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Diffstat (limited to 'Build/source/libs/potrace/potrace-src/src/trace.c')
-rw-r--r-- | Build/source/libs/potrace/potrace-src/src/trace.c | 1249 |
1 files changed, 1249 insertions, 0 deletions
diff --git a/Build/source/libs/potrace/potrace-src/src/trace.c b/Build/source/libs/potrace/potrace-src/src/trace.c new file mode 100644 index 00000000000..b830764447b --- /dev/null +++ b/Build/source/libs/potrace/potrace-src/src/trace.c @@ -0,0 +1,1249 @@ +/* Copyright (C) 2001-2019 Peter Selinger. + This file is part of Potrace. It is free software and it is covered + by the GNU General Public License. See the file COPYING for details. */ + +/* transform jaggy paths into smooth curves */ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#include <stdio.h> +#include <math.h> +#include <stdlib.h> +#include <string.h> + +#include "potracelib.h" +#include "curve.h" +#include "lists.h" +#include "auxiliary.h" +#include "trace.h" +#include "progress.h" + +#define INFTY 10000000 /* it suffices that this is longer than any + path; it need not be really infinite */ +#define COS179 -0.999847695156 /* the cosine of 179 degrees */ + +/* ---------------------------------------------------------------------- */ +#define SAFE_CALLOC(var, n, typ) \ + if ((var = (typ *)calloc(n, sizeof(typ))) == NULL) goto calloc_error + +/* ---------------------------------------------------------------------- */ +/* auxiliary functions */ + +/* return a direction that is 90 degrees counterclockwise from p2-p0, + but then restricted to one of the major wind directions (n, nw, w, etc) */ +static inline point_t dorth_infty(dpoint_t p0, dpoint_t p2) { + point_t r; + + r.y = sign(p2.x-p0.x); + r.x = -sign(p2.y-p0.y); + + return r; +} + +/* return (p1-p0)x(p2-p0), the area of the parallelogram */ +static inline double dpara(dpoint_t p0, dpoint_t p1, dpoint_t p2) { + double x1, y1, x2, y2; + + x1 = p1.x-p0.x; + y1 = p1.y-p0.y; + x2 = p2.x-p0.x; + y2 = p2.y-p0.y; + + return x1*y2 - x2*y1; +} + +/* ddenom/dpara have the property that the square of radius 1 centered + at p1 intersects the line p0p2 iff |dpara(p0,p1,p2)| <= ddenom(p0,p2) */ +static inline double ddenom(dpoint_t p0, dpoint_t p2) { + point_t r = dorth_infty(p0, p2); + + return r.y*(p2.x-p0.x) - r.x*(p2.y-p0.y); +} + +/* return 1 if a <= b < c < a, in a cyclic sense (mod n) */ +static inline int cyclic(int a, int b, int c) { + if (a<=c) { + return (a<=b && b<c); + } else { + return (a<=b || b<c); + } +} + +/* determine the center and slope of the line i..j. Assume i<j. Needs + "sum" components of p to be set. */ +static void pointslope(privpath_t *pp, int i, int j, dpoint_t *ctr, dpoint_t *dir) { + /* assume i<j */ + + int n = pp->len; + sums_t *sums = pp->sums; + + double x, y, x2, xy, y2; + double k; + double a, b, c, lambda2, l; + int r=0; /* rotations from i to j */ + + while (j>=n) { + j-=n; + r+=1; + } + while (i>=n) { + i-=n; + r-=1; + } + while (j<0) { + j+=n; + r-=1; + } + while (i<0) { + i+=n; + r+=1; + } + + x = sums[j+1].x-sums[i].x+r*sums[n].x; + y = sums[j+1].y-sums[i].y+r*sums[n].y; + x2 = sums[j+1].x2-sums[i].x2+r*sums[n].x2; + xy = sums[j+1].xy-sums[i].xy+r*sums[n].xy; + y2 = sums[j+1].y2-sums[i].y2+r*sums[n].y2; + k = j+1-i+r*n; + + ctr->x = x/k; + ctr->y = y/k; + + a = (x2-(double)x*x/k)/k; + b = (xy-(double)x*y/k)/k; + c = (y2-(double)y*y/k)/k; + + lambda2 = (a+c+sqrt((a-c)*(a-c)+4*b*b))/2; /* larger e.value */ + + /* now find e.vector for lambda2 */ + a -= lambda2; + c -= lambda2; + + if (fabs(a) >= fabs(c)) { + l = sqrt(a*a+b*b); + if (l!=0) { + dir->x = -b/l; + dir->y = a/l; + } + } else { + l = sqrt(c*c+b*b); + if (l!=0) { + dir->x = -c/l; + dir->y = b/l; + } + } + if (l==0) { + dir->x = dir->y = 0; /* sometimes this can happen when k=4: + the two eigenvalues coincide */ + } +} + +/* the type of (affine) quadratic forms, represented as symmetric 3x3 + matrices. The value of the quadratic form at a vector (x,y) is v^t + Q v, where v = (x,y,1)^t. */ +typedef double quadform_t[3][3]; + +/* Apply quadratic form Q to vector w = (w.x,w.y) */ +static inline double quadform(quadform_t Q, dpoint_t w) { + double v[3]; + int i, j; + double sum; + + v[0] = w.x; + v[1] = w.y; + v[2] = 1; + sum = 0.0; + + for (i=0; i<3; i++) { + for (j=0; j<3; j++) { + sum += v[i] * Q[i][j] * v[j]; + } + } + return sum; +} + +/* calculate p1 x p2 */ +static inline int xprod(point_t p1, point_t p2) { + return p1.x*p2.y - p1.y*p2.x; +} + +/* calculate (p1-p0)x(p3-p2) */ +static inline double cprod(dpoint_t p0, dpoint_t p1, dpoint_t p2, dpoint_t p3) { + double x1, y1, x2, y2; + + x1 = p1.x - p0.x; + y1 = p1.y - p0.y; + x2 = p3.x - p2.x; + y2 = p3.y - p2.y; + + return x1*y2 - x2*y1; +} + +/* calculate (p1-p0)*(p2-p0) */ +static inline double iprod(dpoint_t p0, dpoint_t p1, dpoint_t p2) { + double x1, y1, x2, y2; + + x1 = p1.x - p0.x; + y1 = p1.y - p0.y; + x2 = p2.x - p0.x; + y2 = p2.y - p0.y; + + return x1*x2 + y1*y2; +} + +/* calculate (p1-p0)*(p3-p2) */ +static inline double iprod1(dpoint_t p0, dpoint_t p1, dpoint_t p2, dpoint_t p3) { + double x1, y1, x2, y2; + + x1 = p1.x - p0.x; + y1 = p1.y - p0.y; + x2 = p3.x - p2.x; + y2 = p3.y - p2.y; + + return x1*x2 + y1*y2; +} + +/* calculate distance between two points */ +static inline double ddist(dpoint_t p, dpoint_t q) { + return sqrt(sq(p.x-q.x)+sq(p.y-q.y)); +} + +/* calculate point of a bezier curve */ +static inline dpoint_t bezier(double t, dpoint_t p0, dpoint_t p1, dpoint_t p2, dpoint_t p3) { + double s = 1-t; + dpoint_t res; + + /* Note: a good optimizing compiler (such as gcc-3) reduces the + following to 16 multiplications, using common subexpression + elimination. */ + + res.x = s*s*s*p0.x + 3*(s*s*t)*p1.x + 3*(t*t*s)*p2.x + t*t*t*p3.x; + res.y = s*s*s*p0.y + 3*(s*s*t)*p1.y + 3*(t*t*s)*p2.y + t*t*t*p3.y; + + return res; +} + +/* calculate the point t in [0..1] on the (convex) bezier curve + (p0,p1,p2,p3) which is tangent to q1-q0. Return -1.0 if there is no + solution in [0..1]. */ +static double tangent(dpoint_t p0, dpoint_t p1, dpoint_t p2, dpoint_t p3, dpoint_t q0, dpoint_t q1) { + double A, B, C; /* (1-t)^2 A + 2(1-t)t B + t^2 C = 0 */ + double a, b, c; /* a t^2 + b t + c = 0 */ + double d, s, r1, r2; + + A = cprod(p0, p1, q0, q1); + B = cprod(p1, p2, q0, q1); + C = cprod(p2, p3, q0, q1); + + a = A - 2*B + C; + b = -2*A + 2*B; + c = A; + + d = b*b - 4*a*c; + + if (a==0 || d<0) { + return -1.0; + } + + s = sqrt(d); + + r1 = (-b + s) / (2 * a); + r2 = (-b - s) / (2 * a); + + if (r1 >= 0 && r1 <= 1) { + return r1; + } else if (r2 >= 0 && r2 <= 1) { + return r2; + } else { + return -1.0; + } +} + +/* ---------------------------------------------------------------------- */ +/* Preparation: fill in the sum* fields of a path (used for later + rapid summing). Return 0 on success, 1 with errno set on + failure. */ +static int calc_sums(privpath_t *pp) { + int i, x, y; + int n = pp->len; + + SAFE_CALLOC(pp->sums, pp->len+1, sums_t); + + /* origin */ + pp->x0 = pp->pt[0].x; + pp->y0 = pp->pt[0].y; + + /* preparatory computation for later fast summing */ + pp->sums[0].x2 = pp->sums[0].xy = pp->sums[0].y2 = pp->sums[0].x = pp->sums[0].y = 0; + for (i=0; i<n; i++) { + x = pp->pt[i].x - pp->x0; + y = pp->pt[i].y - pp->y0; + pp->sums[i+1].x = pp->sums[i].x + x; + pp->sums[i+1].y = pp->sums[i].y + y; + pp->sums[i+1].x2 = pp->sums[i].x2 + (double)x*x; + pp->sums[i+1].xy = pp->sums[i].xy + (double)x*y; + pp->sums[i+1].y2 = pp->sums[i].y2 + (double)y*y; + } + return 0; + + calloc_error: + return 1; +} + +/* ---------------------------------------------------------------------- */ +/* Stage 1: determine the straight subpaths (Sec. 2.2.1). Fill in the + "lon" component of a path object (based on pt/len). For each i, + lon[i] is the furthest index such that a straight line can be drawn + from i to lon[i]. Return 1 on error with errno set, else 0. */ + +/* this algorithm depends on the fact that the existence of straight + subpaths is a triplewise property. I.e., there exists a straight + line through squares i0,...,in iff there exists a straight line + through i,j,k, for all i0<=i<j<k<=in. (Proof?) */ + +/* this implementation of calc_lon is O(n^2). It replaces an older + O(n^3) version. A "constraint" means that future points must + satisfy xprod(constraint[0], cur) >= 0 and xprod(constraint[1], + cur) <= 0. */ + +/* Remark for Potrace 1.1: the current implementation of calc_lon is + more complex than the implementation found in Potrace 1.0, but it + is considerably faster. The introduction of the "nc" data structure + means that we only have to test the constraints for "corner" + points. On a typical input file, this speeds up the calc_lon + function by a factor of 31.2, thereby decreasing its time share + within the overall Potrace algorithm from 72.6% to 7.82%, and + speeding up the overall algorithm by a factor of 3.36. On another + input file, calc_lon was sped up by a factor of 6.7, decreasing its + time share from 51.4% to 13.61%, and speeding up the overall + algorithm by a factor of 1.78. In any case, the savings are + substantial. */ + +/* returns 0 on success, 1 on error with errno set */ +static int calc_lon(privpath_t *pp) { + point_t *pt = pp->pt; + int n = pp->len; + int i, j, k, k1; + int ct[4], dir; + point_t constraint[2]; + point_t cur; + point_t off; + int *pivk = NULL; /* pivk[n] */ + int *nc = NULL; /* nc[n]: next corner */ + point_t dk; /* direction of k-k1 */ + int a, b, c, d; + + SAFE_CALLOC(pivk, n, int); + SAFE_CALLOC(nc, n, int); + + /* initialize the nc data structure. Point from each point to the + furthest future point to which it is connected by a vertical or + horizontal segment. We take advantage of the fact that there is + always a direction change at 0 (due to the path decomposition + algorithm). But even if this were not so, there is no harm, as + in practice, correctness does not depend on the word "furthest" + above. */ + k = 0; + for (i=n-1; i>=0; i--) { + if (pt[i].x != pt[k].x && pt[i].y != pt[k].y) { + k = i+1; /* necessarily i<n-1 in this case */ + } + nc[i] = k; + } + + SAFE_CALLOC(pp->lon, n, int); + + /* determine pivot points: for each i, let pivk[i] be the furthest k + such that all j with i<j<k lie on a line connecting i,k. */ + + for (i=n-1; i>=0; i--) { + ct[0] = ct[1] = ct[2] = ct[3] = 0; + + /* keep track of "directions" that have occurred */ + dir = (3+3*(pt[mod(i+1,n)].x-pt[i].x)+(pt[mod(i+1,n)].y-pt[i].y))/2; + ct[dir]++; + + constraint[0].x = 0; + constraint[0].y = 0; + constraint[1].x = 0; + constraint[1].y = 0; + + /* find the next k such that no straight line from i to k */ + k = nc[i]; + k1 = i; + while (1) { + + dir = (3+3*sign(pt[k].x-pt[k1].x)+sign(pt[k].y-pt[k1].y))/2; + ct[dir]++; + + /* if all four "directions" have occurred, cut this path */ + if (ct[0] && ct[1] && ct[2] && ct[3]) { + pivk[i] = k1; + goto foundk; + } + + cur.x = pt[k].x - pt[i].x; + cur.y = pt[k].y - pt[i].y; + + /* see if current constraint is violated */ + if (xprod(constraint[0], cur) < 0 || xprod(constraint[1], cur) > 0) { + goto constraint_viol; + } + + /* else, update constraint */ + if (abs(cur.x) <= 1 && abs(cur.y) <= 1) { + /* no constraint */ + } else { + off.x = cur.x + ((cur.y>=0 && (cur.y>0 || cur.x<0)) ? 1 : -1); + off.y = cur.y + ((cur.x<=0 && (cur.x<0 || cur.y<0)) ? 1 : -1); + if (xprod(constraint[0], off) >= 0) { + constraint[0] = off; + } + off.x = cur.x + ((cur.y<=0 && (cur.y<0 || cur.x<0)) ? 1 : -1); + off.y = cur.y + ((cur.x>=0 && (cur.x>0 || cur.y<0)) ? 1 : -1); + if (xprod(constraint[1], off) <= 0) { + constraint[1] = off; + } + } + k1 = k; + k = nc[k1]; + if (!cyclic(k,i,k1)) { + break; + } + } + constraint_viol: + /* k1 was the last "corner" satisfying the current constraint, and + k is the first one violating it. We now need to find the last + point along k1..k which satisfied the constraint. */ + dk.x = sign(pt[k].x-pt[k1].x); + dk.y = sign(pt[k].y-pt[k1].y); + cur.x = pt[k1].x - pt[i].x; + cur.y = pt[k1].y - pt[i].y; + /* find largest integer j such that xprod(constraint[0], cur+j*dk) + >= 0 and xprod(constraint[1], cur+j*dk) <= 0. Use bilinearity + of xprod. */ + a = xprod(constraint[0], cur); + b = xprod(constraint[0], dk); + c = xprod(constraint[1], cur); + d = xprod(constraint[1], dk); + /* find largest integer j such that a+j*b>=0 and c+j*d<=0. This + can be solved with integer arithmetic. */ + j = INFTY; + if (b<0) { + j = floordiv(a,-b); + } + if (d>0) { + j = min(j, floordiv(-c,d)); + } + pivk[i] = mod(k1+j,n); + foundk: + ; + } /* for i */ + + /* clean up: for each i, let lon[i] be the largest k such that for + all i' with i<=i'<k, i'<k<=pivk[i']. */ + + j=pivk[n-1]; + pp->lon[n-1]=j; + for (i=n-2; i>=0; i--) { + if (cyclic(i+1,pivk[i],j)) { + j=pivk[i]; + } + pp->lon[i]=j; + } + + for (i=n-1; cyclic(mod(i+1,n),j,pp->lon[i]); i--) { + pp->lon[i] = j; + } + + free(pivk); + free(nc); + return 0; + + calloc_error: + free(pivk); + free(nc); + return 1; +} + + +/* ---------------------------------------------------------------------- */ +/* Stage 2: calculate the optimal polygon (Sec. 2.2.2-2.2.4). */ + +/* Auxiliary function: calculate the penalty of an edge from i to j in + the given path. This needs the "lon" and "sum*" data. */ + +static double penalty3(privpath_t *pp, int i, int j) { + int n = pp->len; + point_t *pt = pp->pt; + sums_t *sums = pp->sums; + + /* assume 0<=i<j<=n */ + double x, y, x2, xy, y2; + double k; + double a, b, c, s; + double px, py, ex, ey; + + int r = 0; /* rotations from i to j */ + + if (j>=n) { + j -= n; + r = 1; + } + + /* critical inner loop: the "if" gives a 4.6 percent speedup */ + if (r == 0) { + x = sums[j+1].x - sums[i].x; + y = sums[j+1].y - sums[i].y; + x2 = sums[j+1].x2 - sums[i].x2; + xy = sums[j+1].xy - sums[i].xy; + y2 = sums[j+1].y2 - sums[i].y2; + k = j+1 - i; + } else { + x = sums[j+1].x - sums[i].x + sums[n].x; + y = sums[j+1].y - sums[i].y + sums[n].y; + x2 = sums[j+1].x2 - sums[i].x2 + sums[n].x2; + xy = sums[j+1].xy - sums[i].xy + sums[n].xy; + y2 = sums[j+1].y2 - sums[i].y2 + sums[n].y2; + k = j+1 - i + n; + } + + px = (pt[i].x + pt[j].x) / 2.0 - pt[0].x; + py = (pt[i].y + pt[j].y) / 2.0 - pt[0].y; + ey = (pt[j].x - pt[i].x); + ex = -(pt[j].y - pt[i].y); + + a = ((x2 - 2*x*px) / k + px*px); + b = ((xy - x*py - y*px) / k + px*py); + c = ((y2 - 2*y*py) / k + py*py); + + s = ex*ex*a + 2*ex*ey*b + ey*ey*c; + + return sqrt(s); +} + +/* find the optimal polygon. Fill in the m and po components. Return 1 + on failure with errno set, else 0. Non-cyclic version: assumes i=0 + is in the polygon. Fixme: implement cyclic version. */ +static int bestpolygon(privpath_t *pp) +{ + int i, j, m, k; + int n = pp->len; + double *pen = NULL; /* pen[n+1]: penalty vector */ + int *prev = NULL; /* prev[n+1]: best path pointer vector */ + int *clip0 = NULL; /* clip0[n]: longest segment pointer, non-cyclic */ + int *clip1 = NULL; /* clip1[n+1]: backwards segment pointer, non-cyclic */ + int *seg0 = NULL; /* seg0[m+1]: forward segment bounds, m<=n */ + int *seg1 = NULL; /* seg1[m+1]: backward segment bounds, m<=n */ + double thispen; + double best; + int c; + + SAFE_CALLOC(pen, n+1, double); + SAFE_CALLOC(prev, n+1, int); + SAFE_CALLOC(clip0, n, int); + SAFE_CALLOC(clip1, n+1, int); + SAFE_CALLOC(seg0, n+1, int); + SAFE_CALLOC(seg1, n+1, int); + + /* calculate clipped paths */ + for (i=0; i<n; i++) { + c = mod(pp->lon[mod(i-1,n)]-1,n); + if (c == i) { + c = mod(i+1,n); + } + if (c < i) { + clip0[i] = n; + } else { + clip0[i] = c; + } + } + + /* calculate backwards path clipping, non-cyclic. j <= clip0[i] iff + clip1[j] <= i, for i,j=0..n. */ + j = 1; + for (i=0; i<n; i++) { + while (j <= clip0[i]) { + clip1[j] = i; + j++; + } + } + + /* calculate seg0[j] = longest path from 0 with j segments */ + i = 0; + for (j=0; i<n; j++) { + seg0[j] = i; + i = clip0[i]; + } + seg0[j] = n; + m = j; + + /* calculate seg1[j] = longest path to n with m-j segments */ + i = n; + for (j=m; j>0; j--) { + seg1[j] = i; + i = clip1[i]; + } + seg1[0] = 0; + + /* now find the shortest path with m segments, based on penalty3 */ + /* note: the outer 2 loops jointly have at most n iterations, thus + the worst-case behavior here is quadratic. In practice, it is + close to linear since the inner loop tends to be short. */ + pen[0]=0; + for (j=1; j<=m; j++) { + for (i=seg1[j]; i<=seg0[j]; i++) { + best = -1; + for (k=seg0[j-1]; k>=clip1[i]; k--) { + thispen = penalty3(pp, k, i) + pen[k]; + if (best < 0 || thispen < best) { + prev[i] = k; + best = thispen; + } + } + pen[i] = best; + } + } + + pp->m = m; + SAFE_CALLOC(pp->po, m, int); + + /* read off shortest path */ + for (i=n, j=m-1; i>0; j--) { + i = prev[i]; + pp->po[j] = i; + } + + free(pen); + free(prev); + free(clip0); + free(clip1); + free(seg0); + free(seg1); + return 0; + + calloc_error: + free(pen); + free(prev); + free(clip0); + free(clip1); + free(seg0); + free(seg1); + return 1; +} + +/* ---------------------------------------------------------------------- */ +/* Stage 3: vertex adjustment (Sec. 2.3.1). */ + +/* Adjust vertices of optimal polygon: calculate the intersection of + the two "optimal" line segments, then move it into the unit square + if it lies outside. Return 1 with errno set on error; 0 on + success. */ + +static int adjust_vertices(privpath_t *pp) { + int m = pp->m; + int *po = pp->po; + int n = pp->len; + point_t *pt = pp->pt; + int x0 = pp->x0; + int y0 = pp->y0; + + dpoint_t *ctr = NULL; /* ctr[m] */ + dpoint_t *dir = NULL; /* dir[m] */ + quadform_t *q = NULL; /* q[m] */ + double v[3]; + double d; + int i, j, k, l; + dpoint_t s; + int r; + + SAFE_CALLOC(ctr, m, dpoint_t); + SAFE_CALLOC(dir, m, dpoint_t); + SAFE_CALLOC(q, m, quadform_t); + + r = privcurve_init(&pp->curve, m); + if (r) { + goto calloc_error; + } + + /* calculate "optimal" point-slope representation for each line + segment */ + for (i=0; i<m; i++) { + j = po[mod(i+1,m)]; + j = mod(j-po[i],n)+po[i]; + pointslope(pp, po[i], j, &ctr[i], &dir[i]); + } + + /* represent each line segment as a singular quadratic form; the + distance of a point (x,y) from the line segment will be + (x,y,1)Q(x,y,1)^t, where Q=q[i]. */ + for (i=0; i<m; i++) { + d = sq(dir[i].x) + sq(dir[i].y); + if (d == 0.0) { + for (j=0; j<3; j++) { + for (k=0; k<3; k++) { + q[i][j][k] = 0; + } + } + } else { + v[0] = dir[i].y; + v[1] = -dir[i].x; + v[2] = - v[1] * ctr[i].y - v[0] * ctr[i].x; + for (l=0; l<3; l++) { + for (k=0; k<3; k++) { + q[i][l][k] = v[l] * v[k] / d; + } + } + } + } + + /* now calculate the "intersections" of consecutive segments. + Instead of using the actual intersection, we find the point + within a given unit square which minimizes the square distance to + the two lines. */ + for (i=0; i<m; i++) { + quadform_t Q; + dpoint_t w; + double dx, dy; + double det; + double min, cand; /* minimum and candidate for minimum of quad. form */ + double xmin, ymin; /* coordinates of minimum */ + int z; + + /* let s be the vertex, in coordinates relative to x0/y0 */ + s.x = pt[po[i]].x-x0; + s.y = pt[po[i]].y-y0; + + /* intersect segments i-1 and i */ + + j = mod(i-1,m); + + /* add quadratic forms */ + for (l=0; l<3; l++) { + for (k=0; k<3; k++) { + Q[l][k] = q[j][l][k] + q[i][l][k]; + } + } + + while(1) { + /* minimize the quadratic form Q on the unit square */ + /* find intersection */ + +#ifdef HAVE_GCC_LOOP_BUG + /* work around gcc bug #12243 */ + free(NULL); +#endif + + det = Q[0][0]*Q[1][1] - Q[0][1]*Q[1][0]; + if (det != 0.0) { + w.x = (-Q[0][2]*Q[1][1] + Q[1][2]*Q[0][1]) / det; + w.y = ( Q[0][2]*Q[1][0] - Q[1][2]*Q[0][0]) / det; + break; + } + + /* matrix is singular - lines are parallel. Add another, + orthogonal axis, through the center of the unit square */ + if (Q[0][0]>Q[1][1]) { + v[0] = -Q[0][1]; + v[1] = Q[0][0]; + } else if (Q[1][1]) { + v[0] = -Q[1][1]; + v[1] = Q[1][0]; + } else { + v[0] = 1; + v[1] = 0; + } + d = sq(v[0]) + sq(v[1]); + v[2] = - v[1] * s.y - v[0] * s.x; + for (l=0; l<3; l++) { + for (k=0; k<3; k++) { + Q[l][k] += v[l] * v[k] / d; + } + } + } + dx = fabs(w.x-s.x); + dy = fabs(w.y-s.y); + if (dx <= .5 && dy <= .5) { + pp->curve.vertex[i].x = w.x+x0; + pp->curve.vertex[i].y = w.y+y0; + continue; + } + + /* the minimum was not in the unit square; now minimize quadratic + on boundary of square */ + min = quadform(Q, s); + xmin = s.x; + ymin = s.y; + + if (Q[0][0] == 0.0) { + goto fixx; + } + for (z=0; z<2; z++) { /* value of the y-coordinate */ + w.y = s.y-0.5+z; + w.x = - (Q[0][1] * w.y + Q[0][2]) / Q[0][0]; + dx = fabs(w.x-s.x); + cand = quadform(Q, w); + if (dx <= .5 && cand < min) { + min = cand; + xmin = w.x; + ymin = w.y; + } + } + fixx: + if (Q[1][1] == 0.0) { + goto corners; + } + for (z=0; z<2; z++) { /* value of the x-coordinate */ + w.x = s.x-0.5+z; + w.y = - (Q[1][0] * w.x + Q[1][2]) / Q[1][1]; + dy = fabs(w.y-s.y); + cand = quadform(Q, w); + if (dy <= .5 && cand < min) { + min = cand; + xmin = w.x; + ymin = w.y; + } + } + corners: + /* check four corners */ + for (l=0; l<2; l++) { + for (k=0; k<2; k++) { + w.x = s.x-0.5+l; + w.y = s.y-0.5+k; + cand = quadform(Q, w); + if (cand < min) { + min = cand; + xmin = w.x; + ymin = w.y; + } + } + } + + pp->curve.vertex[i].x = xmin + x0; + pp->curve.vertex[i].y = ymin + y0; + continue; + } + + free(ctr); + free(dir); + free(q); + return 0; + + calloc_error: + free(ctr); + free(dir); + free(q); + return 1; +} + +/* ---------------------------------------------------------------------- */ +/* Stage 4: smoothing and corner analysis (Sec. 2.3.3) */ + +/* reverse orientation of a path */ +static void reverse(privcurve_t *curve) { + int m = curve->n; + int i, j; + dpoint_t tmp; + + for (i=0, j=m-1; i<j; i++, j--) { + tmp = curve->vertex[i]; + curve->vertex[i] = curve->vertex[j]; + curve->vertex[j] = tmp; + } +} + +/* Always succeeds */ +static void smooth(privcurve_t *curve, double alphamax) { + int m = curve->n; + + int i, j, k; + double dd, denom, alpha; + dpoint_t p2, p3, p4; + + /* examine each vertex and find its best fit */ + for (i=0; i<m; i++) { + j = mod(i+1, m); + k = mod(i+2, m); + p4 = interval(1/2.0, curve->vertex[k], curve->vertex[j]); + + denom = ddenom(curve->vertex[i], curve->vertex[k]); + if (denom != 0.0) { + dd = dpara(curve->vertex[i], curve->vertex[j], curve->vertex[k]) / denom; + dd = fabs(dd); + alpha = dd>1 ? (1 - 1.0/dd) : 0; + alpha = alpha / 0.75; + } else { + alpha = 4/3.0; + } + curve->alpha0[j] = alpha; /* remember "original" value of alpha */ + + if (alpha >= alphamax) { /* pointed corner */ + curve->tag[j] = POTRACE_CORNER; + curve->c[j][1] = curve->vertex[j]; + curve->c[j][2] = p4; + } else { + if (alpha < 0.55) { + alpha = 0.55; + } else if (alpha > 1) { + alpha = 1; + } + p2 = interval(.5+.5*alpha, curve->vertex[i], curve->vertex[j]); + p3 = interval(.5+.5*alpha, curve->vertex[k], curve->vertex[j]); + curve->tag[j] = POTRACE_CURVETO; + curve->c[j][0] = p2; + curve->c[j][1] = p3; + curve->c[j][2] = p4; + } + curve->alpha[j] = alpha; /* store the "cropped" value of alpha */ + curve->beta[j] = 0.5; + } + curve->alphacurve = 1; + + return; +} + +/* ---------------------------------------------------------------------- */ +/* Stage 5: Curve optimization (Sec. 2.4) */ + +/* a private type for the result of opti_penalty */ +struct opti_s { + double pen; /* penalty */ + dpoint_t c[2]; /* curve parameters */ + double t, s; /* curve parameters */ + double alpha; /* curve parameter */ +}; +typedef struct opti_s opti_t; + +/* calculate best fit from i+.5 to j+.5. Assume i<j (cyclically). + Return 0 and set badness and parameters (alpha, beta), if + possible. Return 1 if impossible. */ +static int opti_penalty(privpath_t *pp, int i, int j, opti_t *res, double opttolerance, int *convc, double *areac) { + int m = pp->curve.n; + int k, k1, k2, conv, i1; + double area, alpha, d, d1, d2; + dpoint_t p0, p1, p2, p3, pt; + double A, R, A1, A2, A3, A4; + double s, t; + + /* check convexity, corner-freeness, and maximum bend < 179 degrees */ + + if (i==j) { /* sanity - a full loop can never be an opticurve */ + return 1; + } + + k = i; + i1 = mod(i+1, m); + k1 = mod(k+1, m); + conv = convc[k1]; + if (conv == 0) { + return 1; + } + d = ddist(pp->curve.vertex[i], pp->curve.vertex[i1]); + for (k=k1; k!=j; k=k1) { + k1 = mod(k+1, m); + k2 = mod(k+2, m); + if (convc[k1] != conv) { + return 1; + } + if (sign(cprod(pp->curve.vertex[i], pp->curve.vertex[i1], pp->curve.vertex[k1], pp->curve.vertex[k2])) != conv) { + return 1; + } + if (iprod1(pp->curve.vertex[i], pp->curve.vertex[i1], pp->curve.vertex[k1], pp->curve.vertex[k2]) < d * ddist(pp->curve.vertex[k1], pp->curve.vertex[k2]) * COS179) { + return 1; + } + } + + /* the curve we're working in: */ + p0 = pp->curve.c[mod(i,m)][2]; + p1 = pp->curve.vertex[mod(i+1,m)]; + p2 = pp->curve.vertex[mod(j,m)]; + p3 = pp->curve.c[mod(j,m)][2]; + + /* determine its area */ + area = areac[j] - areac[i]; + area -= dpara(pp->curve.vertex[0], pp->curve.c[i][2], pp->curve.c[j][2])/2; + if (i>=j) { + area += areac[m]; + } + + /* find intersection o of p0p1 and p2p3. Let t,s such that o = + interval(t,p0,p1) = interval(s,p3,p2). Let A be the area of the + triangle (p0,o,p3). */ + + A1 = dpara(p0, p1, p2); + A2 = dpara(p0, p1, p3); + A3 = dpara(p0, p2, p3); + /* A4 = dpara(p1, p2, p3); */ + A4 = A1+A3-A2; + + if (A2 == A1) { /* this should never happen */ + return 1; + } + + t = A3/(A3-A4); + s = A2/(A2-A1); + A = A2 * t / 2.0; + + if (A == 0.0) { /* this should never happen */ + return 1; + } + + R = area / A; /* relative area */ + alpha = 2 - sqrt(4 - R / 0.3); /* overall alpha for p0-o-p3 curve */ + + res->c[0] = interval(t * alpha, p0, p1); + res->c[1] = interval(s * alpha, p3, p2); + res->alpha = alpha; + res->t = t; + res->s = s; + + p1 = res->c[0]; + p2 = res->c[1]; /* the proposed curve is now (p0,p1,p2,p3) */ + + res->pen = 0; + + /* calculate penalty */ + /* check tangency with edges */ + for (k=mod(i+1,m); k!=j; k=k1) { + k1 = mod(k+1,m); + t = tangent(p0, p1, p2, p3, pp->curve.vertex[k], pp->curve.vertex[k1]); + if (t<-.5) { + return 1; + } + pt = bezier(t, p0, p1, p2, p3); + d = ddist(pp->curve.vertex[k], pp->curve.vertex[k1]); + if (d == 0.0) { /* this should never happen */ + return 1; + } + d1 = dpara(pp->curve.vertex[k], pp->curve.vertex[k1], pt) / d; + if (fabs(d1) > opttolerance) { + return 1; + } + if (iprod(pp->curve.vertex[k], pp->curve.vertex[k1], pt) < 0 || iprod(pp->curve.vertex[k1], pp->curve.vertex[k], pt) < 0) { + return 1; + } + res->pen += sq(d1); + } + + /* check corners */ + for (k=i; k!=j; k=k1) { + k1 = mod(k+1,m); + t = tangent(p0, p1, p2, p3, pp->curve.c[k][2], pp->curve.c[k1][2]); + if (t<-.5) { + return 1; + } + pt = bezier(t, p0, p1, p2, p3); + d = ddist(pp->curve.c[k][2], pp->curve.c[k1][2]); + if (d == 0.0) { /* this should never happen */ + return 1; + } + d1 = dpara(pp->curve.c[k][2], pp->curve.c[k1][2], pt) / d; + d2 = dpara(pp->curve.c[k][2], pp->curve.c[k1][2], pp->curve.vertex[k1]) / d; + d2 *= 0.75 * pp->curve.alpha[k1]; + if (d2 < 0) { + d1 = -d1; + d2 = -d2; + } + if (d1 < d2 - opttolerance) { + return 1; + } + if (d1 < d2) { + res->pen += sq(d1 - d2); + } + } + + return 0; +} + +/* optimize the path p, replacing sequences of Bezier segments by a + single segment when possible. Return 0 on success, 1 with errno set + on failure. */ +static int opticurve(privpath_t *pp, double opttolerance) { + int m = pp->curve.n; + int *pt = NULL; /* pt[m+1] */ + double *pen = NULL; /* pen[m+1] */ + int *len = NULL; /* len[m+1] */ + opti_t *opt = NULL; /* opt[m+1] */ + int om; + int i,j,r; + opti_t o; + dpoint_t p0; + int i1; + double area; + double alpha; + double *s = NULL; + double *t = NULL; + + int *convc = NULL; /* conv[m]: pre-computed convexities */ + double *areac = NULL; /* cumarea[m+1]: cache for fast area computation */ + + SAFE_CALLOC(pt, m+1, int); + SAFE_CALLOC(pen, m+1, double); + SAFE_CALLOC(len, m+1, int); + SAFE_CALLOC(opt, m+1, opti_t); + SAFE_CALLOC(convc, m, int); + SAFE_CALLOC(areac, m+1, double); + + /* pre-calculate convexity: +1 = right turn, -1 = left turn, 0 = corner */ + for (i=0; i<m; i++) { + if (pp->curve.tag[i] == POTRACE_CURVETO) { + convc[i] = sign(dpara(pp->curve.vertex[mod(i-1,m)], pp->curve.vertex[i], pp->curve.vertex[mod(i+1,m)])); + } else { + convc[i] = 0; + } + } + + /* pre-calculate areas */ + area = 0.0; + areac[0] = 0.0; + p0 = pp->curve.vertex[0]; + for (i=0; i<m; i++) { + i1 = mod(i+1, m); + if (pp->curve.tag[i1] == POTRACE_CURVETO) { + alpha = pp->curve.alpha[i1]; + area += 0.3*alpha*(4-alpha)*dpara(pp->curve.c[i][2], pp->curve.vertex[i1], pp->curve.c[i1][2])/2; + area += dpara(p0, pp->curve.c[i][2], pp->curve.c[i1][2])/2; + } + areac[i+1] = area; + } + + pt[0] = -1; + pen[0] = 0; + len[0] = 0; + + /* Fixme: we always start from a fixed point -- should find the best + curve cyclically */ + + for (j=1; j<=m; j++) { + /* calculate best path from 0 to j */ + pt[j] = j-1; + pen[j] = pen[j-1]; + len[j] = len[j-1]+1; + + for (i=j-2; i>=0; i--) { + r = opti_penalty(pp, i, mod(j,m), &o, opttolerance, convc, areac); + if (r) { + break; + } + if (len[j] > len[i]+1 || (len[j] == len[i]+1 && pen[j] > pen[i] + o.pen)) { + pt[j] = i; + pen[j] = pen[i] + o.pen; + len[j] = len[i] + 1; + opt[j] = o; + } + } + } + om = len[m]; + r = privcurve_init(&pp->ocurve, om); + if (r) { + goto calloc_error; + } + SAFE_CALLOC(s, om, double); + SAFE_CALLOC(t, om, double); + + j = m; + for (i=om-1; i>=0; i--) { + if (pt[j]==j-1) { + pp->ocurve.tag[i] = pp->curve.tag[mod(j,m)]; + pp->ocurve.c[i][0] = pp->curve.c[mod(j,m)][0]; + pp->ocurve.c[i][1] = pp->curve.c[mod(j,m)][1]; + pp->ocurve.c[i][2] = pp->curve.c[mod(j,m)][2]; + pp->ocurve.vertex[i] = pp->curve.vertex[mod(j,m)]; + pp->ocurve.alpha[i] = pp->curve.alpha[mod(j,m)]; + pp->ocurve.alpha0[i] = pp->curve.alpha0[mod(j,m)]; + pp->ocurve.beta[i] = pp->curve.beta[mod(j,m)]; + s[i] = t[i] = 1.0; + } else { + pp->ocurve.tag[i] = POTRACE_CURVETO; + pp->ocurve.c[i][0] = opt[j].c[0]; + pp->ocurve.c[i][1] = opt[j].c[1]; + pp->ocurve.c[i][2] = pp->curve.c[mod(j,m)][2]; + pp->ocurve.vertex[i] = interval(opt[j].s, pp->curve.c[mod(j,m)][2], pp->curve.vertex[mod(j,m)]); + pp->ocurve.alpha[i] = opt[j].alpha; + pp->ocurve.alpha0[i] = opt[j].alpha; + s[i] = opt[j].s; + t[i] = opt[j].t; + } + j = pt[j]; + } + + /* calculate beta parameters */ + for (i=0; i<om; i++) { + i1 = mod(i+1,om); + pp->ocurve.beta[i] = s[i] / (s[i] + t[i1]); + } + pp->ocurve.alphacurve = 1; + + free(pt); + free(pen); + free(len); + free(opt); + free(s); + free(t); + free(convc); + free(areac); + return 0; + + calloc_error: + free(pt); + free(pen); + free(len); + free(opt); + free(s); + free(t); + free(convc); + free(areac); + return 1; +} + +/* ---------------------------------------------------------------------- */ + +#define TRY(x) if (x) goto try_error + +/* return 0 on success, 1 on error with errno set. */ +int process_path(path_t *plist, const potrace_param_t *param, progress_t *progress) { + path_t *p; + double nn = 0, cn = 0; + + if (progress->callback) { + /* precompute task size for progress estimates */ + nn = 0; + list_forall (p, plist) { + nn += p->priv->len; + } + cn = 0; + } + + /* call downstream function with each path */ + list_forall (p, plist) { + TRY(calc_sums(p->priv)); + TRY(calc_lon(p->priv)); + TRY(bestpolygon(p->priv)); + TRY(adjust_vertices(p->priv)); + if (p->sign == '-') { /* reverse orientation of negative paths */ + reverse(&p->priv->curve); + } + smooth(&p->priv->curve, param->alphamax); + if (param->opticurve) { + TRY(opticurve(p->priv, param->opttolerance)); + p->priv->fcurve = &p->priv->ocurve; + } else { + p->priv->fcurve = &p->priv->curve; + } + privcurve_to_curve(p->priv->fcurve, &p->curve); + + if (progress->callback) { + cn += p->priv->len; + progress_update(cn/nn, progress); + } + } + + progress_update(1.0, progress); + + return 0; + + try_error: + return 1; +} |