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/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
/* cairo - a vector graphics library with display and print output
*
* Copyright © 2002 University of Southern California
* Copyright © 2005 Red Hat, Inc.
* Copyright © 2006 Red Hat, Inc.
*
* 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"
/* XXX We currently have a confusing mix of boxes and rectangles as
* exemplified by this function. A #cairo_box_t is a rectangular area
* represented by the coordinates of the upper left and lower right
* corners, expressed in fixed point numbers. A #cairo_rectangle_int_t is
* also a rectangular area, but represented by the upper left corner
* and the width and the height, as integer numbers.
*
* This function converts a #cairo_box_t to a #cairo_rectangle_int_t by
* increasing the area to the nearest integer coordinates. We should
* standardize on #cairo_rectangle_fixed_t and #cairo_rectangle_int_t, and
* this function could be renamed to the more reasonable
* _cairo_rectangle_fixed_round.
*/
void
_cairo_box_round_to_rectangle (cairo_box_t *box, cairo_rectangle_int_t *rectangle)
{
rectangle->x = _cairo_fixed_integer_floor (box->p1.x);
rectangle->y = _cairo_fixed_integer_floor (box->p1.y);
rectangle->width = _cairo_fixed_integer_ceil (box->p2.x) - rectangle->x;
rectangle->height = _cairo_fixed_integer_ceil (box->p2.y) - rectangle->y;
}
void
_cairo_rectangle_intersect (cairo_rectangle_int_t *dest, cairo_rectangle_int_t *src)
{
int x1, y1, x2, y2;
x1 = MAX (dest->x, src->x);
y1 = MAX (dest->y, src->y);
x2 = MIN (dest->x + dest->width, src->x + src->width);
y2 = MIN (dest->y + dest->height, src->y + src->height);
if (x1 >= x2 || y1 >= y2) {
dest->x = 0;
dest->y = 0;
dest->width = 0;
dest->height = 0;
} else {
dest->x = x1;
dest->y = y1;
dest->width = x2 - x1;
dest->height = y2 - y1;
}
}
#define P1x (line->p1.x)
#define P1y (line->p1.y)
#define P2x (line->p2.x)
#define P2y (line->p2.y)
#define B1x (box->p1.x)
#define B1y (box->p1.y)
#define B2x (box->p2.x)
#define B2y (box->p2.y)
/*
* Check whether any part of line intersects box. This function essentially
* computes whether the ray starting at line->p1 in the direction of line->p2
* intersects the box before it reaches p2. Normally, this is done
* by dividing by the lengths of the line projected onto each axis. Because
* we're in fixed point, this function does a bit more work to avoid having to
* do the division -- we don't care about the actual intersection point, so
* it's of no interest to us.
*/
cairo_bool_t
_cairo_box_intersects_line (cairo_box_t *box, cairo_line_t *line)
{
cairo_fixed_t t1, t2, t3, t4;
cairo_int64_t t1y, t2y, t3x, t4x;
cairo_fixed_t xlen, ylen;
if (_cairo_box_contains_point(box, &line->p1) ||
_cairo_box_contains_point(box, &line->p2))
return TRUE;
xlen = P2x - P1x;
ylen = P2y - P1y;
if (xlen) {
if (xlen > 0) {
t1 = B1x - P1x;
t2 = B2x - P1x;
} else {
t1 = P1x - B2x;
t2 = P1x - B1x;
xlen = - xlen;
}
if ((t1 < 0 || t1 > xlen) &&
(t2 < 0 || t2 > xlen))
return FALSE;
} else {
/* Fully vertical line -- check that X is in bounds */
if (P1x < B1x || P1x > B2x)
return FALSE;
}
if (ylen) {
if (ylen > 0) {
t3 = B1y - P1y;
t4 = B2y - P1y;
} else {
t3 = P1y - B2y;
t4 = P1y - B1y;
ylen = - ylen;
}
if ((t3 < 0 || t3 > ylen) &&
(t4 < 0 || t4 > ylen))
return FALSE;
} else {
/* Fully horizontal line -- check Y */
if (P1y < B1y || P1y > B2y)
return FALSE;
}
/* If we had a horizontal or vertical line, then it's already been checked */
if (P1x == P2x || P1y == P2y)
return TRUE;
/* Check overlap. Note that t1 < t2 and t3 < t4 here. */
t1y = _cairo_int32x32_64_mul (t1, ylen);
t2y = _cairo_int32x32_64_mul (t2, ylen);
t3x = _cairo_int32x32_64_mul (t3, xlen);
t4x = _cairo_int32x32_64_mul (t4, xlen);
if (_cairo_int64_lt(t1y, t4x) &&
_cairo_int64_lt(t3x, t2y))
return TRUE;
return FALSE;
}
cairo_bool_t
_cairo_box_contains_point (cairo_box_t *box, cairo_point_t *point)
{
if (point->x < box->p1.x || point->x > box->p2.x ||
point->y < box->p1.y || point->y > box->p2.y)
return FALSE;
return TRUE;
}
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