//! Calculate contour points from crack codes
t_PointList CBlobContour::GetContourPoints()
{
// it is calculated?
if( m_contourPoints != NULL )
return m_contourPoints;
if ( m_contour == NULL || m_contour->total <= 0 )
{
return NULL;
}
CvSeq *tmpPoints;
CvSeqReader reader;
CvSeqWriter writer;
CvPoint actualPoint;
CvRect boundingBox;
// if aproximation is different than simple extern perimeter will not work
tmpPoints = cvApproxChains( m_contour, m_parentStorage, CV_CHAIN_APPROX_NONE);
// apply an offset to contour points to recover real coordinates
cvStartReadSeq( tmpPoints, &reader);
m_contourPoints = cvCreateSeq( tmpPoints->flags, tmpPoints->header_size, tmpPoints->elem_size, m_parentStorage );
cvStartAppendToSeq(m_contourPoints, &writer );
// also calculate bounding box of the contour to allow cvPointPolygonTest
// work correctly on the generated polygon
boundingBox.x = boundingBox.y = 10000;
boundingBox.width = boundingBox.height = 0;
for( int i=0; i< tmpPoints->total; i++)
{
CV_READ_SEQ_ELEM( actualPoint, reader);
actualPoint.x += m_startPoint.x;
actualPoint.y += m_startPoint.y;
boundingBox.x = MIN( boundingBox.x, actualPoint.x );
boundingBox.y = MIN( boundingBox.y, actualPoint.y );
boundingBox.width = MAX( boundingBox.width, actualPoint.x );
boundingBox.height = MAX( boundingBox.height, actualPoint.y );
CV_WRITE_SEQ_ELEM( actualPoint, writer );
}
cvEndWriteSeq( &writer );
cvClearSeq( tmpPoints );
// assign calculated bounding box
((CvContour*)m_contourPoints)->rect = boundingBox;
return m_contourPoints;
}
/*
* call-seq:
* approx_chains(<i>[approx_chain_option]</i>) -> cvcontour
*
* Approximates Freeman chain(s) with polygonal curve.
* <i>approx_chain_option</i> should be Hash include these keys.
* :method - Approximation method.
* :approx_none - translate all the points from the chain code into points;
* :approx_simple(default) - compress horizontal, vertical, and diagonal segments, that is,
* the function leaves only their ending points.
* :approx_tc89_l1
* :approx_tc89_kcos - apply one of the flavors of Teh-Chin chain approximation algorithm.
* If set the difference between the current pixel and seed pixel is considered,
* otherwise difference between neighbor pixels is considered (the range is floating).
* :parameter - Method parameter (not used now).
* :minimal_perimeter (default 0)
* Approximates only those contours whose perimeters are not less than minimal_perimeter. Other chains are removed from the resulting structure.
* :recursive (default false)
* If not nil or false, the function approximates all chains that access can be obtained to
* from self by h_next or v_next links. If 0, the single chain is approximated.
*
*/
VALUE
rb_approx_chains(int argc, VALUE *argv, VALUE self)
{
VALUE approx_chain_option;
rb_scan_args(argc, argv, "01", &approx_chain_option);
approx_chain_option = APPROX_CHAIN_OPTION(approx_chain_option);
VALUE storage = cCvMemStorage::new_object();
CvSeq *seq = cvApproxChains(CVSEQ(self), CVMEMSTORAGE(storage),
APPROX_CHAIN_METHOD(approx_chain_option),
APPROX_CHAIN_PARAMETER(approx_chain_option),
APPROX_CHAIN_MINIMAL_PERIMETER(approx_chain_option),
APPROX_CHAIN_RECURSIVE(approx_chain_option));
if (seq && seq->total > 0) {
return cCvSeq::new_sequence(cCvChain::rb_class(), seq, cCvPoint::rb_class(), storage);
}
return Qnil;
}
