enhance(windows): support webview2 version before 101 (#1306)

* Support webview2 version < 101

* Add change file

* Use "returns error" instead of fails

* Add docs to `with_incognito` as well

.changes/support-webview2-before-101.md

@@ -0,0 +1,5 @@
+---
+"wry": patch
+---
+
+Support WebView2 version older than 101.0.1210.39 and document `incognito` and `theme` will not work for versions before it

src/lib.rs

@@ -470,6 +470,8 @@ pub struct WebViewAttributes {
   ///
   /// ## Platform-specific:
   ///
+  /// - Windows: Requires WebView2 Runtime version 101.0.1210.39 or higher, does nothing on older versions,
+  /// see https://learn.microsoft.com/en-us/microsoft-edge/webview2/release-notes/archive?tabs=dotnetcsharp#10121039
   /// - **Android:** Unsupported yet.
   pub incognito: bool,
 
@@ -961,6 +963,8 @@ impl<'a> WebViewBuilder<'a> {
   ///
   /// ## Platform-specific:
   ///
+  /// - Windows: Requires WebView2 Runtime version 101.0.1210.39 or higher, does nothing on older versions,
+  /// see https://learn.microsoft.com/en-us/microsoft-edge/webview2/release-notes/archive?tabs=dotnetcsharp#10121039
   /// - **Android:** Unsupported yet.
   pub fn with_incognito(mut self, incognito: bool) -> Self {
     self.attrs.incognito = incognito;
@@ -1110,6 +1114,9 @@ pub trait WebViewBuilderExtWindows {
   /// Specifies the theme of webview2. This affects things like `prefers-color-scheme`.
   ///
   /// Defaults to [`Theme::Auto`] which will follow the OS defaults.
+  ///
+  /// Requires WebView2 Runtime version 101.0.1210.39 or higher, does nothing on older versions,
+  /// see https://learn.microsoft.com/en-us/microsoft-edge/webview2/release-notes/archive?tabs=dotnetcsharp#10121039
   fn with_theme(self, theme: Theme) -> Self;
 
   /// Determines whether the custom protocols should use `https://<scheme>.path/to/page` instead of the default `http://<scheme>.path/to/page`.
@@ -1503,6 +1510,9 @@ pub trait WebViewExtWindows {
   fn controller(&self) -> ICoreWebView2Controller;
 
   /// Changes the webview2 theme.
+  ///
+  /// Requires WebView2 Runtime version 101.0.1210.39 or higher, returns error on older versions,
+  /// see https://learn.microsoft.com/en-us/microsoft-edge/webview2/release-notes/archive?tabs=dotnetcsharp#10121039
   fn set_theme(&self, theme: Theme) -> Result<()>;
 
   /// Sets the [memory usage target level][1].

src/webview2/mod.rs

@@ -328,17 +328,29 @@ impl InnerWebView {
     incognito: bool,
   ) -> Result<ICoreWebView2Controller> {
     let (tx, rx) = mpsc::channel();
-    let env = env.clone().cast::<ICoreWebView2Environment10>()?;
-    let controller_opts = unsafe { env.CreateCoreWebView2ControllerOptions()? };
-
-    unsafe { controller_opts.SetIsInPrivateModeEnabled(incognito)? }
+    let env = env.clone();
+    let env10 = env.cast::<ICoreWebView2Environment10>();
 
     CreateCoreWebView2ControllerCompletedHandler::wait_for_async_operation(
-      Box::new(move |handler| unsafe {
-        env
-          .CreateCoreWebView2ControllerWithOptions(hwnd, &controller_opts, &handler)
-          .map_err(Into::into)
-      }),
+      if let Ok(env10) = env10 {
+        let controller_opts = unsafe { env10.CreateCoreWebView2ControllerOptions()? };
+        unsafe { controller_opts.SetIsInPrivateModeEnabled(incognito)? }
+        Box::new(
+          move |handler: ICoreWebView2CreateCoreWebView2ControllerCompletedHandler| unsafe {
+            env10
+              .CreateCoreWebView2ControllerWithOptions(hwnd, &controller_opts, &handler)
+              .map_err(Into::into)
+          },
+        )
+      } else {
+        Box::new(
+          move |handler: ICoreWebView2CreateCoreWebView2ControllerCompletedHandler| unsafe {
+            env
+              .CreateCoreWebView2Controller(hwnd, &handler)
+              .map_err(Into::into)
+          },
+        )
+      },
       Box::new(move |error_code, controller| {
         error_code?;
         tx.send(controller.ok_or_else(|| windows::core::Error::from(E_POINTER)))
@@ -363,7 +375,15 @@ impl InnerWebView {
 
     // Theme
     if let Some(theme) = pl_attrs.theme {
-      unsafe { set_theme(&webview, theme)? };
+      if let Err(error) = unsafe { set_theme(&webview, theme) } {
+        match error {
+          // Ignore cast error
+          Error::WebView2Error(webview2_com::Error::WindowsError(windows_error))
+            if windows_error.code() == E_NOINTERFACE => {}
+          // Return error if other things went wrong
+          _ => return Err(error),
+        };
+      }
     }
 
     // Background color