#include "tcenterlinevectP.h"
//==========================================================================
//************************
//* Polygonization *
//************************
//--------------------------------------------------------------------------
//===============================
// Raw Borders Extraction
//===============================
// Raw contour class definition
class RawBorderPoint {
TPoint m_position;
int m_ambiguousTurn; // used to remember cases of multiple turning directions
// in a RawBorder extraction.
public:
RawBorderPoint() : m_ambiguousTurn(0) {}
RawBorderPoint(int i, int j) : m_position(i, j), m_ambiguousTurn(0) {}
inline TPoint pos() const { return m_position; }
inline int x() const { return m_position.x; }
inline int y() const { return m_position.y; }
enum { left = 1, right = 2 }; // Direction taken at ambiguous turning point
inline int getAmbiguous() const { return m_ambiguousTurn; }
inline void setAmbiguous(int direction) { m_ambiguousTurn = direction; }
};
//--------------------------------------------------------------------------
class RawBorder final : public std::vector<RawBorderPoint> {
int m_xExternal; // x coordinate of a specific vertex in the outer
// RawBorder which contains this inner one.
TPointD *m_coordinateSums;
TPointD *m_coordinateSquareSums;
double *m_coordinateMixedSums;
public:
RawBorder() {}
~RawBorder() {}
void setXExternalPixel(int a) { m_xExternal = a; }
int xExternalPixel() { return m_xExternal; }
TPointD *&sums() { return m_coordinateSums; }
TPointD *&sums2() { return m_coordinateSquareSums; }
double *&sumsMix() { return m_coordinateMixedSums; }
};
//--------------------------------------------------------------------------
// Of course we don't want RawBorders to be entirely copied whenever STL
// requires to resize a BorderFamily...
typedef std::vector<RawBorder *> BorderFamily;
typedef std::vector<BorderFamily> BorderList;
//--------------------------------------------------------------------------
//==========================================================================
//============================
// Polygonizer Locals
//============================
namespace {
// Const names
enum { white = 0, black = 1 };
enum { inner = 0, outer = 1, none = 2, invalid = 3 };
}
//=======================================================================================
//-------------------------------
// Raster Data Functions
//-------------------------------
// NOTA: Il tono di un TPixelCM32 rappresenta la transizione tra colore ink e
// colore paint.
// di solito, se il tono e' basso abbiamo un colore ink - che puo' anche
// essere bianco,
// in teoria...
// Sarebbe opportuno che il vettorizzatore riconoscesse - per colormap - il
// colore
// delle strokes.
// Approcci: a) la Signaturemap diventa *piu'* di una bitmap e si seguono
// le outline
// dei singoli colori.
// => Sconnessioni tra i colori adiacenti. Bisogna introdurre la
// distanza tra
// colori per seguire l'outline (ossia, i pixel tenuti a dx
// della outline
// devono essere simili).
//
// b) Una volta vettorizzato tutto, si sceglie il colore della
// stroke.
// E' possibile controllare il colore sui vertici delle
// sequenze semplificate
// e fare una media.
// NOTE: Transparency makes colors fade to white. Full transparent black pixels
// are considered white.
//--------------------------------------------------------------------------
template <typename T>
class PixelEvaluator {
TRasterPT<T> m_ras;
int m_threshold;
public:
PixelEvaluator(const TRasterPT<T> &ras, int threshold)
: m_ras(ras), m_threshold(threshold) {}
inline unsigned char getBlackOrWhite(int x, int y);
};
//--------------------------------------------------------------------------
template <>
inline unsigned char PixelEvaluator<TPixel32>::getBlackOrWhite(int x, int y) {
// return ras->pixels(y)[x].r + 2 * ras->pixels(y)[x].g + ras->pixels(y)[x].b
// <
// threshold * (ras->pixels(y)[x].m / 255.0);
// NOTE: Green is considered twice brighter than red or blue channel.
// Using Value of HSV color model
return std::max(m_ras->pixels(y)[x].r,
std::max(m_ras->pixels(y)[x].g, m_ras->pixels(y)[x].b)) <
m_threshold * (m_ras->pixels(y)[x].m / 255.0);
// Using Lightness of HSV color model
// return (max(ras->pixels(y)[x].r, max(ras->pixels(y)[x].g,
// ras->pixels(y)[x].b)) +
// min(ras->pixels(y)[x].r, min(ras->pixels(y)[x].g,
// ras->pixels(y)[x].b))) / 2.0 <
// threshold * (ras->pixels(y)[x].m / 255.0);
// Using (relative) Luminance
// return 0.2126 * ras->pixels(y)[x].r + 0.7152 * ras->pixels(y)[x].g + 0.0722
// * ras->pixels(y)[x].b <
// threshold * (ras->pixels(y)[x].m / 255.0);
}
template <>
inline unsigned char PixelEvaluator<TPixelGR8>::getBlackOrWhite(int x, int y) {
return m_ras->pixels(y)[x].value < m_threshold;
}
template <>
inline unsigned char PixelEvaluator<TPixelCM32>::getBlackOrWhite(int x, int y) {
return m_ras->pixels(y)[x].getTone() < m_threshold;
}
//--------------------------------------------------------------------------
// Signaturemap format:
// stores a map of bytes, whose first bit represents the color (black/white) of
// corresponding pixel, and
// the rest its 'signature', used as an int to store information.
// NOTE: given a TRaster32, the corresponding Signaturemap constructed is
// intended 0(white)-padded
class Signaturemap {
std::unique_ptr<unsigned char[]> m_array;
int m_rowSize;
int m_colSize;
public:
Signaturemap(const TRasterP &ras, int threshold);
template <typename T>
void readRasterData(const TRasterPT<T> &ras, int threshold);
inline int getRowSize() const { return m_rowSize; }
inline int getColSize() const { return m_colSize; }
unsigned char *pixelByte(int x, int y) {
return &m_array[(y + 1) * m_rowSize + x + 1];
}
bool getBitmapColor(int x, int y) const {
return m_array[(y + 1) * m_rowSize + x + 1] & 1;
}
inline unsigned char getSignature(int x, int y) const {
return m_array[(y + 1) * m_rowSize + x + 1] >> 1;
}
void setSignature(int x, int y, int val) {
unsigned char *pixel = pixelByte(x, y);
*pixel &= 1;
*pixel |= (val << 1); // Si puo' fare meglio??
}
};
//--------------------------------------------------------------------------
Signaturemap::Signaturemap(const TRasterP &ras, int threshold) {
// Extrapolate raster type
TRaster32P rr = (TRaster32P)ras;
TRasterGR8P rgr = (TRasterGR8P)ras;
TRasterCM32P rt = (TRasterCM32P)ras;
assert(rr || rgr || rt);
// Read raster data
if (rr) {
rr->lock();
readRasterData(rr, threshold);
rr->unlock();
} else if (rgr) {
rgr->lock();
readRasterData(rgr, threshold);
rgr->unlock();
} else {
rt->lock();
readRasterData(rt, threshold);
rt->unlock();
}
}
//--------------------------------------------------------------------------
template <typename T>
void Signaturemap::readRasterData(const TRasterPT<T> &ras, int threshold) {
unsigned char *currByte;
int x, y;
PixelEvaluator<T> evaluator(ras, threshold);
m_rowSize = ras->getLx() + 2;
m_colSize = ras->getLy() + 2;
m_array.reset(new unsigned char[m_rowSize * m_colSize]);
memset(m_array.get(), none << 1, m_rowSize);
currByte = m_array.get() + m_rowSize;
for (y = 0; y < ras->getLy(); ++y) {
*currByte = none << 1;
currByte++;
for (x = 0; x < ras->getLx(); ++x, ++currByte)
*currByte = evaluator.getBlackOrWhite(x, y) | (none << 1);
*currByte = none << 1;
currByte++;
}
memset(currByte, none << 1, m_rowSize);
}
//--------------------------------------------------------------------------
// Minority check for ambiguous turning directions
inline bool getMinorityCheck(const Signaturemap &ras, int x, int y) {
// Assumes (x,y) is ambiguous case: 2 immediate surrounding pixels are white
// and 2 black
return (ras.getBitmapColor(x + 1, y) + ras.getBitmapColor(x + 1, y - 1) +
ras.getBitmapColor(x - 2, y) + ras.getBitmapColor(x - 2, y - 1) +
ras.getBitmapColor(x - 1, y + 1) + ras.getBitmapColor(x - 1, y - 2) +
ras.getBitmapColor(x, y + 1) + ras.getBitmapColor(x, y - 2)) > 4;
}
//--------------------------------------------------------------------------
// Sets signature of a given border
inline void setSignature(Signaturemap &ras, const RawBorder &border, int val) {
unsigned int j;
int yOld;
// Set border's alpha channel
yOld = border.back().y();
for (j = 0; j < border.size(); ++j) {
if (border[j].y() < yOld) {
ras.setSignature(border[j].x(), border[j].y(), val);
} else if (border[j].y() > yOld) {
ras.setSignature(border[j].x(), yOld, val);
}
yOld = border[j].y();
}
}
//==========================================================================
//-------------------------------
// Raw Borders Extraction
//-------------------------------
// RawBorderPoints correspond to lower-left pixel corners.
// EXAMPLE: (0,0) is the lower-left *corner* of the image, whereas (0,0) also
// represents coordinates of the lower-left *pixel*.
// NOTE: 'Ambiguous turning' vertices are those of kind:
//
// B|W W|B
// -x- -or- -x-
// W|B B|W
//
// Keeping B on the right of our path-seeking direction, we may either turn
// left or right at these points.
static RawBorder *extractPath(Signaturemap &ras, int x0, int y0, int pathType,
int xOuterPixel, int despeckling) {
RawBorder *path = new RawBorder;
int x, y;
short dirX, dirY;
long int area = 0;
bool nextLeftPixel, nextRightPixel;
if (pathType == outer) {
dirX = 0;
dirY = 1;
} else {
dirX = 1;
dirY = 0;
area += y0;
path->setXExternalPixel(xOuterPixel);
}
path->push_back(RawBorderPoint(x0, y0));
// Check here if (x0, y0) is an ambiguous-direction point
nextLeftPixel = ras.getBitmapColor(x0 + (dirY - dirX - 1) / 2,
y0 + (-dirY - dirX - 1) / 2);
nextRightPixel = ras.getBitmapColor(x0 + (-dirX - dirY - 1) / 2,
y0 + (dirX - dirY - 1) / 2);
if ((nextRightPixel == black) && (nextLeftPixel == white))
path->back().setAmbiguous(dirX ? RawBorderPoint::left
: RawBorderPoint::right);
// Begin path extraction
for (x = x0 + dirX, y = y0 + dirY; !(x == x0 && y == y0);
x += dirX, y += dirY) {
path->push_back(RawBorderPoint(x, y));
// Calculate next direction
nextLeftPixel = ras.getBitmapColor(x + (dirX - dirY - 1) / 2,
y + (dirY + dirX - 1) / 2);
nextRightPixel = ras.getBitmapColor(x + (dirX + dirY - 1) / 2,
y + (dirY - dirX - 1) / 2);
if ((nextRightPixel == black) && (nextLeftPixel == black)) {
// Left Turn
std::swap(dirY, dirX);
dirX = -dirX;
} else if ((nextRightPixel == white) && (nextLeftPixel == white)) {
// Right Turn
std::swap(dirY, dirX);
dirY = -dirY;
} else if ((nextRightPixel == white) && (nextLeftPixel == black)) {
// path->back().setAmbiguous();
// Do a surrounding check and connect minority color
if (getMinorityCheck(ras, x, y) == black) {
std::swap(dirY, dirX);
dirY = -dirY;
path->back().setAmbiguous(RawBorderPoint::right);
} // right turn
else {
std::swap(dirY, dirX);
dirX = -dirX;
path->back().setAmbiguous(RawBorderPoint::left);
} // left turn
}
// Also calculate border area
area += y * dirX;
// And sign treated pixel
if (dirY != 0) ras.setSignature(x, y + (dirY - 1) / 2, pathType);
}
// If the inner region's overall area is under a given threshold,
// then erase it (intended as image noise).
if (abs(area) < despeckling) {
setSignature(ras, *path, invalid);
delete path;
path = 0;
}
return path;
}
//--------------------------------------------------------------------------
static BorderList *extractBorders(const TRasterP &ras, int threshold,
int despeckling) {
Signaturemap byteImage(ras, threshold);
BorderList *borderHierarchy = new BorderList;
std::vector<RawBorder *> outerBorders;
std::list<RawBorder *> innerBorders;
RawBorder *foundPath;
int x, y;
bool Color, oldColor;
int xOuterPixel = 0;
bool enteredRegionType;
unsigned char signature;
// Traverse image to extract raw borders
for (y = 0; y < ras->getLy(); ++y) {
oldColor = white;
enteredRegionType = outer;
for (x = 0; x < ras->getLx(); ++x) {
if (oldColor ^ (Color = byteImage.getBitmapColor(x, y))) {
// Region type changes
enteredRegionType = !enteredRegionType;
if ((signature = byteImage.getSignature(x, y)) == none) {
// We've found a border
if ((foundPath = extractPath(byteImage, x, y, !enteredRegionType,
xOuterPixel, despeckling)))
if (enteredRegionType == outer)
innerBorders.push_back(foundPath);
else
outerBorders.push_back(foundPath);
}
// If leaving a white region, remember it - in order to establish
// border hierarchy in the future
if (enteredRegionType == inner && signature != invalid) xOuterPixel = x;
// Invalid pixels got signed by a cut-out path, due to insufficient area
if (signature == invalid)
byteImage.setSignature(x, y, none); // Restore them now
oldColor = Color;
}
}
}
// Now, we have all borders found, but no hierarchy between them.
unsigned int i;
std::list<RawBorder *>::iterator l;
// Build hierarchy
innerBorders.push_front(0); // Just to keep a fixed list head
for (i = 0; i < outerBorders.size(); ++i) {
// Initialize a border family
borderHierarchy->push_back(BorderFamily());
borderHierarchy->back().push_back(outerBorders[i]);
// Reset outerBorders[i]'s signature
setSignature(byteImage, *outerBorders[i], none);
// Now check inner borders for insideness - check if the outerPixel
// remembered in path extraction has been cleared
for (l = innerBorders.begin(), ++l; l != innerBorders.end(); ++l) {
if (byteImage.getSignature((*l)->xExternalPixel(), (**l)[0].y()) ==
none) {
borderHierarchy->back().push_back(*l);
setSignature(byteImage, **l, none);
l = innerBorders.erase(l);
--l;
}
}
}
return borderHierarchy;
}
//--------------------------------------------------------------------------
//==================================
// Calculate optimal polygons
//==================================
// The optimal polygon for a given original border is found like:
// 1) Find couples (i,k(i)), so that k(i) be the largest k:
// d(j,ik) <= 1; for *all* i<j<k. (d is infinite-norm distance)
// It can be shown that such a condition is equivalent to:
// exists line l : d(l,j)<=1/2, for all i<=j<=k(i).
// 2) Clean the above couples - find couples (i,l(i)):
// l(i)=min{k(j)}, j=i..n.
// 3) Calculate clipped couples (i',l'); where i'=i+1, l'=l(i)-1.
// 4) Calculate sums for path penalties.
// 5) Apply optimality algorithm.
// NOTE: Weak simpleness reads like: a set of polygons is weak-simple if no edge
// *crosses* another edge. Superposition and collision of edges with
// vertices
// are still admitted.
// => It can be shown that due to 1) and special conditions on ambiguous
// turnings applied in both 1) and 3), weak simpleness is insured in
// our polygonization.
//--------------------------------------------------------------------------
// Helper functions/classes: circular-indexed vectors
// returns 1 whenever the triple (a,b,c) is 'circular' mod n.
// NOTE: We'll find useful taking (i,i,j) as 1 and (i,j,j) as 0.
inline bool isCircular(int a, int b, int c) {
return a <= c ? a <= b && b < c : c > b || b >= a;
}
//--------------------------------------------------------------------------
// Extracts a 'next corner' array - helps improving overall speed
inline std::unique_ptr<int[]> findNextCorners(RawBorder &path) {
std::unique_ptr<int[]> corners(new int[path.size()]);
// NOTE: 0 is a corner, due to the path extraction procedure.
int currentCorner = 0;
for (int i = path.size() - 1; i >= 0; --i) {
if (path[currentCorner].x() != path[i].x() &&
path[currentCorner].y() != path[i].y())
currentCorner = i + 1;
corners[i] = currentCorner;
}
return corners;
}
//--------------------------------------------------------------------------
// Calculate furthest k satisfying 1) for all fixed i.
inline std::unique_ptr<int[]> furthestKs(RawBorder &path,
std::unique_ptr<int[]> &nextCorners) {
int n = path.size();
std::unique_ptr<int[]> kVector(new int[n]);
enum { left, up, right, down };
int directionsOccurred[4];
nextCorners = findNextCorners(path);
int i, j, k;
TPoint shift;
TPoint leftConstraint, rightConstraint, violatedConstraint;
TPoint newLeftConstraint, newRightConstraint;
TPoint jPoint, jNextPoint, iPoint, direction;
int directionSignature;
for (i = 0; i < n; ++i) {
// Initialize search
leftConstraint = rightConstraint = TPoint();
directionsOccurred[0] = directionsOccurred[1] = directionsOccurred[2] =
directionsOccurred[3] = 0;
j = i;
jNextPoint = iPoint = path[i].pos();
// Search for k(i)
while (1) {
// NOTE: Here using TPoint::operator= is less effective than setting
// its x and y components directly...
jPoint = jNextPoint;
jNextPoint = path[nextCorners[j]].pos();
// Update directions count
directionSignature = jNextPoint.x > jPoint.x
? right
: jNextPoint.x < jPoint.x
? left
: jNextPoint.y > jPoint.y ? up : down;
directionsOccurred[directionSignature] = 1;
// If all 4 axis directions occurred, quit
if (directionsOccurred[left] && directionsOccurred[right] &&
directionsOccurred[up] && directionsOccurred[down]) {
k = j;
goto foundK;
}
// Update displacement from i
shift = jNextPoint - iPoint;
// Test j against constraints
// if(cross(shift, leftConstraint)<0 || cross(shift, rightConstraint)>0)
if (cross(shift, leftConstraint) < 0) {
violatedConstraint = leftConstraint;
break;
}
if (cross(shift, rightConstraint) > 0) {
violatedConstraint = rightConstraint;
break;
}
// Update constraints
if (abs(shift.x) > 1 || abs(shift.y) > 1) {
newLeftConstraint.x =
shift.x + (shift.y < 0 || (shift.y == 0 && shift.x < 0) ? 1 : -1);
newLeftConstraint.y =
shift.y + (shift.x > 0 || (shift.x == 0 && shift.y < 0) ? 1 : -1);
if (cross(newLeftConstraint, leftConstraint) >= 0)
leftConstraint = newLeftConstraint;
newRightConstraint.x =
shift.x + (shift.y > 0 || (shift.y == 0 && shift.x < 0) ? 1 : -1);
newRightConstraint.y =
shift.y + (shift.x < 0 || (shift.x == 0 && shift.y < 0) ? 1 : -1);
if (cross(newRightConstraint, rightConstraint) <= 0)
rightConstraint = newRightConstraint;
}
// Imposing strict constraint for ambiguous turnings, to ensure polygons'
// weak simpleness.
// Has to be defined *outside* abs checks.
if (path[nextCorners[j]].getAmbiguous()) {
if (path[nextCorners[j]].getAmbiguous() == RawBorderPoint::left)
rightConstraint = shift;
else
leftConstraint = shift;
}
j = nextCorners[j];
}
// At this point, constraints are violated by the next corner.
// Then, search for the last k between j and corners[j] not violating them.
direction = convert(normalize(convert(jNextPoint - jPoint)));
k = (j +
cross(jPoint - iPoint, violatedConstraint) /
cross(violatedConstraint, direction)) %
n;
foundK:
kVector[i] = k;
}
return kVector;
}
//--------------------------------------------------------------------------
// Now find the effective intervals inside which we can define possible
// arcs approximating the given raw border:
// for every a in [i,res[i]], the arc connecting border[i] and
// border[a] will be a possible one.
inline std::unique_ptr<int[]> calculateForwardArcs(RawBorder &border,
bool ambiguitiesCheck) {
int const n = (int)border.size();
std::unique_ptr<int[]> nextCorners;
std::unique_ptr<int[]> k = furthestKs(border, nextCorners);
std::unique_ptr<int[]> K(new int[n]);
std::unique_ptr<int[]> res(new int[n]);
// find K[i]= min {k[j]}, j=i..n-1.
for (int i = 0; i < n; ++i) {
int j;
for (j = i, K[i] = k[i]; isCircular(i, j, K[i]); j = (j + 1) % n)
if (isCircular(j, k[j], K[i])) K[i] = k[j];
}
// Finally, we perform the following clean-up operations:
// first, extremities of [i,K[i]] are clipped away, to obtain a
// smoother optimal polygon (and deal with cases like the unitary
// square);
// second, arcs of the kind [i,j] with j<i, become [i,n].
for (int i = n - 1, j = 0; j < n; i = j, ++j) {
res[j] = K[i] < j ? (K[i] == 0 ? n - 1 : n) : K[i] - 1;
}
// Amibiguities check for vertex and edge superpositions. Prevent problems in
// the forecoming
// straight-skeleton thinning process.
if (ambiguitiesCheck) {
for (int i = 1; nextCorners[i] > 0; i = nextCorners[i]) {
if (border[i].getAmbiguous() == RawBorderPoint::right) {
// Check vertices from i (excluded) to res[res[i]]; if in it there
// exists vertex k so that pos(k)==pos(i)...
// This prevents the existence of 0 degree angles in the optimal
// polygon.
int rrPlus1 = (res[res[i] % n] + 1) % n;
for (int j = nextCorners[i];
isCircular(i, j, rrPlus1) &&
j != i; // remember that isCircular(a,a,b) == 1 ...
j = nextCorners[j]) {
if (border[j].getAmbiguous() &&
(border[j].pos() == border[i].pos())) {
res[res[i] % n] = j - 1;
assert((res[i] % n) != j - 1);
// Further, ensure res is increasing
for (int k = res[i] % n; res[k] >= j - 1 && k >= 0; --k) {
res[k] = j - 1;
assert(k != j - 1);
}
break;
}
}
}
}
}
return res;
}
//--------------------------------------------------------------------------
// Let sum[i] and sum2[i] be respectively the sums of vertex coordinates
// from 0 to i, and the sums of their squares; sumsMix contain sums of
// xy terms.
inline void calculateSums(RawBorder &path) {
unsigned int i, n = path.size();
TPointD currentRelativePos;
path.sums() = new TPointD[n + 1];
path.sums2() = new TPointD[n + 1];
path.sumsMix() = new double[n + 1];
path.sums()[0].x = path.sums()[0].y = path.sums2()[0].x = path.sums2()[0].y =
0;
for (i = 1; i < path.size(); ++i) {
currentRelativePos = convert(path[i].pos() - path[0].pos());
path.sums()[i] = path.sums()[i - 1] + currentRelativePos;
path.sums2()[i].x =
path.sums2()[i - 1].x + currentRelativePos.x * currentRelativePos.x;
path.sums2()[i].y =
path.sums2()[i - 1].y + currentRelativePos.y * currentRelativePos.y;
path.sumsMix()[i] =
path.sumsMix()[i - 1] + currentRelativePos.x * currentRelativePos.y;
}
// path[n] is virtually intended as path[0], but we prefer to introduce
// it in the optimality algorithm's count
path.sums()[n].x = path.sums()[n].y = path.sums2()[n].x = path.sums2()[n].y =
0;
}
//--------------------------------------------------------------------------
// Let a,b the index-extremities of an arc of this path.
// Then return its penalty.
inline double penalty(RawBorder &path, int a, int b) {
int n = b - a + 1;
TPointD v =
convert(rotate90(path[b == path.size() ? 0 : b].pos() - path[a].pos()));
TPointD sum = path.sums()[b] - path.sums()[a];
TPointD sum2 = path.sums2()[b] - path.sums2()[a];
double sumMix = path.sumsMix()[b] - path.sumsMix()[a];
double F1 = sum2.x - 2 * sum.x * path[a].x() + n * path[a].x() * path[a].x();
double F2 = sum2.y - 2 * sum.y * path[a].y() + n * path[a].y() * path[a].y();
double F3 = sumMix - sum.x * path[a].y() - sum.y * path[a].x() +
n * path[a].x() * path[a].y();
return sqrt((v.y * v.y * F1 + v.x * v.x * F2 - 2 * v.x * v.y * F3) / n);
}
//--------------------------------------------------------------------------
// NOTA: Il seguente algoritmo di riduzione assicura la semplicita' (debole) dei
// poligoni prodotti.
//
inline void reduceBorder(RawBorder &border, Contour &res,
bool ambiguitiesCheck) {
int n = border.size();
int minPenaltyNext;
std::unique_ptr<int[]> minPenaltyNextArray(new int[n]);
// Calculate preliminary infos
std::unique_ptr<int[]> longestArcFrom =
calculateForwardArcs(border, ambiguitiesCheck);
calculateSums(border);
std::unique_ptr<double[]> penaltyToEnd(new double[n + 1]);
// EXPLANATION:
// The fastest way to extract the optimal reduced border is based on the
// weakly monotonic property of longestArc[].
// The minimal number of its vertices 'm' is easily found by
// traversing the path with the longest step allowed. Let b[] be that
// succession; then, given res[i], it has to be reached by a vertex in
// the interval: {a[i-1], .. , b[i-1]}, where longestArc[a[i-1]]=a[i],
// longestArc[a[i-1]-1]<a[i], and a[m]=n.
// Calculate m
int m = 0;
for (int i = 0; i < n; i = longestArcFrom[i]) ++m;
// Calculate b[]
std::unique_ptr<int[]> b(new int[m + 1]);
b[m] = n;
for (int i = 0, j = 0; j < m; i = longestArcFrom[i], ++j) b[j] = i;
// NOTE: a[] need not be completely found - we just remember the
// a=a[j+1] currently needed.
// Now, build the optimal polygon
for (int j = m - 1, a = n; j >= 0; --j) {
int k;
for (k = b[j]; k >= 0 && longestArcFrom[k] >= a; --k) {
penaltyToEnd[k] = infinity;
for (int i = a; i <= longestArcFrom[k]; ++i) {
double newPenalty = penaltyToEnd[i] + penalty(border, k, i);
if (newPenalty < penaltyToEnd[k]) penaltyToEnd[k] = newPenalty;
minPenaltyNext = i;
}
minPenaltyNextArray[k] = minPenaltyNext;
}
a = k + 1;
}
// Finally, read off the optimal polygon
res.resize(m);
for (int i = 0, j = 0; i < n; i = minPenaltyNextArray[i], ++j) {
res[j] = ContourNode(border[i].x(), border[i].y());
// Ambiguities are still remembered in the output polygon.
if (border[i].getAmbiguous() == RawBorderPoint::left)
res[j].setAttribute(ContourNode::AMBIGUOUS_LEFT);
if (border[i].getAmbiguous() == RawBorderPoint::right)
res[j].setAttribute(ContourNode::AMBIGUOUS_RIGHT);
}
delete[] border.sums();
delete[] border.sums2();
delete[] border.sumsMix();
}
//--------------------------------------------------------------------------
// Reduction caller and list copier.
inline void reduceBorders(BorderList &borders, Contours &result,
bool ambiguitiesCheck) {
unsigned int i, j;
// Initialize output container
result.resize(borders.size());
// Copy results
for (i = 0; i < borders.size(); ++i) {
result[i].resize(borders[i].size());
for (j = 0; j < borders[i].size(); ++j) {
reduceBorder(*borders[i][j], result[i][j], ambiguitiesCheck);
delete borders[i][j];
}
}
}
//--------------------------------------------------------------------------
//===========================
// Polygonization Main
//===========================
// Extracts a polygonal, minimal yet faithful representation of image contours
// Contours* polygonize(const TRasterP &ras){
void polygonize(const TRasterP &ras, Contours &polygons,
VectorizerCoreGlobals &g) {
BorderList *borders;
borders = extractBorders(ras, g.currConfig->m_threshold,
g.currConfig->m_despeckling);
reduceBorders(*borders, polygons, g.currConfig->m_maxThickness > 0.0);
}