slider%

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 minumum 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.

• (make-object slider% label min-value max-value parent callback init-value style) -> slider% object
      label : string or #f
      min-value : exact integer in [-10000, 10000]
      max-value : exact integer in [-10000, 10000]
      parent : frame%, dialog%, panel%, or pane% object
      callback : 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)

  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 MacOS, 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). Mnemonic keyboard events are handled by on-traverse-char (but not under MacOS).

  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:application:mismatch 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.

  
  

• get-value
• set-value

• 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-graphical-min-size from area<%>
• 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<%>
• 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<%>