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cairo/src/cairo-color.c
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/* 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., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, 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; | |
case CAIRO_STOCK_NUM_COLORS: | |
default: | |
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); | |
} | |
/* Convert a double in [0.0, 1.0] to an integer in [0, 65535] | |
* The conversion is designed to divide the input range into 65536 | |
* equally-sized regions. This is achieved by multiplying by 65536 and | |
* then special-casing the result of an input value of 1.0 so that it | |
* maps to 65535 instead of 65536. | |
*/ | |
uint16_t | |
_cairo_color_double_to_short (double d) | |
{ | |
uint32_t i; | |
i = (uint32_t) (d * 65536); | |
i -= (i >> 16); | |
return i; | |
} | |
static void | |
_cairo_color_compute_shorts (cairo_color_t *color) | |
{ | |
color->red_short = _cairo_color_double_to_short (color->red * color->alpha); | |
color->green_short = _cairo_color_double_to_short (color->green * color->alpha); | |
color->blue_short = _cairo_color_double_to_short (color->blue * color->alpha); | |
color->alpha_short = _cairo_color_double_to_short (color->alpha); | |
} | |
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; | |
} | |
cairo_bool_t | |
_cairo_color_equal (const cairo_color_t *color_a, | |
const cairo_color_t *color_b) | |
{ | |
if (color_a == color_b) | |
return TRUE; | |
return color_a->red_short == color_b->red_short && | |
color_a->green_short == color_b->green_short && | |
color_a->blue_short == color_b->blue_short && | |
color_a->alpha_short == color_b->alpha_short; | |
} |