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/* Copyright (C) 2001-2017 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. */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <cstdint>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_INTTYPES_H
#include <inttypes.h>
#endif
#include "bitmap.h"
#include "curve.h"
#include "decompose.h"
#include "lists.h"
#include "potracelib.h"
#include "progress.h"
/* ---------------------------------------------------------------------- *//* 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;}
/* ---------------------------------------------------------------------- *//* auxiliary bitmap manipulations */
/* set the excess padding to 0 */static void bm_clearexcess( potrace_bitmap_t* bm ){ potrace_word mask; int y;
if( bm->w % BM_WORDBITS != 0 ) { mask = BM_ALLBITS << ( BM_WORDBITS - ( bm->w % BM_WORDBITS ) );
for( y = 0; y < bm->h; y++ ) { *bm_index( bm, bm->w, y ) &= mask; } }}
struct bbox_s{ int x0, x1, y0, y1; /* bounding box */};typedef struct bbox_s bbox_t;
/* clear the bm, assuming the bounding box is set correctly (faster
* than clearing the whole bitmap) */static void clear_bm_with_bbox( potrace_bitmap_t* bm, bbox_t* bbox ){ int imin = ( bbox->x0 / BM_WORDBITS ); int imax = ( ( bbox->x1 + BM_WORDBITS - 1 ) / BM_WORDBITS ); int i, y;
for( y = bbox->y0; y < bbox->y1; y++ ) { for( i = imin; i < imax; i++ ) { bm_scanline( bm, y )[i] = 0; } }}
/* ---------------------------------------------------------------------- *//* auxiliary functions */
/* 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 ){ int i, a, ct;
for( i = 2; i < 5; i++ ) { /* check at "radius" i */ ct = 0;
for( a = -i + 1; a <= i - 1; a++ ) { ct += BM_GET( bm, x + a, y + i - 1 ) ? 1 : -1; ct += BM_GET( bm, x + i - 1, y + a - 1 ) ? 1 : -1; ct += BM_GET( bm, x + a - 1, y - i ) ? 1 : -1; ct += BM_GET( bm, x - i, y + a ) ? 1 : -1; }
if( ct > 0 ) { return 1; } else if( ct < 0 ) { return 0; } }
return 0;}
/* ---------------------------------------------------------------------- *//* decompose image into paths */
/* efficiently invert bits [x,infty) and [xa,infty) in line y. Here xa
* must be a multiple of BM_WORDBITS. */static void xor_to_ref( potrace_bitmap_t* bm, int x, int y, int xa ){ int xhi = x & - BM_WORDBITS; int xlo = x & ( BM_WORDBITS - 1 ); /* = x % BM_WORDBITS */ int i;
if( xhi < xa ) { for( i = xhi; i < xa; i += BM_WORDBITS ) { *bm_index( bm, i, y ) ^= BM_ALLBITS; } } else { for( i = xa; i < xhi; i += BM_WORDBITS ) { *bm_index( bm, i, y ) ^= BM_ALLBITS; } }
/* note: the following "if" is needed because x86 treats a<<b as
* a<<(b&31). I spent hours looking for this bug. */ if( xlo ) { *bm_index( bm, xhi, y ) ^= ( BM_ALLBITS << ( BM_WORDBITS - xlo ) ); }}
/* a path is represented as an array of points, which are thought to
* lie on the corners of pixels (not on their centers). The path point * (x,y) is the lower left corner of the pixel (x,y). Paths are * represented by the len/pt components of a path_t object (which * also stores other information about the path) */
/* xor the given pixmap with the interior of the given path. Note: the
* path must be within the dimensions of the pixmap. */static void xor_path( potrace_bitmap_t* bm, path_t* p ){ int xa, x, y, k, y1;
if( p->priv->len <= 0 ) { /* a path of length 0 is silly, but legal */ return; }
y1 = p->priv->pt[p->priv->len - 1].y;
xa = p->priv->pt[0].x & - BM_WORDBITS;
for( k = 0; k < p->priv->len; k++ ) { x = p->priv->pt[k].x; y = p->priv->pt[k].y;
if( y != y1 ) { /* efficiently invert the rectangle [x,xa] x [y,y1] */ xor_to_ref( bm, x, min( y, y1 ), xa ); y1 = y; } }}
/* Find the bounding box of a given path. Path is assumed to be of
* non-zero length. */static void setbbox_path( bbox_t* bbox, path_t* p ){ int x, y; int k;
bbox->y0 = INT_MAX; bbox->y1 = 0; bbox->x0 = INT_MAX; bbox->x1 = 0;
for( k = 0; k < p->priv->len; k++ ) { x = p->priv->pt[k].x; y = p->priv->pt[k].y;
if( x < bbox->x0 ) { bbox->x0 = x; }
if( x > bbox->x1 ) { bbox->x1 = x; }
if( y < bbox->y0 ) { bbox->y0 = y; }
if( y > bbox->y1 ) { bbox->y1 = y; } }}
/* compute a path in the given pixmap, separating black from white.
* Start path at the point (x0,x1), which must be an upper left corner * of the path. Also compute the area enclosed by the path. Return a * new path_t object, or NULL on error (note that a legitimate path * cannot have length 0). Sign is required for correct interpretation * of turnpolicies. */static path_t* findpath( potrace_bitmap_t* bm, int x0, int y0, int sign, int turnpolicy ){ int x, y, dirx, diry, len, size; uint64_t area; int c, d, tmp; point_t* pt, * pt1; path_t* p = NULL;
x = x0; y = y0; dirx = 0; diry = -1;
len = size = 0; pt = NULL; area = 0;
while( 1 ) { /* add point to path */ if( len >= size ) { size += 100; size = (int) ( 1.3 * size ); pt1 = (point_t*) realloc( pt, size * sizeof( point_t ) );
if( !pt1 ) { goto error; }
pt = pt1; }
pt[len].x = x; pt[len].y = y; len++;
/* move to next point */ x += dirx; y += diry; area += x * diry;
/* path complete? */ if( x == x0 && y == y0 ) { break; }
/* determine next direction */ c = BM_GET( bm, x + ( dirx + diry - 1 ) / 2, y + ( diry - dirx - 1 ) / 2 ); d = BM_GET( bm, x + ( dirx - diry - 1 ) / 2, y + ( diry + dirx - 1 ) / 2 );
if( c && !d ) { /* ambiguous turn */ if( turnpolicy == POTRACE_TURNPOLICY_RIGHT || ( turnpolicy == POTRACE_TURNPOLICY_BLACK && sign == '+' ) || ( turnpolicy == POTRACE_TURNPOLICY_WHITE && sign == '-' ) || ( turnpolicy == POTRACE_TURNPOLICY_RANDOM && detrand( x, y ) ) || ( turnpolicy == POTRACE_TURNPOLICY_MAJORITY && majority( bm, x, y ) ) || ( turnpolicy == POTRACE_TURNPOLICY_MINORITY && !majority( bm, x, y ) ) ) { tmp = dirx; /* right turn */ dirx = diry; diry = -tmp; } else { tmp = dirx; /* left turn */ dirx = -diry; diry = tmp; } } else if( c ) { /* right turn */ tmp = dirx; dirx = diry; diry = -tmp; } else if( !d ) { /* left turn */ tmp = dirx; dirx = -diry; diry = tmp; } } /* while this path */
/* allocate new path object */ p = path_new();
if( !p ) { goto error; }
p->priv->pt = pt; p->priv->len = len; p->area = area <= INT_MAX ? area : INT_MAX; /* avoid overflow */ p->sign = sign;
return p;
error: free( pt ); return NULL;}
/* Give a tree structure to the given path list, based on "insideness"
* testing. I.e., path A is considered "below" path B if it is inside * path B. The input pathlist is assumed to be ordered so that "outer" * paths occur before "inner" paths. The tree structure is stored in * the "childlist" and "sibling" components of the path_t * structure. The linked list structure is also changed so that * negative path components are listed immediately after their * positive parent. Note: some backends may ignore the tree * structure, others may use it e.g. to group path components. We * assume that in the input, point 0 of each path is an "upper left" * corner of the path, as returned by bm_to_pathlist. This makes it * easy to find an "interior" point. The bm argument should be a * bitmap of the correct size (large enough to hold all the paths), * and will be used as scratch space. Return 0 on success or -1 on * error with errno set. */
static void pathlist_to_tree( path_t* plist, potrace_bitmap_t* bm ){ path_t* p, * p1; path_t* heap, * heap1; path_t* cur; path_t* head; 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 );
/* save original "next" pointers */ list_forall( p, plist ) { p->sibling = p->next; p->childlist = NULL; }
heap = plist;
/* the heap holds a list of lists of paths. Use "childlist" field
* for outer list, "next" field for inner list. Each of the sublists * is to be turned into a tree. This code is messy, but it is * actually fast. Each path is rendered exactly once. We use the * heap to get a tail recursive algorithm: the heap holds a list of * pathlists which still need to be transformed. */
while( heap ) { /* unlink first sublist */ cur = heap; heap = heap->childlist; cur->childlist = NULL;
/* unlink first path */ head = cur; cur = cur->next; head->next = NULL;
/* render path */ xor_path( bm, head ); setbbox_path( &bbox, head );
/* now do insideness test for each element of cur; append it to
* head->childlist if it's inside head, else append it to * head->next. */ hook_in = &head->childlist; hook_out = &head->next; list_forall_unlink( p, cur ) { if( p->priv->pt[0].y <= bbox.y0 ) { list_insert_beforehook( p, hook_out ); /* append the remainder of the list to hook_out */ *hook_out = cur; break; }
if( BM_GET( bm, p->priv->pt[0].x, p->priv->pt[0].y - 1 ) ) { list_insert_beforehook( p, hook_in ); } else { list_insert_beforehook( p, hook_out ); } }
/* clear bm */ clear_bm_with_bbox( bm, &bbox );
/* now schedule head->childlist and head->next for further
* processing */ if( head->next ) { head->next->childlist = heap; heap = head->next; }
if( head->childlist ) { head->childlist->childlist = heap; heap = head->childlist; } }
/* copy sibling structure from "next" to "sibling" component */ p = plist;
while( p ) { p1 = p->sibling; p->sibling = p->next; p = p1; }
/* reconstruct a new linked list ("next") structure from tree
* ("childlist", "sibling") structure. This code is slightly messy, * because we use a heap to make it tail recursive: the heap * contains a list of childlists which still need to be * processed. */ heap = plist;
if( heap ) { heap->next = NULL; /* heap is a linked list of childlists */ }
plist = NULL; 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, plist_hook );
/* go through its children */ for( p1 = p->childlist; p1; p1 = p1->sibling ) { /* append to linked list */ list_insert_beforehook( p1, plist_hook );
/* append its childlist to heap, if non-empty */ if( p1->childlist ) { list_append( path_t, heap1, p1->childlist ); } } }
heap = heap1; }}
/* find the next set pixel in a row <= y. Pixels are searched first
* left-to-right, then top-down. In other words, (x,y)<(x',y') if y>y' * or y=y' and x<x'. If found, return 0 and store pixel in * (*xp,*yp). Else return 1. Note that this function assumes that * excess bytes have been cleared with bm_clearexcess. */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 = x0; x < bm->w && x >= 0; x += (unsigned) BM_WORDBITS ) { if( *bm_index( bm, x, y ) ) { while( !BM_GET( bm, x, y ) ) { x++; }
/* found */ *xp = x; *yp = y; return 0; } }
x0 = 0; }
/* not found */ return 1;}
/* Decompose the given bitmap into paths. Returns a linked list of
* path_t objects with the fields len, pt, area, sign filled * in. Returns 0 on success with plistp set, or -1 on error with errno * set. */
int bm_to_pathlist( const potrace_bitmap_t* bm, path_t** plistp, const potrace_param_t* param, progress_t* progress ){ int x; int y; path_t* p; path_t* plist = NULL; /* linked list of path objects */ path_t** plist_hook = &plist; /* used to speed up appending to linked list */ potrace_bitmap_t* bm1 = NULL; int sign;
bm1 = bm_dup( bm );
if( !bm1 ) { goto error; }
/* be sure the byte padding on the right is set to 0, as the fast
* pixel search below relies on it */ 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 */ sign = BM_GET( bm, x, y ) ? '+' : '-';
/* calculate the path */ p = findpath( bm1, x, y + 1, sign, param->turnpolicy );
if( p == NULL ) { goto error; }
/* update buffered image */ xor_path( bm1, p );
/* if it's a turd, eliminate it, else append it to the list */ if( p->area <= param->turdsize ) { path_free( p ); } else { list_insert_beforehook( p, plist_hook ); }
if( bm1->h > 0 ) { /* to be sure */ progress_update( 1 - y / (double) bm1->h, progress ); } }
pathlist_to_tree( plist, bm1 ); bm_free( bm1 ); *plistp = plist;
progress_update( 1.0, progress );
return 0;
error: bm_free( bm1 ); list_forall_unlink( p, plist ) { path_free( p ); } return -1;}
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