/* cairo - a vector graphics library with display and print output
 *
 * Copyright © 2002 University of Southern California
 * Copyright © 2005 Red Hat, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it either under the terms of the GNU Lesser General Public
 * License version 2.1 as published by the Free Software Foundation
 * (the "LGPL") or, at your option, under the terms of the Mozilla
 * Public License Version 1.1 (the "MPL"). If you do not alter this
 * notice, a recipient may use your version of this file under either
 * the MPL or the LGPL.
 *
 * You should have received a copy of the LGPL along with this library
 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 * You should have received a copy of the MPL along with this library
 * in the file COPYING-MPL-1.1
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
 * the specific language governing rights and limitations.
 *
 * The Original Code is the cairo graphics library.
 *
 * The Initial Developer of the Original Code is University of Southern
 * California.
 *
 * Contributor(s):
 *	Carl D. Worth <cworth@cworth.org>
 */

#include "cairoint.h"

static cairo_color_t const cairo_color_white = {
    1.0,    1.0,    1.0,    1.0,
    0xffff, 0xffff, 0xffff, 0xffff
};

static cairo_color_t const cairo_color_black = {
    0.0, 0.0, 0.0, 1.0,
    0x0, 0x0, 0x0, 0xffff
};

static cairo_color_t const cairo_color_transparent = {
    0.0, 0.0, 0.0, 0.0,
    0x0, 0x0, 0x0, 0x0
};

static cairo_color_t const cairo_color_magenta = {
    1.0,    0.0, 1.0,    1.0,
    0xffff, 0x0, 0xffff, 0xffff
};

const cairo_color_t *
_cairo_stock_color (cairo_stock_t stock)
{
    switch (stock) {
    case CAIRO_STOCK_WHITE:
	return &cairo_color_white;
    case CAIRO_STOCK_BLACK:
	return &cairo_color_black;
    case CAIRO_STOCK_TRANSPARENT:
	return &cairo_color_transparent;
    }

    ASSERT_NOT_REACHED;

    /* If the user can get here somehow, give a color that indicates a
     * problem. */
    return &cairo_color_magenta;
}

void
_cairo_color_init (cairo_color_t *color)
{
    *color = cairo_color_white;
}

void
_cairo_color_init_rgb (cairo_color_t *color,
		       double red, double green, double blue)
{
    _cairo_color_init_rgba (color, red, green, blue, 1.0);
}


/* XXX: The calculation of:

		channel * 0xffff

	isn't really what we want since:

		(1.0 - epsilon) * 0xffff = 0xfffe

	In other words, given an input range of [0.0, 1.0], we have an
	infinitely small range tha maps to the output value 0xffff,
	(while having large, uniformly sized input ranges for all
	other output values). This is undesirable, particularly when
	we want to do optimizations for "opaque" colors specfied as
	floating-point.
*/
static void
_cairo_color_compute_shorts (cairo_color_t *color)
{
    color->red_short   = color->red   * color->alpha * 0xffff;
    color->green_short = color->green * color->alpha * 0xffff;
    color->blue_short  = color->blue  * color->alpha * 0xffff;
    color->alpha_short = color->alpha * 0xffff;
}

void
_cairo_color_init_rgba (cairo_color_t *color,
			double red, double green, double blue,
			double alpha)
{
    color->red   = red;
    color->green = green;
    color->blue  = blue;
    color->alpha = alpha;

    _cairo_color_compute_shorts (color);
}

void
_cairo_color_multiply_alpha (cairo_color_t *color,
			     double	    alpha)
{
    color->alpha *= alpha;

    _cairo_color_compute_shorts (color);
}

void
_cairo_color_get_rgba (cairo_color_t *color,
		       double	     *red,
		       double	     *green,
		       double	     *blue,
		       double	     *alpha)
{
    *red   = color->red;
    *green = color->green;
    *blue  = color->blue;
    *alpha = color->alpha;
}

void
_cairo_color_get_rgba_premultiplied (cairo_color_t *color,
				     double	   *red,
				     double	   *green,
				     double	   *blue,
				     double	   *alpha)
{
    *red   = color->red   * color->alpha;
    *green = color->green * color->alpha;
    *blue  = color->blue  * color->alpha;
    *alpha = color->alpha;
}