Description

A Gnome::Gtk4::Scale is a slider control used to select a numeric value.

To use it, you’ll probably want to investigate the methods on its base class, Gnome::Gtk4::Range, in addition to the methods for Gnome::Gtk4::Scale itself. To set the value of a scale, you would normally use .set-value() in class Gnome::Gtk4::Range. To detect changes to the value, you would normally use the value-changed defined in Range signal.

Note that using the same upper and lower bounds for the Gnome::Gtk4::Scale (through the Gnome::Gtk4::Range methods) will hide the slider itself. This is useful for applications that want to show an undeterminate value on the scale, without changing the layout of the application (such as movie or music players).

GtkScale as GtkBuildable

Gnome::Gtk4::Scale supports a custom `<marks>` element, which can contain multiple `<mark\>` elements. The “value” and “position” attributes have the same meaning as .add-mark() parameters of the same name. If the element is not empty, its content is taken as the markup to show at the mark. It can be translated with the usual ”translatable” and “context” attributes.

CSS nodes

Gnome::Gtk4::Scale has a main CSS node with name scale and a subnode for its contents, with subnodes named trough and slider.

The main node gets the style class .fine-tune added when the scale is in 'fine-tuning' mode.

If the scale has an origin (see .set-has-origin()), there is a subnode with name highlight below the trough node that is used for rendering the highlighted part of the trough.

If the scale is showing a fill level (see .set-show-fill-level() in class Gnome::Gtk4::Range), there is a subnode with name fill below the trough node that is used for rendering the filled in part of the trough.

If marks are present, there is a marks subnode before or after the trough node, below which each mark gets a node with name mark. The marks nodes get either the .top or .bottom style class.

The mark node has a subnode named indicator. If the mark has text, it also has a subnode named label. When the mark is either above or left of the scale, the label subnode is the first when present. Otherwise, the indicator subnode is the first.

The main CSS node gets the 'marks-before' and/or 'marks-after' style classes added depending on what marks are present.

If the scale is displaying the value (see draw-value), there is subnode with name value. This node will get the .top or .bottom style classes similar to the marks node.

Accessibility

Gnome::Gtk4::Scale uses the GTK_ACCESSIBLE_ROLE_SLIDER role.

Class initialization

new

:native-object

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

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

new-scale

Creates a new Gnome::Gtk4::Scale.

method new-scale ( GtkOrientation $orientation, N-Object() $adjustment --> Gnome::Gtk4::Scale \)

• $orientation; the scale’s orientation..

• $adjustment; the Gnome::Gtk4::Adjustment which sets the range of the scale, or undefined to create a new adjustment..

new-with-range

Creates a new scale widget with a range from $min to $max.

The returns scale will have the given orientation and will let the user input a number between $min and $max (including $min and $max) with the increment $step. $step must be nonzero; it’s the distance the slider moves when using the arrow keys to adjust the scale value.

Note that the way in which the precision is derived works best if $step is a power of ten. If the resulting precision is not suitable for your needs, use .set-digits() to correct it.

method new-with-range ( GtkOrientation $orientation, Num() $min, Num() $max, Num() $step --> Gnome::Gtk4::Scale \)

• $orientation; the scale’s orientation..

• $min; minimum value.

• $max; maximum value.

• $step; step increment (tick size) used with keyboard shortcuts.

Methods

add-mark

Adds a mark at $value.

A mark is indicated visually by drawing a tick mark next to the scale, and GTK makes it easy for the user to position the scale exactly at the marks value.

If $markup is defined, text is shown next to the tick mark.

To remove marks from a scale, use .clear-marks().

method add-mark ( Num() $value, GtkPositionType $position, Str $markup )

• $value; the value at which the mark is placed, must be between the lower and upper limits of the scales’ adjustment.

• $position; where to draw the mark. For a horizontal scale, GTK_POS_TOP and GTK_POS_LEFT are drawn above the scale, anything else below. For a vertical scale, GTK_POS_LEFT and GTK_POS_TOP are drawn to the left of the scale, anything else to the right..

• $markup; Text to be shown at the mark, using Pango markup.

clear-marks

Removes any marks that have been added.

method clear-marks ( )

get-digits

Gets the number of decimal places that are displayed in the value.

method get-digits (--> Int )

Return value; the number of decimal places that are displayed.

get-draw-value

Returns whether the current value is displayed as a string next to the slider.

method get-draw-value (--> Bool )

Return value; whether the current value is displayed as a string.

get-has-origin

Returns whether the scale has an origin.

method get-has-origin (--> Bool )

Return value; True if the scale has an origin..

get-layout

Gets the Gnome::Pango::Layout used to display the scale.

The returned object is owned by the scale so does not need to be freed by the caller.

method get-layout (--> N-Object )

Return value; the Gnome::Pango::Layout for this scale, or undefined if the draw-value property is False..

get-layout-offsets

Obtains the coordinates where the scale will draw the Gnome::Pango::Layout representing the text in the scale.

Remember when using the Gnome::Pango::Layout function you need to convert to and from pixels using PANGO_PIXELS()` or Gnome::Pango::T-types.

If the draw-value property is False, the return values are undefined.

method get-layout-offsets ( Array[Int] $x, Array[Int] $y )

• $x; (transfer ownership: full) location to store X offset of layout.

• $y; (transfer ownership: full) location to store Y offset of layout.

get-value-pos

Gets the position in which the current value is displayed.

method get-value-pos (--> GtkPositionType )

Return value; the position in which the current value is displayed.

set-digits

Sets the number of decimal places that are displayed in the value.

Also causes the value of the adjustment to be rounded to this number of digits, so the retrieved value matches the displayed one, if draw-value is True when the value changes. If you want to enforce rounding the value when draw-value is False, you can set round-digits defined in Gnome::Gtk4::Range instead.

Note that rounding to a small number of digits can interfere with the smooth autoscrolling that is built into Gnome::Gtk4::Scale. As an alternative, you can use .set-format-value-func() to format the displayed value yourself.

method set-digits ( Int() $digits )

• $digits; the number of decimal places to display, e.g. use 1 to display 1.0, 2 to display 1.00, etc.

set-draw-value

Specifies whether the current value is displayed as a string next to the slider.

method set-draw-value ( Bool() $draw-value )

• $draw-value; True to draw the value.

set-format-value-func This function is not yet available

C<$func> allows you to change how the scale value is displayed.

The given function will return an allocated string representing $value. That string will then be used to display the scale's value.

If #NULL is passed as $func, the value will be displayed on its own, rounded according to the value of the digits property.

method set-format-value-func ( &func, gpointer $user-data, … )

• &func; function that formats the value. Tthe function must be specified with following signature; :( N-Object $scale, gdouble $value, gpointer $user-data -- Str )>.

• $user-data; user data to pass to $func.

• destroy-notify; destroy function for $user-data. Note that each argument must be specified as a type followed by its value!

set-has-origin

Sets whether the scale has an origin.

If has-origin is set to True (the default), the scale will highlight the part of the trough between the origin (bottom or left side) and the current value.

method set-has-origin ( Bool() $has-origin )

• $has-origin; True if the scale has an origin.

set-value-pos

Sets the position in which the current value is displayed.

method set-value-pos ( GtkPositionType $pos )

• $pos; the position in which the current value is displayed.