Gnome::Gtk3::ColorChooser

Interface implemented by widgets for choosing colors

Description

Gnome::Gtk3::ColorChooser is an interface that is implemented by widgets for choosing colors. Depending on the situation, colors may be allowed to have alpha (translucency).

In GTK+, the main widgets that implement this interface are Gnome::Gtk3::ColorChooserWidget, Gnome::Gtk3::ColorChooserDialog and Gnome::Gtk3::ColorButton.

Synopsis

Declaration

unit role Gnome::Gtk3::ColorChooser;

Example

my Gnome::Gtk3::ColorChooserDialog $ccdialog .= new(
  :title('my color dialog')
);

# Use methods defined in the interface
note "Green channel: ", $ccdialog.get-rgba($color).green;

Methods

add-palette

Adds a palette to the color chooser. If $orientation is horizontal, the colors are grouped in rows, with $colors_per_line colors in each row. If $horizontal is 0, the colors are grouped in columns instead.

The default color palette of Gnome::Gtk3::ColorChooserWidget has 27 colors, organized in columns of 3 colors. The default gray palette has 9 grays in a single row.

The layout of the color chooser widget works best when the palettes have 9-10 columns.

Calling this function for the first time has the side effect of removing the default color and gray palettes from the color chooser.

If $colors is undefined, the method removes all previously added palettes.

method add-palette (
  GtkOrientation $orientation,
  Int $colors_per_line, Int $n_colors,
  Array[Num] $colors
)

$orientation; GTK_ORIENTATION_HORIZONTAL if the palette should be displayed in rows, GTK_ORIENTATION_VERTICAL for columns.
$colors_per_line; the number of colors to show in each row/column.
$n_colors; the total number of elements in @colors.
or Array[N-GdkRGBA] $colors; the colors of the palette, or Any.

An Example

According to the documentation, an array of N-GdkRGBA Structures should be given. Raku however, turns a CArray[N-GdkRGBA] into references to the structure so it becomes an array of pointers. The sub is modified in such a way that either Array[N-GdkRGBA] or Array[Num] can be given. The latter one must always have elems % 4 == 0.

use NativeCall;
use Gnome::Gdk3::RGBA;
use Gnome::Gtk3::ColorChooser;

my Array $palette = [
  .0e0, .0e0, .0e0, 1e0, # color1: red, green, blue, opacity
  .1e0, .0e0, .0e0, 1e0, # color2: ...
  .2e0, .0e0, .0e0, 1e0,
  .3e0, .0e0, .0e0, 1e0,
  .4e0, .0e0, .0e0, 1e0,
  .5e0, .0e0, .0e0, 1e0,
  .6e0, .0e0, .0e0, 1e0,
  .7e0, .0e0, .0e0, 1e0,
  .8e0, .0e0, .0e0, 1e0,
  .9e0, .0e0, .0e0, 1e0,
  .0e0, .0e0, .0e0, 1e0,
  .0e0, .1e0, .0e0, 1e0,
  .0e0, .2e0, .0e0, 1e0,
  .0e0, .3e0, .0e0, 1e0,
  .0e0, .4e0, .0e0, 1e0,
  .0e0, .5e0, .0e0, 1e0,
  .0e0, .6e0, .0e0, 1e0,
  .0e0, .7e0, .0e0, 1e0,
  .0e0, .8e0, .0e0, 1e0,
  .0e0, .9e0, .0e0, 1e0, # color20: ...
];

my Gnome::Gdk3::RGBA $color .= new(
  :red(1e0), :green(.0e0), :blue(.0e0), :alpha(1e0)
);

my Gnome::Gtk3::ColorButton $cb .= new(:$color);
$cb.add-palette( GTK_ORIENTATION_HORIZONTAL, 10, 20, $palette);

Or it can be done like this

my Array $palette = [];
for .0, .1 ... .9 -> Num $rgb-gray {
  $palette.push: N-GdkRGBA.new(
    :red($rgb-gray), :green($rgb-gray), :blue($rgb-gray), :alpha(1e0)
  );
}

my N-GdkRGBA $color .= new(
  :red(0e0), :green(.0e0), :blue(.0e0), :alpha(1e0)
);
my Gnome::Gtk3::ColorButton $cb .= new(:$color);
$cb.add-palette( GTK_ORIENTATION_HORIZONTAL, 10, 10, $palette);

get-rgba

Gets the currently-selected color.

method get-rgba ( --> Gnome::Gdk3::RGBA )

Returns a Gnome::Gdk3::RGBA filled in with the current color. Note; Previously the method returned an N-GdkRGBA native object. Now that a real method is defined, a Raku object is returned.

get-use-alpha

Returns whether the color chooser shows the alpha channel.

Returns: True if the color chooser uses the alpha channel, False if not

method get-use-alpha ( --> Bool )

set-rgba

Sets the color.

method set-rgba ( N-GObject() $color )

$color; the new color

set-use-alpha

Sets whether or not the color chooser should use the alpha channel.

method set-use-alpha ( Bool $use_alpha )

$use_alpha; True if color chooser should use alpha channel, False if not

Signals

There are two ways to connect to a signal. The first option you have is to use register-signal() from Gnome::GObject::Object. The second option is to use connect-object() directly from Gnome::GObject::Signal.

First method

The positional arguments of the signal handler are all obligatory as well as their types. The named attributes :$widget and user data are optional.

# handler method
method mouse-event ( GdkEvent $event, :$widget ) { ... }

# connect a signal on window object
my Gnome::Gtk3::Window $w .= new( ... );
$w.register-signal( self, 'mouse-event', 'button-press-event');

Second method

my Gnome::Gtk3::Window $w .= new( ... );
my Callable $handler = sub (
  N-GObject $native, GdkEvent $event, OpaquePointer $data
) {
  ...
}

$w.connect-object( 'button-press-event', $handler);

Also here, the types of positional arguments in the signal handler are important. This is because both methods register-signal() and connect-object() are using the signatures of the handler routines to setup the native call interface.

Supported signals

color-activated

Emitted when a color is activated from the color chooser. This usually happens when the user clicks a color swatch, or a color is selected and the user presses one of the keys Space, Shift+Space, Return or Enter.

method handler (
  N-GdkRGBA $color,
  Int :$_handle_id,
  Gnome::GObject::Object :_widget($chooser),
  *%user-options
);

$chooser; the object which received the signal
$color; the color

Properties

An example of using a string type property of a Gnome::Gtk3::Label object. This is just showing how to set/read a property, not that it is the best way to do it. This is because a) The class initialization often provides some options to set some of the properties and b) the classes provide many methods to modify just those properties. In the case below one can use new(:label(‘my text label’)) or gtk_label_set_text(‘my text label’).

my Gnome::Gtk3::Label $label .= new;
my Gnome::GObject::Value $gv .= new(:init(G_TYPE_STRING));
$label.g-object-get-property( 'label', $gv);
$gv.g-value-set-string('my text label');

Supported properties

Color: rgba

The rgba property contains the currently selected color, as a Gnome::Gdk3::RGBA struct. The property can be set to change the current selection programmatically.

The Gnome::GObject::Value type of property rgba is G_TYPE_BOXED.

Use alpha: use-alpha

When use-alpha is True, colors may have alpha (translucency) information. When it is False, the Gnome::Gdk3::RGBA struct obtained via the rgba property will be forced to have alpha == 1.

Implementations are expected to show alpha by rendering the color over a non-uniform background (like a checkerboard pattern).

The Gnome::GObject::Value type of property use-alpha is G_TYPE_BOOLEAN.