New Architecture for React Native for Windows

[chrisglein]

This issue is a hub for the various workstreams underway to bring the current "Paper" implementation of React Native on Windows to become a Fabric implementation.

About Fabric

Fabric is the new rendering system for React Native, designed to share more rendering logic cross-platform in C++. RNW's existing Paper renderer is built on XAML, with various parts dropping down into native Composition as need be; the new Fabric renderer will target Composition from the start, but with the ability to host XAML islands within.

Apps on the new architecture will be Win32 by default (This is a change from the Paper architecture where apps were UWP by default). The move away from UWP was a decision made to stay in alignment with the new WinAppSDK and WinUI3 which support Win32 apps (See here for more information). For our customers with UWP RNW apps, we will have clear migration instructions out once we reach official support for Fabric.

Can I Try It?

We aren't ready for most people to try out Fabric on Windows at this moment. There are still significant gaps in both the functionality and the developer experience. If you are an early adopter who is comfortable with an unpolished experience, you can try it out here. However understand that documentation will be thin, and please consult all of the below lists for what is not yet implemented before making any bug reports. As we progress further into our milestones the level of support will increase.

Milestones

Milestone	Milestone Nickname	Milestone Description
☑️ M0	Proof of Concept	Internal contributors can manually create a Win32 app that renders JSX using Composition
☑️ M1	Experimental	User can successfully initialize, build, and run a React Native Windows app on the new architecture. User can use the most common props/API’s. User can use the most common accessibility props/API’s. User can observe basic accessibility support within their app. User will not have access to full API parity with Paper. User can use community modules within their app. User cannot use community modules with native UI within their app.
🔜 M2	Parity and Accessibility	User can use all props/API’s that were supported on Paper. User can use all accessibility props/API’s that were supported on Paper. User can observe compliant/delightful accessibility support within their app.
⬜ M3	Ready for Modules	User can use the subset of community modules with native UI which have support for Fabric on Windows.
⬜ M4	Production Ready (Fabric now officially in support)	User can use most community modules with native UI which had been supported on Paper. User can view documentation for the new architecture on the React Native Windows website. Platform will be validated against most common app scenarios.
⬜ M5	New Default	Platform will be validated against all app scenarios. Paper architecture will be deprecated; Fabric will be the new default.

Host Component Parity

(updated February 2024)

Priority	Component	Available	Properties
0	View	✅	90%
0	Text	✅	85%
0	Image	✅	89%
0	TextInput	✅	80%
1	ScrollView	✅	84%
1	Modal	🟥	64%
2	ActivityIndicator	✅	86%
2	Switch	✅	90%
2	RefreshControl	🟥	28%

Host Components are the core RN primitive components directly backed by native UI. This table tracks our progress to reach parity in Fabric (Composition) with our Paper (XAML) implementation. See the parity tracking issue here

Paper Parity

Note that Paper itself never reached 100% parity. So 100% completion in the table above represents reaching 100% of what Paper accomplished, which is represented here:

Component	Completed %
View	79% (116/147)
Text	72% (111/155)
Image	77% (151/196)
TextInput	72% (165/230)
ScrollView	69% (143/208)
Modal	57% (41/72)
ActivityIndicator	78% (117/150)
Switch	79% (121/154)
RefreshControl	74% (116/156)

Task list

Tasks

Preview Give feedback

1. Host Components in RNW have parity between Paper and Fabric renderers #11135
   9 of 9
   Area: Fabric Deliverable New Architecture Parity: Fabric vs. Paper enhancement +5
   
2. Migrate from react-native-windows-init to react-native init-windows for new RNW projects #11920
   18 of 20
   Area: Developer Experience Deliverable Developer First Experience Documentation New Architecture Workstream: Developer Experience enhancement +7
   
3. Enable creation of a new Fabric app from template via the CLI #11908
   Area: App Template Area: CLI Area: Fabric New Architecture enhancement +5
   
4. Make Hermes the default JS engine #6136
   Area: JavaScript Engine enhancement +2
   
5. Ensure XAML controls can be hosted within a Fabric app's Composition tree #11907
   Area: Fabric New Architecture Workstream: Module Support enhancement +4
6. E2E testing for Fabric #11422
   9 of 20
   Area: Fabric Area: Test Infrastructure Area: Tests New Architecture Workstream: Test Coverage enhancement +6
7. Accessibility for Fabric #11898
   5 of 12
   Area: Accessibility Area: Fabric Deliverable New Architecture Workstream: Accessibility enhancement +6
8. Modal component parity for Fabric #11157
   API: Completion Area: Component Views Area: Fabric Area: Modal Deliverable New Architecture Parity: Fabric vs. Paper enhancement +8
   
9. Flyout/Popup components for Fabric #11921
   Area: Fabric Area: Flyout Area: Modal Area: Popup New Architecture Workstream: Component Parity enhancement +7
   
10. Migrate (or fork) samples from Paper to Fabric react-native-windows-samples#862
    enhancement samples +2
    
11. Migrate Supported Community Modules to Fabric #12027
    Area: Fabric Extensions New Architecture Workstream: Module Support enhancement +5
    

    
12. New apps created against 0.77+ should default to the new architecture #13683
    1 of 3
    Area: CLI New Architecture Workstream: Developer Experience enhancement +4
    

Other milestones

Tasks

Preview Give feedback

1. Enable creation of a new Fabric app from template via the CLI #11908
   Area: App Template Area: CLI Area: Fabric New Architecture enhancement +5
   
2. Fabric version of an app in the store (potentially Artificial Chat)
3. Create version of Gallery app that uses Fabric instead of Paper react-native-gallery#349
   enhancement +1
   
4. Fabric version of Gallery, accessibility parity gets passing grade
5. Production brownfield app ships a single experience on Fabric

[TatianaKapos]

As RNW's Fabric support has yet to reach Beta status, details on it are not included in our usual release notes (0.75.0-preview.1 example). But there's a ton of RNW Fabric progress contained in each release and we wanted to highlight it here for those tracking closely! 😊

📝 0.74

• Add Switch animations (https://github.com/microsoft/react-native-windows/pull/12631 and https://github.com/microsoft/react-native-windows/pull/12207 and https://github.com/microsoft/react-native-windows/pull/12301)
• Fixed BinSkim errors to be compliant with publishing standards (https://github.com/microsoft/react-native-windows/pull/12295)
• Add CharacterRecieved Event (https://github.com/microsoft/react-native-windows/pull/12254)
• Adds testing suites to Fabric (https://github.com/microsoft/react-native-windows/pull/12250 and https://github.com/microsoft/react-native-windows/pull/12442 and https://github.com/microsoft/react-native-windows/pull/12539 and https://github.com/microsoft/react-native-windows/pull/12602 and https://github.com/microsoft/react-native-windows/pull/12610 and https://github.com/microsoft/react-native-windows/pull/12675)
• Add support for loading image files from local files (https://github.com/microsoft/react-native-windows/pull/12264)
• Expand native theming implementation (https://github.com/microsoft/react-native-windows/pull/12287)
• Move E2E fabric app to WinAppSDK and lifted composition (https://github.com/microsoft/react-native-windows/pull/12242)
• Enable concurrentRoot (https://github.com/microsoft/react-native-windows/pull/12367)
• The new Fabric app template now supports yarn windows as an alias to react-native run-windows (https://github.com/microsoft/react-native-windows/pull/12374)
• The new Fabric app template supports yarn test:windows to run jest app rendering tests with react-test-renderer (https://github.com/microsoft/react-native-windows/pull/12376)
• Add support for custom native component to have c++ state and custom measure (https://github.com/microsoft/react-native-windows/pull/12418)
• Add DeviceInfoModule (https://github.com/microsoft/react-native-windows/pull/12450)
• Add caretHidden to TextInput (https://github.com/microsoft/react-native-windows/pull/12430)
• Add support for custom themes and support runtime theme change (https://github.com/microsoft/react-native-windows/pull/12474)
• Move to using winrt objects for ComponentViews (https://github.com/microsoft/react-native-windows/pull/12580)
• Expose public APIs to navigate native UI tree (https://github.com/microsoft/react-native-windows/pull/12614)
• Initial scrollbar implementation for ScrollViewComponentView (https://github.com/microsoft/react-native-windows/pull/12622)
• Add scrollbar show/hide logic (https://github.com/microsoft/react-native-windows/pull/12625)
• Fix issue causing PointerMove events to have incorrect position when using WM_msg input (https://github.com/microsoft/react-native-windows/pull/12638)
• Implement ActivityIndicator's size property (https://github.com/microsoft/react-native-windows/pull/12122)
• Capture pointer input during scroll thumb drag (https://github.com/microsoft/react-native-windows/pull/12642)
• Allow unimplemented native views to have children (https://github.com/microsoft/react-native-windows/pull/12650)
• Remove AbiCompositionViewComponent and move to inheritance overrides for custom components (https://github.com/microsoft/react-native-windows/pull/12668)
• Mouse wheel handling when use WM_MSG hosting uses wrong mouse position (https://github.com/microsoft/react-native-windows/pull/12672)
• Fix visual issue when quickly dragging scrollthumb before it finishes animating in (https://github.com/microsoft/react-native-windows/pull/12671)
• LogBox crashes when running lifted composition (https://github.com/microsoft/react-native-windows/pull/12725)
• Expose (un)MountChildComponentView to 3P components (https://github.com/microsoft/react-native-windows/pull/12720)
• Add onSubmitEditing and clearTextOnSubmit (https://github.com/microsoft/react-native-windows/pull/12746)
• Add additional functionality to support implementing more advanced custom components (https://github.com/microsoft/react-native-windows/pull/12739)
• Updated @react-native-windows/automation to support launching and connecting to packaged new-app fabric apps for UIA automation and testing (https://github.com/microsoft/react-native-windows/pull/12769)
• Add onKeyPress for TextInput and enable legacyTextInputTests (https://github.com/microsoft/react-native-windows/pull/12771)
• Add experimental bridgeless mode (https://github.com/microsoft/react-native-windows/pull/12781)
• Fix various issues with instance shutdown when using bridgeless (https://github.com/microsoft/react-native-windows/pull/12790)
• Add UIBatchingQueue to bridgeless mode (https://github.com/microsoft/react-native-windows/pull/12812/files)
• Implement LoadingUI and DebuggingOverlay (https://github.com/microsoft/react-native-windows/pull/12809)
• Update ActivityIndicator to newer visuals (https://github.com/microsoft/react-native-windows/pull/12865)
• Extract RenderText into helper function + clean up Loading visuals (https://github.com/microsoft/react-native-windows/pull/12866)

📝 0.75

• Fixes hang on shutdown. Fix hang on shutdown when JS instance failed to start (#12867) · microsoft/react-native-windows@b99ccd7 (github.com)
• Fix OnSelectionChanged running multiple times. Fix OnSelectionChanged running multiple times (#12903) · microsoft/react-native-windows@187f3a6 (github.com)
• Start of implementation of TextLayoutManager::measureLines. Partial implementation of TextLayoutManager::measureLines (#12930) · microsoft/react-native-windows@3067b5a (github.com)
• Move CompositionSwitcher to Experimental namespace. Move CompositionSwitcher to Experimental namespace (#12960) · microsoft/react-native-windows@347922f (github.com)
• Unify some DPI drawing logic. Unify some DPI drawing logic (#12974) · microsoft/react-native-windows@8953893 (github.com)
• Don’t use CoreWindow to determine key state. Dont use CoreWindow to determine key state (#12998) · microsoft/react-native-windows@a4f55e5 (github.com)
• Ensure D2D device context is not used outside Begin/End draw. Ensure D2D device context is not used outside Begin/End draw (#13011) · microsoft/react-native-windows@5fa1ba4 (github.com)
• Rework custom resources API. Rework custom resources API (#13013) · microsoft/react-native-windows@c15f1bb (github.com)
• Fix a reference cycle between CompositionRootView and CompositionEventHandler. Fix a reference cycle between CompositionRootView and CompositionEventHandler (#13163) · microsoft/react-native-windows@7bace67 (github.com)
• Add ability to provide custom image uri handlers. Add ability to provide custom image uri handlers (#13180) · microsoft/react-native-windows@a645675 (github.com)
• Add support for data: images. Add support for data: images (#13191) · microsoft/react-native-windows@974ae25 (github.com)
• Move UriHandler registration to PackageProvider. Move UriHandler registration to PackageProvider (#13197) · microsoft/react-native-windows@de5c307 (github.com)
• Fix experimental winui3 builds. Fix experimental winui3 builds (#13203) · microsoft/react-native-windows@dea1b59 (github.com)
• Expose ImageProps from ImageComponentView's and add ImageSource type. Expose ImageProps from ImageComponentView's and add ImageSource type (#13206) · microsoft/react-native-windows@8f366c5 (github.com)
• Introduce clearTextOnFocus property for TextInput. Introduce clearTextOnFocus property for TextInput (#13227) · microsoft/react-native-windows@d38ba13 (github.com)
• Add various native focus APIs. Add various native focus APIs (#13234) · microsoft/react-native-windows@0d5ad19 (github.com)
• APIs to enable RootViews that size to content. APIs to enable RootViews that size to content (#13269) · microsoft/react-native-windows@b150f8e (github.com)
• Support blob: images, and provide better image.onError callbacks. Support blob: images, and provide better image.onError callbacks (#13285) · microsoft/react-native-windows@adc4d09 (github.com)
• Touch pointer moved was being reported to richedit as a pointerup. Touch pointer moved was being reported to richedit as a pointerup (#13313) · microsoft/react-native-windows@71feab2 (github.com)