//-----------------------------------------------------------------------------
// Copyright © 2006 - Philip Howard - All rights reserved
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//-----------------------------------------------------------------------------
// package	libh/arith
// homepage	http://libh.slashusr.org/
//-----------------------------------------------------------------------------
// author	Philip Howard
// email	libh at ipal dot org
// homepage	http://phil.ipal.org/
//-----------------------------------------------------------------------------
// This file is best viewed using a fixed spaced font such as Courier
// and in a display at least 120 columns wide.
//-----------------------------------------------------------------------------

#include "arith_lib.h"

__PROTO_BEGIN__
//-----------------------------------------------------------------------------
// function	zoom_calc_d
//
// purpose	Given a set of multiply/add values from a zoom scan, and a set
//		of 2D view coordinates, transform the coordinates into the new
//		zoomed in view.
//
// arguments	1 (double *) edge position on X axis on left
//		2 (double *) edge position on Y axis on top
//		3 (double *) edge position on X axis on right
//		4 (double *) edge position on Y axis on bottom
//		5 (double) already scanned X axis multiplier
//		6 (double) already scanned Y axis multiplier
//		7 (double) already scanned X axis adder
//		8 (double) already scanned Y axis adder
//
// returns	(int) == -1 : failure
//		(int) >=  0 : success
//-----------------------------------------------------------------------------
int
zoom_calc_d (
    double *		arg_xl_p
    ,
    double *		arg_yt_p
    ,
    double *		arg_xr_p
    ,
    double *		arg_yb_p
    ,
    double		arg_mul_x
    ,
    double		arg_mul_y
    ,
    double		arg_add_x
    ,
    double		arg_add_y
    )
__PROTO_END__
{
    {
	double dx,mx,xl,xr;
	xl = * arg_xl_p;
	xr = * arg_xr_p;
	dx = ( xr - xl ) * arg_mul_x / 2.0;
	mx = ( xr + xl ) / 2.0 + arg_add_x;
	* arg_xl_p = mx - dx;
	* arg_xr_p = mx + dx;
    }

    {
	double dy,my,yt,yb;
	yt = * arg_yt_p;
	yb = * arg_yb_p;
	dy = ( yt - yb ) * arg_mul_y / 2.0;
	my = ( yt + yb ) / 2.0 + arg_add_y;
	* arg_yt_p = my + dy;
	* arg_yb_p = my - dy;
    }

    return 0;
}