Interfacing Raku to Gnome GTK+

Gnome::Gdk3::Rgba

RGBA colors

Description

Gnome::Gdk3::RGBA 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.

Synopsis

Declaration

unit class Gnome::Gdk3::RGBA;
also is Gnome::GObject::Boxed;

Example

my Gnome::Gdk3::RGBA $color .= new(
  :red(.5e0), :green(.5e0), :blue(.5e0), :alpha(.5e0)
);

Types

N-GdkRGBA

N-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.

The colors originally where Num type but they can now also be Int, Rat, Str or Num as long as they represent a number between 0 and 1.

  • $.red; The intensity of the red channel from 0.0 to 1.0 inclusive

  • $.green; The intensity of the green channel from 0.0 to 1.0 inclusive

  • $.blue; The intensity of the blue channel from 0.0 to 1.0 inclusive

  • $.alpha; The opacity of the color from 0.0 for completely translucent to 1.0 for opaque

    my N-GdkRGBA $c .= new( :red(1), :green(1), :blue(0.5), :alpha(0.99));

Methods

new

:red, :green, :blue, :alpha

Create a new object using colors and transparency values. Their ranges are from 0 to 1. All values are optional and are set to 1e0 by default.

multi method new (
  Num() :$red, Num() :$green, Num() :$blue, Num() :$alpha
)

  • $.red; The intensity of the red channel from 0.0 to 1.0 inclusive

  • $.green; The intensity of the green channel from 0.0 to 1.0 inclusive

  • $.blue; The intensity of the blue channel from 0.0 to 1.0 inclusive

  • $.alpha; The opacity of the color from 0.0 for completely translucent to 1.0 for opaque

:rgba

Create an object using a string which is parsed with parse(). If parsing fails, the color is set to opaque white.

multi method new ( Str :$rgba! )

:native-object

Create an object using a native object from elsewhere. See also Gnome::N::TopLevelSupportClass.

multi method new ( N-GObject :$native-object! )

alpha

Set the alpha transparency to a new value if provided. Returns original or newly set value.

method alpha ( Num $c? --> Num )

blue

Set the blue color to a new value if provided. Returns original or newly set color value.

method blue ( Num $c? --> Num )

copy

Makes a copy of a Gnome::Gdk3::RGBA.

Returns: A newly allocated Gnome::Gdk3::RGBA, with the same contents as this rgba object

method copy ( --> N-GObject )
  • N-GdkRGBA $rgba; a Gnome::Gdk3::RGBA

equal

Compare native RGBA color with a given one.

Returns: True if the two colors compare equal

method equal ( N-GObject() $compare-with --> Bool )
  • $compare-with; another Gnome::Gdk3::RGBA object

green

Set the green color to a new value if provided. Returns original or newly set color value.

method green ( Num $c? --> Num )

hash

A method that stores Gnome::Gdk3::RGBA objects in a hash or to return a value. Note that the original GTK function only returns a UInt value and does not provide a hash table storage facility.

multi method hash ( N-GObject() $p --> UInt )

multi method hash ( UInt $key --> N-GObject )

  • $p; a Gnome::Gdk3::RGBA value to store

  • $key; a key to return a previously stored N-GdkRGBA value

parse

Parses a textual representation of a color and set / overwrite the values in the red, green, blue and alpha fields in this Gnome::Gdk3::RGBA object.

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.

Returns: True if the parsing succeeded

method parse ( Str $spec --> Bool )
  • Str $spec; the string specifying the color

red

Set the red color to a new value if provided. Returns original or newly set color value.

method red ( Num() $c? --> Num )

to-string

Returns a textual specification of this rgba object 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 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.

Returns: A newly allocated text string

method to-string ( --> Str )
  • N-GObject $rgba; a native Gnome::Gdk3::RGBA