WinUI 3 Designer for Visual Studio

Design and preview WinUI 3 layouts in Visual Studio.

Usage

Download and open a vsix file from Visual Studio Marketplace. WinUI 3 designer will be automatically available for WinUI 3 projects.

Limitations

• Only C# WinUI projects are supported.
• x86 is not supported.
• Window and its subclasses cannot be previewed; only FrameworkElement subclasses are supported.
• Windows App SDK 2.5.1 is required.

Structure

WinUIDesigner.Shared

A Visual Studio shared source project compiled into WinUIDesigner.Surface, WinUIDesigner.Vsix, and the VSIX tests. It contains the common designer protocol message IDs, the app-resources request contract, and WinUIDesignerLogger; it does not produce a separate runtime DLL.

WinUIDesigner.DiagnosticsTap

A native DLL, packaged for x64 and ARM64, loaded by the isolated WinUI surface process. It attaches to WinUI XAML Diagnostics, exposes property-value-source queries and rendering control to the managed surface, and implements the diagnostics TAP COM entry points.

WinUIDesigner.Surface

The out-of-process WinUI 3 designer surface, published as the self-contained WinUISurface.exe. It connects to Visual Studio through the designer's TAP/pipe contracts, builds and updates the XAML document, and handles designer operations such as selection, hit testing, property values, and layout. It calls WinUIDesigner.DiagnosticsTap.dll for native XAML diagnostics that are not exposed by the public WinUI API.

WinUIDesigner.Vsix

The in-process Visual Studio extension. It registers the WinUI XAML runtime, selects the WinUI platform implementation, reuses Visual Studio's designer host and process-isolation services, stages and launches WinUISurface.exe, and provides Toolbox integration.

flowchart TB
    VS["Visual Studio designer"] -->|Load extension| VSIX["WinUIDesigner.Vsix"]
    VSIX -->|Stage and launch through the VS host| SURFACE["WinUISurface.exe"]
    VS <-->|Designer protocol over pipes| SURFACE
    SURFACE -->|Native diagnostics| TAP["WinUIDesigner.DiagnosticsTap.dll"]
    TAP <-->|XAML diagnostics| XAML["WinUI 3 XAML runtime"]
    SURFACE -->|Create and update objects| XAML

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Architecture

See Architecture for the designer's processing flow and implementation details.