refactor(window): block main thread when creating a new window (#4298)

Author: lucasfernog

.changes/refactor-window-creation.md

@@ -0,0 +1,5 @@
+---
+"tauri": patch
+---
+
+**Breaking change:** Revert the window creation to be blocking in the main thread. This ensures the window is created before using other methods, but has an issue on Windows where the program deadlocks when creating a window in a Tauri command if it is not `async`. The documentation now states that commands must be `async` in other to prevent it until the issue is fixed in Webview2.

core/tauri-runtime-wry/src/lib.rs

@@ -225,16 +225,15 @@ impl<T: UserEvent> Context<T> {
 
     self.prepare_window(window_id);
 
-    // we cannot use `send_user_message` here, see https://github.com/tauri-apps/wry/issues/583
-    self
-      .proxy
-      .send_event(Message::CreateWebview(
+    send_user_message(
+      self,
+      Message::CreateWebview(
         window_id,
         Box::new(move |event_loop, web_context| {
           create_webview(window_id, event_loop, web_context, context, pending)
         }),
-      ))
-      .map_err(|_| Error::FailedToSendMessage)?;
+      ),
+    )?;
 
     let dispatcher = WryDispatcher {
       window_id,

core/tauri-runtime/src/lib.rs

@@ -81,7 +81,7 @@ impl SystemTray {
 }
 
 /// Type of user attention requested on a window.
-#[derive(Debug, Clone, Copy, PartialEq, Deserialize)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Deserialize)]
 #[serde(tag = "type")]
 pub enum UserAttentionType {
   /// ## Platform-specific

core/tauri-utils/src/config.rs

@@ -38,7 +38,7 @@ impl<R: Read + Seek> ArchiveReader<R> {
 }
 
 /// The supported archive formats.
-#[derive(Debug, Clone, Copy, PartialEq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 #[non_exhaustive]
 pub enum ArchiveFormat {
   /// Tar archive.
@@ -48,7 +48,7 @@ pub enum ArchiveFormat {
 }
 
 /// The supported compression types.
-#[derive(Debug, Clone, Copy, PartialEq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 #[non_exhaustive]
 pub enum Compression {
   /// Gz compression (e.g. `.tar.gz` archives)

core/tauri/src/api/file/extract.rs

@@ -275,7 +275,7 @@ impl Command {
         Ok(status) => {
           let _l = guard.write().unwrap();
           commands().lock().unwrap().remove(&child_.id());
-          let _ = block_on_task(async move {
+          block_on_task(async move {
             tx.send(CommandEvent::Terminated(TerminatedPayload {
               code: status.code(),
               #[cfg(windows)]
@@ -284,11 +284,11 @@ impl Command {
               signal: status.signal(),
             }))
             .await
-          });
+          })
         }
         Err(e) => {
           let _l = guard.write().unwrap();
-          let _ = block_on_task(async move { tx.send(CommandEvent::Error(e.to_string())).await });
+          block_on_task(async move { tx.send(CommandEvent::Error(e.to_string())).await })
         }
       };
     });

core/tauri/src/api/process/command.rs

@@ -269,7 +269,7 @@ fn set_default_path(
       if parent.components().count() > 0 {
         dialog_builder = dialog_builder.set_directory(parent);
       }
-      dialog_builder = dialog_builder.set_file_name(&file_name.to_string_lossy().to_string());
+      dialog_builder = dialog_builder.set_file_name(&file_name.to_string_lossy());
     } else {
       dialog_builder = dialog_builder.set_directory(default_path);
     }

core/tauri/src/endpoints/dialog.rs

@@ -120,6 +120,52 @@ impl<'a, R: Runtime> fmt::Debug for WindowBuilder<'a, R> {
 
 impl<'a, R: Runtime> WindowBuilder<'a, R> {
   /// Initializes a webview window builder with the given window label and URL to load on the webview.
+  ///
+  /// # Examples
+  ///
+  /// - Create a window in the setup hook:
+  ///
+  /// ```
+  /// tauri::Builder::default()
+  ///   .setup(|app| {
+  ///     let window = tauri::WindowBuilder::new(app, "label", tauri::WindowUrl::App("index.html".into()))
+  ///       .build()?;
+  ///     Ok(())
+  ///   });
+  /// ```
+  ///
+  /// - Create a window in a separate thread:
+  ///
+  /// ```
+  /// tauri::Builder::default()
+  ///   .setup(|app| {
+  ///     let handle = app.handle();
+  ///     std::thread::spawn(move || {
+  ///       let window = tauri::WindowBuilder::new(&handle, "label", tauri::WindowUrl::App("index.html".into()))
+  ///         .build()
+  ///         .unwrap();
+  ///     });
+  ///     Ok(())
+  ///   });
+  /// ```
+  ///
+  /// - Create a window in a command:
+  ///
+  /// ```
+  /// #[tauri::command]
+  /// async fn create_window(app: tauri::AppHandle) {
+  ///   let window = tauri::WindowBuilder::new(&app, "label", tauri::WindowUrl::External("https://tauri.studio/".parse().unwrap()))
+  ///     .build()
+  ///     .unwrap();
+  /// }
+  /// ```
+  ///
+  /// # Known issues
+  ///
+  /// On Windows, this function deadlocks when used in a synchronous command, see [the Webview2 issue].
+  /// You should use `async` commands when creating windows.
+  ///
+  /// [the Webview2 issue]: https://github.com/tauri-apps/wry/issues/583
   pub fn new<M: Manager<R>, L: Into<String>>(manager: &'a M, label: L, url: WindowUrl) -> Self {
     let runtime = manager.runtime();
     let app_handle = manager.app_handle();
@@ -600,7 +646,7 @@ impl Window<crate::Wry> {
   ///           use webkit2gtk::traits::WebViewExt;
   ///           webview.inner().set_zoom_level(4.);
   ///         }
-  ///   
+  ///
   ///         #[cfg(windows)]
   ///         unsafe {
   ///           // see https://docs.rs/webview2-com/latest/webview2_com/Microsoft/Web/WebView2/Win32/struct.ICoreWebView2Controller.html