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#include "_cv.h"
/****************************************************************************************\
* Chain Approximation *
\****************************************************************************************/
typedef struct _CvPtInfo
{
CvPoint pt;
int k; /* support region */
int s; /* curvature value */
struct _CvPtInfo *next;
}
_CvPtInfo;
/* curvature: 0 - 1-curvature, 1 - k-cosine curvature. */
CvStatus
icvApproximateChainTC89( CvChain* chain,
int header_size,
CvMemStorage* storage,
CvSeq** contour,
int method )
{
static const int abs_diff[] = { 1, 2, 3, 4, 3, 2, 1, 0, 1, 2, 3, 4, 3, 2, 1 };
char local_buffer[1 << 16];
char* buffer = local_buffer;
int buffer_size;
_CvPtInfo temp;
_CvPtInfo *array, *first = 0, *current = 0, *prev_current = 0;
int i, j, i1, i2, s, len;
int count;
CvChainPtReader reader;
CvSeqWriter writer;
CvPoint pt = chain->origin;
assert( chain && contour && buffer );
buffer_size = (chain->total + 8) * sizeof( _CvPtInfo );
*contour = 0;
if( !CV_IS_SEQ_CHAIN_CONTOUR( chain ))
return CV_BADFLAG_ERR;
if( header_size < (int)sizeof(CvContour) )
return CV_BADSIZE_ERR;
cvStartWriteSeq( (chain->flags & ~CV_SEQ_ELTYPE_MASK) | CV_SEQ_ELTYPE_POINT,
header_size, sizeof( CvPoint ), storage, &writer );
if( chain->total == 0 )
{
CV_WRITE_SEQ_ELEM( pt, writer );
goto exit_function;
}
cvStartReadChainPoints( chain, &reader );
if( method > CV_CHAIN_APPROX_SIMPLE && buffer_size > (int)sizeof(local_buffer))
{
buffer = (char *) cvAlloc( buffer_size );
if( !buffer )
return CV_OUTOFMEM_ERR;
}
array = (_CvPtInfo *) buffer;
count = chain->total;
temp.next = 0;
current = &temp;
/* Pass 0.
Restores all the digital curve points from the chain code.
Removes the points (from the resultant polygon)
that have zero 1-curvature */
for( i = 0; i < count; i++ )
{
int prev_code = *reader.prev_elem;
reader.prev_elem = reader.ptr;
CV_READ_CHAIN_POINT( pt, reader );
/* calc 1-curvature */
s = abs_diff[reader.code - prev_code + 7];
if( method <= CV_CHAIN_APPROX_SIMPLE )
{
if( method == CV_CHAIN_APPROX_NONE || s != 0 )
{
CV_WRITE_SEQ_ELEM( pt, writer );
}
}
else
{
if( s != 0 )
current = current->next = array + i;
array[i].s = s;
array[i].pt = pt;
}
}
//assert( pt.x == chain->origin.x && pt.y == chain->origin.y );
if( method <= CV_CHAIN_APPROX_SIMPLE )
goto exit_function;
current->next = 0;
len = i;
current = temp.next;
assert( current );
/* Pass 1.
Determines support region for all the remained points */
do
{
CvPoint pt0;
int k, l = 0, d_num = 0;
i = (int)(current - array);
pt0 = array[i].pt;
/* determine support region */
for( k = 1;; k++ )
{
int lk, dk_num;
int dx, dy;
int di;
float d;
assert( k <= len );
/* calc indices */
i1 = i - k;
i1 += i1 < 0 ? len : 0;
i2 = i + k;
i2 -= i2 >= len ? len : 0;
dx = array[i2].pt.x - array[i1].pt.x;
dy = array[i2].pt.y - array[i1].pt.y;
/* distance between p_(i - k) and p_(i + k) */
lk = dx * dx + dy * dy;
/* distance between p_i and the line (p_(i-k), p_(i+k)) */
dk_num = (pt0.x - array[i1].pt.x) * dy - (pt0.y - array[i1].pt.y) * dx;
d = (float) (((double) d_num) * lk - ((double) dk_num) * l);
di = *(int *) &d;
if( k > 1 && (l >= lk || (d_num > 0 && di <= 0 || d_num < 0 && di >= 0)))
break;
d_num = dk_num;
l = lk;
}
current->k = --k;
/* determine cosine curvature if it should be used */
if( method == CV_CHAIN_APPROX_TC89_KCOS )
{
/* calc k-cosine curvature */
for( j = k, s = 0; j > 0; j-- )
{
double temp_num;
float t;
int sk, dx1, dy1, dx2, dy2;
i1 = i - j;
i1 += i1 < 0 ? len : 0;
i2 = i + j;
i2 -= i2 >= len ? len : 0;
dx1 = array[i1].pt.x - pt0.x;
dy1 = array[i1].pt.y - pt0.y;
dx2 = array[i2].pt.x - pt0.x;
dy2 = array[i2].pt.y - pt0.y;
if( (dx1 | dy1) == 0 || (dx2 | dy2) == 0 )
break;
temp_num = dx1 * dx2 + dy1 * dy2;
temp_num =
(float) (temp_num /
sqrt( ((double)dx1 * dx1 + (double)dy1 * dy1) *
((double)dx2 * dx2 + (double)dy2 * dy2) ));
t = (float) (temp_num + 1.1);
sk = *((int*)&t);
assert( 0 <= t && t <= 2.2 );
if( j < k && sk <= s )
break;
s = sk;
}
current->s = s;
}
current = current->next;
}
while( current != 0 );
prev_current = &temp;
current = temp.next;
/* Pass 2.
Performs non-maxima supression */
do
{
int k2 = current->k >> 1;
s = current->s;
i = (int)(current - array);
for( j = 1; j <= k2; j++ )
{
i2 = i - j;
i2 += i2 < 0 ? len : 0;
if( array[i2].s > s )
break;
i2 = i + j;
i2 -= i2 >= len ? len : 0;
if( array[i2].s > s )
break;
}
if( j <= k2 ) /* exclude point */
{
prev_current->next = current->next;
current->s = 0; /* "clear" point */
}
else
prev_current = current;
current = current->next;
}
while( current != 0 );
/* Pass 3.
Removes non-dominant points with 1-length support region */
current = temp.next;
assert( current );
prev_current = &temp;
do
{
if( current->k == 1 )
{
s = current->s;
i = (int)(current - array);
i1 = i - 1;
i1 += i1 < 0 ? len : 0;
i2 = i + 1;
i2 -= i2 >= len ? len : 0;
if( s <= array[i1].s || s <= array[i2].s )
{
prev_current->next = current->next;
current->s = 0;
}
else
prev_current = current;
}
else
prev_current = current;
current = current->next;
}
while( current != 0 );
if( method == CV_CHAIN_APPROX_TC89_KCOS )
goto copy_vect;
/* Pass 4.
Cleans remained couples of points */
assert( temp.next );
if( array[0].s != 0 && array[len - 1].s != 0 ) /* specific case */
{
for( i1 = 1; i1 < len && array[i1].s != 0; i1++ )
{
array[i1 - 1].s = 0;
}
if( i1 == len )
goto copy_vect; /* all points survived */
i1--;
for( i2 = len - 2; i2 > 0 && array[i2].s != 0; i2-- )
{
array[i2].next = 0;
array[i2 + 1].s = 0;
}
i2++;
if( i1 == 0 && i2 == len - 1 ) /* only two points */
{
i1 = (int)(array[0].next - array);
array[len] = array[0]; /* move to the end */
array[len].next = 0;
array[len - 1].next = array + len;
}
temp.next = array + i1;
}
current = temp.next;
first = prev_current = &temp;
count = 1;
/* do last pass */
do
{
if( current->next == 0 || current->next - current != 1 )
{
if( count >= 2 )
{
if( count == 2 )
{
int s1 = prev_current->s;
int s2 = current->s;
if( s1 > s2 || s1 == s2 && prev_current->k <= current->k )
/* remove second */
prev_current->next = current->next;
else
/* remove first */
first->next = current;
}
else
first->next->next = current;
}
first = current;
count = 1;
}
else
count++;
prev_current = current;
current = current->next;
}
while( current != 0 );
copy_vect:
/* gather points */
current = temp.next;
assert( current );
do
{
CV_WRITE_SEQ_ELEM( current->pt, writer );
current = current->next;
}
while( current != 0 );
exit_function:
*contour = cvEndWriteSeq( &writer );
assert( writer.seq->total > 0 );
if( buffer != local_buffer )
cvFree( (void**)&buffer );
return CV_OK;
}
/*Applies some approximation algorithm to chain-coded contour(s) and
converts it/them to polygonal representation */
CV_IMPL CvSeq*
cvApproxChains( CvSeq* src_seq,
CvMemStorage* storage,
int method,
double /*parameter*/,
int minimal_perimeter,
int recursive )
{
CvSeq *prev_contour = 0, *parent = 0;
CvSeq *dst_seq = 0;
CV_FUNCNAME( "cvApproxChains" );
__BEGIN__;
if( !src_seq || !storage )
CV_ERROR( CV_StsNullPtr, "" );
if( method > CV_CHAIN_APPROX_TC89_KCOS || method <= 0 || minimal_perimeter < 0 )
CV_ERROR( CV_StsOutOfRange, "" );
while( src_seq != 0 )
{
int len = src_seq->total;
if( len >= minimal_perimeter )
{
CvSeq *contour;
switch( method )
{
case CV_CHAIN_APPROX_NONE:
case CV_CHAIN_APPROX_SIMPLE:
case CV_CHAIN_APPROX_TC89_L1:
case CV_CHAIN_APPROX_TC89_KCOS:
IPPI_CALL( icvApproximateChainTC89( (CvChain *) src_seq,
sizeof( CvContour ), storage,
(CvSeq**)&contour, method ));
break;
default:
assert(0);
CV_ERROR( CV_StsOutOfRange, "" );
}
assert( contour );
if( contour->total > 0 )
{
cvBoundingRect( contour, 1 );
contour->v_prev = parent;
contour->h_prev = prev_contour;
if( prev_contour )
prev_contour->h_next = contour;
else if( parent )
parent->v_next = contour;
prev_contour = contour;
if( !dst_seq )
dst_seq = prev_contour;
}
else /* if resultant contour has zero length, skip it */
{
len = -1;
}
}
if( !recursive )
break;
if( src_seq->v_next && len >= minimal_perimeter )
{
assert( prev_contour != 0 );
parent = prev_contour;
prev_contour = 0;
src_seq = src_seq->v_next;
}
else
{
while( src_seq->h_next == 0 )
{
src_seq = src_seq->v_prev;
if( src_seq == 0 )
break;
prev_contour = parent;
if( parent )
parent = parent->v_prev;
}
if( src_seq )
src_seq = src_seq->h_next;
}
}
__END__;
return dst_seq;
}
/****************************************************************************************\
* Polygonal Approximation *
\****************************************************************************************/
/* Ramer-Douglas-Peucker algorithm for polygon simplification */
static CvStatus
icvApproxPolyDP( CvSeq* src_contour, int header_size,
CvMemStorage* storage,
CvSeq** dst_contour, float eps )
{
int init_iters = 3;
CvSlice slice = {0, 0}, right_slice = {0, 0};
CvSeqReader reader, reader2;
CvSeqWriter writer;
CvPoint start_pt = {INT_MIN, INT_MIN}, end_pt = { 0, 0 }, pt;
int i = 0, j, count = src_contour->total, new_count;
int is_closed = CV_IS_SEQ_CLOSED( src_contour );
int le_eps = 0;
CvMemStorage* temp_storage = 0;
CvSeq* stack = 0;
int is_float = CV_SEQ_ELTYPE(src_contour)==CV_32FC2;
cvStartWriteSeq( src_contour->flags, header_size,
sizeof( CvPoint ), storage, &writer );
if( src_contour->total == 0 )
{
*dst_contour = cvEndWriteSeq( &writer );
return CV_OK;
}
temp_storage = cvCreateChildMemStorage( storage );
assert( src_contour->first != 0 );
stack = cvCreateSeq( 0, sizeof( CvSeq ), sizeof( CvSlice ), temp_storage );
eps *= eps;
cvStartReadSeq( src_contour, &reader, 0 );
if( !is_closed )
{
right_slice.start_index = count;
end_pt = *(CvPoint*)(reader.ptr);
start_pt = *(CvPoint*)cvGetSeqElem( src_contour, -1 );
if( start_pt.x != end_pt.x || start_pt.y != end_pt.y )
{
slice.start_index = 0;
slice.end_index = count - 1;
cvSeqPush( stack, &slice );
}
else
{
is_closed = 1;
init_iters = 1;
}
}
if( is_closed )
{
/* 1. Find approximately two farthest points of the contour */
right_slice.start_index = 0;
for( i = 0; i < init_iters; i++ )
{
cvSetSeqReaderPos( &reader, right_slice.start_index, 1 );
CV_READ_SEQ_ELEM( start_pt, reader ); /* read the first point */
if( !is_float )
{
int max_dist = 0;
for( j = 1; j < count; j++ )
{
int dx, dy, dist;
CV_READ_SEQ_ELEM( pt, reader );
dx = pt.x - start_pt.x;
dy = pt.y - start_pt.y;
dist = dx * dx + dy * dy;
if( dist > max_dist )
{
max_dist = dist;
right_slice.start_index = j;
}
}
le_eps = max_dist <= eps;
}
else
{
CvPoint2D32f start_ptfl = {(float&)start_pt.x,(float&)start_pt.y};
float max_dist = 0;
for( j = 1; j < count; j++ )
{
float dx, dy, dist;
CvPoint2D32f ptfl;
CV_READ_SEQ_ELEM( ptfl, reader );
dx = ptfl.x - start_ptfl.x;
dy = ptfl.y - start_ptfl.y;
dist = dx * dx + dy * dy;
if( dist > max_dist )
{
max_dist = dist;
right_slice.start_index = j;
}
}
le_eps = max_dist <= eps;
}
}
/* 2. initialize the stack */
if( !le_eps )
{
slice.start_index = cvGetSeqReaderPos( &reader );
slice.end_index = right_slice.start_index += slice.start_index;
right_slice.start_index -= right_slice.start_index >= count ? count : 0;
right_slice.end_index = slice.start_index;
if( right_slice.end_index < right_slice.start_index )
right_slice.end_index += count;
cvSeqPush( stack, &right_slice );
cvSeqPush( stack, &slice );
}
else
{
CV_WRITE_SEQ_ELEM( start_pt, writer );
}
}
/* 3. run recursive process */
while( stack->total != 0 )
{
cvSeqPop( stack, &slice );
assert( slice.start_index < slice.end_index );
if( slice.end_index - slice.start_index != 1 )
{
cvSetSeqReaderPos( &reader, slice.end_index );
CV_READ_SEQ_ELEM( end_pt, reader );
cvSetSeqReaderPos( &reader, slice.start_index );
CV_READ_SEQ_ELEM( start_pt, reader );
if( !is_float )
{
int dx = end_pt.x - start_pt.x;
int dy = end_pt.y - start_pt.y;
int max_dist = 0;
assert( (dx | dy) != 0 );
for( i = slice.start_index + 1; i < slice.end_index; i++ )
{
int dist;
CV_READ_SEQ_ELEM( pt, reader );
dist = (pt.y - start_pt.y) * dx - (pt.x - start_pt.x) * dy;
dist = CV_IABS( dist );
if( dist > max_dist )
{
max_dist = dist;
right_slice.start_index = i;
}
}
le_eps = (double)max_dist * max_dist <= eps * ((double)dx * dx + (double)dy * dy);
}
else
{
float sx = (float&)start_pt.x;
float sy = (float&)start_pt.y;
float dx = (float&)end_pt.x - sx;
float dy = (float&)end_pt.y - sy;
float max_dist = 0;
assert( ((int&)dx | (int&)dy) != 0 );
for( i = slice.start_index + 1; i < slice.end_index; i++ )
{
float dist;
CvPoint2D32f ptfl;
CV_READ_SEQ_ELEM( ptfl, reader );
dist = (float)fabs((ptfl.y - sy)*dx - (ptfl.x - sx)*dy);
if( dist > max_dist )
{
max_dist = dist;
right_slice.start_index = i;
}
}
le_eps = (double)max_dist * max_dist <= eps * ((double)dx * dx + (double)dy * dy);
}
}
else
{
le_eps = 1;
/* read starting point */
cvSetSeqReaderPos( &reader, slice.start_index );
CV_READ_SEQ_ELEM( start_pt, reader );
}
if( le_eps )
{
CV_WRITE_SEQ_ELEM( start_pt, writer );
}
else
{
right_slice.end_index = slice.end_index;
slice.end_index = right_slice.start_index;
cvSeqPush( stack, &right_slice );
cvSeqPush( stack, &slice );
}
}
is_closed = CV_IS_SEQ_CLOSED( src_contour );
if( !is_closed )
CV_WRITE_SEQ_ELEM( end_pt, writer );
*dst_contour = cvEndWriteSeq( &writer );
cvStartReadSeq( *dst_contour, &reader, is_closed );
CV_READ_SEQ_ELEM( start_pt, reader );
reader2 = reader;
CV_READ_SEQ_ELEM( pt, reader );
new_count = count = (*dst_contour)->total;
for( i = !is_closed; i < count - !is_closed && new_count > 2; i++ )
{
CV_READ_SEQ_ELEM( end_pt, reader );
if( !is_float )
{
int dx, dy, dist;
dx = end_pt.x - start_pt.x;
dy = end_pt.y - start_pt.y;
dist = abs((pt.x - start_pt.x)*dy - (pt.y - start_pt.y)*dx);
le_eps = (double)dist * dist <= 0.5*eps*((double)dx*dx + (double)dy*dy);
}
else
{
double dx, dy, dist;
dx = (float&)end_pt.x - (float&)start_pt.x;
dy = (float&)end_pt.y - (float&)start_pt.y;
dist = fabs(((float&)pt.x - (float&)start_pt.x)*dy - ((float&)pt.y - (float&)start_pt.y)*dx);
le_eps = (double)dist * dist <= 0.5*eps*((double)dx*dx + (double)dy*dy);
}
if( le_eps )
{
new_count--;
*((CvPoint*)reader2.ptr) = start_pt = end_pt;
CV_NEXT_SEQ_ELEM( sizeof(CvPoint), reader2 );
CV_READ_SEQ_ELEM( pt, reader );
i++;
continue;
}
*((CvPoint*)reader2.ptr) = start_pt = pt;
CV_NEXT_SEQ_ELEM( sizeof(CvPoint), reader2 );
pt = end_pt;
}
if( !is_closed )
*((CvPoint*)reader2.ptr) = pt;
if( new_count < count )
cvSeqPopMulti( *dst_contour, 0, count - new_count );
cvReleaseMemStorage( &temp_storage );
return CV_OK;
}
CV_IMPL CvSeq*
cvApproxPoly( const void* array, int header_size,
CvMemStorage* storage, int method,
double parameter, int parameter2 )
{
CvSeq* dst_seq = 0;
CvSeq *prev_contour = 0, *parent = 0;
CvContour contour_header;
CvSeq* src_seq = 0;
CvSeqBlock block;
int recursive = 0;
CV_FUNCNAME( "cvApproxPoly" );
__BEGIN__;
if( CV_IS_SEQ( array ))
{
src_seq = (CvSeq*)array;
if( !CV_IS_SEQ_POLYLINE( src_seq ))
CV_ERROR( CV_StsBadArg, "Unsupported sequence type" );
recursive = parameter2;
if( !storage )
storage = src_seq->storage;
}
else
{
CV_CALL( src_seq = cvPointSeqFromMat(
CV_SEQ_KIND_CURVE | (parameter2 ? CV_SEQ_FLAG_CLOSED : 0),
array, &contour_header, &block ));
}
if( !storage )
CV_ERROR( CV_StsNullPtr, "NULL storage pointer " );
if( header_size < 0 )
CV_ERROR( CV_StsOutOfRange, "header_size is negative. "
"Pass 0 to make the destination header_size == input header_size" );
if( header_size == 0 )
header_size = src_seq->header_size;
if( !CV_IS_SEQ_POLYLINE( src_seq ))
{
if( CV_IS_SEQ_CHAIN( src_seq ))
{
CV_ERROR( CV_StsBadArg, "Input curves are not polygonal. "
"Use cvApproxChains first" );
}
else
{
CV_ERROR( CV_StsBadArg, "Input curves have uknown type" );
}
}
if( header_size == 0 )
header_size = src_seq->header_size;
if( header_size < (int)sizeof(CvContour) )
CV_ERROR( CV_StsBadSize, "New header size must be non-less than sizeof(CvContour)" );
if( method != CV_POLY_APPROX_DP )
CV_ERROR( CV_StsOutOfRange, "Unknown approximation method" );
while( src_seq != 0 )
{
CvSeq *contour = 0;
switch (method)
{
case CV_POLY_APPROX_DP:
if( parameter < 0 )
CV_ERROR( CV_StsOutOfRange, "Accuracy must be non-negative" );
IPPI_CALL( icvApproxPolyDP( src_seq, header_size,
storage, &contour, (float)parameter ));
break;
default:
assert(0);
CV_ERROR( CV_StsBadArg, "Invalid approximation method" );
}
assert( contour );
if( header_size >= (int)sizeof(CvContour))
cvBoundingRect( contour, 1 );
contour->v_prev = parent;
contour->h_prev = prev_contour;
if( prev_contour )
prev_contour->h_next = contour;
else if( parent )
parent->v_next = contour;
prev_contour = contour;
if( !dst_seq )
dst_seq = prev_contour;
if( !recursive )
break;
if( src_seq->v_next )
{
assert( prev_contour != 0 );
parent = prev_contour;
prev_contour = 0;
src_seq = src_seq->v_next;
}
else
{
while( src_seq->h_next == 0 )
{
src_seq = src_seq->v_prev;
if( src_seq == 0 )
break;
prev_contour = parent;
if( parent )
parent = parent->v_prev;
}
if( src_seq )
src_seq = src_seq->h_next;
}
}
__END__;
return dst_seq;
}
/* End of file. */