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RGBA Colors

RGBA Colors — RGBA colors

Functions

Types and Values

  GdkRGBA

Includes

#include <gdk/gdk.h>

Description

GdkRGBA is a convenient way to pass rgba colors around. It’s based on cairo’s way to deal with colors and mirrors its behavior. All values are in the range from 0.0 to 1.0 inclusive. So the color (0.0, 0.0, 0.0, 0.0) represents transparent black and (1.0, 1.0, 1.0, 1.0) is opaque white. Other values will be clamped to this range when drawing.

Functions

gdk_rgba_copy ()

GdkRGBA *
gdk_rgba_copy (const GdkRGBA *rgba);

Makes a copy of a GdkRGBA.

The result must be freed through gdk_rgba_free().

Parameters

rgba

a GdkRGBA

 

Returns

A newly allocated GdkRGBA, with the same contents as rgba

Since 3.0


gdk_rgba_free ()

void
gdk_rgba_free (GdkRGBA *rgba);

Frees a GdkRGBA created with gdk_rgba_copy()

Parameters

rgba

a GdkRGBA

 

Since 3.0


gdk_rgba_parse ()

gboolean
gdk_rgba_parse (GdkRGBA *rgba,
                const gchar *spec);

Parses a textual representation of a color, filling in the red , green , blue and alpha fields of the rgba GdkRGBA.

The string can be either one of:

  • A standard name (Taken from the X11 rgb.txt file).

  • A hexadecimal value in the form “#rgb”, “#rrggbb”, “#rrrgggbbb” or ”#rrrrggggbbbb”

  • A RGB color in the form “rgb(r,g,b)” (In this case the color will have full opacity)

  • A RGBA color in the form “rgba(r,g,b,a)”

Where “r”, “g”, “b” and “a” are respectively the red, green, blue and alpha color values. In the last two cases, r g and b are either integers in the range 0 to 255 or precentage values in the range 0% to 100%, and a is a floating point value in the range 0 to 1.

Parameters

rgba

the GdkRGBA to fill in

 

spec

the string specifying the color

 

Returns

TRUE if the parsing succeeded

Since 3.0


gdk_rgba_equal ()

gboolean
gdk_rgba_equal (gconstpointer p1,
                gconstpointer p2);

Compares two RGBA colors.

Parameters

p1

a GdkRGBA pointer.

[type GdkRGBA]

p2

another GdkRGBA pointer.

[type GdkRGBA]

Returns

TRUE if the two colors compare equal

Since 3.0


gdk_rgba_hash ()

guint
gdk_rgba_hash (gconstpointer p);

A hash function suitable for using for a hash table that stores GdkRGBAs.

Parameters

p

a GdkRGBA pointer.

[type GdkRGBA]

Returns

The hash value for p

Since 3.0


gdk_rgba_to_string ()

gchar *
gdk_rgba_to_string (const GdkRGBA *rgba);

Returns a textual specification of rgba in the form rgb (r, g, b) or rgba (r, g, b, a), where “r”, “g”, “b” and “a” represent the red, green, blue and alpha values respectively. r, g, and b are represented as integers in the range 0 to 255, and a is represented as floating point value in the range 0 to 1.

These string forms are string forms those supported by the CSS3 colors module, and can be parsed by gdk_rgba_parse().

Note that this string representation may lose some precision, since r, g and b are represented as 8-bit integers. If this is a concern, you should use a different representation.

Parameters

rgba

a GdkRGBA

 

Returns

A newly allocated text string

Since 3.0

Types and Values

GdkRGBA

typedef struct {
  gdouble red;
  gdouble green;
  gdouble blue;
  gdouble alpha;
} GdkRGBA;

A GdkRGBA is used to represent a (possibly translucent) color, in a way that is compatible with cairos notion of color.

Members

gdouble red;

The intensity of the red channel from 0.0 to 1.0 inclusive

 

gdouble green;

The intensity of the green channel from 0.0 to 1.0 inclusive

 

gdouble blue;

The intensity of the blue channel from 0.0 to 1.0 inclusive

 

gdouble alpha;

The opacity of the color from 0.0 for completely translucent to 1.0 for opaque