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4b29988939
Adrian Johnson discovered cases where we mistakenly compared the result of unsigned arithmetic where we need signed quantities. Look for similar cases in the users of cairo_rectangle_int_t.
225 lines
6.8 KiB
C
225 lines
6.8 KiB
C
/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
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/* cairo - a vector graphics library with display and print output
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*
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* Copyright © 2002 University of Southern California
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* Copyright © 2005 Red Hat, Inc.
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* Copyright © 2006 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it either under the terms of the GNU Lesser General Public
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* License version 2.1 as published by the Free Software Foundation
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* (the "LGPL") or, at your option, under the terms of the Mozilla
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* Public License Version 1.1 (the "MPL"). If you do not alter this
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* notice, a recipient may use your version of this file under either
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* the MPL or the LGPL.
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*
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* You should have received a copy of the LGPL along with this library
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* in the file COPYING-LGPL-2.1; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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* You should have received a copy of the MPL along with this library
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* in the file COPYING-MPL-1.1
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*
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* The contents of this file are subject to the Mozilla Public License
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* Version 1.1 (the "License"); you may not use this file except in
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* compliance with the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
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* OF ANY KIND, either express or implied. See the LGPL or the MPL for
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* the specific language governing rights and limitations.
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*
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* The Original Code is the cairo graphics library.
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*
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* The Initial Developer of the Original Code is University of Southern
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* California.
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*
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* Contributor(s):
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* Carl D. Worth <cworth@cworth.org>
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*/
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#include "cairoint.h"
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cairo_private void
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_cairo_box_from_doubles (cairo_box_t *box,
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double *x1, double *y1,
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double *x2, double *y2)
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{
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box->p1.x = _cairo_fixed_from_double (*x1);
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box->p1.y = _cairo_fixed_from_double (*y1);
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box->p2.x = _cairo_fixed_from_double (*x2);
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box->p2.y = _cairo_fixed_from_double (*y2);
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}
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cairo_private void
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_cairo_box_to_doubles (const cairo_box_t *box,
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double *x1, double *y1,
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double *x2, double *y2)
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{
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*x1 = _cairo_fixed_to_double (box->p1.x);
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*y1 = _cairo_fixed_to_double (box->p1.y);
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*x2 = _cairo_fixed_to_double (box->p2.x);
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*y2 = _cairo_fixed_to_double (box->p2.y);
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}
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void
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_cairo_box_from_rectangle (cairo_box_t *box,
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const cairo_rectangle_int_t *rect)
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{
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box->p1.x = _cairo_fixed_from_int (rect->x);
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box->p1.y = _cairo_fixed_from_int (rect->y);
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box->p2.x = _cairo_fixed_from_int (rect->x + rect->width);
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box->p2.y = _cairo_fixed_from_int (rect->y + rect->height);
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}
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/* XXX We currently have a confusing mix of boxes and rectangles as
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* exemplified by this function. A #cairo_box_t is a rectangular area
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* represented by the coordinates of the upper left and lower right
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* corners, expressed in fixed point numbers. A #cairo_rectangle_int_t is
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* also a rectangular area, but represented by the upper left corner
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* and the width and the height, as integer numbers.
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*
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* This function converts a #cairo_box_t to a #cairo_rectangle_int_t by
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* increasing the area to the nearest integer coordinates. We should
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* standardize on #cairo_rectangle_fixed_t and #cairo_rectangle_int_t, and
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* this function could be renamed to the more reasonable
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* _cairo_rectangle_fixed_round.
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*/
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void
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_cairo_box_round_to_rectangle (const cairo_box_t *box,
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cairo_rectangle_int_t *rectangle)
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{
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rectangle->x = _cairo_fixed_integer_floor (box->p1.x);
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rectangle->y = _cairo_fixed_integer_floor (box->p1.y);
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rectangle->width = _cairo_fixed_integer_ceil (box->p2.x) - rectangle->x;
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rectangle->height = _cairo_fixed_integer_ceil (box->p2.y) - rectangle->y;
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}
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cairo_bool_t
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_cairo_rectangle_intersect (cairo_rectangle_int_t *dst,
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const cairo_rectangle_int_t *src)
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{
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int x1, y1, x2, y2;
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x1 = MAX (dst->x, src->x);
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y1 = MAX (dst->y, src->y);
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/* Beware the unsigned promotion, fortunately we have bits to spare
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* as (CAIRO_RECT_INT_MAX - CAIRO_RECT_INT_MIN) < UINT_MAX
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*/
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x2 = MIN (dst->x + (int) dst->width, src->x + (int) src->width);
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y2 = MIN (dst->y + (int) dst->height, src->y + (int) src->height);
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if (x1 >= x2 || y1 >= y2) {
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dst->x = 0;
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dst->y = 0;
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dst->width = 0;
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dst->height = 0;
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return FALSE;
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} else {
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dst->x = x1;
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dst->y = y1;
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dst->width = x2 - x1;
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dst->height = y2 - y1;
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return TRUE;
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}
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}
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#define P1x (line->p1.x)
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#define P1y (line->p1.y)
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#define P2x (line->p2.x)
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#define P2y (line->p2.y)
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#define B1x (box->p1.x)
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#define B1y (box->p1.y)
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#define B2x (box->p2.x)
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#define B2y (box->p2.y)
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/*
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* Check whether any part of line intersects box. This function essentially
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* computes whether the ray starting at line->p1 in the direction of line->p2
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* intersects the box before it reaches p2. Normally, this is done
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* by dividing by the lengths of the line projected onto each axis. Because
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* we're in fixed point, this function does a bit more work to avoid having to
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* do the division -- we don't care about the actual intersection point, so
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* it's of no interest to us.
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*/
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cairo_bool_t
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_cairo_box_intersects_line_segment (cairo_box_t *box, cairo_line_t *line)
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{
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cairo_fixed_t t1=0, t2=0, t3=0, t4=0;
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cairo_int64_t t1y, t2y, t3x, t4x;
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cairo_fixed_t xlen, ylen;
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if (_cairo_box_contains_point(box, &line->p1) ||
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_cairo_box_contains_point(box, &line->p2))
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return TRUE;
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xlen = P2x - P1x;
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ylen = P2y - P1y;
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if (xlen) {
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if (xlen > 0) {
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t1 = B1x - P1x;
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t2 = B2x - P1x;
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} else {
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t1 = P1x - B2x;
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t2 = P1x - B1x;
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xlen = - xlen;
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}
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if ((t1 < 0 || t1 > xlen) &&
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(t2 < 0 || t2 > xlen))
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return FALSE;
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} else {
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/* Fully vertical line -- check that X is in bounds */
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if (P1x < B1x || P1x > B2x)
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return FALSE;
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}
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if (ylen) {
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if (ylen > 0) {
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t3 = B1y - P1y;
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t4 = B2y - P1y;
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} else {
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t3 = P1y - B2y;
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t4 = P1y - B1y;
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ylen = - ylen;
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}
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if ((t3 < 0 || t3 > ylen) &&
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(t4 < 0 || t4 > ylen))
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return FALSE;
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} else {
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/* Fully horizontal line -- check Y */
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if (P1y < B1y || P1y > B2y)
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return FALSE;
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}
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/* If we had a horizontal or vertical line, then it's already been checked */
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if (P1x == P2x || P1y == P2y)
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return TRUE;
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/* Check overlap. Note that t1 < t2 and t3 < t4 here. */
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t1y = _cairo_int32x32_64_mul (t1, ylen);
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t2y = _cairo_int32x32_64_mul (t2, ylen);
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t3x = _cairo_int32x32_64_mul (t3, xlen);
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t4x = _cairo_int32x32_64_mul (t4, xlen);
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if (_cairo_int64_lt(t1y, t4x) &&
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_cairo_int64_lt(t3x, t2y))
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return TRUE;
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return FALSE;
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}
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cairo_bool_t
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_cairo_box_contains_point (cairo_box_t *box, cairo_point_t *point)
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{
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if (point->x < box->p1.x || point->x > box->p2.x ||
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point->y < box->p1.y || point->y > box->p2.y)
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return FALSE;
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return TRUE;
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}
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