COMInterop
1.2.0indexedSmall COM runtime enabling binding/invocation of COM interfaces and classes via C interop; builds v-tables, caches functions, handles IID/CLSID, and provides init/uninit.
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COMInterop
A basic COM runtime for Kotlin/Native based on CInterop.
This can be used to interop with WinRT/Windows SDK functionality otherwise only available through Microsoft compiler
extensions and C++ code.
How to use it
First, add the official Maven Central repository to your settings.gradle.kts:
dependencyResolutionManagement {
repositories {
mavenCentral()
}
}
Then add a dependency on the library in your buildscript:
kotlin {
mingwMain {
dependencies {
implementation("dev.karmakrafts.cominterop:cominterop-core:<version>")
}
}
}
Initialization
Before using any COM APIs, you need to call ComRuntime.init() to ensure the runtime
is properly initialized. This will invoke CoInitializeEx and RoInitialize allowing multi-threaded use.
When you are done using the COM runtime, you also should ensure proper resource cleanup
using the provided ComRuntime.uninit() function.
fun main() {
ComRuntime.init()
// Your code here
ComRuntime.uninit()
}
Binding a COM interface
The primary use of this library is to bind COM interface into the Kotlin world, by providing wrapper classes
which can be constructed from arbitrary CInterop pointers.
Much like in C/C++ on Windows, interfaces require an IID which uniquely identifies them. This IID is primarily
used to query one interface from another.
Note: Interface IIDs can be obtained from the IDL files shipped with Windows and the Windows SDK.
Just like its OOP counterpart, a COM interface also contains/uses a v-table to invoke its implementation functions.
The v-table is built by this library at runtime and cached throughout the lifetime of the program.
Let's assume we want to bind the IShellLinkW interface:
This will let us take a given COpaquePointer, and turn it into an instance of the IShellLinkW interface:
fun main() = memScoped {
ComRuntime.init()
val myPointer = someFunction()
val shellLink = myPointer.asCom<IShellLinkW, _>(IShellLinkW)
val path = shellLink.path // Internally calls GetPath on the COM interface
shellLink.release()
ComRuntime.uninit()
}
Binding a COM class
COM interfaces become especially useful, if you can also construct them by one of their
implementations directly from within the Kotlin code:
class INetworkListManager : ComInterface<INetworkListManager.Companion>(Companion) {
// ...
}
// We can define COM classes as simple singleton objects
object NetworkListManager : ComClass<INetworkListManager.Companion> {
override {
ComRuntime.iidFromString(, clsid)
}
defaultInterface: INetworkListManager.Companion = INetworkListManager
}
This will allow us to obtain a new INetworkListManager instance as follows:
fun main() {
ComRuntime.init()
val manager = NetworkListManager.new<INetworkListManager, _, _>()
// Do something with the network manager instance
manager.release()
ComRuntime.uninit()
}
Note: this is purely meant as example code, in reality
NetworkListManagerneeds to be instantiated with theCLSCTX_ALLcontext flag.