/*
 *                         *  BOOH  *
 *
 * A.k.a `Best web-album Of the world, Or your money back, Humerus'.
 *
 * The acronyn sucks, however this is a tribute to Dragon Ball by
 * Akira Toriyama, where the last enemy beaten by heroes of Dragon
 * Ball is named "Boo". But there was already a free software project
 * called Boo, so this one will be it "Booh". Or whatever.
 *
 *
 * Copyright (c) 2005 Guillaume Cottenceau
 *
 * This software may be freely redistributed under the terms of the GNU
 * public license version 2.
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <math.h>

#define GDK_PIXBUF_ENABLE_BACKEND
#include <gdk-pixbuf/gdk-pixbuf.h>
#include <gdk-pixbuf/gdk-pixdata.h>
#include "rbgobject.h"

#define _SELF(s) GDK_PIXBUF(RVAL2GOBJ(s)) 

static VALUE
whitebalance(self, level)
    VALUE self, level; 
{
        double red_filter[256], blue_filter[256];
        int i, x, y;
        guchar* pixels = gdk_pixbuf_get_pixels(_SELF(self));
        int rowstride = gdk_pixbuf_get_rowstride(_SELF(self));

        double factor = 1 + fabs(NUM2DBL(level))/100;
        if (NUM2DBL(level) < 0) {
                factor = 1/factor;
        }

        for (i = 0; i < 256; i++) {
                red_filter[i]  = pow(((double)i)/255, 1/factor) * 255;
                blue_filter[i] = pow(((double)i)/255, factor) * 255;
        }
    
        for (y = 0; y < gdk_pixbuf_get_height(_SELF(self)); y++) {
                guchar* pixline = &(pixels[rowstride*y]);
                for (x = 0; x < gdk_pixbuf_get_width(_SELF(self)); x++) {
                        pixline[x*3]   = red_filter[pixline[x*3]];
                        pixline[x*3+2] = blue_filter[pixline[x*3+2]];
                }
        }

        return self;
}

static VALUE
gammacorrect(self, level)
    VALUE self, level; 
{
        double filter[256];
        int i, x, y;
        guchar* pixels = gdk_pixbuf_get_pixels(_SELF(self));
        int rowstride = gdk_pixbuf_get_rowstride(_SELF(self));

        double factor = 1 + fabs(NUM2DBL(level))/100;
        if (NUM2DBL(level) > 0) {
                factor = 1/factor;
        }

        for (i = 0; i < 256; i++) {
                filter[i] = pow(((double)i)/255, factor) * 255;
        }
    
        for (y = 0; y < gdk_pixbuf_get_height(_SELF(self)); y++) {
                guchar* pixline = &(pixels[rowstride*y]);
                for (x = 0; x < gdk_pixbuf_get_width(_SELF(self)); x++) {
                        pixline[x*3]   = filter[pixline[x*3]];
                        pixline[x*3+1] = filter[pixline[x*3+1]];
                        pixline[x*3+2] = filter[pixline[x*3+2]];
                }
        }

        return self;
}

void 
Init_gtkadds()
{
    RGObjClassInfo* cinfo = (RGObjClassInfo*)rbgobj_lookup_class_by_gtype(GDK_TYPE_PIXBUF, Qnil);
    rb_define_method(cinfo->klass, "whitebalance!", whitebalance, 1); 
    rb_define_method(cinfo->klass, "gammacorrect!", gammacorrect, 1); 
}