Windows: the Coucou window opens and closes with Windows' own motion

windows/src-tauri/src/hub_motion.rs

@@ -0,0 +1,116 @@
+// The Coucou window opens and closes with Windows 11's own motion:
+// it rises out of its taskbar button and folds back down into it, the system's
+// minimise / restore animation. Nothing is drawn by the page, and Windows' own
+// "Animation effects" setting turns it off like for any other window.
+//
+// Closing still ends with the window hidden, as before: minimised first, so
+// the fold plays, then hidden once it has, which takes the button off the
+// taskbar. Opening reverses it: shown minimised, which puts the button back,
+// then restored from there. Elsewhere (Linux), plain hide and show.
+
+use tauri::WebviewWindow;
+
+/// Shows the window, focused.
+pub fn open(win: &WebviewWindow) {
+    #[cfg(windows)]
+    if native::open(win) {
+        return;
+    }
+    let _ = win.unminimize();
+    let _ = win.show();
+    let _ = win.set_focus();
+}
+
+/// Hides the window.
+pub fn close(win: &WebviewWindow) {
+    #[cfg(windows)]
+    if native::close(win) {
+        return;
+    }
+    let _ = win.hide();
+}
+
+#[cfg(windows)]
+mod native {
+    use std::sync::atomic::{AtomicU64, Ordering};
+    use std::time::Duration;
+
+    use tauri::WebviewWindow;
+    use windows::Win32::Foundation::HWND;
+    use windows::Win32::UI::WindowsAndMessaging::{
+        IsIconic, IsWindowVisible, ShowWindow, SW_HIDE, SW_MINIMIZE, SW_RESTORE, SW_SHOWMINNOACTIVE,
+    };
+
+    /// Lets the taskbar add the button before the window rises from it: restored
+    /// at once, Windows has no button to start the motion from.
+    const BUTTON_MS: u64 = 60;
+    /// Past the fold (about 250 ms on Windows 11) before the window is hidden.
+    const FOLD_MS: u64 = 400;
+
+    /// Bumped by every open and close: a hide still waiting for its fold to end
+    /// is dropped when the window was opened again in the meantime.
+    static MOTION: AtomicU64 = AtomicU64::new(0);
+
+    fn raw_hwnd(win: &WebviewWindow) -> Option<isize> {
+        let raw = win.hwnd().ok()?.0 as isize;
+        (raw != 0).then_some(raw)
+    }
+
+    fn hwnd(raw: isize) -> HWND {
+        HWND(raw as *mut _)
+    }
+
+    pub fn open(win: &WebviewWindow) -> bool {
+        let Some(raw) = raw_hwnd(win) else { return false };
+        let motion = MOTION.fetch_add(1, Ordering::SeqCst) + 1;
+        let hidden = unsafe { !IsWindowVisible(hwnd(raw)).as_bool() };
+        if !hidden && unsafe { !IsIconic(hwnd(raw)).as_bool() } {
+            let _ = win.set_focus();
+            return true;
+        }
+        if hidden {
+            // Back on the taskbar, folded: the button the window rises from.
+            unsafe {
+                let _ = ShowWindow(hwnd(raw), SW_SHOWMINNOACTIVE);
+            }
+        }
+        let win = win.clone();
+        std::thread::spawn(move || {
+            std::thread::sleep(Duration::from_millis(if hidden { BUTTON_MS } else { 0 }));
+            let this = win.clone();
+            let _ = win.run_on_main_thread(move || {
+                if MOTION.load(Ordering::SeqCst) != motion {
+                    return;
+                }
+                unsafe {
+                    let _ = ShowWindow(hwnd(raw), SW_RESTORE);
+                }
+                let _ = this.set_focus();
+            });
+        });
+        true
+    }
+
+    pub fn close(win: &WebviewWindow) -> bool {
+        let Some(raw) = raw_hwnd(win) else { return false };
+        let motion = MOTION.fetch_add(1, Ordering::SeqCst) + 1;
+        unsafe {
+            let _ = ShowWindow(hwnd(raw), SW_MINIMIZE);
+        }
+        let win = win.clone();
+        std::thread::spawn(move || {
+            std::thread::sleep(Duration::from_millis(FOLD_MS));
+            let _ = win.run_on_main_thread(move || {
+                if MOTION.load(Ordering::SeqCst) != motion {
+                    return;
+                }
+                unsafe {
+                    if IsIconic(hwnd(raw)).as_bool() {
+                        let _ = ShowWindow(hwnd(raw), SW_HIDE);
+                    }
+                }
+            });
+        });
+        true
+    }
+}

windows/src-tauri/src/lib.rs

@@ -11,6 +11,7 @@ mod files;
 mod flow;
 mod github;
 mod hooks;
+mod hub_motion;
 mod i18n;
 mod identity;
 mod integrations;
@@ -709,7 +710,7 @@ fn create_settings_window(app: &AppHandle) {
                 // Closing it must only hide it, or it could never be reopened.
                 tauri::WindowEvent::CloseRequested { api, .. } => {
                     api.prevent_close();
-                    let _ = this.hide();
+                    hub_motion::close(&this);
                     set_hub_shown(&this, false);
                 }
                 // Minimised (a 0×0 resize on Windows) or back from it.
@@ -756,9 +757,7 @@ pub fn show_hub(app: &AppHandle, page: Option<&str>) {
     if let Some(page) = page {
         let _ = win.emit("hub-page", page.to_string());
     }
-    let _ = win.unminimize();
-    let _ = win.show();
-    let _ = win.set_focus();
+    hub_motion::open(&win);
     set_hub_shown(&win, true);
 }