gecko-dev/lib/layout/ptinpoly.c
1998-03-28 02:44:41 +00:00

130 lines
3.4 KiB
C

/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* The contents of this file are subject to the Netscape Public License
* Version 1.0 (the "NPL"); you may not use this file except in
* compliance with the NPL. You may obtain a copy of the NPL at
* http://www.mozilla.org/NPL/
*
* Software distributed under the NPL is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
* for the specific language governing rights and limitations under the
* NPL.
*
* The Initial Developer of this code under the NPL is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All Rights
* Reserved.
*/
#include "xp.h"
Bool
lo_is_location_in_poly(int32 x, int32 y, int32 *coords, int32 coord_cnt)
{
int32 totalv = 0;
int32 totalc = 0;
int32 intersects = 0;
int32 wherex = x;
int32 wherey = y;
int32 xval, yval;
int32 *pointer;
int32 *end;
totalv = coord_cnt / 2;
totalc = totalv * 2;
xval = coords[totalc - 2];
yval = coords[totalc - 1];
end = &coords[totalc];
pointer = coords + 1;
if ((yval >= wherey) != (*pointer >= wherey))
if ((xval >= wherex) == (*coords >= wherex))
intersects += (xval >= wherex);
else
intersects += (xval - (yval - wherey) *
(*coords - xval) /
(*pointer - yval)) >= wherex;
while(pointer < end) {
yval = *pointer;
pointer += 2;
if(yval >= wherey) {
while((pointer < end) && (*pointer >= wherey))
pointer+=2;
if (pointer >= end)
break;
if( (*(pointer-3) >= wherex) == (*(pointer-1) >= wherex) )
intersects += (*(pointer-3) >= wherex);
else
intersects += (*(pointer-3) - (*(pointer-2) - wherey) *
(*(pointer-1) - *(pointer-3)) /
(*pointer - *(pointer - 2))) >= wherex;
} else {
while((pointer < end) && (*pointer < wherey))
pointer+=2;
if (pointer >= end)
break;
if( (*(pointer-3) >= wherex) == (*(pointer-1) >= wherex) )
intersects += (*(pointer-3) >= wherex);
else
intersects += (*(pointer-3) - (*(pointer-2) - wherey) *
(*(pointer-1) - *(pointer-3)) /
(*pointer - *(pointer - 2))) >= wherex;
}
}
if (intersects & 1)
return (TRUE);
else
return (FALSE);
}
/* #ifndef NO_TAB_NAVIGATION */
Bool
lo_find_location_in_poly(int32 *xx, int32 *yy, int32 *coords, int32 coord_cnt)
{
int32 x1, y1, x2, y2, px1, py1, px2, py2;
int32 ii;
/* get a edge of the polygon */
x1 = y1 = x2 = y2 = 0;
for( ii = 0; (ii <= coord_cnt-4) && (x1==x2) && (y1==y2); ii+=2 ) {
x1 = coords[ii];
y1 = coords[ii+1];
x2 = coords[ii+2];
y2 = coords[ii+3];
if( (x1!=x2) || (y1!=y2) ) {
/* got a good edge, try it. */
/* get a point on each side of the edge, 2 pixels away, not too close */
px1 = ( x1 + x2 ) / 2 + 2;
px2 = px1 - 4;
py1 = ( y1 + y2 ) / 2 + 2;
py2 = py1 - 4;
if( lo_is_location_in_poly( px1, py1, coords, coord_cnt) ) {
*xx = px1;
*yy = py1;
return( TRUE );
}
if( lo_is_location_in_poly( px2, py2, coords, coord_cnt) ) {
*xx = px2;
*yy = py2;
return( TRUE );
}
}
}
return( FALSE );
}
/* NO_TAB_NAVIGATION */