/*
trace contour until certain point is met.
returns 1 if met, 0 else.
*/
static int
icvTraceContour( char *ptr, int step, char *stop_ptr, int is_hole )
{
int deltas[16];
char *i0 = ptr, *i1, *i3, *i4;
int s, s_end;
/* initialize local state */
CV_INIT_3X3_DELTAS( deltas, step, 1 );
memcpy( deltas + 8, deltas, 8 * sizeof( deltas[0] ));
assert( (*i0 & -2) != 0 );
s_end = s = is_hole ? 0 : 4;
do
{
s = (s - 1) & 7;
i1 = i0 + deltas[s];
if( *i1 != 0 )
break;
}
while( s != s_end );
i3 = i0;
/* check single pixel domain */
if( s != s_end )
{
/* follow border */
for( ;; )
{
s_end = s;
for( ;; )
{
i4 = i3 + deltas[++s];
if( *i4 != 0 )
break;
}
if( i3 == stop_ptr || (i4 == i0 && i3 == i1) )
break;
i3 = i4;
s = (s + 4) & 7;
} /* end of border following loop */
}
return i3 == stop_ptr;
}
static CvSeq*
icvGetComponent(uchar* img, int step, CvRect rect,
CvMemStorage* storage) {
const char nbd = 4;
int deltas[16];
int x, y;
CvSeq* exterior = 0;
char* ptr;
/* initialize local state */
CV_INIT_3X3_DELTAS(deltas, step, 1);
memcpy(deltas + 8, deltas, 8 * sizeof(deltas[0]));
ptr = (char*)(img + step * rect.y);
rect.width += rect.x;
rect.height += rect.y;
for (y = rect.y; y < rect.height; y++, ptr += step) {
int prev = ptr[rect.x - 1] & -2;
for (x = rect.x; x < rect.width; x++) {
int p = ptr[x] & -2;
//assert( exterior || ((p | prev) & -4) == 0 );
if (p != prev) {
CvSeq* seq = 0;
int is_hole = 0;
CvSeqWriter writer;
char* i0, *i1, *i3, *i4 = 0;
int prev_s = -1, s, s_end;
CvPoint pt = { x, y };
if (!(prev == 0 && p == 2)) { /* if not external contour */
/* check hole */
if (p != 0 || prev < 1) {
prev = p;
continue;
}
is_hole = 1;
if (!exterior) {
assert(0);
return 0;
}
}
cvStartWriteSeq(CV_SEQ_CONTOUR | (is_hole ? CV_SEQ_FLAG_HOLE : 0),
sizeof(CvContour), sizeof(CvPoint), storage, &writer);
s_end = s = is_hole ? 0 : 4;
i0 = ptr + x - is_hole;
do {
s = (s - 1) & 7;
i1 = i0 + deltas[s];
if ((*i1 & -2) != 0) {
break;
}
} while (s != s_end);
if (s == s_end) { /* single pixel domain */
*i0 = (char)(nbd | -128);
CV_WRITE_SEQ_ELEM(pt, writer);
} else {
i3 = i0;
prev_s = s ^ 4;
/* follow border */
for (;;) {
s_end = s;
for (;;) {
i4 = i3 + deltas[++s];
if ((*i4 & -2) != 0) {
break;
}
}
s &= 7;
/* check "right" bound */
if ((unsigned)(s - 1) < (unsigned) s_end) {
*i3 = (char)(nbd | -128);
} else if (*i3 > 0) {
*i3 = nbd;
}
if (s != prev_s) {
CV_WRITE_SEQ_ELEM(pt, writer);
prev_s = s;
}
pt.x += icvCodeDeltas[s].x;
pt.y += icvCodeDeltas[s].y;
if (i4 == i0 && i3 == i1) {
break;
}
i3 = i4;
s = (s + 4) & 7;
} /* end of border following loop */
}
seq = cvEndWriteSeq(&writer);
cvContourBoundingRect(seq, 1);
if (!is_hole) {
exterior = seq;
} else {
seq->v_prev = exterior;
seq->h_next = exterior->v_next;
if (seq->h_next) {
seq->h_next->h_prev = seq;
}
exterior->v_next = seq;
}
prev = ptr[x] & -2;
}
}
}
return exterior;
}
static CvStatus
icvFetchContourEx( char* ptr,
int step,
CvPoint pt,
CvSeq* contour,
int _method,
int nbd,
CvRect* _rect )
{
int deltas[16];
CvSeqWriter writer;
char *i0 = ptr, *i1, *i3, *i4;
CvRect rect;
int prev_s = -1, s, s_end;
int method = _method - 1;
assert( (unsigned) _method <= CV_CHAIN_APPROX_SIMPLE );
assert( 1 < nbd && nbd < 128 );
/* initialize local state */
CV_INIT_3X3_DELTAS( deltas, step, 1 );
memcpy( deltas + 8, deltas, 8 * sizeof( deltas[0] ));
/* initialize writer */
cvStartAppendToSeq( contour, &writer );
if( method < 0 )
((CvChain *)contour)->origin = pt;
rect.x = rect.width = pt.x;
rect.y = rect.height = pt.y;
s_end = s = CV_IS_SEQ_HOLE( contour ) ? 0 : 4;
do
{
s = (s - 1) & 7;
i1 = i0 + deltas[s];
if( *i1 != 0 )
break;
}
while( s != s_end );
if( s == s_end ) /* single pixel domain */
{
*i0 = (char) (nbd | 0x80);
if( method >= 0 )
{
CV_WRITE_SEQ_ELEM( pt, writer );
}
}
else
{
i3 = i0;
prev_s = s ^ 4;
/* follow border */
for( ;; )
{
s_end = s;
for( ;; )
{
i4 = i3 + deltas[++s];
if( *i4 != 0 )
break;
}
s &= 7;
/* check "right" bound */
if( (unsigned) (s - 1) < (unsigned) s_end )
{
*i3 = (char) (nbd | 0x80);
}
else if( *i3 == 1 )
{
*i3 = (char) nbd;
}
if( method < 0 )
{
char _s = (char) s;
CV_WRITE_SEQ_ELEM( _s, writer );
}
else if( s != prev_s || method == 0 )
{
CV_WRITE_SEQ_ELEM( pt, writer );
}
if( s != prev_s )
{
/* update bounds */
if( pt.x < rect.x )
rect.x = pt.x;
else if( pt.x > rect.width )
rect.width = pt.x;
if( pt.y < rect.y )
rect.y = pt.y;
else if( pt.y > rect.height )
rect.height = pt.y;
}
prev_s = s;
pt.x += icvCodeDeltas[s].x;
pt.y += icvCodeDeltas[s].y;
if( i4 == i0 && i3 == i1 ) break;
i3 = i4;
s = (s + 4) & 7;
} /* end of border following loop */
}
rect.width -= rect.x - 1;
rect.height -= rect.y - 1;
cvEndWriteSeq( &writer );
if( _method != CV_CHAIN_CODE )
((CvContour*)contour)->rect = rect;
assert( writer.seq->total == 0 && writer.seq->first == 0 ||
writer.seq->total > writer.seq->first->count ||
(writer.seq->first->prev == writer.seq->first &&
writer.seq->first->next == writer.seq->first) );
if( _rect ) *_rect = rect;
return CV_OK;
}
