Windows 11, PerMonitorV2 is NOT automatically scaling non-client areas of my window.

Question

Windows 11, PerMonitorV2 is NOT automatically scaling non-client areas of my window.

Robinson 146

I have a manifest containing:

<asmv3:windowsSettings xmlns='http://schemas.microsoft.com/SMI/2005/WindowsSettings'>
	<dpiAware>True/PM</dpiAware>
</asmv3:windowsSettings>
<asmv3:windowsSettings xmlns='https://schemas.microsoft.com/SMI/2016/WindowsSettings'>
	<dpiAwareness>PerMonitorV2,PerMonitor</dpiAwareness>
</asmv3:windowsSettings>

I am asserting this is the case in my _tWinMain function:

#ifdef _DEBUG
	{
		auto context = GetThreadDpiAwarenessContext();
		auto awareness = GetAwarenessFromDpiAwarenessContext(context);

		assert(awareness == DPI_AWARENESS::DPI_AWARENESS_PER_MONITOR_AWARE);
	}

#endif // _DEBUG

GetWindowDpiAwarenessContext also returns DPI_AWARENESS_PER_MONITOR_AWARE. I'm wondering why it doesn't return DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2, and why DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2 isn't in the enum defined in WinDef.h. I'm using platform SDK version 10.0.22621.0, Visual Studio 2022 17.5.5.

The documentation claims this setting automatically scales non-client areas of my window. However it does not. On my 4K monitor the non-client areas are tiny. The rest of the application correctly calculates the scale factor for the components I scale myself however.

I have checked the .exe properties in Explorer to make sure there's no behaviour override going on. Both boxes on its high DPI settings are unchecked.

What mistake have I made? Or does this stuff just not work correctly out of the box?

EDIT: If I call EnableNonClientDpiScaling in WM_NCCREATE, I get the correct non-client area scaling. This is a hint that my process, thread or window isn't DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2. It must just be as it said, DPI_AWARENESS_PER_MONITOR_AWARE. So the question then, is why, when I specified _V2 in the manifest.

Robinson 146 Reputation points

2023-05-16T03:48:34.29+00:00

Thanks for the reply. This is a tricky area to get support with.

I've tried setting it manually like that and also through the manifest. It's like it's not going to DPI_AWARENESS_PER_MONITOR_AWARE_V2, it's staying at DPI_AWARENESS_PER_MONITOR_AWARE. The dialogs I launch are not scaled. I don't get non-client area scaling without EnableNonClientDpiScaling. I get no errors. I'm on Windows 11. I don't know how to EnableNonClientDpiScaling for a dialog (there's no WM_NCCREATE for those).

The DPI settings on the property page for the .exe are both unchecked ("Program DPI" and "High DPI Scaling Override"), that is to say, via Explorer or Task Manager.
Robinson 146 Reputation points

2023-05-16T03:58:14.96+00:00

Forgive me, I made a mistake. Calling SetProcessDpiAwarenessContext in main returns FALSE and GetLastError gives me 5 (Access Denied).
Robinson 146 Reputation points

2023-05-16T04:01:14.64+00:00

OK! I removed it from the manifest and now SetProcessDpiAwarenessContext succeeds. My dialogs are also now scaled. So the issue here concerns the manifest, i.e. it isn't set correctly using it. However it now works if I do as you suggest.

2 answers

Your answer

Robinson 146 Reputation points

2023-05-16T03:48:34.29+00:00

Thanks for the reply. This is a tricky area to get support with.

I've tried setting it manually like that and also through the manifest. It's like it's not going to DPI_AWARENESS_PER_MONITOR_AWARE_V2, it's staying at DPI_AWARENESS_PER_MONITOR_AWARE. The dialogs I launch are not scaled. I don't get non-client area scaling without EnableNonClientDpiScaling. I get no errors. I'm on Windows 11. I don't know how to EnableNonClientDpiScaling for a dialog (there's no WM_NCCREATE for those).

The DPI settings on the property page for the .exe are both unchecked ("Program DPI" and "High DPI Scaling Override"), that is to say, via Explorer or Task Manager.
Robinson 146 Reputation points

2023-05-16T03:58:14.96+00:00

Forgive me, I made a mistake. Calling SetProcessDpiAwarenessContext in main returns FALSE and GetLastError gives me 5 (Access Denied).
Robinson 146 Reputation points

2023-05-16T04:01:14.64+00:00

OK! I removed it from the manifest and now SetProcessDpiAwarenessContext succeeds. My dialogs are also now scaled. So the issue here concerns the manifest, i.e. it isn't set correctly using it. However it now works if I do as you suggest.

Answer 1

Robinson 146

I've come here with the actual answer in case someone else has this problem. If you look carefully at my manifest xlm from the original post you'll see a little mistake. The url should be http not https. This is apparently very important!

<asmv3:windowsSettings xmlns='http://schemas.microsoft.com/SMI/2016/WindowsSettings'>

Darran Rowe 2,611 Reputation points

2024-07-21T10:38:49.4166667+00:00

It is important, and the schema actually had https for the xml namespaces at some point and was incorrect for years. It took a lot of effort to get that changed back to http.

Answer 2

Xiaopo Yang - MSFT 12,736 Microsoft External Staff

Older APIs offer less functionality. Have you checked your process DPI Awareness in Task Manager? Have you tried to set default awareness programmatically with recommended SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2)?

Xiaopo Yang - MSFT 12,736 Microsoft External Staff

@Robinson You can also try the following manifest to see if it works.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" xmlns:asmv3="urn:schemas-microsoft-com:asm.v3">
  <asmv3:application>
    <asmv3:windowsSettings>
      <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true</dpiAware>
      <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2</dpiAwareness>
    </asmv3:windowsSettings>
  </asmv3:application>
</assembly>

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Robinson 146 Reputation points

2024-07-20T14:10:59.8733333+00:00

Although this worked, I've removed accepted answer and posted the solution to the actual problem, which was a typo in my manifest.

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Windows 11, PerMonitorV2 is NOT automatically scaling non-client areas of my window.

2 answers

Your answer