► |  | GUI: PLT Graphics Toolkit

1 | Overview
2 | Reference
3 | Configuration
4 | Dynamic Loading
| Bibliography
| Index

► | 2 | Reference

2.1 | Windowing Classes
2.2 | Windowing Functions
2.3 | Drawing Classes
2.4 | Drawing Functions
2.5 | Editor Classes
2.6 | Editor Functions
2.7 | WXME Decoding

▼ | 2.1 | Windowing Classes

2.1.1 | area<%>
2.1.2 | area-container<%>
2.1.3 | area-container-window<%>
2.1.4 | button%
2.1.5 | canvas<%>
2.1.6 | canvas%
2.1.7 | check-box%
2.1.8 | checkable-menu-item%
2.1.9 | choice%
2.1.10 | clipboard-client%
2.1.11 | clipboard<%>
2.1.12 | combo-field%
2.1.13 | control<%>
2.1.14 | control-event%
2.1.15 | cursor%
2.1.16 | dialog%
2.1.17 | event%
2.1.18 | frame%
2.1.19 | gauge%
2.1.20 | group-box-panel%
2.1.21 | grow-box-spacer-pane%
2.1.22 | horizontal-pane%
2.1.23 | horizontal-panel%
2.1.24 | key-event%
2.1.25 | labelled-menu-item<%>
2.1.26 | list-box%
2.1.27 | list-control<%>
2.1.28 | menu%
2.1.29 | menu-bar%
2.1.30 | menu-item<%>
2.1.31 | menu-item%
2.1.32 | menu-item-container<%>
2.1.33 | message%
2.1.34 | mouse-event%
2.1.35 | pane%
2.1.36 | panel%
2.1.37 | popup-menu%
2.1.38 | radio-box%
2.1.39 | selectable-menu-item<%>
2.1.40 | separator-menu-item%
2.1.41 | scroll-event%
2.1.42 | slider%
2.1.43 | subarea<%>
2.1.44 | subwindow<%>
2.1.45 | tab-panel%
2.1.46 | text-field%
2.1.47 | timer%
2.1.48 | top-level-window<%>
2.1.49 | vertical-pane%
2.1.50 | vertical-panel%
2.1.51 | window<%>

On this page:

get-value
set-value

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slider% : class?
superclass: object%

extends: | control<%>

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.

(new slider% |  | [label label] |
|  | [min-value min-value] |
|  | [max-value max-value] |
|  | [parent parent] |
| [ | [callback callback] |
|  | [init-value init-value] |
|  | [style style] |
|  | [font font] |
|  | [enabled enabled] |
|  | [vert-margin vert-margin] |
|  | [horiz-margin horiz-margin] |
|  | [min-width min-width] |
|  | [min-height min-height] |
|  | [stretchable-width stretchable-width] |
|  | [stretchable-height stretchable-height]]) |

→ (is-a?/c slider%)
label : (or/c label-string? false/c)
min-value : (integer-in -10000 10000)
max-value : (integer-in -10000 10000)

parent

:

(or/c (is-a?/c frame%) (is-a?/c dialog%)
(is-a?/c panel%) (is-a?/c pane%))

| callback |  | : |  | ((is-a?/c slider%) (is-a?/c control-event%) . -> . any)
|  |  | = |  | (lambda (b e) (void))

init-value : (integer-in -10000 10000) = min-value

style

:

(listof (one-of/c 'horizontal 'vertical 'plain
'vertical-label 'horizontal-label
'deleted))

|  |  | = |  | '(horizontal)

font : (is-a?/c font%) = normal-control-font
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
stretchable-width : any/c = (memq 'horizontal style)
stretchable-height : any/c = (memq 'vertical style)

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 callback procedure is called (with the event type 'slider) when the user changes the slider’s value.

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<%>.

(send a-slider get-value) → (integer-in -10000 10000)

Gets the current slider value.

(send a-slider set-value value) → void?
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.
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