The panel library can handle the redrawing of your
The window being managed by the panel library is implicitly treated as
part of a deck including all other panel windows. The deck is treated
as a stack with the top panel being completely visible and the other
panels may or may not be obscured according to their positions. So the
basic idea is to create a stack of overlapping panels and use panels
library to display them correctly. There is a function similar to
refresh which, when called , displays panels in the correct
order. Functions are provided to hide or show panels, move panels,
change its size, etc. The overlapping problem is managed by the panels
library during all the calls to these functions.
The general flow of a panel program goes like this:
newwin) to be attached to the panels.
make-panel!is used to create convert a standard window to a panel window.
update-panelsto write the panels to the virtual screen in correct visibility order. Do a
doupdateto show it on the screen.
move-paneletc. Make use of helper functions like
del-panel!to delete the panel functionality from the window.
delwinfrees the window.
Note that there is also a shorter way to create and window and
convert it to a panel window. The procedure
newwin (as well
derwin take an optional parameter
that, when true, creates the window as a panel window, as in the code snippet below:
(define pwin (newwin 10 10 10 10 #:panel #t))
Let’s make the concepts clear, with some programs. The following is a simple program which creates 3 overlapping panels and shows them on the screen.