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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. */
/* calculations with coordinate transformations and bounding boxes */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <math.h>
#include <string.h>
#include "trans.h"
#include "bbox.h"
/* rotate the coordinate system counterclockwise by alpha degrees. The
new bounding box will be the smallest box containing the rotated
old bounding box */
void trans_rotate(trans_t *r, double alpha) {
double s, c, x0, x1, y0, y1, o0, o1;
trans_t t_struct;
trans_t *t = &t_struct;
memcpy(t, r, sizeof(trans_t));
s = sin(alpha/180*M_PI);
c = cos(alpha/180*M_PI);
/* apply the transformation matrix to the sides of the bounding box */
x0 = c * t->bb[0];
x1 = s * t->bb[0];
y0 = -s * t->bb[1];
y1 = c * t->bb[1];
/* determine new bounding box, and origin of old bb within new bb */
r->bb[0] = fabs(x0) + fabs(y0);
r->bb[1] = fabs(x1) + fabs(y1);
o0 = - min(x0,0) - min(y0,0);
o1 = - min(x1,0) - min(y1,0);
r->orig[0] = o0 + c * t->orig[0] - s * t->orig[1];
r->orig[1] = o1 + s * t->orig[0] + c * t->orig[1];
r->x[0] = c * t->x[0] - s * t->x[1];
r->x[1] = s * t->x[0] + c * t->x[1];
r->y[0] = c * t->y[0] - s * t->y[1];
r->y[1] = s * t->y[0] + c * t->y[1];
}
/* return the standard cartesian coordinate system for an w x h rectangle. */
void trans_from_rect(trans_t *r, double w, double h) {
r->bb[0] = w;
r->bb[1] = h;
r->orig[0] = 0.0;
r->orig[1] = 0.0;
r->x[0] = 1.0;
r->x[1] = 0.0;
r->y[0] = 0.0;
r->y[1] = 1.0;
r->scalex = 1.0;
r->scaley = 1.0;
}
/* rescale the coordinate system r by factor sc >= 0. */
void trans_rescale(trans_t *r, double sc) {
r->bb[0] *= sc;
r->bb[1] *= sc;
r->orig[0] *= sc;
r->orig[1] *= sc;
r->x[0] *= sc;
r->x[1] *= sc;
r->y[0] *= sc;
r->y[1] *= sc;
r->scalex *= sc;
r->scaley *= sc;
}
/* rescale the coordinate system to size w x h */
void trans_scale_to_size(trans_t *r, double w, double h) {
double xsc = w/r->bb[0];
double ysc = h/r->bb[1];
r->bb[0] = w;
r->bb[1] = h;
r->orig[0] *= xsc;
r->orig[1] *= ysc;
r->x[0] *= xsc;
r->x[1] *= ysc;
r->y[0] *= xsc;
r->y[1] *= ysc;
r->scalex *= xsc;
r->scaley *= ysc;
if (w<0) {
r->orig[0] -= w;
r->bb[0] = -w;
}
if (h<0) {
r->orig[1] -= h;
r->bb[1] = -h;
}
}
/* adjust the bounding box to the actual vector outline */
void trans_tighten(trans_t *r, potrace_path_t *plist) {
interval_t i;
dpoint_t dir;
int j;
/* if pathlist is empty, do nothing */
if (!plist) {
return;
}
for (j=0; j<2; j++) {
dir.x = r->x[j];
dir.y = r->y[j];
path_limits(plist, dir, &i);
if (i.min == i.max) {
/* make the extent non-zero to avoid later division by zero errors */
i.max = i.min+0.5;
i.min = i.min-0.5;
}
r->bb[j] = i.max - i.min;
r->orig[j] = -i.min;
}
}
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