5.17.3 ActiveX Controls
An ActiveX control is a COM object that needs a container to manage its graphical representation. Although ffi/com does not provide direct support for ActiveX controls, you can use ffi/com to drive Internet Explorer as an ActiveX container.
The following code demonstrates using Internet Explorer to instantiate the “Sysmon” ActiveX control that is included with Windows.
#lang racket (require ffi/com xml) ;; The control we want to run: (define control-progid "Sysmon") ;; Start IE: (define ie (com-create-instance "InternetExplorer.Application.1")) ;; Set up an event callback so that we know when the initial document ;; is ready: (define ex (com-make-event-executor)) (void (thread (lambda () (let loop () ((sync ex)) (loop))))) (define ready (make-semaphore)) (com-register-event-callback ie "DocumentComplete" (lambda (doc url) (semaphore-post ready)) ex) ;; Navigate to get an initial document: (com-invoke ie "Navigate" "about:blank") (define READYSTATE_COMPLETE 4) (unless (= (com-get-property ie "READYSTATE") READYSTATE_COMPLETE) (semaphore-wait ready)) (define doc (com-get-property ie "Document")) ;; Install HTML to show the ActiveX control: (com-invoke doc "write" (xexpr->string `(html (head (title "Demo")) (body (object ((class "object") (CLASSID ,(format "CLSID:~a" (let ([s (guid->string (progid->clsid control-progid))]) ;; must remove curly braces: (define len (string-length s)) (substring s 1 (sub1 len))))))))))) ;; Configure the IE window and show it: (com-set-property! ie "MenuBar" #f) (com-set-property! ie "ToolBar" 0) (com-set-property! ie "StatusBar" #f) (com-set-property! ie "Visible" #t) ;; Extract the ActiveX control from the IE document: (define ctl (com-get-property (com-invoke (com-invoke doc "getElementsByTagName" "object") "item" 0) "object")) ;; At this point, `ctl' is the ActiveX control; ;; demonstrate by getting a list of method names: (com-methods ctl)