The distance scrolled by the scroll-line gesture.
The distance scrolled by clicking inside the scroll bar.
A function called after a scroll gesture, or
nil
.
The class
scroll-bar
implements panes which display a scroll bar and call a callback when the user scrolls. It is not however the most usual way to add scroll bars - see the note below about simple-pane.
line-size is the logical size of a line, and is the distance moved when the user enters a scroll-line gesture, that is clicking on one of the arrow buttons at either end of the scroll bar or using a suitable arrow key. The default value of line-size is 1.
page-size is the logical size of a page, and is the distance moved when the user clicks inside the scroll bar. The default value of page-size is 10.
callback
can be
nil
, meaning there is no callback. This is the default value. Otherwise, is a function of four arguments, the interface containing the scroll-bar, the scroll-bar itself, the mode of scrolling and the amount of scrolling. It has this signature:
callback interface scroll-bar how where
how
can be one of
:line
,
:page
,
:move
, or
:drag
.
If
how
is
:line
, then
where
is an integer indicating how many lines were scrolled.
If
how
is
:page
, then
where
is an integer indicating how many pages were scrolled.
If
how
is
:move
or
:drag
, then
where
is an integer giving the new location of the
slug-start
, or
:start
or
:end
.
Note: the location of the slug can be found by the range-pane accessor
range-slug-start
.
Note: Rather than using
scroll-bar
, it is more usual to add scroll bars to a pane by the simple-pane initargs
:horizontal-scroll and
:vertical-scroll
(defun sb-callback (interface sb how where)
(declare (ignorable interface))
(format t "Scrolled ~a where ~a : ~a~%"
how where (range-slug-start sb)))
(contain
(make-instance 'capi:scroll-bar
:callback 'sb-callback
:page-size 10
:line-size 2
:visible-min-width 200))