► |  | 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 | Defining Bindings
5.5 | Allocation and Finalization
5.6 | Custodian Shutdown Registration
5.7 | Atomic Execution
5.8 | Speculatively Atomic Execution
5.9 | Objective-C FFI
5.10 | Cocoa Foundation
5.11 | COM (Common Object Model)
5.12 | File Security-Guard Checks
5.13 | Windows API Helpers

▼ | 5.11 | COM (Common Object Model)

5.11.1 | COM Automation
5.11.2 | COM Classes and Interfaces
5.11.3 | Active X Controls

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##### 5.11.3`` 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 an empty URL to get an initial document:
> ( com-invoke ie "Navigate" "")
> ( 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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