libpipi/pipi/pixels.c

/*
 *  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.
 */

/*
 * pixels.c: pixel-level image manipulation
 */

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

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

#include <math.h>

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

#define C2I(p) ((int)255.999*pow(((double)p)/255., 2.2))
#define I2C(p) ((int)255.999*pow(((double)p)/255., 1./2.2))

int pipi_getgray(pipi_image_t const *img, int x, int y, int *g)
{
    if(x < 0 || y < 0 || x >= img->width || y >= img->height)
    {
        *g = 255;
        return -1;
    }

    *g = (unsigned char)img->pixels[y * img->pitch + x * img->channels + 1];

    return 0;
}

int pipi_getpixel(pipi_image_t const *img,
                  int x, int y, int *r, int *g, int *b)
{
    uint8_t *pixel;

    if(x < 0 || y < 0 || x >= img->width || y >= img->height)
    {
        *r = 255;
        *g = 255;
        *b = 255;
        return -1;
    }

    pixel = img->pixels + y * img->pitch + x * img->channels;

    *b = C2I((unsigned char)pixel[0]);
    *g = C2I((unsigned char)pixel[1]);
    *r = C2I((unsigned char)pixel[2]);

    return 0;
}

int pipi_setpixel(pipi_image_t *img, int x, int y, int r, int g, int b)
{
    uint8_t *pixel;

    if(x < 0 || y < 0 || x >= img->width || y >= img->height)
        return -1;

    pixel = img->pixels + y * img->pitch + x * img->channels;

    pixel[0] = I2C(b);
    pixel[1] = I2C(g);
    pixel[2] = I2C(r);

    return 0;
}