A slider object is a panel item with a handle that the user can drag to change the control’s value. Each slider has a fixed minimum and maximum value.
Whenever the user changes the value of a slider, its callback procedure is invoked. A callback procedure is provided as an initialization argument when each slider is created.
min-value : (integer-in -10000 10000)
max-value : (integer-in -10000 10000)
init-value : (integer-in -10000 10000) = min-value
enabled : any/c = #t
vert-margin : (integer-in 0 1000) = 2
horiz-margin : (integer-in 0 1000) = 2
min-width : (integer-in 0 10000) = graphical-minimum-width
min-height : (integer-in 0 10000) = graphical-minimum-height
If label is a string, it is used as the label for the slider. Otherwise, the slider does not display its label.
If & occurs in label, it is specially parsed as for button%.
The min-value and max-value arguments specify the range of the slider, inclusive. The init-value argument optionally specifies the slider’s initial value. If the sequence [min-value, initial-value, maximum-value] is not increasing, an exn:fail:contract exception is raised.
The style argument must include either 'vertical for a vertical slider, or 'horizontal for a horizontal slider. If style includes 'plain, the slider does not display numbers for its range and current value to the user. If style includes 'vertical-label, then the slider is created with a label above the control; if style does not include 'vertical-label (and optionally includes 'horizontal-label), then the label is created to the left of the slider. If style includes 'deleted, then the slider is created as hidden, and it does not affect its parent’s geometry; the slider can be made active later by calling parent’s add-child method.
The font argument determines the font for the control. For information about the enabled argument, see window<%>. For information about the horiz-margin and vert-margin arguments, see subarea<%>. For information about the min-width, min-height, stretchable-width, and stretchable-height arguments, see area<%>.
Gets the current slider value.
value : (integer-in -10000 10000)
Sets the value (and displayed position) of the slider. (The control’s callback procedure is not invoked.) If value is outside the slider’s minimum and maximum range, an exn:fail:contract exception is raised.
A slider’s value can be changed by the user clicking the control, and such changes do not go through this method; use the controlcallback procedure (provided as an initialization argument) to monitor value changes.