C++ CLI lambda expression with handle to managed object - c++-cli

Question

I'm trying to convert he following C# code to C++/CLI
// create the output bitmap
var bitmap = new SKBitmap();
SKImageInfo info = new SKImageInfo();
info = new SKImageInfo(input.Width, input.Height, SKColorType.Bgra8888);
// create the buffer that will hold the pixels
var buffer = new byte[input.Width * input.Height * 4];
// get a pointer to the buffer, and give it to the bitmap
var outputPtr = GCHandle.Alloc(buffer, GCHandleType.Pinned);
bitmap.InstallPixels(info, outputPtr.AddrOfPinnedObject(), info.RowBytes, (addr, ctx) => outputPtr.Free(), null);
I've tried different options and but I keep getting stuck. I now have this:
static void FreeHandle(System::Runtime::InteropServices::GCHandle handle)
{
handle.Free();
}
static void Test()
{
// create the output bitmap
SKBitmap^ bitmap = gcnew SKBitmap();
SKImageInfo^ info = gcnew SKImageInfo(input.cols, input.rows, SKColorType::Bgra8888);
// Create a buffer, pin it and give its pointer to the bitmap
array<System::Byte>^ buffer = gcnew array<System::Byte>(input.cols * input.rows * 4);
GCHandle outputPtr = GCHandle::Alloc(buffer, GCHandleType::Pinned);
bitmap->InstallPixels(info, outputPtr.AddrOfPinnedObject(), info->RowBytes, gcnew Action<GCHandle>(outputPtr, &FreeHandle), nullptr);
}
This gives me the error
invalid delegate initializer -- object is not needed for the specified function.
I also tried:
// create the output bitmap
SKBitmap^ bitmap = gcnew SKBitmap();
SKImageInfo^ info = gcnew SKImageInfo(input.cols, input.rows, SKColorType::Bgra8888);
// Create a buffer, pin it and give its pointer to the bitmap
array<System::Byte>^ buffer = gcnew array<System::Byte>(input.cols * input.rows * 4);
gcroot<GCHandle> outputPtr = GCHandle::Alloc(buffer, GCHandleType::Pinned);
bitmap->InstallPixels(info, outputPtr.AddrOfPinnedObject(), info->RowBytes, [&]() -> void { outputPtr->Free(); }, nullptr);
but then I get:
expression must have pointer or handle type but it has type "System::Runtime::InteropServices::GCHandle".
I searched a lot, but I'm not sure how to search this anymore.