https://learn.microsoft.com/en-us/dotnet/api/system.windows.media.animation.discreterectkeyframe?view=windowsdesktop-9.0
DiscreteRectKeyFrame Class (System.Windows.Media.Animation) | Microsoft Learn
Animates from the Rect value of the previous key frame to its own Value using discrete interpolation.
class systemwindows mediaanimationmicrosoftlearn