papyrus_windows

Windows WebView2 implementation package for Papyrus.

The native implementation detects missing WebView2 Runtime, maps policy to CoreWebView2 settings, intercepts navigation/resources, handles process failure events, and reports capability differences.

If WebView2 runtime creation fails, Papyrus reports webViewUnavailable with actionable diagnostics.

Windows uses the shared desktop overlay model rather than a Flutter platform view. PapyrusView lays out a Flutter placeholder and the plugin positions the native WebView2 surface over that rectangle via setViewport. Initial loads are scheduled after viewport synchronization so first paint does not race zero-sized bounds during startup.

Native Windows tests

From examples/papyrus_example:

flutter pub get
flutter build windows --debug
cmake -S windows -B build/windows/x64 "-Dinclude_papyrus_windows_tests=ON" "-DCMAKE_POLICY_VERSION_MINIMUM=3.10"
cmake --build build/windows/x64 --config Debug --target papyrus_windows_test
ctest --test-dir build/windows/x64/plugins/papyrus_windows -C Debug --output-on-failure

Packaging Windows installers (WebView2 dependencies)

Papyrus links the WebView2 loader statically, so apps do not need to ship WebView2Loader.dll. The required runtime dependency is Microsoft Edge WebView2 Runtime.

Recommended installer strategies:

1. Evergreen Bootstrapper (small online installer)

   • Bundle or download MicrosoftEdgeWebView2Setup.exe.
   • Run silently during install: /silent /install.
   • Best when internet access is available.

2. Evergreen Standalone Installer (offline)

   • Bundle architecture-specific runtime installers (x64/x86/arm64).
   • Run silently during install: /silent /install.
   • Best for offline or controlled enterprise environments.

Current Papyrus behavior:

• The Windows plugin creates WebView2 with CreateCoreWebView2EnvironmentWithOptions(nullptr, nullptr, ...).
• This targets installed runtime discovery (Evergreen runtime model).
• Fixed Version runtime folders are not wired through plugin configuration.

Practical packaging checklist:

• Match runtime installer architecture to your app build architecture.
• Install WebView2 Runtime before first launch of the app.
• Keep the app-side error handling for webViewUnavailable as a fallback for machines where runtime installation fails or is blocked.