Example cpp/ScreenCaptureforHWND not working - Unhandled exception at 0x00007FFD3B8B9129 (KernelBase.dll) in ScreenCaptureforHWND.exe

[gileli121]

Hello, I tried to run the example
ScreenCaptureforHWND

Using Visual Studio 2019 on Windows 10 64bit with SDK 10.0.18362.0

The example app was successfully built and working until I select some window to capture.

When I select a window, it always throws an exception

Unhandled exception at 0x00007FFD3B8B9129 (KernelBase.dll) in ScreenCaptureforHWND.exe: 0xC000041D: An unhandled exception was encountered during a user callback.

It is no matter what window I select. It always fails in this like.

Please fix the example.

Thank you.

[robmikh]

It seems that you're failing the QI to get the IGraphicsCaptureItemInterop interface. Which version of Windows are you running? This feature was added in the 1903 update.

[gileli121]

I have OS Build 10.0.17763.557
I will try it again after updating and will let you know if the issue resolved

[gileli121]

Hello, after I updated the example works. Good. is there an otption to not capture the mouse pointer?

And now I have another issue with the API function DwmRegisterThumbnail from here:
https://docs.microsoft.com/en-us/windows/win32/api/dwmapi/nf-dwmapi-dwmregisterthumbnail

My program makes some big use with this function and after this update the function is not working as expected. Please see the issue I reported to Microsoft:

https://answers.microsoft.com/en-us/windows/forum/windows_10-update/dwmregisterthumbnail-is-not-working-as-expected-in/72dcf82e-7e8e-46f6-b7f3-d80f6f34fefa?tm=1562540172919

I know that the issue is not related to this. I just don't know where to get the support.
Please let me know where to get support about this issue. I am not sure that I reported it in the right place.

The issue is big and it broke something in my program...
Please help me to get support about this.

Thanks

[robmikh]

Glad to hear the sample is working. The current Insider builds have an API we plan to add that makes the cursor rendering configurable. Look for a new property on GraphicsCaptureSession named IsCursorCaptureEnabled.

As for your issue with DwmRegisterThumbnail, what exactly are you having a problem with? Multiple thumbnails that are assigned to a single window, or the same thumbnail (or at least thumbnails targeting the same window) across multiple windows? I tried both just now and couldn't reproduce any issues. What would I do to reproduce this?

[gileli121]

Hello, I think that the problem is when you use the API via DLL file.. I could reproduce the bug only by using the API from a script that written in Autoit.

Please try to run this code:
https://pastebin.com/MNABim8w

Note that you will need to update the target window to display a preview for in line:
$targetGUI = HWnd(0x000000000002004C)

The problem is that you will see only one window getting the live preview. it did not happned before the update.

This is how it looks:

The preview 2 window don't get a live preview. Only the first one.
If I will remove this line that create the first preview:
$handle1 = RegisterWindowLivePreview($targetGUI,$hGUI1)

The second preview will work.

I think that the problem is because the API returns the same HTHUMBNAIL twice.
The this line:
$aRet = DllCall("dwmapi.dll", "int", "DwmRegisterThumbnail", "hwnd", $hwnd, "hwnd", $hWndOw, "ptr*", DllStructGetPtr($tID))
Will call to this function. the function returns the ID 1 even the second time. I think that this is the bug..
But in C++ version I did not saw this. The ID was 2 on the second call and not 1.

[gileli121]

It seems that you did some change in dwmapi.dll in this update.
It seems that this dll now stores some global memory for the HTHUMBNAIL ID.

I know this because I found the solution.
The solution is open the dll file using:
$dwmDll = DllOpen('dwmapi.dll')

And then in any line that calls the dll, I need to use the dll handle $dwmDll
So instead of
DllCall('dwmapi.dll', ...
I write
DllCall($dwmDll, ...

This was solved the issue and now the script print different HTHUMBNAIL on the second call as expected.

[robmikh]

That seems like there was a behavior change in Autoit, I can't get this to happen in C++. Glad everything was sorted out for you.

[krenner]

Hi gileli121 - I wanted to comment on your question re: mouse cursors. Insider preview builds 18894 or greater have a new property on GraphicsCaptureSession named IsCursorCaptureEnabled. Release notes are here.

[gileli121]

Thanks.
Will be also an option to remove the yellow frame of the window that under capture mode?

[robotogre]

@robmikh I am seeing this error in the latest version of Windows 10 LTSC 1809 (17763.1728).

Am I out of luck?