## GimpRGB

GimpRGB — Definitions and Functions relating to RGB colors.

## Synopsis

    struct              GimpRGB;
    enum                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);
    gboolean            gimp_rgb_parse_name                 (GimpRGB *rgb,
                                                             const gchar *name,
                                                             gint len);
    gboolean            gimp_rgb_parse_hex                  (GimpRGB *rgb,
                                                             const gchar *hex,
                                                             gint len);
    gboolean            gimp_rgb_parse_css                  (GimpRGB *rgb,
                                                             const gchar *css,
                                                             gint len);
    gint                gimp_rgb_list_names                 (const gchar ***names,
                                                             GimpRGB **colors);
    void                gimp_rgb_add                        (GimpRGB *rgb1,
                                                             const GimpRGB *rgb2);
    void                gimp_rgb_subtract                   (GimpRGB *rgb1,
                                                             const GimpRGB *rgb2);
    void                gimp_rgb_multiply                   (GimpRGB *rgb1,
                                                             gdouble factor);
    gdouble             gimp_rgb_distance                   (const GimpRGB *rgb1,
                                                             const GimpRGB *rgb2);
    gdouble             gimp_rgb_max                        (const GimpRGB *rgb);
    gdouble             gimp_rgb_min                        (const GimpRGB *rgb);
    void                gimp_rgb_clamp                      (GimpRGB *rgb);
    void                gimp_rgb_gamma                      (GimpRGB *rgb,
                                                             gdouble gamma);
    gdouble             gimp_rgb_luminance                  (const GimpRGB *rgb);
    guchar              gimp_rgb_luminance_uchar            (const GimpRGB *rgb);
    gdouble             gimp_rgb_intensity                  (const GimpRGB *rgb);
    guchar              gimp_rgb_intensity_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);
    gboolean            gimp_rgba_parse_css                 (GimpRGB *rgba,
                                                             const gchar *css,
                                                             gint len);
    void                gimp_rgba_add                       (GimpRGB *rgba1,
                                                             const GimpRGB *rgba2);
    void                gimp_rgba_subtract                  (GimpRGB *rgba1,
                                                             const GimpRGB *rgba2);
    void                gimp_rgba_multiply                  (GimpRGB *rgba,
                                                             gdouble factor);
    gdouble             gimp_rgba_distance                  (const GimpRGB *rgba1,
                                                             const GimpRGB *rgba2);
    #define             GIMP_RGB_LUMINANCE                  (r,
                                                             g,
                                                             b)
    #define             GIMP_RGB_LUMINANCE_RED
    #define             GIMP_RGB_LUMINANCE_GREEN
    #define             GIMP_RGB_LUMINANCE_BLUE
    #define             GIMP_RGB_INTENSITY                  (r,
                                                             g,
                                                             b)
    #define             GIMP_RGB_INTENSITY_RED
    #define             GIMP_RGB_INTENSITY_GREEN
    #define             GIMP_RGB_INTENSITY_BLUE
    #define             GIMP_TYPE_RGB
    #define             GIMP_TYPE_PARAM_RGB
    GParamSpec *        gimp_param_spec_rgb                 (const gchar *name,
                                                             const gchar *nick,
                                                             const gchar *blurb,
                                                             gboolean has_alpha,
                                                             const GimpRGB *default_value,
                                                             GParamFlags flags);
    gboolean            gimp_param_spec_rgb_has_alpha       (GParamSpec *pspec);
    #define             GIMP_VALUE_HOLDS_RGB                (value)
    void                gimp_value_get_rgb                  (const GValue *value,
                                                             GimpRGB *rgb);
    void                gimp_value_set_rgb                  (GValue *value,
                                                             const GimpRGB *rgb);

## Description

Definitions and Functions relating to RGB colors.

## Details

### struct GimpRGB

    struct GimpRGB {
      gdouble r, g, b, a;
    };

Used to keep RGB and RGBA colors. All components are in a range of [0.0..1.0].

gdouble `r`; | the red component
gdouble `g`; | the green component
gdouble `b`; | the blue component
gdouble `a`; | the alpha component

### enum GimpRGBCompositeMode

    typedef enum {
      GIMP_RGB_COMPOSITE_NONE = 0,
      GIMP_RGB_COMPOSITE_NORMAL,
      GIMP_RGB_COMPOSITE_BEHIND
    } GimpRGBCompositeMode;

### gimp_rgb_set ()

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

Sets the red, green and blue components of `rgb` and leaves the alpha component unchanged. The color values should be between 0.0 and 1.0 but there is no check to enforce this and the values are set exactly as they are passed in.

`rgb` : | a GimpRGB struct
`red` : | the red component
`green` : | the green component
`blue` : | the blue component

### gimp_rgb_set_alpha ()

    void                gimp_rgb_set_alpha                  (GimpRGB *rgb,
                                                             gdouble alpha);

Sets the alpha component of `rgb` and leaves the RGB components unchanged.

`rgb` : | a GimpRGB struct
`alpha` : | the alpha component

### gimp_rgb_set_uchar ()

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

Sets the red, green and blue components of `rgb` from 8bit values (0 to 255) and leaves the alpha component unchanged.

`rgb` : | a GimpRGB struct
`red` : | the red component
`green` : | the green component
`blue` : | the blue component

### gimp_rgb_get_uchar ()

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

### gimp_rgb_parse_name ()

    gboolean            gimp_rgb_parse_name                 (GimpRGB *rgb,
                                                             const gchar *name,
                                                             gint len);

Attempts to parse a color name. This function accepts SVG 1.0 color keywords.

This function does not touch the alpha component of `rgb`.

`rgb` : | a GimpRGB struct used to return the parsed color
`name` : | a color name (in UTF-8 encoding)
`len` : | the length of `name`, in bytes. or -1 if `name` is nul-terminated
Returns : | `TRUE` if `name` was parsed successfully and `rgb` has been set, `FALSE` otherwise

Since GIMP 2.2

### gimp_rgb_parse_hex ()

    gboolean            gimp_rgb_parse_hex                  (GimpRGB *rgb,
                                                             const gchar *hex,
                                                             gint len);

Attempts to parse a string describing an RGB color in hexadecimal notation (optionally prefixed with a '#').

This function does not touch the alpha component of `rgb`.

`rgb` : | a GimpRGB struct used to return the parsed color
`hex` : | a string describing a color in hexadecimal notation
`len` : | the length of `hex`, in bytes. or -1 if `hex` is nul-terminated
Returns : | `TRUE` if `hex` was parsed successfully and `rgb` has been set, `FALSE` otherwise

Since GIMP 2.2

### gimp_rgb_parse_css ()

    gboolean            gimp_rgb_parse_css                  (GimpRGB *rgb,
                                                             const gchar *css,
                                                             gint len);

Attempts to parse a string describing an RGB color in CSS notation. This can be either a numerical representation (`rgb(255,0,0)` or `rgb(100%,0%,0%)`) or a hexadecimal notation as parsed by `gimp_rgb_parse_hex()` (`#ff0000`) or a color name as parsed by `gimp_rgb_parse_name()` (`red`).

This function does not touch the alpha component of `rgb`.

`rgb` : | a GimpRGB struct used to return the parsed color
`css` : | a string describing a color in CSS notation
`len` : | the length of `hex`, in bytes. or -1 if `hex` is nul-terminated
Returns : | `TRUE` if `css` was parsed successfully and `rgb` has been set, `FALSE` otherwise

Since GIMP 2.2

### gimp_rgb_list_names ()

    gint                gimp_rgb_list_names                 (const gchar ***names,
                                                             GimpRGB **colors);

Allows to retrieve the list of SVG 1.0 color keywords that is used by `gimp_rgb_parse_name()`.

The returned strings are const and must not be freed. Only the two arrays are allocated dynamically. You must call `g_free()` on the `names` and `colors` arrays when they are not any longer needed.

`names` : | return location for an array of color names
`colors` : | return location for an array of GimpRGB structs
Returns : | the number of named colors (i.e. the length of the returned arrays)

Since GIMP 2.2

### gimp_rgb_add ()

    void                gimp_rgb_add                        (GimpRGB *rgb1,
                                                             const GimpRGB *rgb2);

### gimp_rgb_subtract ()

    void                gimp_rgb_subtract                   (GimpRGB *rgb1,
                                                             const GimpRGB *rgb2);

### gimp_rgb_multiply ()

    void                gimp_rgb_multiply                   (GimpRGB *rgb1,
                                                             gdouble factor);

### gimp_rgb_distance ()

    gdouble             gimp_rgb_distance                   (const GimpRGB *rgb1,
                                                             const GimpRGB *rgb2);

### gimp_rgb_max ()

    gdouble             gimp_rgb_max                        (const GimpRGB *rgb);

### gimp_rgb_min ()

    gdouble             gimp_rgb_min                        (const GimpRGB *rgb);

### gimp_rgb_clamp ()

    void                gimp_rgb_clamp                      (GimpRGB *rgb);

### gimp_rgb_gamma ()

    void                gimp_rgb_gamma                      (GimpRGB *rgb,
                                                             gdouble gamma);

### gimp_rgb_luminance ()

    gdouble             gimp_rgb_luminance                  (const GimpRGB *rgb);

`rgb` : | a GimpRGB struct
Returns : | the luminous intensity of the range from 0.0 to 1.0.

Since GIMP 2.4

### gimp_rgb_luminance_uchar ()

    guchar              gimp_rgb_luminance_uchar            (const GimpRGB *rgb);

`rgb` : | a GimpRGB struct
Returns : | the luminous intensity in the range from 0 to 255.

Since GIMP 2.4

### gimp_rgb_intensity ()

    gdouble             gimp_rgb_intensity                  (const GimpRGB *rgb);

### Warning

`gimp_rgb_intensity` is deprecated and should not be used in newly-written code.

This function is deprecated! Use `gimp_rgb_luminance()` instead.

`rgb` : | a GimpRGB struct
Returns : | the intensity in the range from 0.0 to 1.0.

### gimp_rgb_intensity_uchar ()

    guchar              gimp_rgb_intensity_uchar            (const GimpRGB *rgb);

### Warning

`gimp_rgb_intensity_uchar` is deprecated and should not be used in newly-written code.

This function is deprecated! Use `gimp_rgb_luminance_uchar()` instead.

`rgb` : | a GimpRGB struct
Returns : | the intensity in the range from 0 to 255.

### gimp_rgb_composite ()

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

### gimp_rgba_set ()

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

Sets the red, green, blue and alpha components of `rgb`. The values should be between 0.0 and 1.0 but there is no check to enforce this and the values are set exactly as they are passed in.

`rgba` : | a GimpRGB struct
`red` : | the red component
`green` : | the green component
`blue` : | the blue component
`alpha` : | the alpha component

### gimp_rgba_set_uchar ()

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

Sets the red, green, blue and alpha components of `rgb` from 8bit values (0 to 255).

`rgba` : | a GimpRGB struct
`red` : | the red component
`green` : | the green component
`blue` : | the blue component
`alpha` : | the alpha component

### gimp_rgba_get_uchar ()

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

### gimp_rgba_parse_css ()

    gboolean            gimp_rgba_parse_css                 (GimpRGB *rgba,
                                                             const gchar *css,
                                                             gint len);

Similar to `gimp_rgb_parse_css()` but handles RGB colors with alpha channel in the numerical CSS notation (`rgba(255,0,0,255)` or `rgba(100%,0%,0%,1000%)`).

It doesn't handle the hexadecimal notation or color names because they leave the alpha channel unspecified.

`rgba` : | a GimpRGB struct used to return the parsed color
`css` : | a string describing a color in CSS notation
`len` : | the length of `hex`, in bytes. or -1 if `hex` is nul-terminated
Returns : | `TRUE` if `css` was parsed successfully and `rgb` has been set, `FALSE` otherwise

Since GIMP 2.2

### gimp_rgba_add ()

    void                gimp_rgba_add                       (GimpRGB *rgba1,
                                                             const GimpRGB *rgba2);

### gimp_rgba_subtract ()

    void                gimp_rgba_subtract                  (GimpRGB *rgba1,
                                                             const GimpRGB *rgba2);

### gimp_rgba_multiply ()

    void                gimp_rgba_multiply                  (GimpRGB *rgba,
                                                             gdouble factor);

### gimp_rgba_distance ()

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

### GIMP_RGB_LUMINANCE()

    #define             GIMP_RGB_LUMINANCE(r,g,b)

### GIMP_RGB_LUMINANCE_RED

    #define GIMP_RGB_LUMINANCE_RED    (0.2126)

### GIMP_RGB_LUMINANCE_GREEN

    #define GIMP_RGB_LUMINANCE_GREEN  (0.7152)

### GIMP_RGB_LUMINANCE_BLUE

    #define GIMP_RGB_LUMINANCE_BLUE   (0.0722)

### GIMP_RGB_INTENSITY()

    #define             GIMP_RGB_INTENSITY(r,g,b)

### Warning

`GIMP_RGB_INTENSITY` is deprecated and should not be used in newly-written code.

### GIMP_RGB_INTENSITY_RED

    #define GIMP_RGB_INTENSITY_RED    (0.30)

### Warning

`GIMP_RGB_INTENSITY_RED` is deprecated and should not be used in newly-written code.

### GIMP_RGB_INTENSITY_GREEN

    #define GIMP_RGB_INTENSITY_GREEN  (0.59)

### Warning

`GIMP_RGB_INTENSITY_GREEN` is deprecated and should not be used in newly-written code.

### GIMP_RGB_INTENSITY_BLUE

    #define GIMP_RGB_INTENSITY_BLUE   (0.11)

### Warning

`GIMP_RGB_INTENSITY_BLUE` is deprecated and should not be used in newly-written code.

### GIMP_TYPE_RGB

    #define GIMP_TYPE_RGB               (gimp_rgb_get_type ())

### GIMP_TYPE_PARAM_RGB

    #define GIMP_TYPE_PARAM_RGB           (gimp_param_rgb_get_type ())

### gimp_param_spec_rgb ()

    GParamSpec *        gimp_param_spec_rgb                 (const gchar *name,
                                                             const gchar *nick,
                                                             const gchar *blurb,
                                                             gboolean has_alpha,
                                                             const GimpRGB *default_value,
                                                             GParamFlags flags);

Creates a param spec to hold an GimpRGB value. See `g_param_spec_internal()` for more information.

`name` : | Canonical name of the param
`nick` : | Nickname of the param
`blurb` : | Brief desciption of param.
`has_alpha` : | `TRUE` if the alpha channel has relevance.
`default_value` : | Value to use if none is assigned.
`flags` : | a combination of GParamFlags
Returns : | a newly allocated GParamSpec instance

Since GIMP 2.4

### gimp_param_spec_rgb_has_alpha ()

    gboolean            gimp_param_spec_rgb_has_alpha       (GParamSpec *pspec);

`pspec` : | a GParamSpec to hold an GimpRGB value.
Returns : | `TRUE` if the alpha channel is relevant.

Since GIMP 2.4

### GIMP_VALUE_HOLDS_RGB()

    #define GIMP_VALUE_HOLDS_RGB(value) (G_TYPE_CHECK_VALUE_TYPE ((value), GIMP_TYPE_RGB))

### gimp_value_get_rgb ()

    void                gimp_value_get_rgb                  (const GValue *value,
                                                             GimpRGB *rgb);

### gimp_value_set_rgb ()

    void                gimp_value_set_rgb                  (GValue *value,
                                                             const GimpRGB *rgb);