refactor(windows): use http scheme by default for custom protocols and add option to change it

.changes/windows-http.md

@@ -0,0 +1,5 @@
+---
+"wry": "minor"
+---
+
+Add `WebViewBuilderExtWindows::with_http_scheme` to be able to choose between `http` and `https` for custom protocols on Windows.

src/webview/mod.rs

@@ -277,6 +277,7 @@ pub(crate) struct PlatformSpecificWebViewAttributes {
   additional_browser_args: Option<String>,
   browser_accelerator_keys: bool,
   theme: Option<Theme>,
+  http_scheme: bool,
 }
 #[cfg(windows)]
 impl Default for PlatformSpecificWebViewAttributes {
@@ -285,6 +286,7 @@ impl Default for PlatformSpecificWebViewAttributes {
       additional_browser_args: None,
       browser_accelerator_keys: true, // This is WebView2's default behavior
       theme: None,
+      http_scheme: false,
     }
   }
 }
@@ -695,6 +697,14 @@ pub trait WebViewBuilderExtWindows {
   ///
   /// Defaults to [`Theme::Auto`] which will follow the OS defaults.
   fn with_theme(self, theme: Theme) -> Self;
+
+  /// Determines whether the custom protocols should use `http://<scheme>.localhost` instead of `http://<scheme>.localhost`.
+  ///
+  /// Using a `http` scheme will prevent mixed content warnings when trying to fetch `http` endpoints
+  /// and is therefore less secure but will match the behavior of the `<scheme>://localhost` protocols on macOS and Linux.
+  ///
+  /// The default value is `false`.
+  fn with_http_scheme(self, enabled: bool) -> Self;
 }
 
 #[cfg(windows)]
@@ -713,6 +723,11 @@ impl WebViewBuilderExtWindows for WebViewBuilder<'_> {
     self.platform_specific.theme = Some(theme);
     self
   }
+
+  fn with_http_scheme(mut self, enabled: bool) -> Self {
+    self.platform_specific.http_scheme = enabled;
+    self
+  }
 }
 
 #[cfg(target_os = "android")]

src/webview/webview2/mod.rs

@@ -537,15 +537,20 @@ window.addEventListener('mousemove', (e) => window.chrome.webview.postMessage('_
       }
     }
 
+    let scheme = if pl_attrs.http_scheme {
+      "http"
+    } else {
+      "https"
+    };
     let mut custom_protocol_names = HashSet::new();
     if !attributes.custom_protocols.is_empty() {
       for (name, _) in &attributes.custom_protocols {
-        // WebView2 doesn't support non-standard protocols yet, so we have to use this workaround
+        // WebView2 supports non-standard protocols only on Windows 10+, so we have to use this workaround
         // See https://github.com/MicrosoftEdge/WebView2Feedback/issues/73
         custom_protocol_names.insert(name.clone());
         unsafe {
           webview.AddWebResourceRequestedFilter(
-            PCWSTR::from_raw(encode_wide(format!("https://{}.*", name)).as_ptr()),
+            PCWSTR::from_raw(encode_wide(format!("{scheme}://{name}.*")).as_ptr()),
             COREWEBVIEW2_WEB_RESOURCE_CONTEXT_ALL,
           )
         }
@@ -616,11 +621,11 @@ window.addEventListener('mousemove', (e) => window.chrome.webview.postMessage('_
 
                 if let Some(custom_protocol) = custom_protocols
                   .iter()
-                  .find(|(name, _)| uri.starts_with(&format!("https://{}.", name)))
+                  .find(|(name, _)| uri.starts_with(&format!("{scheme}://{name}.")))
                 {
                   // Undo the protocol workaround when giving path to resolver
                   let path = uri.replace(
-                    &format!("https://{}.", custom_protocol.0),
+                    &format!("{scheme}://{}.", custom_protocol.0),
                     &format!("{}://", custom_protocol.0),
                   );
 
@@ -741,11 +746,11 @@ window.addEventListener('mousemove', (e) => window.chrome.webview.postMessage('_
         let mut url_string = String::from(url.as_str());
         let name = url.scheme();
         if custom_protocol_names.contains(name) {
-          // WebView2 doesn't support non-standard protocols yet, so we have to use this workaround
+          // WebView2 supports non-standard protocols only on Windows 10+, so we have to use this workaround
           // See https://github.com/MicrosoftEdge/WebView2Feedback/issues/73
           url_string = url
             .as_str()
-            .replace(&format!("{}://", name), &format!("https://{}.", name))
+            .replace(&format!("{}://", name), &format!("{scheme}://{name}."))
         }
 
         if let Some(headers) = attributes.headers {