Add desktop multi-window support (Stirling-Tools#6463)

Author: Frooodle

frontend/editor/public/locales/en-GB/translation.toml

@@ -90,6 +90,7 @@ nothingToUndo = "Nothing to undo"
 noticeTopUpOrPlan = "Not enough credits, please top up or upgrade to a plan"
 noValidFiles = "No valid files to process"
 oops = "Oops!"
+openInNewWindow = "Open in new window"
 openInViewer = "Open in Viewer"
 operationCancelled = "Operation cancelled"
 page = "Page"

frontend/editor/src-tauri/capabilities/default.json

@@ -2,7 +2,7 @@
   "$schema": "../gen/schemas/desktop-schema.json",
   "identifier": "default",
   "description": "enables the default permissions",
-  "windows": ["main"],
+  "windows": ["main", "main-*"],
   "permissions": [
     "core:default",
     "core:window:allow-destroy",

frontend/editor/src-tauri/src/commands/mod.rs

@@ -5,9 +5,18 @@ pub mod auth;
 pub mod default_app;
 pub mod platform;
 pub mod print;
+pub mod window;
 
 pub use backend::{cleanup_backend, get_backend_port, start_backend};
 pub use files::{add_opened_file, clear_opened_files, get_opened_files, pop_opened_files};
+pub use window::{
+    forward_files_to_window,
+    open_files_in_new_window,
+    open_in_new_window,
+    pop_window_file_ids,
+    target_window_label,
+    MAIN_WINDOW_LABEL,
+};
 pub use connection::{
     get_connection_config,
     is_first_launch,

frontend/editor/src-tauri/src/commands/window.rs

@@ -0,0 +1,216 @@
+use crate::commands::files::add_opened_file;
+use crate::utils::add_log;
+use std::collections::HashMap;
+use std::sync::atomic::{AtomicU32, Ordering};
+use std::sync::Mutex;
+use tauri::{AppHandle, Emitter, Manager, WebviewUrl, WebviewWindow, WebviewWindowBuilder};
+
+// The primary window created from tauri.conf.json.
+pub const MAIN_WINDOW_LABEL: &str = "main";
+
+static NEXT_WINDOW_ID: AtomicU32 = AtomicU32::new(2);
+
+// Per-window queues of stored-file IDs waiting to be opened. Unlike disk paths
+// (which use the global OPENED_FILES queue), these reference files already in
+// the shared IndexedDB store, so a "new window" opened from the My Files page
+// loads the same file by reference. Keyed by the new window's label.
+static PENDING_FILE_IDS: Mutex<Option<HashMap<String, Vec<String>>>> = Mutex::new(None);
+
+fn next_window_label() -> String {
+    let id = NEXT_WINDOW_ID.fetch_add(1, Ordering::SeqCst);
+    format!("main-{}", id)
+}
+
+fn queue_file_ids(label: &str, ids: Vec<String>) {
+    let mut guard = PENDING_FILE_IDS.lock().unwrap();
+    let map = guard.get_or_insert_with(HashMap::new);
+    map.entry(label.to_string()).or_default().extend(ids);
+}
+
+// Shared window builder: every Stirling window must use identical WebView2
+// browser args so they can share one user-data folder (see the note below),
+// so all spawn paths funnel through here.
+fn build_window(app: &AppHandle, label: &str, url: &str) -> Result<WebviewWindow, String> {
+    let builder = WebviewWindowBuilder::new(app, label, WebviewUrl::App(url.into()))
+        .title("Stirling-PDF")
+        .inner_size(1280.0, 800.0)
+        // Below this width the file manager collapses to its mobile layout,
+        // so keep new windows above the breakpoint.
+        .min_inner_size(1030.0, 600.0)
+        .resizable(true);
+
+    // WebView2 (Windows only) requires every webview sharing a user-data folder
+    // to use identical additional_browser_args. wry's behaviour
+    // (webview2/mod.rs:294): when the user provides args it uses them as-is and
+    // does NOT prepend its own default `--disable-features=msWebOOUI,...`. So the
+    // main window's actual args are EXACTLY what tauri.conf.json declares -
+    // nothing more. We mirror that string byte-for-byte so windows share one data
+    // dir (and thus IndexedDB / localStorage / cookies). macOS (WKWebView) and
+    // Linux (WebKitGTK) don't have this constraint, so the arg is Windows-only.
+    #[cfg(target_os = "windows")]
+    let builder =
+        builder.additional_browser_args("--enable-features=CertVerifierBuiltinFeature");
+
+    builder.build().map_err(|e| e.to_string())
+}
+
+// Run `work` on the main thread and await its result. WebView2 on Windows
+// refuses to create a webview off the main thread (HRESULT 0x8007139F), but
+// Tauri command handlers run on a worker thread - so any window creation has to
+// hop over first. Centralised here so every command does it the same way.
+async fn run_on_main_thread_result<F, R>(app: &AppHandle, work: F) -> Result<R, String>
+where
+    F: FnOnce() -> R + Send + 'static,
+    R: Send + 'static,
+{
+    let (tx, rx) = tokio::sync::oneshot::channel();
+    app.run_on_main_thread(move || {
+        let _ = tx.send(work());
+    })
+    .map_err(|e| e.to_string())?;
+    rx.await.map_err(|e| e.to_string())
+}
+
+// Spawn a new webview window in the same Tauri process.
+// The backend stays single; only the frontend is duplicated.
+// If `paths` is non-empty, they're enqueued under the new window's label,
+// so the React app pops them on mount just like a fresh launch with a file.
+fn spawn_new_window(app: &AppHandle, paths: Vec<String>) -> Result<String, String> {
+    let label = next_window_label();
+
+    for path in &paths {
+        add_opened_file(path.clone());
+    }
+
+    match build_window(app, &label, "/") {
+        Ok(window) => {
+            add_log(format!(
+                "🪟 Spawned new window '{}' with {} initial file(s)",
+                label,
+                paths.len()
+            ));
+            // The new window pops the shared queue on mount, so the files are
+            // already waiting for it. We target the emit at this window only
+            // (not a broadcast) so already-open windows don't race to pop them.
+            if !paths.is_empty() {
+                let _ = window.emit_to(label.as_str(), "files-changed", ());
+            }
+            Ok(label)
+        }
+        Err(err) => {
+            add_log(format!(
+                "❌ Failed to spawn new window '{}': {}",
+                label, err
+            ));
+            Err(err)
+        }
+    }
+}
+
+#[tauri::command]
+pub async fn open_in_new_window(app: AppHandle, paths: Vec<String>) -> Result<String, String> {
+    let valid_paths: Vec<String> = paths
+        .into_iter()
+        .filter(|p| {
+            let exists = std::path::Path::new(p).exists();
+            if !exists {
+                add_log(format!(
+                    "⚠️ Ignoring non-existent path for new window: {}",
+                    p
+                ));
+            }
+            exists
+        })
+        .collect();
+
+    let app_clone = app.clone();
+    run_on_main_thread_result(&app, move || spawn_new_window(&app_clone, valid_paths)).await?
+}
+
+// Open already-stored files (by IndexedDB id) in a fresh window. Used by the
+// "Open in new window" action on the My Files page. The ids are queued under
+// the new window's label; the new window pops them on mount and loads them from
+// the shared store into its workspace.
+#[tauri::command]
+pub async fn open_files_in_new_window(
+    app: AppHandle,
+    file_ids: Vec<String>,
+) -> Result<String, String> {
+    let label = next_window_label();
+    let app_clone = app.clone();
+    run_on_main_thread_result(&app, move || {
+        build_window(&app_clone, &label, "/").map(|window| {
+            let count = file_ids.len();
+            // Queue the ids only after the window is created, so a failed build
+            // doesn't leave orphaned ids under a label no window will consume.
+            queue_file_ids(&label, file_ids);
+            add_log(format!(
+                "🪟 Spawned new window '{}' for {} stored file(s)",
+                label, count
+            ));
+            // The new window also pops on mount; this emit is a nudge in case it
+            // mounted before the ids were queued.
+            let _ = window.emit_to(label.as_str(), "window-files-ready", ());
+            label.clone()
+        })
+    })
+    .await?
+}
+
+// Pop (return and clear) the stored-file ids queued for the calling window.
+#[tauri::command]
+pub async fn pop_window_file_ids(window: WebviewWindow) -> Result<Vec<String>, String> {
+    let label = window.label().to_string();
+    let ids = {
+        let mut guard = PENDING_FILE_IDS.lock().unwrap();
+        guard
+            .as_mut()
+            .and_then(|map| map.remove(&label))
+            .unwrap_or_default()
+    };
+    if !ids.is_empty() {
+        add_log(format!(
+            "📂 Returning {} stored file id(s) for window '{}'",
+            ids.len(),
+            label
+        ));
+    }
+    Ok(ids)
+}
+
+// Pick the best existing window to receive an opened file: the focused one,
+// else the main window, else any open window. Returns None only if there are
+// no windows at all. Used so file-opens (file association, "open with") land in
+// the window the user is actually looking at, and still work if the original
+// "main" window has been closed.
+pub fn target_window_label(app: &AppHandle) -> Option<String> {
+    let windows = app.webview_windows();
+    if let Some((label, _)) = windows
+        .iter()
+        .find(|(_, w)| w.is_focused().unwrap_or(false))
+    {
+        return Some(label.clone());
+    }
+    if windows.contains_key(MAIN_WINDOW_LABEL) {
+        return Some(MAIN_WINDOW_LABEL.to_string());
+    }
+    windows.keys().next().cloned()
+}
+
+// Add files to the shared queue and notify a specific window to consume them.
+// Used by drag-drop, the macOS open event, and the second-instance callback
+// (when --new-window is NOT set). The emit is targeted at `label` so only that
+// window pops the queue - other windows ignore it and keep their own files.
+pub fn forward_files_to_window(app: &AppHandle, label: &str, paths: Vec<String>) {
+    for path in &paths {
+        add_opened_file(path.clone());
+    }
+    if let Some(window) = app.get_webview_window(label) {
+        let _ = app.emit_to(label, "files-changed", ());
+        let _ = window.set_focus();
+        let _ = window.unminimize();
+    } else {
+        // Target window is gone; let any window pick the files up.
+        let _ = app.emit("files-changed", ());
+    }
+}