[rdnzl-devel] attaching handler / Tablet PC ink/ stroke/ not working

Edi Weitz edi at agharta.de
Thu Dec 22 21:28:26 UTC 2005

On Thu, 22 Dec 2005 18:47:39 +0100, Edi Weitz <edi at agharta.de> wrote:

> My guess is that this doesn't work because of threading issues -
> .NET is trying to call into Lisp from a thread which wasn't created
> by Lisp.

And I was right.  Here's a solution that avoids these problems and
works for me.  Files are at the end of this message.

1. Build a DLL (they don't have the threading problems I mentioned -
   see link in my earlier email) using LispWorks as usual, something
   like (from a console window):

     "\Program Files\LispWorks\lispworks-4460.exe" -init deliver.lisp

2. Make sure RDNZL.dll can be found - put it into c:\Windows\System32
   for example.

3. Start the DLL as a program:

     rundll32 demo.dll,demo

You should now see a window on which you can "draw" using the mouse.
After every fifth stroke a message should come up telling you how many
strokes the app has counted so far.

If you don't have a LispWorks license to deliver executables you can
download the DLL to play with from


and start with #2 above.

I don't know how to do that with AllegroCL but I guess Franz' support
will help you.  If they come up with a solution it'd be nice if you
could post it here.



-------------------- deliver.lisp --------------------


;; modify to match the location of RDNZL on your PC
(load "/home/lisp/RDNZL/load.lisp")

(use-package :rdnzl)

(load (compile-file "tablet.lisp"))


(deliver 'init "demo" 1
         :dll-exports '("demo"))


-------------------- tablet.lisp --------------------


(import-types "Microsoft.Ink" "InkOverlay" "InkCollectorStrokeEventHandler")
(import-types "System.Windows.Forms" "Form" "Application" "MessageBox")
(import-type "System.EventHandler")
(use-namespace "Microsoft.Ink")
(use-namespace "System.Windows.Forms")
(use-namespace "System")

(defparameter *stroke-counter* 0)

(defun handle-stroke (object event)
  (declare (ignore object event))
  (when (zerop (mod (incf *stroke-counter*) 5))
    [MessageBox.Show (format nil "~A strokes so far..." *stroke-counter*)]))

(defun demo () 
  (let ((window (new "Form"))
    (flet ((on-load (object event)
             (declare (ignore object event))
             (setf ink-overlay (new "InkOverlay" [%Handle window])
                   [%Enabled ink-overlay] t)
             [+Stroke ink-overlay (new "InkCollectorStrokeEventHandler" #'handle-stroke)]))
      [+Load window (new "EventHandler" #'on-load)]
      [Application.Run window])))


(fli:define-foreign-callable ("demo" :calling-convention :stdcall)
    ((hwnd w:hwnd)
     (hinst w:hinstance)
     (string :pointer)
     (cmd-show :int))
  (declare (ignore hwnd hinst string cmd-show))

(defun init ()

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