basebmp/inc/basebmp/paletteimageaccessor.hxx

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  30
  31 #ifndef INCLUDED_BASEBMP_PALETTEIMAGEACCESSOR_HXX
  32 #define INCLUDED_BASEBMP_PALETTEIMAGEACCESSOR_HXX
  33
  34 #include <basebmp/colortraits.hxx>
  35 #include <basebmp/accessortraits.hxx>
  36
  37 #include <vigra/numerictraits.hxx>
  38 #include <vigra/metaprogramming.hxx>
  39
  40 #include <algorithm>
  41 #include <functional>
  42
  43 namespace basebmp
  44 {
  45
  46 /** Access pixel data via palette indirection
  47
  48     @tpl Accessor
  49     Raw accessor, to be used to actually access the pixel values
  50
  51     @tpl ColorType
  52     The color value type to use - e.g. the palette is an array of that
  53     type
  54  */
  55 template< class Accessor, typename ColorType > class PaletteImageAccessor
  56 {
  57 public:
  58     typedef typename Accessor::value_type  data_type;
  59     typedef ColorType                      value_type;
  60
  61 #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
  62 // making all members public, if no member template friends
  63 private:
  64     template<class A, typename C> friend class PaletteImageAccessor;
  65 #endif
  66
  67     Accessor          maAccessor;
  68     const value_type* mpPalette;
  69     std::size_t       mnNumEntries;
  70
  71 public:
  72     PaletteImageAccessor() :
  73         maAccessor(),
  74         mpPalette(0),
  75         mnNumEntries(0)
  76     {}
  77
  78     template< class A > explicit
  79     PaletteImageAccessor( PaletteImageAccessor<A,ColorType> const& rSrc ) :
  80         maAccessor( rSrc.maAccessor ),
  81         mpPalette( rSrc.mpPalette ),
  82         mnNumEntries( rSrc.mnNumEntries )
  83     {}
  84
  85     PaletteImageAccessor( const value_type* pPalette,
  86                           std::size_t       numEntries ) :
  87         maAccessor(),
  88         mpPalette(pPalette),
  89         mnNumEntries(numEntries)
  90     {}
  91
  92     template< class T > PaletteImageAccessor( T                 accessor,
  93                                               const value_type* pPalette,
  94                                               std::size_t       numEntries ) :
  95         maAccessor(accessor),
  96         mpPalette(pPalette),
  97         mnNumEntries(numEntries)
  98     {}
  99
 100     // -------------------------------------------------------
 101
 102     Accessor const& getWrappedAccessor() const { return maAccessor; }
 103     Accessor&       getWrappedAccessor() { return maAccessor; }
 104
 105     // -------------------------------------------------------
 106
 107     data_type lookup(value_type const& v) const
 108     {
 109         // TODO(P3): use table-based/octree approach here!
 110         const value_type* best_entry;
 111         const value_type* palette_end( mpPalette+mnNumEntries );
 112         if( (best_entry=std::find( mpPalette, palette_end, v)) != palette_end )
 113             return best_entry-mpPalette;
 114
 115         const value_type* curr_entry( mpPalette );
 116         best_entry = curr_entry;
 117         while( curr_entry != palette_end )
 118         {
 119             if( ColorTraits<value_type>::distance(*curr_entry,
 120                                                   *best_entry)
 121                 > ColorTraits<value_type>::distance(*curr_entry,
 122                                                     v) )
 123             {
 124                 best_entry = curr_entry;
 125             }
 126
 127             ++curr_entry;
 128         }
 129
 130         return best_entry-mpPalette;
 131     }
 132
 133     // -------------------------------------------------------
 134
 135     template< class Iterator >
 136     value_type operator()(Iterator const& i) const
 137     {
 138         return mpPalette[ maAccessor(i) ];
 139     }
 140
 141     template< class Iterator, class Difference >
 142     value_type operator()(Iterator const& i, Difference const& diff) const
 143     {
 144         return mpPalette[ maAccessor(i,diff) ];
 145     }
 146
 147     // -------------------------------------------------------
 148
 149     template< typename V, class Iterator >
 150     void set(V const& value, Iterator const& i) const
 151     {
 152         maAccessor.set(
 153             lookup(
 154                 vigra::detail::RequiresExplicitCast<value_type>::cast(value) ),
 155             i );
 156     }
 157
 158     template< typename V, class Iterator, class Difference >
 159     void set(V const& value, Iterator const& i, Difference const& diff) const
 160     {
 161         maAccessor.set(
 162             lookup(
 163                 vigra::detail::RequiresExplicitCast<value_type>::cast(value) ),
 164             i,
 165             diff );
 166     }
 167 };
 168
 169 } // namespace basebmp
 170
 171 #endif /* INCLUDED_BASEBMP_PALETTEIMAGEACCESSOR_HXX */