mirror of
https://gitlab.freedesktop.org/cairo/cairo.git
synced 2026-05-24 07:48:11 +02:00
ef10a0403a
This patch was produced by running git-stripspace on all *.[ch] files within cairo. Note that this script would have also created all the changes from the previous commits to remove trailing whitespace.
99 lines
3 KiB
C
99 lines
3 KiB
C
/* cairo - a vector graphics library with display and print output
|
|
*
|
|
* Copyright © 2002 University of Southern California
|
|
*
|
|
* This library is free software; you can redistribute it and/or
|
|
* modify it either under the terms of the GNU Lesser General Public
|
|
* License version 2.1 as published by the Free Software Foundation
|
|
* (the "LGPL") or, at your option, under the terms of the Mozilla
|
|
* Public License Version 1.1 (the "MPL"). If you do not alter this
|
|
* notice, a recipient may use your version of this file under either
|
|
* the MPL or the LGPL.
|
|
*
|
|
* You should have received a copy of the LGPL along with this library
|
|
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
* You should have received a copy of the MPL along with this library
|
|
* in the file COPYING-MPL-1.1
|
|
*
|
|
* The contents of this file are subject to the Mozilla Public License
|
|
* Version 1.1 (the "License"); you may not use this file except in
|
|
* compliance with the License. You may obtain a copy of the License at
|
|
* http://www.mozilla.org/MPL/
|
|
*
|
|
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
|
|
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
|
|
* the specific language governing rights and limitations.
|
|
*
|
|
* The Original Code is the cairo graphics library.
|
|
*
|
|
* The Initial Developer of the Original Code is University of Southern
|
|
* California.
|
|
*
|
|
* Contributor(s):
|
|
* Carl D. Worth <cworth@cworth.org>
|
|
*/
|
|
|
|
#include "cairoint.h"
|
|
|
|
void
|
|
_cairo_slope_init (cairo_slope_t *slope, cairo_point_t *a, cairo_point_t *b)
|
|
{
|
|
slope->dx = b->x - a->x;
|
|
slope->dy = b->y - a->y;
|
|
}
|
|
|
|
/* Compare two slopes. Slope angles begin at 0 in the direction of the
|
|
positive X axis and increase in the direction of the positive Y
|
|
axis.
|
|
|
|
WARNING: This function only gives correct results if the angular
|
|
difference between a and b is less than PI.
|
|
|
|
< 0 => a less positive than b
|
|
== 0 => a equal to be
|
|
> 0 => a more positive than b
|
|
*/
|
|
int
|
|
_cairo_slope_compare (cairo_slope_t *a, cairo_slope_t *b)
|
|
{
|
|
cairo_fixed_48_16_t diff;
|
|
|
|
diff = ((cairo_fixed_48_16_t) a->dy * (cairo_fixed_48_16_t) b->dx
|
|
- (cairo_fixed_48_16_t) b->dy * (cairo_fixed_48_16_t) a->dx);
|
|
|
|
if (diff > 0)
|
|
return 1;
|
|
if (diff < 0)
|
|
return -1;
|
|
|
|
if (a->dx == 0 && a->dy == 0)
|
|
return 1;
|
|
if (b->dx == 0 && b->dy ==0)
|
|
return -1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* XXX: It might be cleaner to move away from usage of
|
|
_cairo_slope_clockwise/_cairo_slope_counter_clockwise in favor of
|
|
directly using _cairo_slope_compare.
|
|
*/
|
|
|
|
/* Is a clockwise of b?
|
|
*
|
|
* NOTE: The strict equality here is not significant in and of itself,
|
|
* but there are functions up above that are sensitive to it,
|
|
* (cf. _cairo_pen_find_active_cw_vertex_index).
|
|
*/
|
|
int
|
|
_cairo_slope_clockwise (cairo_slope_t *a, cairo_slope_t *b)
|
|
{
|
|
return _cairo_slope_compare (a, b) < 0;
|
|
}
|
|
|
|
int
|
|
_cairo_slope_counter_clockwise (cairo_slope_t *a, cairo_slope_t *b)
|
|
{
|
|
return ! _cairo_slope_clockwise (a, b);
|
|
}
|