3.43  slider%

Implements: 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 _) (min-value _) (max-value _) (parent _) [(callback _)] [(init-value _)] [(style _)] [(font _)] [(enabled _)] [(vert-margin _)] [(horiz-margin _)] [(min-width _)] [(min-height _)] [(stretchable-width _)] [(stretchable-height _)]) -> slider% object
     label : string (up to 200 characters) or #f
   min-value : exact integer in [-10000, 10000]
     max-value : exact integer in [-10000, 10000]
     parent : frame%, dialog%, panel%, or pane% object
     callback = (lambda (s e) (void)) : procedure of two arguments: a slider% object and a control-event% object
     init-value = min-value : exact integer in [-10000, 10000]
     style = '(horizontal) : list of symbols in '(horizontal vertical plain vertical-label horizontal-label deleted)
   font = normal-control-font : font% object
     enabled = #t : boolean
     vert-margin = 2 : exact integer in [0, 1000]
     horiz-margin = 2 : exact integer in [0, 1000]
     min-width = graphical minimum width : exact integer in [0, 10000]
     min-height = graphical minimum width : exact integer in [0, 10000]
     stretchable-width = #t for 'horizontal style, #f for 'vertical : boolean
     stretchable-height = #t for 'vertical style, #f for 'horizontal : boolean

  If label is a string, it is used as the label for the slider. Otherwise, the slider does not display its label.

  If an ampersand (``&'') occurs in label, it is specially parsed; under Windows and X, the character following an ampersand is underlined in the displayed control to indicate a keyboard mnemonic. (Under Mac OS X, mnemonic underlines are not shown.) The underlined mnemonic character must be a letter or a digit. The user can move the keyboard focus to the slider by typing the mnemonic when the control's top-level-window contains the keyboard focus. The user must also hold down the Meta or Alt key if the keyboard focus is currently in a control that handles normal alphanumeric input. The ampersand itself is removed from label before it is displayed for the control; a double-ampersand in label is converted to a single ampersand (with no mnemonic underlining). Under Mac OS X, a parenthesized mnemonic character is removed (along with any surrounding space) before the label is displayed, since a parenthesized mnemonic is often used for non-Roman languages. Finally, any text after a tab character is removed on all platforms. Mnemonic keyboard events are handled by on-traverse-char (but not under Mac OS X).

  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<%>.

  
  

Methods
    get-value
    set-value

All Methods
    accept-drop-files from window<%>
    client->screen from window<%>
    command from control<%>
    enable from window<%>
    focus from window<%>
    get-client-size from window<%>
    get-cursor from window<%>
    get-font from control<%>
    get-graphical-min-size from area<%>
    get-handle from window<%>
    get-height from window<%>
    get-label from window<%>
    get-parent from area<%>
    get-plain-label from window<%>
    get-size from window<%>
    get-top-level-window from area<%>
    get-value from slider%
    get-width from window<%>
    get-x from window<%>
    get-y from window<%>
    has-focus? from window<%>
    horiz-margin from subarea<%>
    is-enabled? from window<%>
    is-shown? from window<%>
    min-height from area<%>
    min-width from area<%>
    on-drop-file from window<%>
    on-focus from window<%>
    on-move from window<%>
    on-size from window<%>
    on-subwindow-char from window<%>
    on-subwindow-event from window<%>
    on-superwindow-enable from window<%>
    on-superwindow-show from window<%>
    popup-menu from window<%>
    refresh from window<%>
    screen->client from window<%>
    set-cursor from window<%>
    set-label from window<%>
    set-value from slider%
    show from window<%>
    stretchable-height from area<%>
    stretchable-width from area<%>
    vert-margin from subarea<%>