► |  | The Racket Foreign Interface

1 | Overview
2 | Loading Foreign Libraries
3 | C Types
4 | Pointer Functions
5 | Derived Utilities
6 | Miscellaneous Support
7 | Unexported Primitive Functions
| Bibliography
| Index

► | 5 | Derived Utilities

5.1 | Safe Homogenous Vectors
5.2 | Safe C Vectors
5.3 | Tagged C Pointer Types
5.4 | Serializable C Struct Types
5.5 | Defining Bindings
5.6 | Allocation and Finalization
5.7 | Custodian Shutdown Registration
5.8 | Atomic Execution
5.9 | Speculatively Atomic Execution
5.10 | Objective-C FFI
5.11 | Cocoa Foundation
5.12 | COM (Common Object Model)
5.13 | File Security-Guard Checks
5.14 | Windows API Helpers

▼ | 5.12 | COM (Common Object Model)

5.12.1 | COM Automation
5.12.2 | COM Classes and Interfaces
5.12.3 | Active X Controls

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##### 5.12.3`` 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)

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