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This example defines an input handler for a CLX display connection. It only
recognizes :key-press
events. The body of the example loops over
system:serve-event
to get input.
(in-package "SERVER-EXAMPLE") (defun my-input-handler (display) (xlib:event-case (display :timeout 0) (:key-press (event-window code state) (format t "KEY-PRESSED (Window = ~D) = ~S.~%" (xlib:window-id event-window) ;; See Hemlock Command Implementor's Manual for convenient ;; input mapping function. (ext:translate-character display code state)) ;; Make XLIB:EVENT-CASE discard the event. t)))
(defun server-example () "An example of using the SYSTEM:SERVE-EVENT function and object sets to handle CLX events." (let* ((display (ext:open-clx-display)) (screen (display-default-screen display)) (black (screen-black-pixel screen)) (white (screen-white-pixel screen)) (window (create-window :parent (screen-root screen) :x 0 :y 0 :width 200 :height 200 :background white :border black :border-width 2 :event-mask (xlib:make-event-mask :key-press)))) ;; Wrap code in UNWIND-PROTECT, so we clean up after ourselves. (unwind-protect (progn ;; Enable event handling on the display. (ext:enable-clx-event-handling display #'my-input-handler) ;; Map the windows to the screen. (map-window window) ;; Make sure we send all our requests. (display-force-output display) ;; Call serve-event for 100,000 events or immediate timeouts. (dotimes (i 100000) (system:serve-event))) ;; Disable event handling on this display. (ext:disable-clx-event-handling display) ;; Get rid of the window. (destroy-window window) ;; Pick off any events the X server has already queued for our ;; windows, so we don't choke since SYSTEM:SERVE-EVENT is no longer ;; prepared to handle events for us. (loop (unless (deleting-window-drop-event *display* window) (return))) ;; Close the display. (xlib:close-display display)))) (defun deleting-window-drop-event (display win) "Check for any events on win. If there is one, remove it from the event queue and return t; otherwise, return nil." (xlib:display-finish-output display) (let ((result nil)) (xlib:process-event display :timeout 0 :handler #'(lambda (&key event-window &allow-other-keys) (if (eq event-window win) (setf result t) nil))) result))
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