/*
 *  libpipi       Proper image processing implementation library
 *  Copyright (c) 2004-2008 Sam Hocevar <sam@zoy.org>
 *                All Rights Reserved
 *
 *  $Id$
 *
 *  This library is free software. It comes without any warranty, to
 *  the extent permitted by applicable law. You can redistribute it
 *  and/or modify it under the terms of the Do What The Fuck You Want
 *  To Public License, Version 2, as published by Sam Hocevar. See
 *  http://sam.zoy.org/wtfpl/COPYING for more details.
 */

/*
 * resize.c: image resizing functions
 */

#include "config.h"
#include "common.h"

#include <stdlib.h>
#include <string.h>

#include "pipi.h"
#include "pipi_internals.h"

pipi_image_t *pipi_resize(pipi_image_t const *src, int w, int h)
{
    double *aline, *line;
    pipi_image_t *dst;
    int x, y, x0, y0, sw, dw, sh, dh, remy;

    dst = pipi_new(w, h);

    sw = src->width; sh = src->height;
    dw = dst->width; dh = dst->height;

    aline = malloc(3 * dw * sizeof(double));
    line = malloc(3 * dw * sizeof(double));

    memset(line, 0, 3 * dw * sizeof(double));
    remy = 0;

    for(y = 0, y0 = 0; y < dst->height; y++)
    {
        int toty = 0, ny;

        memset(aline, 0, 3 * dw * sizeof(double));

        while(toty < sh)
        {
            if(remy == 0)
            {
                double r = 0, g = 0, b = 0;
                int remx = 0;

                for(x = 0, x0 = 0; x < dst->width; x++)
                {
                    double ar = 0, ag = 0, ab = 0;
                    int totx = 0, nx;

                    while(totx < sw)
                    {
                        if(remx == 0)
                        {
                            pipi_getpixel(src, x0, y0, &r, &g, &b);
                            x0++;
                            remx = dw;
                        }

                        nx = (totx + remx <= sw) ? remx : sw - totx;
                        ar += nx * r; ag += nx * g; ab += nx * b;
                        totx += nx;
                        remx -= nx;
                    }

                    line[3 * x] = ar;
                    line[3 * x + 1] = ag;
                    line[3 * x + 2] = ab;
                }

                y0++;
                remy = dh;
            }

            ny = (toty + remy <= sh) ? remy : sh - toty;
            for(x = 0; x < dst->width; x++)
            {
                aline[3 * x] += ny * line[3 * x];
                aline[3 * x + 1] += ny * line[3 * x + 1];
                aline[3 * x + 2] += ny * line[3 * x + 2];
            }
            toty += ny;
            remy -= ny;
        }

        for(x = 0; x < dst->width; x++)
            pipi_setpixel(dst, x, y,
                          aline[3 * x] / (sw * sh),
                          aline[3 * x + 1] / (sw * sh),
                          aline[3 * x + 2] / (sw * sh));
    }

    free(aline);
    free(line);

    return dst;
}