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/* Libart_LGPL - library of basic graphic primitives
* Copyright (C) 1998-2000 Raph Levien
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/* Sort vector paths into sorted vector paths */
#include "config.h"
#include "art_svp_vpath.h"
#include <stdlib.h>
#include <math.h>
#include "art_misc.h"
#include "art_vpath.h"
#include "art_svp.h"
/* reverse a list of points in place */
static void
reverse_points (ArtPoint *points, int n_points)
{
int i;
ArtPoint tmp_p;
for (i = 0; i < (n_points >> 1); i++)
{
tmp_p = points[i];
points[i] = points[n_points - (i + 1)];
points[n_points - (i + 1)] = tmp_p;
}
}
/**
* art_svp_from_vpath: Convert a vpath to a sorted vector path.
* @vpath: #ArtVPath to convert.
*
* Converts a vector path into sorted vector path form. The svp form is
* more efficient for rendering and other vector operations.
*
* Basically, the implementation is to traverse the vector path,
* generating a new segment for each "run" of points in the vector
* path with monotonically increasing Y values. All the resulting
* values are then sorted.
*
* Note: I'm not sure that the sorting rule is correct with respect
* to numerical stability issues.
*
* Return value: Resulting sorted vector path.
**/
ArtSVP *
art_svp_from_vpath (ArtVpath *vpath)
{
int n_segs, n_segs_max;
ArtSVP *svp;
int dir;
int new_dir;
int i;
ArtPoint *points;
int n_points, n_points_max;
double x, y;
double x_min, x_max;
n_segs = 0;
n_segs_max = 16;
svp = (ArtSVP *)art_alloc (sizeof(ArtSVP) +
(n_segs_max - 1) * sizeof(ArtSVPSeg));
dir = 0;
n_points = 0;
n_points_max = 0;
points = NULL;
i = 0;
x = y = 0; /* unnecessary, given "first code must not be LINETO" invariant,
but it makes gcc -Wall -ansi -pedantic happier */
x_min = x_max = 0; /* same */
while (vpath[i].code != ART_END) {
if (vpath[i].code == ART_MOVETO || vpath[i].code == ART_MOVETO_OPEN)
{
if (points != NULL && n_points >= 2)
{
if (n_segs == n_segs_max)
{
n_segs_max <<= 1;
svp = (ArtSVP *)art_realloc (svp, sizeof(ArtSVP) +
(n_segs_max - 1) *
sizeof(ArtSVPSeg));
}
svp->segs[n_segs].n_points = n_points;
svp->segs[n_segs].dir = (dir > 0);
if (dir < 0)
reverse_points (points, n_points);
svp->segs[n_segs].points = points;
svp->segs[n_segs].bbox.x0 = x_min;
svp->segs[n_segs].bbox.x1 = x_max;
svp->segs[n_segs].bbox.y0 = points[0].y;
svp->segs[n_segs].bbox.y1 = points[n_points - 1].y;
n_segs++;
points = NULL;
}
if (points == NULL)
{
n_points_max = 4;
points = art_new (ArtPoint, n_points_max);
}
n_points = 1;
points[0].x = x = vpath[i].x;
points[0].y = y = vpath[i].y;
x_min = x;
x_max = x;
dir = 0;
}
else /* must be LINETO */
{
new_dir = (vpath[i].y > y ||
(vpath[i].y == y && vpath[i].x > x)) ? 1 : -1;
if (dir && dir != new_dir)
{
/* new segment */
x = points[n_points - 1].x;
y = points[n_points - 1].y;
if (n_segs == n_segs_max)
{
n_segs_max <<= 1;
svp = (ArtSVP *)art_realloc (svp, sizeof(ArtSVP) +
(n_segs_max - 1) *
sizeof(ArtSVPSeg));
}
svp->segs[n_segs].n_points = n_points;
svp->segs[n_segs].dir = (dir > 0);
if (dir < 0)
reverse_points (points, n_points);
svp->segs[n_segs].points = points;
svp->segs[n_segs].bbox.x0 = x_min;
svp->segs[n_segs].bbox.x1 = x_max;
svp->segs[n_segs].bbox.y0 = points[0].y;
svp->segs[n_segs].bbox.y1 = points[n_points - 1].y;
n_segs++;
n_points = 1;
n_points_max = 4;
points = art_new (ArtPoint, n_points_max);
points[0].x = x;
points[0].y = y;
x_min = x;
x_max = x;
}
if (points != NULL)
{
if (n_points == n_points_max)
art_expand (points, ArtPoint, n_points_max);
points[n_points].x = x = vpath[i].x;
points[n_points].y = y = vpath[i].y;
if (x < x_min) x_min = x;
else if (x > x_max) x_max = x;
n_points++;
}
dir = new_dir;
}
i++;
}
if (points != NULL)
{
if (n_points >= 2)
{
if (n_segs == n_segs_max)
{
n_segs_max <<= 1;
svp = (ArtSVP *)art_realloc (svp, sizeof(ArtSVP) +
(n_segs_max - 1) *
sizeof(ArtSVPSeg));
}
svp->segs[n_segs].n_points = n_points;
svp->segs[n_segs].dir = (dir > 0);
if (dir < 0)
reverse_points (points, n_points);
svp->segs[n_segs].points = points;
svp->segs[n_segs].bbox.x0 = x_min;
svp->segs[n_segs].bbox.x1 = x_max;
svp->segs[n_segs].bbox.y0 = points[0].y;
svp->segs[n_segs].bbox.y1 = points[n_points - 1].y;
n_segs++;
}
else
art_free (points);
}
svp->n_segs = n_segs;
qsort (&svp->segs, n_segs, sizeof (ArtSVPSeg), art_svp_seg_compare);
return svp;
}
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