Question: How to use CompositionPathGeometry and CompositionPath?

[zed220]

Hello,

I try to use CompositionPathGeometry like this:

IGeometrySource2D source = <...>
var pathGeometry = Compositor.CreatePathGeometry(new CompositionPath(source));

But I can't find how to create the source (IGeometrySource2D).

Can you create an example?

[StephenLPeters]

@jesbis @jeffstall could one of you weigh in here?

[jesbis]

@duncanmacmichael do we have a sample for this or should we update the docs?

@zed220 I believe you can use the Win2D CanvasGeometry as a concrete implementation:

http://microsoft.github.io/Win2D/html/T_Microsoft_Graphics_Canvas_Geometry_CanvasGeometry.htm

e.g.:

var pathBuilder = new CanvasPathBuilder(new CanvasDevice());
pathBuilder...
var pathGeometry = CanvasGeometry.CreatePath(pathBuilder);
var path = new CompositionPath(pathGeometry);

[zed220]

@jesbis As I can see, the CanvasPathBuilder is a part of the nuget package Win2d.uwp. In my opinion, it shouldn't be used in WinUI?

[jesbis]

There are a couple issues tracking enabling WinUI support:

microsoft/Win2D/issues/707

microsoft/WindowsAppSDK/issues/213

[tom-huntington]

@jesbis Can Direct2D implement IGeometrySource2D? I've tried full copy-paste

ID2D1PathGeometry* m_pPathGeometry;
...
auto iGeometrySource2D = Windows::Graphics::IGeometrySource2D{ m_pPathGeometry, winrt::take_ownership_from_abi };
auto compositionPath = Microsoft::UI::Composition::CompositionPath{ iGeometrySource2D };
// 0x80070057 : 'Invalid argument to parameter source. Object parameter must not be null.'.

but maybe there is some QueryInterface trick I'm not doing right.

[ChewWorker]

I haven't had a chance to try raw D2D, but it can be done with Win2D. The following example works to use Win2D to build the geometry source. One possible issue with the code you pasted is that there aren't open/add geometry/close steps being done before creating the composition path. It's possible the d2d object defaults to a bad/closed state unless the geometry has beeen created. This code was used in a basic UWP/Win2D project:

        var c = Window.Current.Compositor;

        // CanvasGeometry and CanvasPathBuilder are Win2D objects
        CanvasPathBuilder pathBuilder = new CanvasPathBuilder(sender);
        pathBuilder.BeginFigure(1, 1);
        pathBuilder.AddLine(300, 300);
        pathBuilder.AddLine(1, 300);
        pathBuilder.EndFigure(CanvasFigureLoop.Closed);

        CanvasGeometry geometry = CanvasGeometry.CreatePath(pathBuilder);

        // These are Composition Path objects
        var pathGeometry = c.CreatePathGeometry(new CompositionPath(geometry));

        // Need to create a sprite shape from the rounded rect
        var roundedRectSpriteShape              = c.CreateSpriteShape(pathGeometry);
        roundedRectSpriteShape.FillBrush        = c.CreateColorBrush(Colors.Red);

        _shapeContainer.Shapes.Add(roundedRectSpriteShape);

[duncanmacmichael]

[like] Duncan MacMichael reacted to your message:

…

________________________________ From: Chris Raubacher ***@***.***> Sent: Tuesday, June 27, 2023 10:40:16 PM To: microsoft/microsoft-ui-xaml ***@***.***> Cc: Duncan MacMichael ***@***.***>; Mention ***@***.***> Subject: Re: [microsoft/microsoft-ui-xaml] Question: How to use CompositionPathGeometry and CompositionPath? (#3609) I haven't had a chance to try raw D2D, but it can be done with Win2D. The following example works to use Win2D to build the geometry source. One possible issue with the code you pasted is that there aren't open/add geometry/close steps being done before creating the composition path. It's possible the d2d object defaults to a bad/closed state unless the geometry has beeen created. This code was used in a basic UWP/Win2D project: var c = Window.Current.Compositor; // CanvasGeometry and CanvasPathBuilder are Win2D objects CanvasPathBuilder pathBuilder = new CanvasPathBuilder(sender); pathBuilder.BeginFigure(1, 1); pathBuilder.AddLine(300, 300); pathBuilder.AddLine(1, 300); pathBuilder.EndFigure(CanvasFigureLoop.Closed); CanvasGeometry geometry = CanvasGeometry.CreatePath(pathBuilder); // These are Composition Path objects var pathGeometry = c.CreatePathGeometry(new CompositionPath(geometry)); // Need to create a sprite shape from the rounded rect var roundedRectSpriteShape = c.CreateSpriteShape(pathGeometry); roundedRectSpriteShape.FillBrush = c.CreateColorBrush(Colors.Red); _shapeContainer.Shapes.Add(roundedRectSpriteShape); — Reply to this email directly, view it on GitHub<#3609 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AEMILZNIBGF57XV4PXUL5CTXNNONBANCNFSM4TVRUURQ>. You are receiving this because you were mentioned.Message ID: ***@***.***>

[tom-huntington]

ID2D1Geometry is COM interface (IUnknown) but not a WinRT interface (IInspectable) but

IGeometrySource2D(void* ptr, take_ownership_from_abi_t) noexcept : winrt::Windows::Foundation::IInspectable(ptr, take_ownership_from_abi) {}

expects ptr to be Inspectable. No doubt what I did shouldn't work.

I guess IGeometrySource2D is the WinRT placeholder for ID2D1Geometry and you have to do some kind of dance creating an object that inherits from both. Maybe I should just use the Win2D bloat

[castorix]

With Windows.UI.Composition, it is done with IGeometrySource2DInterop, like in https://github.com/microsoft/Windows.UI.Composition-Win32-Samples/blob/master/cpp/HelloVectors/HelloVectors_win32.cpp,
but not sure if it works with Microsoft.UI.Composition (I could only test in C# and I got 0x80070057 like @tom-huntington )

[tom-huntington]

@castorix Thanks! I managed create the Microsoft::UI::Composition::CompositionPath in c++. Hopefully there aren't any more problems. It should work since it only wants a Windows::Graphics::IGeometrySource2D.

[RoyLicx]

Currently, Win2d is supported in Winui3. You could check the document-Overview of Win2D - Windows apps | Microsoft Learn. You could use CompositionPathGeometry and CompositionPath just like @jesbis shows.
Please also note that Win2D for WinUI 3 (Windows App SDK) is a work-in-progress now, and some features aren't supported.

[duncanmacmichael]

Closing as completed, as this appears to have been answered with no activity since June (other than Roy's comment).