/************************************************************************/ /* */ /* Copyright 1998-2002 by Ullrich Koethe */ /* Cognitive Systems Group, University of Hamburg, Germany */ /* */ /* This file is part of the VIGRA computer vision library. */ /* The VIGRA Website is */ /* http://kogs-www.informatik.uni-hamburg.de/~koethe/vigra/ */ /* Please direct questions, bug reports, and contributions to */ /* koethe@informatik.uni-hamburg.de or */ /* vigra@kogs1.informatik.uni-hamburg.de */ /* */ /* Permission is hereby granted, free of charge, to any person */ /* obtaining a copy of this software and associated documentation */ /* files (the "Software"), to deal in the Software without */ /* restriction, including without limitation the rights to use, */ /* copy, modify, merge, publish, distribute, sublicense, and/or */ /* sell copies of the Software, and to permit persons to whom the */ /* Software is furnished to do so, subject to the following */ /* conditions: */ /* */ /* The above copyright notice and this permission notice shall be */ /* included in all copies or substantial portions of the */ /* Software. */ /* */ /* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND */ /* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES */ /* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND */ /* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT */ /* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, */ /* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING */ /* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR */ /* OTHER DEALINGS IN THE SOFTWARE. */ /* */ /************************************************************************/ #ifndef VIGRA_CONTOURCIRCULATOR_HXX #define VIGRA_CONTOURCIRCULATOR_HXX #include namespace vigra { /** \addtogroup ImageIteratorAdapters */ //@{ /********************************************************/ /* */ /* CrackContourCirculator */ /* */ /********************************************************/ /** \brief Circulator that walks around a given region. The circulator follows the crack contour of a given region. Here, a region is an 8-connected component of pixels with the same value, such as the regions in a label image. The crack contour is located between the inside and outside pixels, that is "on the crack" between the region and the background. Thus, the circulator moves from pixel corner to pixel corner. By definition, the first corner (where the circulator was initialized) gets the coordinate (0,0), and calls to *circulator return the distance of the current corner to the initial one. The circulator can be used to calculate the area of a region (in pixels): \code // start with a pixel within the region, whose left neighbor is outside // (see CrackContourCirculator constructor) ImageIterator region_anchor = ...; int area = 0; // calculate area from following the crack contour of the region CrackContourCirculator crack(region_anchor); CrackContourCirculator crackend(crack); do { area += crack.diff().x * crack.pos().y - crack.diff().y * crack.pos().x; } while(++crack != crackend); area /= 2; std::cout << "Area of region " << *region_anchor << ": " << area << std::endl; \endcode \#include "vigra/contourcirculator.hxx"
Namespace: vigra */ template class CrackContourCirculator { typedef NeighborhoodCirculator NEIGHBORHOODCIRCULATOR; typedef typename IMAGEITERATOR::value_type label_type; protected: NEIGHBORHOODCIRCULATOR neighborCirc_; label_type label_; Point2D pos_; CrackContourCirculator(NEIGHBORHOODCIRCULATOR const & circ) : neighborCirc_(circ), label_(*(circ.center())), pos_(0, 0) {} public: /** the circulator's value type */ typedef Point2D value_type; /** the circulator's reference type (return type of *circ) */ typedef Point2D const & reference; /** the circulator's pointer type (return type of operator->) */ typedef Point2D const * pointer; /** the circulator tag */ typedef forward_circulator_tag iterator_category; /** Initialize the circulator for a given region. The image iterator in_the_region must refer to a boundary pixel of the region to be analysed. The direction code dir must point to a pixel outside the region (the default assumes that the pixel left of the given region pixel belongs to the background). The first corner of the crack contour is the corner to the right of this direction (i.e. the north west corner of the region pixel, if the direction was West). */ CrackContourCirculator(IMAGEITERATOR const & in_the_region, vigra::FourNeighborCode::Direction dir = vigra::FourNeighborCode::West) : neighborCirc_(in_the_region, EightNeighborCode::code(dir)), label_(*in_the_region), pos_(0, 0) { neighborCirc_.turnLeft(); } /** Move to the next crack corner of the contour (pre-increment). */ CrackContourCirculator & operator++() { pos_ += neighborCirc_.diff(); neighborCirc_--; if(*neighborCirc_ == label_) { neighborCirc_.moveCenterToNeighbor(); // TODO: simplify moveCenterToNeighbor()s --neighborCirc_; } else { neighborCirc_.moveCenterToNeighbor(); // jump out neighborCirc_ += 3; if(*neighborCirc_ == label_) { neighborCirc_.moveCenterToNeighbor(); neighborCirc_.turnRight(); } else { neighborCirc_.moveCenterToNeighbor(); neighborCirc_.turnLeft(); neighborCirc_.moveCenterToNeighbor(); neighborCirc_.turnRight(); } } return *this; } /** Move to the next crack corner of the contour (post-increment). */ CrackContourCirculator operator++(int) { CrackContourCirculator ret(*this); ++(*this); return ret; } /** equality */ bool operator==(CrackContourCirculator const & o) const { return neighborCirc_ == o.neighborCirc_; } /** inequality */ bool operator!=(CrackContourCirculator const & o) const { return neighborCirc_ != o.neighborCirc_; } /** Get the coordinate of the current corner (relative to the first corner). */ reference pos() const { return pos_; } /** Equivalent to pos() */ reference operator*() const { return pos_; } /** Access member of the current coordinate. */ pointer operator->() const { return &pos_; } /** Access pixel to the right of the crack edge (outside of * the region bounded by the crack contour we walk on). Note * that after operator++, the iterator can still point to the * same pixel (looking from another direction now). */ IMAGEITERATOR outerPixel() const { return NEIGHBORHOODCIRCULATOR(neighborCirc_).turnRight().base(); } /** Get the offset from the current corner of the contour to the next one. */ Diff2D const & diff() const { return neighborCirc_.diff(); } }; //@} } // namespace vigra #endif /* VIGRA_CONTOURCIRCULATOR_HXX */