How to use C++/WinRt API like as part of DLL without user interface(UI)

sunil maurya 21

Hi, I am attempting to utilize the C++/WinRT code provided in the sample of LampArray, cppwinrt to create a DLL. However due to the tight coupling of this sample with the UI, I am not able to use below API independently within my DLL code, without incorporating UI Code.

 m_deviceAddedRevoker = m_deviceWatcher.Added(winrt::auto_revoke, { get_weak(), &Scenario1_Basics::Watcher_Added});


    m_deviceRemovedRevoker = m_deviceWatcher.Removed(winrt::auto_revoke, { get_weak(), &Scenario1_Basics::Watcher_Removed });

Could you please guide me on whether there's a method to directly invoke the API in my code without relying on the UWP UI portion?

Note: I am trying to create a DLL to access the lamp devices attached to system like lights/LEDs, etc.

Regard,
Sunil

Junjie Zhu - MSFT 15,366 Reputation points Microsoft Vendor

2024-04-23T08:14:47.3766667+00:00

Hi @sunil maurya ,

Welcome to Microsoft Q&A!

What is your Main project? win32? winui3?

Even if the DLL is successfully generated, it may not be successfully called in other projects.
sunil maurya 21 Reputation points

2024-04-23T09:34:56.48+00:00

Thank you Junjie,

My main project is win32.

And I want to create a C++ DLL where I can access the lamp devices(Lights/LEDs,) attached to system.

As you mentioned that "Even if the DLL is successfully generated, it may not be successfully called in other projects" So can you suggest me is there any way so that I can access the lamp devices from C++ DLL?
Junjie Zhu - MSFT 15,366 Reputation points Microsoft Vendor

2024-04-24T08:08:53.18+00:00

Hi @sunil maurya ,

Will using Windows Runtime components meet your needs? You can refer to this blog use Windows Runtime Components in Desktop Apps.

sunil maurya 21

Hi Junjie,

Thank you for sharing the link, I am looking into that.

My current objective of writing C++ DLL is to access the lampArray devices(LEDs) so that I can get the status(On/Off) of lampArray device. And if required in the future I will create an application to manage the other features of lampArray device like SetColor or BrightnessLevel of LEDs.

// Set all Lamps on the LampArray to green .

 lampArray.SetColor(Colors::Green());
```// Set all Lamps on the LampArray to black, turning them off.

```cppwinrt
lampArray.SetColor(Colors::Black());
```// Apply the brightness.

  lampArray.BrightnessLevel(BrightnessSlider().Value() / BrightnessSlider().Maximum());

Above code snippet  is from git sample:

[https://github.com/microsoft/Windows-universal-samples/blob/main/Samples/LampArray/cppwinrt/Scenario1_Basics.cpp](https://github.com/microsoft/Windows-universal-samples/blob/main/Samples/LampArray/cppwinrt/Scenario1_Basics.cpp)

Regards,

Sunil

Junjie Zhu - MSFT 15,366 Reputation points Microsoft Vendor

2024-04-25T09:42:43.74+00:00

Hi @sunil maurya ,

This API won't affected by the UI thread, you can use Windows Runtime components in win32.