136     // -------------------------------------------------------
 137
 138     template< typename V, class Iterator >
 139     void set(V const& value, Iterator const& i) const
 140     {
 141         maAccessor.set(
 142             lookup(
 143                 vigra::detail::RequiresExplicitCast<value_type>::cast(value) ),
 144             i );
 145     }
 146
 147     template< typename V, class Iterator, class Difference >
 148     void set(V const& value, Iterator const& i, Difference const& diff) const
 149     {
 150         maAccessor.set(
 151             lookup(
 152                 vigra::detail::RequiresExplicitCast<value_type>::cast(value) ),
 153             i,
 154             diff );
 155     }
 156 };
 157
 158 } // namespace basebmp
 159
 160 #endif /* INCLUDED_BASEBMP_PALETTEIMAGEACCESSOR_HXX */
 161
 162 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */