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+/*************************************************************************
+ *
+ *  OpenOffice.org - a multi-platform office productivity suite
+ *
+ *  $RCSfile: paletteimageaccessor.hxx,v $
+ *
+ *  $Revision: 1.1 $
+ *
+ *  last change: $Author: thb $ $Date: 2006-05-31 09:49:42 $
+ *
+ *  The Contents of this file are made available subject to
+ *  the terms of GNU Lesser General Public License Version 2.1.
+ *
+ *
+ *    GNU Lesser General Public License Version 2.1
+ *    =============================================
+ *    Copyright 2005 by Sun Microsystems, Inc.
+ *    901 San Antonio Road, Palo Alto, CA 94303, USA
+ *
+ *    This library is free software; you can redistribute it and/or
+ *    modify it under the terms of the GNU Lesser General Public
+ *    License version 2.1, as published by the Free Software Foundation.
+ *
+ *    This library is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *    Lesser General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Lesser General Public
+ *    License along with this library; if not, write to the Free Software
+ *    Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ *    MA  02111-1307  USA
+ *
+ ************************************************************************/
+
+#ifndef INCLUDED_BASEBMP_PALETTEIMAGEACCESSOR_HXX
+#define INCLUDED_BASEBMP_PALETTEIMAGEACCESSOR_HXX
+
+#include "metafunctions.hxx"
+
+#include <vigra/numerictraits.hxx>
+#include <vigra/mathutil.hxx>
+
+#include <algorithm>
+
+
+namespace basebmp
+{
+
+/** Access (possibly packed-pixel) data via palette indirection
+ */
+template< typename Valuetype, typename Datatype > class PaletteImageAccessor
+{
+public:
+    typedef Valuetype                                   value_type;
+    typedef Datatype                                    data_type;
+    typedef typename remove_const<data_type>::type      count_type;
+
+
+private:
+    const value_type* palette;
+    count_type        num_entries;
+
+    double norm( value_type const& rLHS,
+                 value_type const& rRHS ) const
+    {
+        return (rRHS - rLHS).magnitude();
+    }
+
+    data_type find_best_match(value_type const& v) const
+    {
+        // TODO(P3): use table-based/octree approach here!
+        const value_type* best_entry;
+        const value_type* palette_end( palette+num_entries );
+        if( (best_entry=std::find( palette, palette_end, v)) != palette_end )
+            return best_entry-palette;
+
+        // TODO(F3): HACK. Need palette traits, and an error function
+        // here. We blatantly assume value_type is a normed linear
+        // space.
+        const value_type* curr_entry( palette );
+        best_entry = curr_entry;
+        while( curr_entry != palette_end )
+        {
+            if( norm(*curr_entry,*best_entry) > norm(*curr_entry,v) )
+                best_entry = curr_entry;
+
+            ++curr_entry;
+        }
+
+        return best_entry-palette;
+    }
+
+    value_type toCol( value_type const& rCol ) const
+    {
+        return rCol;
+    }
+
+public:
+    PaletteImageAccessor() :
+        palette(0),
+        num_entries(0)
+    {}
+
+    PaletteImageAccessor( const value_type* pPalette,
+                          data_type         entries ) :
+        palette(pPalette),
+        num_entries(entries)
+    {}
+
+    template< class Iterator >
+    value_type operator()(Iterator const& i) const { return toCol(palette[i.get()]); }
+    value_type operator()(data_type const* i) const { return toCol(palette[*i]); }
+
+    template< class Iterator, class Difference >
+    value_type operator()(Iterator const& i, Difference const& diff) const
+    {
+        return toCol(palette[i.get(diff)]);
+    }
+
+    template< typename V, class Iterator >
+    void set(V const& value, Iterator const& i) const
+    {
+        i.set(
+            find_best_match(
+                vigra::detail::RequiresExplicitCast<value_type>::cast(value) ));
+    }
+
+    template< typename V, class Iterator, class Difference >
+    void set(V const& value, Iterator const& i, Difference const& diff) const
+    {
+        i.set(
+            find_best_match(
+                vigra::detail::RequiresExplicitCast<value_type>::cast(value)),
+            diff );
+    }
+};
+
+} // namespace basebmp
+
+#endif /* INCLUDED_BASEBMP_PALETTEIMAGEACCESSOR_HXX */