3.44 slider%

► |  | The Racket Graphical Interface Toolkit

1 | Windowing
2 | Widget Gallery
3 | Windowing Classes
4 | Windowing Functions
5 | Editors
6 | Snip and Style Classes
7 | Editor Classes
8 | Editor Functions
9 | WXME Decoding
10 | Preferences
11 | Dynamic Loading
12 | Startup Actions
13 | Init Libraries
14 | Platform Dependencies
| Index

▼ | 3 | Windowing Classes

3.1 | area<%>
3.2 | area-container<%>
3.3 | area-container-window<%>
3.4 | button%
3.5 | canvas<%>
3.6 | canvas%
3.7 | check-box%
3.8 | checkable-menu-item%
3.9 | choice%
3.10 | clipboard-client%
3.11 | clipboard<%>
3.12 | combo-field%
3.13 | control<%>
3.14 | column-control-event%
3.15 | control-event%
3.16 | cursor%
3.17 | dialog%
3.18 | event%
3.19 | frame%
3.20 | gauge%
3.21 | group-box-panel%
3.22 | grow-box-spacer-pane%
3.23 | horizontal-pane%
3.24 | horizontal-panel%
3.25 | key-event%
3.26 | labelled-menu-item<%>
3.27 | list-box%
3.28 | list-control<%>
3.29 | menu%
3.30 | menu-bar%
3.31 | menu-item<%>
3.32 | menu-item%
3.33 | menu-item-container<%>
3.34 | message%
3.35 | mouse-event%
3.36 | pane%
3.37 | panel%
3.38 | popup-menu%
3.39 | printer-dc%
3.40 | radio-box%
3.41 | selectable-menu-item<%>
3.42 | separator-menu-item%
3.43 | scroll-event%
3.44 | slider%
3.45 | subarea<%>
3.46 | subwindow<%>
3.47 | tab-panel%
3.48 | text-field%
3.49 | timer%
3.50 | top-level-window<%>
3.51 | vertical-pane%
3.52 | vertical-panel%
3.53 | window<%>

On this page:

new
get-value
set-value

Inherited methods:
from control<%>
command
from subwindow<%>
reparent
from window<%>
accept-drop-files
client->screen
enable
focus
get-client-handle
get-client-size
get-cursor
get-handle
get-height
get-label
get-plain-label
get-size
get-width
get-x
get-y
has-focus?
is-enabled?
is-shown?
on-drop-file
on-focus
on-move
on-size
on-subwindow-char
on-subwindow-event
on-subwindow-focus
on-superwindow-activate
on-superwindow-enable
on-superwindow-show
popup-menu
refresh
screen->client
set-cursor
set-label
show
warp-pointer
wheel-event-mode
from area<%>
get-graphical-min-size
get-parent
get-top-level-window
min-height
min-width
stretchable-height
stretchable-width
from subarea<%>
horiz-margin
vert-margin

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class 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.

> > constructor
> > (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? #f)
> min-value : position-integer?
> max-value : position-integer?
> | 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 : position-integer? = min-value
> | style |  | : |  |
> (listof (or/c 'horizontal 'vertical 'upward 'plain
> 'vertical-label 'horizontal-label
> 'deleted))
> |  |  | = |  | '(horizontal)
> font : (is-a?/c font%) = normal-control-font
> enabled : any/c = #t
> vert-margin : spacing-integer? = 2
> horiz-margin : spacing-integer? = 2
> min-width : (or/c dimension-integer? #f) = #f
> min-height : (or/c dimension-integer? #f) = #f
> 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. The sequence [min-value, init-value, max-value] must be non-decreasing. Otherwise, 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 'horizontal for a horizontal slider going left-to-right, 'upward for a vertical slider going up, or 'vertical for a vertical slider going down (but beware that 'vertical might render with misleading colors on Mac OS, where the system toolkit supports only upward sliders). 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<%>.

Changed in version 1.73 of package gui-lib: Added 'upward as a possible style element.

> method (send a-slider get-value) → position-integer?

Gets the current slider value.

> method (send a-slider set-value value) → void?
> value : position-integer?

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 control callback procedure (provided as an initialization argument) to monitor value changes.
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