• .NET Core Version: (e.g. 3.0 Preview1, or daily build number, use dotnet --info)
• Windows version: (winver)
• Does the bug reproduce also in WPF for .NET Framework 4.8?: Yes/No
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Problem description:

After #2891 , we call calculate the point with stylusDevice.CriticalActiveSource. But the stylusDevice.CriticalActiveSource must be null when first touch down, because the wpf do not touch any element and do not get the AcitveSource before first touch down.

Actual behavior:

All of the StylusPlugin will reviece the wrong coordinate point.

Expected behavior:

These points can be calculated correctly.

Minimal repro:

Before you try repro this issues, please make sure you own a touch screen.

Preparation:

1. Set the touch screen DPI to 150% (Not 100% is enough)

Step:

1. Create an empty WPF project.
2. Add the InkCanvas control to WPF project.
3. Run the project in the device with the touch screen and then try write an ink.

Actual behavior: you will find the first point in ink will skew, just as the image shows.

The other repro step: Create an empty WPF project and add the StylusPlugin and then output the point received.

cc @rladuca @singhashish-wpf