Tracing. Potrace 1.9 update (see http://potrace.sourceforge.net/ChangeLog).

(bzr r10163)

16 files changed, 166 insertions, 128 deletions

diff --git a/src/trace/potrace/auxiliary.h b/src/trace/potrace/auxiliary.h
index 7baab851c..1c2765816 100644
--- a/src/trace/potrace/auxiliary.h
+++ b/src/trace/potrace/auxiliary.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
@@ -75,4 +75,31 @@ static inline int floordiv(int a, int n) {
 #define sq(a) ((a)*(a))
 #define cu(a) ((a)*(a)*(a))
 
+/* ---------------------------------------------------------------------- */
+/* deterministically and efficiently hash (x,y) into a pseudo-random bit */
+static inline int detrand(int x, int y) {
+  unsigned int z;
+  static const unsigned char t[256] = { 
+    /* non-linear sequence: constant term of inverse in GF(8), 
+       mod x^8+x^4+x^3+x+1 */
+    0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 1, 
+    0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 
+    0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 
+    1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 1, 
+    0, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 
+    0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 
+    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 
+    0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 
+    1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 
+    0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1, 
+    1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 
+  };
+
+  /* 0x04b3e375 and 0x05a8ef93 are chosen to contain every possible
+     5-bit sequence */
+  z = ((0x04b3e375 * x) ^ y) * 0x05a8ef93;
+  z = t[z & 0xff] ^ t[(z>>8) & 0xff] ^ t[(z>>16) & 0xff] ^ t[(z>>24) & 0xff];
+  return z;
+}
+
 #endif /* AUXILIARY_H */
diff --git a/src/trace/potrace/bitmap.h b/src/trace/potrace/bitmap.h
index 2a172b1ad..671382dc2 100644
--- a/src/trace/potrace/bitmap.h
+++ b/src/trace/potrace/bitmap.h
@@ -1,14 +1,10 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
 #ifndef BITMAP_H
 #define BITMAP_H
 
-#ifdef HAVE_CONFIG_H
-#include "config.h"
-#endif
-
 #include <string.h>
 #include <stdlib.h>
 
diff --git a/src/trace/potrace/curve.cpp b/src/trace/potrace/curve.cpp
index c9a6fbe04..00d7bd2db 100644
--- a/src/trace/potrace/curve.cpp
+++ b/src/trace/potrace/curve.cpp
@@ -1,8 +1,8 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
-/* $Id$ */
+/* $Id: curve.c 227 2010-12-16 05:47:19Z selinger $ */
 /* private part of the path and curve data structures */
 
 #include <stdio.h>
diff --git a/src/trace/potrace/curve.h b/src/trace/potrace/curve.h
index 45c0790be..bfde0af1a 100644
--- a/src/trace/potrace/curve.h
+++ b/src/trace/potrace/curve.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
diff --git a/src/trace/potrace/decompose.cpp b/src/trace/potrace/decompose.cpp
index 15c39825e..8219234c4 100644
--- a/src/trace/potrace/decompose.cpp
+++ b/src/trace/potrace/decompose.cpp
@@ -1,8 +1,8 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
-/* $Id$ */
+/* $Id: decompose.c 227 2010-12-16 05:47:19Z selinger $ */
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -55,32 +55,6 @@ static void clear_bm_with_bbox(potrace_bitmap_t *bm, bbox_t *bbox) {
 /* ---------------------------------------------------------------------- */
 /* auxiliary functions */
 
-/* deterministically and efficiently hash (x,y) into a pseudo-random bit */
-static inline int detrand(int x, int y) {
-  unsigned int z;
-  static const unsigned char t[256] = { 
-    /* non-linear sequence: constant term of inverse in GF(8), 
-       mod x^8+x^4+x^3+x+1 */
-    0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 1, 
-    0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 
-    0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 
-    1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 1, 
-    0, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 
-    0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 
-    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 
-    0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 
-    1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 
-    0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1, 
-    1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 
-  };
-
-  /* 0x04b3e375 and 0x05a8ef93 are chosen to contain every possible
-     5-bit sequence */
-  z = ((0x04b3e375 * x) ^ y) * 0x05a8ef93;
-  z = t[z & 0xff] ^ t[(z>>8) & 0xff] ^ t[(z>>16) & 0xff] ^ t[(z>>24) & 0xff];
-  return z & 1;
-}
-
 /* return the "majority" value of bitmap bm at intersection (x,y). We
    assume that the bitmap is balanced at "radius" 1.  */
 static int majority(potrace_bitmap_t *bm, int x, int y) {
@@ -304,7 +278,8 @@ static void pathlist_to_tree(path_t *plist, potrace_bitmap_t *bm) {
   path_t *heap, *heap1;
   path_t *cur;
   path_t *head;
-  path_t **hook, **hook_in, **hook_out; /* for fast appending to linked list */
+  path_t **plist_hook;          /* for fast appending to linked list */
+  path_t **hook_in, **hook_out; /* for fast appending to linked list */
   bbox_t bbox;
   
   bm_clear(bm, 0);
@@ -391,18 +366,18 @@ static void pathlist_to_tree(path_t *plist, potrace_bitmap_t *bm) {
     heap->next = NULL;  /* heap is a linked list of childlists */
   }
   plist = NULL;
-  hook = &plist;
+  plist_hook = &plist;
   while (heap) {
     heap1 = heap->next;
     for (p=heap; p; p=p->sibling) {
       /* p is a positive path */
       /* append to linked list */
-      list_insert_beforehook(p, hook);
+      list_insert_beforehook(p, plist_hook);
       
       /* go through its children */
       for (p1=p->childlist; p1; p1=p1->sibling) {
 	/* append to linked list */
-	list_insert_beforehook(p1, hook);
+	list_insert_beforehook(p1, plist_hook);
 	/* append its childlist to heap, if non-empty */
 	if (p1->childlist) {
 	  list_append(path_t, heap1, p1->childlist);
@@ -423,9 +398,12 @@ static void pathlist_to_tree(path_t *plist, potrace_bitmap_t *bm) {
 static int findnext(potrace_bitmap_t *bm, int *xp, int *yp) {
   int x;
   int y;
+  int x0;
+
+  x0 = (*xp) & ~(BM_WORDBITS-1);
 
   for (y=*yp; y>=0; y--) {
-    for (x=0; x<bm->w; x+=BM_WORDBITS) {
+    for (x=x0; x<bm->w; x+=BM_WORDBITS) {
       if (*bm_index(bm, x, y)) {
 	while (!BM_GET(bm, x, y)) {
 	  x++;
@@ -436,6 +414,7 @@ static int findnext(potrace_bitmap_t *bm, int *xp, int *yp) {
 	return 0;
       }
     }
+    x0 = 0;
   }
   /* not found */
   return 1;
@@ -451,7 +430,7 @@ int bm_to_pathlist(const potrace_bitmap_t *bm, path_t **plistp, const potrace_pa
   int y;
   path_t *p;
   path_t *plist = NULL;  /* linked list of path objects */
-  path_t **hook = &plist;  /* used to speed up appending to linked list */
+  path_t **plist_hook = &plist;  /* used to speed up appending to linked list */
   potrace_bitmap_t *bm1 = NULL;
   int sign;
 
@@ -465,6 +444,7 @@ int bm_to_pathlist(const potrace_bitmap_t *bm, path_t **plistp, const potrace_pa
   bm_clearexcess(bm1);
 
   /* iterate through components */
+  x = 0;
   y = bm1->h - 1;
   while (findnext(bm1, &x, &y) == 0) { 
     /* calculate the sign by looking at the original */
@@ -483,7 +463,7 @@ int bm_to_pathlist(const potrace_bitmap_t *bm, path_t **plistp, const potrace_pa
     if (p->area <= param->turdsize) {
       path_free(p);
     } else {
-      list_insert_beforehook(p, hook);
+      list_insert_beforehook(p, plist_hook);
     }
 
     if (bm1->h > 0) { /* to be sure */
diff --git a/src/trace/potrace/decompose.h b/src/trace/potrace/decompose.h
index 5552fa0a1..409439c62 100644
--- a/src/trace/potrace/decompose.h
+++ b/src/trace/potrace/decompose.h
@@ -1,14 +1,15 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
-/* $Id$ */
+/* $Id: decompose.h 227 2010-12-16 05:47:19Z selinger $ */
 
 #ifndef DECOMPOSE_H
 #define DECOMPOSE_H
 
 #include "potracelib.h"
 #include "progress.h"
+#include "curve.h"
 
 int bm_to_pathlist(const potrace_bitmap_t *bm, path_t **plistp, const potrace_param_t *param, progress_t *progress);
 
diff --git a/src/trace/potrace/greymap.cpp b/src/trace/potrace/greymap.cpp
index 646ecc3a5..770dd72e6 100644
--- a/src/trace/potrace/greymap.cpp
+++ b/src/trace/potrace/greymap.cpp
@@ -1,14 +1,13 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
-/* $Id$ */
+/* $Id: greymap.c 227 2010-12-16 05:47:19Z selinger $ */
 
 /* Routines for manipulating greymaps, including reading pgm files. We
    only deal with greymaps of depth 8 bits. */
 
 #include <stdlib.h>
-#include <errno.h>
 #include <string.h>
 #include <math.h>
 
@@ -28,7 +27,6 @@ static int gm_readbody_bmp(FILE *f, greymap_t **gmp);
 
 greymap_t *gm_new(int w, int h) {
   greymap_t *gm;
-  int errno_save;
 
   gm = (greymap_t *) malloc(sizeof(greymap_t));
   if (!gm) {
@@ -38,9 +36,7 @@ greymap_t *gm_new(int w, int h) {
   gm->h = h;
   gm->map = (signed short int *) malloc(w*h*sizeof(signed short int));
   if (!gm->map) {
-    errno_save = errno;
     free(gm);
-    errno = errno_save;
     return NULL;
   }
   return gm;
@@ -60,7 +56,7 @@ greymap_t *gm_dup(greymap_t *gm) {
   if (!gm1) {
     return NULL;
   }
-  memcpy(gm1->map, gm->map, gm->w*gm->h*2);
+  memcpy(gm1->map, gm->map, gm->w*gm->h*sizeof(signed short int));
   return gm1;
 }
 
@@ -69,7 +65,7 @@ void gm_clear(greymap_t *gm, int b) {
   int i;
 
   if (b==0) {
-    memset(gm->map, 0, gm->w*gm->h*2);
+    memset(gm->map, 0, gm->w*gm->h*sizeof(signed short int));
   } else {
     for (i=0; i<gm->w*gm->h; i++) {
       gm->map[i] = b;
@@ -161,16 +157,16 @@ static int readbit(FILE *f) {
 
 /* ---------------------------------------------------------------------- */
 
-char const *gm_read_error = NULL;
-
-/** Read a PNM stream: P1-P6 format (see pnm(5)), or a BMP stream, and
+/* read a PNM stream: P1-P6 format (see pnm(5)), or a BMP stream, and
    convert the output to a greymap. Return greymap in *gmp. Return 0
    on success, -1 on error with errno set, -2 on bad file format (with
    error message in gm_read_error), and 1 on premature end of file, -3
    on empty file (including files with only whitespace and comments),
    -4 if wrong magic number. If the return value is >=0, *gmp is
-   valid.
-   */
+   valid. */
+
+char const *gm_read_error = NULL;
+
 int gm_read(FILE *f, greymap_t **gmp) {
   int magic[2];
 
@@ -413,6 +409,7 @@ struct bmp_info_s {
   unsigned int ncolors;        /* number of colors in palette */
   unsigned int ColorsImportant;
   unsigned int ctbits;         /* sample size for color table */
+  int topdown;                 /* top-down mode? */
 };
 typedef struct bmp_info_s bmp_info_t;
 
@@ -481,6 +478,9 @@ static int bmp_forward(FILE *f, int pos) {
 #define TRY(x) if (x) goto try_error
 #define TRY_EOF(x) if (x) goto eof
 
+/* correct y-coordinate for top-down format */
+#define ycorr(y) (bmpinfo.topdown ? bmpinfo.h-1-y : y)
+
 /* read BMP stream after magic number. Return values as for gm_read.
    We choose to be as permissive as possible, since there are many
    programs out there which produce BMP. For instance, ppmtobmp can
@@ -512,7 +512,8 @@ static int gm_readbody_bmp(FILE *f, greymap_t **gmp) {
 
   /* info header */
   TRY(bmp_readint(f, 4, &bmpinfo.InfoSize));
-  if (bmpinfo.InfoSize == 40 || bmpinfo.InfoSize == 64) {
+  if (bmpinfo.InfoSize == 40 || bmpinfo.InfoSize == 64
+      || bmpinfo.InfoSize == 108 || bmpinfo.InfoSize == 124) {
     /* Windows or new OS/2 format */
     bmpinfo.ctbits = 32; /* sample size in color table */
     TRY(bmp_readint(f, 4, &bmpinfo.w));
@@ -525,6 +526,12 @@ static int gm_readbody_bmp(FILE *f, greymap_t **gmp) {
     TRY(bmp_readint(f, 4, &bmpinfo.YpixelsPerM));
     TRY(bmp_readint(f, 4, &bmpinfo.ncolors));
     TRY(bmp_readint(f, 4, &bmpinfo.ColorsImportant));
+    if ((signed int)bmpinfo.h < 0) {
+      bmpinfo.h = -bmpinfo.h;
+      bmpinfo.topdown = 1;
+    } else {
+      bmpinfo.topdown = 0;
+    }
   } else if (bmpinfo.InfoSize == 12) {
     /* old OS/2 format */
     bmpinfo.ctbits = 24; /* sample size in color table */
@@ -534,11 +541,12 @@ static int gm_readbody_bmp(FILE *f, greymap_t **gmp) {
     TRY(bmp_readint(f, 2, &bmpinfo.bits));
     bmpinfo.comp = 0;
     bmpinfo.ncolors = 0;
+    bmpinfo.topdown = 0;
   } else {
     goto format_error;
   }
 
-  /* forward to color table (i.e., if bmpinfo.InfoSize == 64) */
+  /* forward to color table (e.g., if bmpinfo.InfoSize == 64) */
   TRY(bmp_forward(f, 14+bmpinfo.InfoSize));
 
   if (bmpinfo.Planes != 1) {
@@ -593,7 +601,7 @@ static int gm_readbody_bmp(FILE *f, greymap_t **gmp) {
       for (i=0; 8*i<bmpinfo.w; i++) {
 	TRY_EOF(bmp_readint(f, 1, &b));
 	for (j=0; j<8; j++) {
-	  GM_PUT(gm, i*8+j, y, b & (0x80 >> j) ? coltable[1] : coltable[0]);
+	  GM_PUT(gm, i*8+j, ycorr(y), b & (0x80 >> j) ? coltable[1] : coltable[0]);
 	}
       }
       TRY(bmp_pad(f));
@@ -620,7 +628,7 @@ static int gm_readbody_bmp(FILE *f, greymap_t **gmp) {
 	b = bitbuf >> (INTBITS - bmpinfo.bits);
 	bitbuf <<= bmpinfo.bits;
 	n -= bmpinfo.bits;
-	GM_UPUT(gm, x, y, coltable[b]);
+	GM_UPUT(gm, x, ycorr(y), coltable[b]);
       }
       TRY(bmp_pad(f));
     }
@@ -640,7 +648,7 @@ static int gm_readbody_bmp(FILE *f, greymap_t **gmp) {
       for (x=0; x<bmpinfo.w; x++) {
         TRY_EOF(bmp_readint(f, bmpinfo.bits/8, &c));
 	c = ((c>>16) & 0xff) + ((c>>8) & 0xff) + (c & 0xff);
-        GM_UPUT(gm, x, y, c/3);
+        GM_UPUT(gm, x, ycorr(y), c/3);
       }
       TRY(bmp_pad(f));
     }
@@ -664,7 +672,7 @@ static int gm_readbody_bmp(FILE *f, greymap_t **gmp) {
 	  if (y>=bmpinfo.h) {
 	    break;
 	  }
-	  GM_UPUT(gm, x, y, col[i&1]);
+	  GM_UPUT(gm, x, ycorr(y), col[i&1]);
 	  x++;
 	}
       } else if (c == 0) {
@@ -693,7 +701,7 @@ static int gm_readbody_bmp(FILE *f, greymap_t **gmp) {
 	  if (y>=bmpinfo.h) {
 	    break;
 	  }
-	  GM_PUT(gm, x, y, coltable[(b>>(4-4*(i&1))) & 0xf]);
+	  GM_PUT(gm, x, ycorr(y), coltable[(b>>(4-4*(i&1))) & 0xf]);
 	  x++;
 	}
 	if ((c+1) & 2) {
@@ -720,7 +728,7 @@ static int gm_readbody_bmp(FILE *f, greymap_t **gmp) {
 	  if (y>=bmpinfo.h) {
 	    break;
 	  }
-	  GM_UPUT(gm, x, y, coltable[c]);
+	  GM_UPUT(gm, x, ycorr(y), coltable[c]);
 	  x++;
 	}
       } else if (c == 0) {
@@ -747,7 +755,7 @@ static int gm_readbody_bmp(FILE *f, greymap_t **gmp) {
           if (y>=bmpinfo.h) {
             break;
           }
-	  GM_PUT(gm, x, y, coltable[b]);
+	  GM_PUT(gm, x, ycorr(y), coltable[b]);
 	  x++;
 	}
 	if (c & 1) {
diff --git a/src/trace/potrace/greymap.h b/src/trace/potrace/greymap.h
index 059fec4e4..0736232a7 100644
--- a/src/trace/potrace/greymap.h
+++ b/src/trace/potrace/greymap.h
@@ -1,11 +1,11 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
-/* $Id$ */
+/* $Id: greymap.h 227 2010-12-16 05:47:19Z selinger $ */
 
-#ifndef PGM_H
-#define PGM_H
+#ifndef GREYMAP_H
+#define GREYMAP_H
 
 #include <stdio.h>
 
@@ -55,4 +55,4 @@ int gm_read(FILE *f, greymap_t **gmp);
 int gm_writepgm(FILE *f, greymap_t *gm, char *comment, int raw, int mode, double gamma);
 int gm_print(FILE *f, greymap_t *gm);
 
-#endif /* PGM_H */
+#endif /* GREYMAP_H */
diff --git a/src/trace/potrace/lists.h b/src/trace/potrace/lists.h
index fc853398a..4f78bf20f 100644
--- a/src/trace/potrace/lists.h
+++ b/src/trace/potrace/lists.h
@@ -1,8 +1,8 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
-/* $Id$ */
+/* $Id: lists.h 227 2010-12-16 05:47:19Z selinger $ */
 
 #ifndef _PS_LISTS_H
 #define _PS_LISTS_H
diff --git a/src/trace/potrace/potracelib.cpp b/src/trace/potrace/potracelib.cpp
index 17e04cabb..3dbf3230b 100644
--- a/src/trace/potrace/potracelib.cpp
+++ b/src/trace/potrace/potracelib.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
@@ -48,15 +48,16 @@ potrace_param_t *potrace_param_default(void) {
 /* On success, returns a Potrace state st with st->status ==
    POTRACE_STATUS_OK. On failure, returns NULL if no Potrace state
    could be created (with errno set), or returns an incomplete Potrace
-   state (with st->status == POTRACE_STATUS_INCOMPLETE). Complete or
-   incomplete Potrace state can be freed with potrace_state_free(). */
+   state (with st->status == POTRACE_STATUS_INCOMPLETE, and with errno
+   set). Complete or incomplete Potrace state can be freed with
+   potrace_state_free(). */
 potrace_state_t *potrace_trace(const potrace_param_t *param, const potrace_bitmap_t *bm) {
     int r;
     path_t *plist = NULL;
     potrace_state_t *st;
     progress_t prog;
     progress_t subprog;
-
+    
     /* prepare private progress bar state */
     prog.callback = param->progress.callback;
     prog.data = param->progress.data;
diff --git a/src/trace/potrace/potracelib.h b/src/trace/potrace/potracelib.h
index 0b93d65de..d15b05e5c 100644
--- a/src/trace/potrace/potracelib.h
+++ b/src/trace/potrace/potracelib.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
@@ -6,7 +6,11 @@
 #define POTRACELIB_H
 
 /* this file defines the API for the core Potrace library. For a more
-   detailed description of the API, see doc/potracelib.txt */
+   detailed description of the API, see potracelib.pdf */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 /* ---------------------------------------------------------------------- */
 /* tracing parameters */
@@ -128,4 +132,8 @@ void potrace_state_free(potrace_state_t *st);
    of potracelib */
 char *potrace_version(void);
 
+#ifdef  __cplusplus
+} /* end of extern "C" */
+#endif
+
 #endif /* POTRACELIB_H */
diff --git a/src/trace/potrace/progress.h b/src/trace/potrace/progress.h
index 0e077430d..220639c6e 100644
--- a/src/trace/potrace/progress.h
+++ b/src/trace/potrace/progress.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
@@ -28,7 +28,7 @@ typedef struct progress_s progress_t;
 static inline void progress_update(double d, progress_t *prog) {
   double d_scaled;
 
-  if (prog->callback != NULL) {
+  if (prog != NULL && prog->callback != NULL) {
     d_scaled = prog->min * (1-d) + prog->max * d;
     if (d == 1.0 || d_scaled >= prog->d_prev + prog->epsilon) {
       prog->callback(prog->min * (1-d) + prog->max * d, prog->data);
@@ -43,7 +43,7 @@ static inline void progress_update(double d, progress_t *prog) {
 static inline void progress_subrange_start(double a, double b, const progress_t *prog, progress_t *sub) {
   double min, max;
 
-  if (prog->callback == NULL) {
+  if (prog == NULL || prog->callback == NULL) {
     sub->callback = NULL;
     return;
   }
@@ -66,7 +66,7 @@ static inline void progress_subrange_start(double a, double b, const progress_t
 }
 
 static inline void progress_subrange_end(progress_t *prog, progress_t *sub) {
-  if (prog->callback != NULL) {
+  if (prog != NULL && prog->callback != NULL) {
     if (sub->callback == NULL) {
       progress_update(sub->b, prog);
     } else {
diff --git a/src/trace/potrace/render.cpp b/src/trace/potrace/render.cpp
index f9183b931..39bec0684 100644
--- a/src/trace/potrace/render.cpp
+++ b/src/trace/potrace/render.cpp
@@ -1,8 +1,8 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
-/* $Id$ */
+/* $Id: render.c 227 2010-12-16 05:47:19Z selinger $ */
 
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/src/trace/potrace/render.h b/src/trace/potrace/render.h
index 9c9d921d2..6cfbe0964 100644
--- a/src/trace/potrace/render.h
+++ b/src/trace/potrace/render.h
@@ -1,8 +1,8 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
-/* $Id$ */
+/* $Id: render.h 227 2010-12-16 05:47:19Z selinger $ */
 
 #ifndef RENDER_H
 #define RENDER_H
diff --git a/src/trace/potrace/trace.cpp b/src/trace/potrace/trace.cpp
index 909ffb712..8fe1a1bc4 100644
--- a/src/trace/potrace/trace.cpp
+++ b/src/trace/potrace/trace.cpp
@@ -1,8 +1,8 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
-/* $Id$ */
+/* $Id: trace.c 227 2010-12-16 05:47:19Z selinger $ */
 /* transform jaggy paths into smooth curves */
 
 #include <stdio.h>
@@ -483,28 +483,38 @@ static double penalty3(privpath_t *pp, int i, int j) {
   double a, b, c, s;
   double px, py, ex, ey;
 
-  int r=0; /* rotations from i to j */
+  int r = 0; /* rotations from i to j */
 
   if (j>=n) {
-    j-=n;
-    r+=1;
+    j -= 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;
-  
-  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);
+  /* 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;
 
@@ -513,7 +523,7 @@ static double penalty3(privpath_t *pp, int i, int j) {
 
 /* 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. */
+   is in the polygon. Fixme: implement cyclic version. */
 static int bestpolygon(privpath_t *pp)
 {
   int i, j, m, k;     
@@ -576,7 +586,7 @@ static int bestpolygon(privpath_t *pp)
   seg1[0] = 0;
 
   /* now find the shortest path with m segments, based on penalty3 */
-  /* note: the outer 2 loops jointly have at most n interations, thus
+  /* 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;
@@ -828,24 +838,27 @@ static int adjust_vertices(privpath_t *pp) {
 /* ---------------------------------------------------------------------- */
 /* Stage 4: smoothing and corner analysis (Sec. 2.3.3) */
 
-/* Always succeeds and returns 0 */
-static int smooth(privcurve_t *curve, int sign, double alphamax) {
+/* 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;
 
-  if (sign == '-') {
-    /* reverse orientation of negative paths */
-    for (i=0, j=m-1; i<j; i++, j--) {
-      dpoint_t tmp;
-      tmp = curve->vertex[i];
-      curve->vertex[i] = curve->vertex[j];
-      curve->vertex[j] = tmp;
-    }
-  }
-
   /* examine each vertex and find its best fit */
   for (i=0; i<m; i++) {
     j = mod(i+1, m);
@@ -885,7 +898,7 @@ static int smooth(privcurve_t *curve, int sign, double alphamax) {
   }
   curve->alphacurve = 1;
 
-  return 0;
+  return;
 }
 
 /* ---------------------------------------------------------------------- */
@@ -1098,7 +1111,7 @@ static int opticurve(privpath_t *pp, double opttolerance) {
   len[0] = 0;
 
   /* Fixme: we always start from a fixed point -- should find the best
-     curve cyclically ### */
+     curve cyclically */
 
   for (j=1; j<=m; j++) {
     /* calculate best path from 0 to j */
@@ -1206,7 +1219,10 @@ int process_path(path_t *plist, const potrace_param_t *param, progress_t *progre
     TRY(calc_lon(p->priv));
     TRY(bestpolygon(p->priv));
     TRY(adjust_vertices(p->priv));
-    TRY(smooth(&p->priv->curve, p->sign, param->alphamax));
+    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;
diff --git a/src/trace/potrace/trace.h b/src/trace/potrace/trace.h
index b33f8ba4d..72d1a3696 100644
--- a/src/trace/potrace/trace.h
+++ b/src/trace/potrace/trace.h
@@ -1,14 +1,15 @@
-/* Copyright (C) 2001-2007 Peter Selinger.
+/* Copyright (C) 2001-2010 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. */
 
-/* $Id$ */
+/* $Id: trace.h 227 2010-12-16 05:47:19Z selinger $ */
 
 #ifndef TRACE_H
 #define TRACE_H
 
 #include "potracelib.h"
 #include "progress.h"
+#include "curve.h"
 
 int process_path(path_t *plist, const potrace_param_t *param, progress_t *progress);