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vigra/navigator.hxx VIGRA

00001 /************************************************************************/
00002 /*                                                                      */
00003 /*                Copyright 2004 by Ullrich Koethe                      */
00004 /*                                                                      */
00005 /*    This file is part of the VIGRA computer vision library.           */
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00009 /*        ullrich.koethe@iwr.uni-heidelberg.de    or                    */
00010 /*        vigra@informatik.uni-hamburg.de                               */
00011 /*                                                                      */
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00019 /*    conditions:                                                       */
00020 /*                                                                      */
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00023 /*    Software.                                                         */
00024 /*                                                                      */
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00033 /*                                                                      */
00034 /************************************************************************/
00035 
00036 #ifndef VIGRA_NAVIGATOR_HXX
00037 #define VIGRA_NAVIGATOR_HXX
00038 
00039 namespace vigra {
00040 
00041 /********************************************************/
00042 /*                                                      */
00043 /*                MultiArrayNavigator                   */
00044 /*                                                      */
00045 /********************************************************/
00046 
00047 /** \brief A navigator that provides access to the 1D subranges of an
00048     n-dimensional range given by a \ref vigra::MultiIterator and an nD shape.
00049 
00050     Normally, the innermost loop of an iteration extends over the innermost
00051     dimension of a given array. Sometimes, however, it is necessary to have
00052     some other dimension in the inner loop. For example, instead of iterating over
00053     the rows, the inner loop should extend over the columns. The class MultiArrayNavigator
00054     encapsulates the necessary functionality. Given an arbitrary dimensional
00055     array (represented by a vigra::MultiIterator/shape pair), and the desired
00056     inner loop dimension <TT>d</TT>, it moves the encapsulated iterator to all possible
00057     starting points of 1D subsets along the given dimension (e.g. all columns). By calling
00058     <TT>begin()</TT> and <TT>end()</TT>, one can then obtain an STL-compatible 1-dimensional
00059     iterator for the current subset.
00060 
00061     The template parameters specify the embedded iterator type and its dimension.
00062 
00063     <b>Usage:</b>
00064 
00065     <b>\#include</b> <vigra/navigator.hxx>
00066 
00067     Namespace: vigra
00068 
00069     \code
00070     typedef vigra::MultiArray<3, int>  Array;
00071 
00072     Array a(Array::size_type(X, Y, Z));
00073 
00074     typedef vigra::MultiArrayNavigator<Array::traverser, 3> Navigator;
00075 
00076     for(int d=0; d<3; ++d)
00077     {
00078         // create Navigator for dimension d
00079         Navigator nav(a.traverser_begin(), a.shape(), d);
00080 
00081         // outer loop: move navigator to all starting points
00082         // of 1D subsets that run parallel to coordinate axis d
00083         for(; nav.hasMore(); ++nav)
00084         {
00085             // inner loop: linear iteration over current subset
00086             //             d == {0, 1, 2}: iterate along {x, y, z}-axis respectively
00087             Navigator::iterator i = nav.begin(), end = nav.end();
00088             for(; i != end; ++i)
00089                 // do something
00090         }
00091     }
00092     \endcode
00093 */
00094 template <class MULTI_ITERATOR, unsigned int N>
00095 class MultiArrayNavigator
00096 #ifndef DOXYGEN  // doxygen doesn't understand this inheritance
00097 : public MultiArrayNavigator<MULTI_ITERATOR, N-1>
00098 #endif
00099 {
00100     typedef MultiArrayNavigator<MULTI_ITERATOR, N-1> base_type;
00101 
00102   public:
00103     enum { level = N-1 };
00104 
00105         /** The required shape type for the given iterator type.
00106          */
00107     typedef typename MULTI_ITERATOR::multi_difference_type shape_type;
00108 
00109         /** The iterator type for the inner loop (result of begin() and end()).
00110          */
00111     typedef typename MULTI_ITERATOR::iterator iterator;
00112 
00113         /** Construct navigator for multi-dimensional iterator <TT>i</TT>, array shape <TT>shape</TT>
00114             and inner loop dimension <TT>inner_dimension</TT>.
00115          */
00116     MultiArrayNavigator(MULTI_ITERATOR const & i, shape_type const & shape, unsigned int inner_dimension)
00117     : base_type(i, shape, inner_dimension)
00118     {}
00119 
00120     MultiArrayNavigator(MULTI_ITERATOR const & i, shape_type const & start, shape_type const & stop, 
00121                         unsigned int inner_dimension)
00122     : base_type(i, start, stop, inner_dimension)
00123     {}
00124 
00125         /** Advance to next starting location.
00126          */
00127     void operator++()
00128     {
00129         base_type::operator++();
00130         if(this->point_[level-1] == this->stop_[level-1])
00131         {
00132             base_type::reset();
00133             ++this->point_[level];
00134             ++this->i_.template dim<level>();
00135         }
00136     }
00137 
00138         /** Advance to next starting location.
00139          */
00140     void operator++(int)
00141     {
00142         ++*this;
00143     }
00144 
00145         /** true if there are more elements.
00146          */
00147     bool hasMore() const
00148     {
00149         return this->point_[level] < this->stop_[level];
00150     }
00151 
00152         /** true if iterator is exhausted.
00153          */
00154     bool atEnd() const
00155     {
00156         return this->point_[level] >= this->stop_[level];
00157     }
00158 
00159   protected:
00160     void reset()
00161     {
00162         this->point_[level] = this->start_[level];
00163         this->i_.template dim<level>() -= (this->stop_[level] - this->start_[level]);
00164     }
00165 };
00166 
00167 template <class MULTI_ITERATOR>
00168 class MultiArrayNavigator<MULTI_ITERATOR, 1>
00169 {
00170   public:
00171     enum { level = 0 };
00172     typedef typename MULTI_ITERATOR::multi_difference_type shape_type;
00173     typedef typename MULTI_ITERATOR::iterator iterator;
00174 
00175     MultiArrayNavigator(MULTI_ITERATOR const & i, shape_type const & shape, unsigned int inner_dimension)
00176     : start_(), stop_(shape), point_(start_),
00177       inner_dimension_(inner_dimension),
00178       inner_shape_(stop_[inner_dimension] - start_[inner_dimension]),
00179       i_(i + start_)
00180     {
00181         stop_[inner_dimension] = start_[inner_dimension] + 1;
00182     }
00183 
00184     MultiArrayNavigator(MULTI_ITERATOR const & i, shape_type const & start, shape_type const & stop, 
00185                         unsigned int inner_dimension)
00186     : start_(start), stop_(stop), point_(start_),
00187       inner_dimension_(inner_dimension),
00188       inner_shape_(stop_[inner_dimension] - start_[inner_dimension]),
00189       i_(i + start_)
00190     {
00191         stop_[inner_dimension] = start_[inner_dimension] + 1;
00192     }
00193 
00194     void operator++()
00195     {
00196         ++point_[level];
00197         ++i_.template dim<level>();
00198     }
00199 
00200     void operator++(int)
00201     {
00202         ++*this;
00203     }
00204 
00205     iterator begin() const
00206     {
00207         return i_.iteratorForDimension(inner_dimension_);
00208     }
00209 
00210     iterator end() const
00211     {
00212         return begin() + inner_shape_;
00213     }
00214 
00215     bool hasMore() const
00216     {
00217         return point_[level] < stop_[level];
00218     }
00219 
00220     bool atEnd() const
00221     {
00222         return point_[level] >= stop_[level];
00223     }
00224     
00225     shape_type const & point() const
00226     {
00227         return point_;
00228     }
00229 
00230   protected:
00231     void reset()
00232     {
00233         point_[level] = start_[level];
00234         i_.template dim<level>() -= (stop_[level] - start_[level]);
00235    }
00236 
00237     shape_type start_, stop_, point_;
00238     unsigned int inner_dimension_, inner_shape_;
00239     MULTI_ITERATOR i_;
00240 };
00241 
00242 /********************************************************/
00243 /*                                                      */
00244 /*               MultiCoordinateNavigator               */
00245 /*                                                      */
00246 /********************************************************/
00247 
00248 /** \brief A navigator that provides access to the 1D subranges of an
00249     n-dimensional range given by an nD shape.
00250 
00251     This class works similarly to \ref MultiArrayNavigator, but instead of a 
00252     1-dimensional iterator pair, it returns a pair of shapes whose difference
00253     specifies a 1-dimensional range along the desired dimension. That is, when
00254     the navigator refers to dimension <tt>d</tt>, the difference between
00255     <tt>end()</tt> and <tt>begin()</tt> is <tt>1</tt> along all dimensions
00256     except <tt>d</tt>.
00257 
00258     The template parameters specifies the dimension of the shape.
00259 
00260     <b>Usage:</b>
00261 
00262     <b>\#include</b> <vigra/navigator.hxx>
00263 
00264     Namespace: vigra
00265 
00266     \code
00267     typedef vigra::MultiArrayShape<3>::type Shape;
00268     typedef vigra::MultiArray<3, int>  Array;
00269     typedef vigra::MultiCoordinateNavigator<3> Navigator;
00270 
00271     Array a(Shape(X, Y, Z));
00272 
00273     for(int d=0; d<3; ++d)
00274     {
00275         // create Navigator for dimension d
00276         Navigator nav(a.shape(), d);
00277 
00278         // outer loop: move navigator to all starting points
00279         // of 1D subsets that run parallel to coordinate axis d
00280         for(; nav.hasMore(); ++nav)
00281         {
00282             // inner loop: linear iteration over current subset
00283             //             d == {0, 1, 2}: iterate along {x, y, z}-axis respectively
00284             Shape point = nav.begin(), end = nav.end();
00285             for(; point[d] != end[d]; ++point[d])
00286                 a[point] = 5;
00287         }
00288     }
00289     \endcode
00290 */
00291 template <unsigned int Dimensions, unsigned int N = Dimensions>
00292 class MultiCoordinateNavigator
00293 #ifndef DOXYGEN  // doxygen doesn't understand this inheritance
00294 : public MultiCoordinateNavigator<Dimensions, N-1>
00295 #endif
00296 {
00297     typedef MultiCoordinateNavigator<Dimensions, N-1> base_type;
00298 
00299   public:
00300     enum { level = N-1 };
00301 
00302         /** The shape type for the given iterator type.
00303          */
00304     typedef typename MultiArrayShape<Dimensions>::type value_type;
00305 
00306 
00307         /** Construct navigator for multi-dimensional iterator <TT>i</TT>, array shape <TT>shape</TT>
00308             and inner loop dimension <TT>inner_dimension</TT>.
00309          */
00310     MultiCoordinateNavigator(value_type const & shape, unsigned int inner_dimension)
00311     : base_type(shape, inner_dimension)
00312     {
00313         this->end_[level] = (this->inner_dimension_ == level)
00314                                  ? 1
00315                                  : this->shape_[level];
00316     }
00317 
00318         /** Advance to next starting location.
00319          */
00320     void operator++()
00321     {
00322         base_type::operator++();
00323         if(base_type::atEnd() && this->i_[level] < this->end_[level])
00324         {
00325             ++this->i_[level];
00326             if(this->i_[level] < this->end_[level])
00327                 base_type::reset();
00328         }
00329     }
00330 
00331         /** Advance to next starting location.
00332          */
00333     void operator++(int)
00334     {
00335         ++*this;
00336     }
00337 
00338         /** true if there are more elements.
00339          */
00340     bool hasMore() const
00341     {
00342         return this->inner_dimension_ == level 
00343                      ? base_type::hasMore() 
00344                      : this->i_[level] < this->end_[level];
00345     }
00346 
00347         /** true if iterator is exhausted.
00348          */
00349     bool atEnd() const
00350     {
00351         return !hasMore();
00352         // return this->inner_dimension_ == level 
00353                      // ? base_type::atEnd()
00354                      // : !(this->i_[level] < this->end_[level]);
00355     }
00356 
00357   protected:
00358     void reset()
00359     {
00360         this->i_[level] = 0;
00361         this->end_[level] = (this->inner_dimension_ == level)
00362                                  ? 1
00363                                  : this->shape_[level];
00364         base_type::reset();
00365     }
00366 };
00367 
00368 template <unsigned int Dimensions>
00369 class MultiCoordinateNavigator<Dimensions, 1>
00370 {
00371   public:
00372     enum { level = 0 };
00373     typedef typename MultiArrayShape<Dimensions>::type value_type;
00374  
00375     MultiCoordinateNavigator(value_type const & shape, unsigned int inner_dimension)
00376     : shape_(shape),
00377       inner_dimension_(inner_dimension)
00378     {
00379         end_[level] = (inner_dimension_ == level)
00380                          ? 1
00381                          : shape_[level];
00382     }
00383 
00384     void operator++()
00385     {
00386         ++i_[level];
00387     }
00388 
00389     void operator++(int)
00390     {
00391         ++*this;
00392     }
00393 
00394     value_type const & begin() const
00395     {
00396         return i_;
00397     }
00398 
00399     value_type end() const
00400     {
00401         value_type res = i_ + value_type(MultiArrayIndex(1));
00402         res[inner_dimension_] = shape_[inner_dimension_];
00403         return res;
00404     }
00405 
00406     bool hasMore() const
00407     {
00408         return i_[level] < end_[level];
00409     }
00410 
00411     bool atEnd() const
00412     {
00413       return !hasMore();
00414     }
00415 
00416   protected:
00417     void reset()
00418     {
00419         i_[level] = 0;
00420         end_[level] = (inner_dimension_ == level)
00421                          ? 1
00422                          : shape_[level];
00423     }
00424 
00425     value_type shape_, i_, end_;
00426     unsigned int inner_dimension_;
00427 };
00428 
00429 } // namespace vigra
00430 
00431 #endif /* VIGRA_NAVIGATOR_HXX */

© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de)
Heidelberg Collaboratory for Image Processing, University of Heidelberg, Germany

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vigra 1.9.0 (Tue Nov 6 2012)