gimp/libgimpcolor/gimprgb.h

/* LIBGIMP - The GIMP Library
 * Copyright (C) 1995-1997 Peter Mattis and Spencer Kimball
 *
 * This library is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library.  If not, see
 * <https://www.gnu.org/licenses/>.
 */

#if !defined (__GIMP_COLOR_H_INSIDE__) && !defined (GIMP_COLOR_COMPILATION)
#error "Only <libgimpcolor/gimpcolor.h> can be included directly."
#endif

#ifndef __GIMP_RGB_H__
#define __GIMP_RGB_H__

G_BEGIN_DECLS

/* For information look into the C source or the html documentation */


/*
 * GIMP_TYPE_RGB
 */

#define GIMP_TYPE_RGB               (gimp_rgb_get_type ())

GType   gimp_rgb_get_type           (void) G_GNUC_CONST;


/*  RGB and RGBA color types and operations taken from LibGCK  */

/**
 * GimpRGBCompositeMode:
 * @GIMP_RGB_COMPOSITE_NONE: don't do compositing
 * @GIMP_RGB_COMPOSITE_NORMAL: composite on top
 * @GIMP_RGB_COMPOSITE_BEHIND: composite behind
 **/
typedef enum
{
  GIMP_RGB_COMPOSITE_NONE = 0,
  GIMP_RGB_COMPOSITE_NORMAL,
  GIMP_RGB_COMPOSITE_BEHIND
} GimpRGBCompositeMode;


void      gimp_rgb_set             (GimpRGB       *rgb,
                                    gdouble        red,
                                    gdouble        green,
                                    gdouble        blue);
void      gimp_rgb_set_alpha       (GimpRGB       *rgb,
                                    gdouble        alpha);

void      gimp_rgb_set_uchar       (GimpRGB       *rgb,
                                    guchar         red,
                                    guchar         green,
                                    guchar         blue);
void      gimp_rgb_get_uchar       (const GimpRGB *rgb,
                                    guchar        *red,
                                    guchar        *green,
                                    guchar        *blue);

void      gimp_rgb_add             (GimpRGB       *rgb1,
                                    const GimpRGB *rgb2);
void      gimp_rgb_multiply        (GimpRGB       *rgb1,
                                    gdouble        factor);

gdouble   gimp_rgb_max             (const GimpRGB *rgb);
gdouble   gimp_rgb_min             (const GimpRGB *rgb);
void      gimp_rgb_clamp           (GimpRGB       *rgb);

gdouble   gimp_rgb_luminance       (const GimpRGB *rgb);
guchar    gimp_rgb_luminance_uchar (const GimpRGB *rgb);

void      gimp_rgb_composite       (GimpRGB              *color1,
                                    const GimpRGB        *color2,
                                    GimpRGBCompositeMode  mode);

void      gimp_rgba_set            (GimpRGB       *rgba,
                                    gdouble        red,
                                    gdouble        green,
                                    gdouble        blue,
                                    gdouble        alpha);

void      gimp_rgba_set_uchar      (GimpRGB       *rgba,
                                    guchar         red,
                                    guchar         green,
                                    guchar         blue,
                                    guchar         alpha);
void      gimp_rgba_get_uchar      (const GimpRGB *rgba,
                                    guchar        *red,
                                    guchar        *green,
                                    guchar        *blue,
                                    guchar        *alpha);

void      gimp_rgba_add            (GimpRGB       *rgba1,
                                    const GimpRGB *rgba2);
void      gimp_rgba_multiply       (GimpRGB       *rgba,
                                    gdouble        factor);

gdouble   gimp_rgba_distance       (const GimpRGB *rgba1,
                                    const GimpRGB *rgba2);



/*  Map D50-adapted sRGB to luminance  */

/*
 * The weights to compute true CIE luminance from linear red, green
 * and blue as defined by the sRGB color space specs in an ICC profile
 * color managed application. The weights below have been chromatically
 * adapted from D65 (as specified by the sRGB color space specs)
 * to D50 (as specified by D50 illuminant values in the ICC V4 specs).
 */

#define GIMP_RGB_LUMINANCE_RED    (0.22248840)
#define GIMP_RGB_LUMINANCE_GREEN  (0.71690369)
#define GIMP_RGB_LUMINANCE_BLUE   (0.06060791)

#define GIMP_RGB_LUMINANCE(r,g,b) ((r) * GIMP_RGB_LUMINANCE_RED   + \
                                   (g) * GIMP_RGB_LUMINANCE_GREEN + \
                                   (b) * GIMP_RGB_LUMINANCE_BLUE)


G_END_DECLS

#endif  /* __GIMP_RGB_H__ */