Creating a CompositionPath in WinUI

[jennHarper]

I want to create a wave animation in WinUI.
I have a PathGeometry that implements a Bezier curve but I can't seem to convert it to the CompositionPath that I need.

PathGeometry animationPath = new PathGeometry();
PathFigure pFigure = new PathFigure();
pFigure.StartPoint = new Point(00, 300);
PolyBezierSegment pBezierSegment = new PolyBezierSegment();
pBezierSegment.Points.Add(new Point(600, 300 - 820));
pBezierSegment.Points.Add(new Point(1200, 300 + 820));
pBezierSegment.Points.Add(new Point(1800, 300));
pFigure.Segments.Add(pBezierSegment);
animationPath.Figures.Add(pFigure);

Online searches have suggested the following:
CompositionEasingFunction linearEasingFunction = compositor.CreateLinearEasingFunction();

PathKeyFrameAnimation wave = compositor.CreatePathKeyFrameAnimation();

CanvasGeometry result;
using (var builder = new CanvasPathBuilder(null))
{
builder.BeginFigure(new Vector2(-13.6639996F, -0.144999996F));
builder.AddLine(new Vector2(375.663002F, 400.289999992F));
builder.EndFigure(CanvasFigureLoop.Open);
result = CanvasGeometry.CreatePath(builder);
}

CompositionPath p = new CompositionPath((IGeometrySource2D)(object)result);

wave.InsertKeyFrame(1.0f, p, linearEasingFunction);

wave.Duration = TimeSpan.FromSeconds(10);
visual.StartAnimation("Offset", wave);

However, I seem to need to install the Win2D.uwp package to get CanvasGeometry, but then on run I get errors. Is there anything native to WinUI, not UWP, that I can use to create a path. I just haven't seen anything other than CanvasGeometry that implements IGeometrySource2D.

Thanks!

[robmikh]

If your app is in C#, your best bet will be to get Win2D working. Given that you're seeing runtime errors when using Win2D, I'm guessing you're creating a traditional Win32 application and not a UWP application. To use the Win2D.uwp package from a traditional Win32 application, you'll need to add some CRT forwarders to bridge the gap between the runtimes used for UWP binaries and Win32 binaries. That package can be found here: https://www.nuget.org/packages/Microsoft.VCRTForwarders.140

If you're using the WinAppSDK (meaning your compositor object is a Microsoft.UI.Composition.Compositor as opposed to a Windows.UI.Composition.Compositor), there's actually a different Win2D package you can use that should work out of the box. You can find that package here: https://www.nuget.org/packages/Microsoft.Graphics.Win2D

For completeness, you can technically implement the IGeometrySource2D yourself. I've done that in my prototyping library, robmikh.common, which allows me to use Direct2D directly (pardon the pun):

https://github.com/robmikh/robmikh.common/blob/5b17ef46d28e0d188baaa1d091ef1354eeb3c42c/DesktopTestApp/main.cpp#L61-L99

The implementation is here: https://github.com/robmikh/robmikh.common/blob/master/robmikh.common/include/robmikh.common/graphics.interop.h. Keep in mind that implementing both IGeometrySource2D and IGeometrySource2DInterop is required for it to work if you go that route.

Let me know if I've misunderstood your application's structure or if using the VCRT forwarders doesn't resolve your issue.