The slider widget is useful for inputting numeric values.

rtk.Slider supports both continuous and discrete modes (depending on whether step is defined), with optional ticks and tick labels.

somebox:add(rtk.Slider())

Sliders can be made discrete via the step attribute, and tick marks can be enabled using the ticks attribute:

somebox:add(rtk.Slider{step=10, ticks=true})

Ticks positions can also be labeled:

somebox:add(rtk.Slider{step=1, ticks=true, min=1, max=3, ticklabels={'Low', 'Medium', 'High'}})

If you want labels on either end of the slider, it's easy enough to place it in an rtk.HBox with rtk.Text instances for labels. This example also shows that the slider color can be changed, and its value initialized:

local hbox = somebox:add(rtk.HBox{spacing=5, valign='center'})
hbox:add(rtk.Text{'0%'})
hbox:add(rtk.Slider{color='crimson', value=67})
hbox:add(rtk.Text{'100%'})

Sliders may contain arbitrarily many thumbs, by passing a table of values as the value attribute, rather than a scalar. This is commonly used to implement range sliders. Here's a more complete example showing a range slider with labels on either end, all packed into an rtk.HBox, and updating the labels based on current slider values. Note here we must use a fixed-width rtk.Text to ensure the slider size doesn't shift around as the value changes:

local hbox = somebox:add(rtk.HBox{spacing=5, valign='center'})
local min = hbox:add(rtk.Text{'25', w=25})
local slider = hbox:add(rtk.Slider{value={25, 75}, step=1})
local max = hbox:add(rtk.Text{'75', w=25})
slider.onchange = function(self)
    min:attr('text', self.value[1])
    max:attr('text', self.value[2])
end

Used with the ticks attribute, where lowercase versions of these constants without the TICKS_ prefix can be used for convenience.

rtk.Slider.value number or table read/write ¶

The current value of the slider, between min and max (default 0).

Multiple slider thumbs can be created by setting this value to a table of values, rather than a single scalar value. Arbitrarily many thumb values may be specified here, but a common use case is to specify two thumbs to implement a range slider.

This attribute may be passed as the first positional argument during initialization. (In other words, rtk.Slider{42} is equivalent to rtk.Slider{value=42}.)

The calculated version of this attribute is always a table, even when you pass a scalar value.

rtk.Slider.color colortype or nil read/write ¶

Overall slider color, affecting the thumb (unless overridden by thumbcolor) plus the active portion drawn over the track, which uses the theme's slider value by default.

rtk.Slider.trackcolor colortype or nil read/write ¶

Track color along which the thumbs are dragged, which uses the theme's slider_track value by default.

rtk.Slider.thumbsize number read/write ¶

The radius of the circular slider thumb (default 6).

rtk.Slider.thumbcolor colortype or nil read/write ¶

The color of thumb handles, which defaults to color.

rtk.Slider.ticklabels table read/write ¶

When step is defined, this is an optional table of strings to be displayed next to each tick mark (default nil). The labels provided are mapped in index order. ticks may be disabled -- labels will still be drawn at the tick positions -- but this attribute is ignored if step is nil.

rtk.Slider.ticklabelcolor colortype or nil read/write ¶

The color of the labels written next to ticks when ticklabels is defined, which defaults to the theme's slider_tick_label value.

rtk.Slider.spacing number read/write ¶

The amount of additional space between ticks and ticklabels (default 2).

rtk.Slider.ticks tickconst or bool read/write ¶

Controls whether and how ticks should be displayed when step is defined (default TICKS_NEVER).

For convenience, a boolean value can also be provided, where false is TICKS_NEVER and true is TICKS_ALWAYS.

rtk.Slider.ticksize number read/write ¶

The size of the square tick marks when ticks is enabled (default 4).

rtk.Slider.tracksize number read/write ¶

The size of the slider track (default 2).

rtk.Slider.min number read/write ¶

The minimum allowed value of any thumb in the slider (default 0). Thumb values will be clamped to this minimum value.

rtk.Slider.max number read/write ¶

The minimum allowed value of any thumb in the slider (default 100). Thumb values will be clamped to this minimum value.

rtk.Slider.step number or nil read/write ¶

Snaps slider thumb values to discrete step boundaries (default nil). When disabled (nil), the thumb values are continuous.

rtk.Slider.font string or nil read/write ¶

The name of the font face (e.g. 'Calibri') for all labels, which uses the global slider font by default.

rtk.Slider.fontsize number or nil read/write ¶

The pixel size of the slider font (e.g. 18) for all labels, which uses the global slider font size by default.

rtk.Slider.fontscale number read/write ¶

Scales all font sizes by the given multiplier (default 1.0). This is a convenient way to adjust the relative font size without specifying the exact size.

rtk.Slider.fontflags number or nil read/write ¶

A bitmap of font flags to alter the label appearance (default nil). Nil (or 0) does not style the font.

See also handlers for rtk.Widget.

rtk.Slider:onchange() ¶

Called when the slider value changes.

The value attribute reflects the current state.

Return Values

(nil)

Return value has no significance. This is a notification event only.