winui-wpf-migration

作成者： microsoft

WPFアプリケーションをWinUI 3に移行 — 名前空間の置き換え（System.Windows → Microsoft.UI.Xaml）、コントロールのマッピング（DataGrid→ListView、WrapPanel→ItemsRepeater、…）

npx skills add https://github.com/microsoft/win-dev-skills --skill winui-wpf-migration

ZIPダウンロード GitHub

370

Migration Process

Step 1: Audit the WPF Source

Before writing code, inventory WPF-specific APIs:

# Find all WPF namespace usage
Select-String -Path (Get-ChildItem -Recurse -Filter "*.cs" | Where-Object { $_.FullName -notlike "*\obj\*" }) -Pattern "System\.Windows\." | Select-Object -Property Filename, LineNumber, Line

List: WPF controls used, custom MVVM framework, imaging APIs, threading patterns, Win32 interop.

Step 2: Create WinUI 3 Project and Align Namespaces

dotnet new winui-mvvm -n <AppName>

Immediately set <RootNamespace> in .csproj to match the WPF namespace. Update x:Class in App.xaml, MainWindow.xaml and their code-behind files. Build to verify before porting any code.

Step 3: Replace Namespaces

WPF	WinUI 3
`System.Windows`	`Microsoft.UI.Xaml`
`System.Windows.Controls`	`Microsoft.UI.Xaml.Controls`
`System.Windows.Media`	`Microsoft.UI.Xaml.Media`
`System.Windows.Input`	`Microsoft.UI.Xaml.Input`
`System.Windows.Data`	`Microsoft.UI.Xaml.Data`
`System.Windows.Threading.Dispatcher`	`Microsoft.UI.Dispatching.DispatcherQueue`
`PresentationCore` / `PresentationFramework`	Remove entirely

Step 4: Replace Controls

WPF Control	WinUI 3 Equivalent
`DataGrid`	`ListView` with Grid column headers
`WrapPanel`	`ItemsRepeater` + `UniformGridLayout`
`TabControl`	`TabView`
`StatusBar`	`Grid` row at bottom with `TextBlock` elements
`Menu` / `MenuItem`	`MenuBar` / `MenuBarItem` / `MenuFlyoutItem`
`ToolBar`	`CommandBar`
`Expander` (custom)	`Expander` (built-in)

Step 5: Replace Threading

// WPF
Application.Current.Dispatcher.Invoke(() => { /* UI work */ });

// WinUI 3
dispatcherQueue.TryEnqueue(() => { /* UI work */ });

Get via DispatcherQueue.GetForCurrentThread(). No Application.Current.Dispatcher in WinUI 3.

Step 6: Replace Imaging

Critical: PresentationCore.dll and System.Windows.Media.Imaging crash the WinUI XAML compiler. This is an architectural incompatibility — no workaround exists.

Remove ALL System.Windows.Media.Imaging references at migration start
Replace with Windows.Graphics.Imaging (WinRT) or Microsoft.UI.Xaml.Media.Imaging.BitmapImage
Do NOT add <UseWPF>true</UseWPF> — it silently corrupts the build
If heavy imaging code exists, migrate it early (step 2, not step 7)

Step 7: Replace MVVM Framework

Delete custom ObservableObject/RelayCommand/DelegateCommand. Use CommunityToolkit.Mvvm:

INotifyPropertyChanged base → ObservableObject with [ObservableProperty] partial properties
Custom RelayCommand → [RelayCommand] attribute
{Binding} → {x:Bind Mode=OneWay}
DynamicResource → {ThemeResource}

Step 8: Replace Resources

.resx → .resw (copy + rename to Strings\en-us\)
{x:Static} → x:Uid for localized strings
Properties.Resources.Key → ResourceLoader.GetString("Key")

Critical Rules

❌ NEVER reference PresentationCore, PresentationFramework, or System.Windows.Controls assemblies
❌ NEVER add <UseWPF>true</UseWPF> or <WindowsPackageType>None</WindowsPackageType>
❌ NEVER delete Package.appxmanifest
❌ NEVER overwrite App.xaml / App.xaml.cs — merge WPF code into the WinUI 3 boilerplate
✅ Always use winapp run to launch — never run the .exe directly
✅ Break migration into file-level tasks — not one massive rewrite

Post-Migration Validation

# Check for remaining WPF references (should return nothing)
Select-String -Path (Get-ChildItem -Recurse -Filter "*.cs" | Where-Object { $_.FullName -notlike "*\obj\*" }) -Pattern "System\.Windows\."

# Verify packaging preserved
Test-Path "Package.appxmanifest"  # should be True

# Build and run
.\BuildAndRun.ps1