feat: add Window::is_always_on_top method

.changes/is-always-on-top.md

@@ -0,0 +1,5 @@
+---
+"tao": patch
+---
+
+Add `Window::is_always_on_top` method to check if a window is always on top on macOS, Linux and Windows.

src/platform_impl/android/mod.rs

@@ -569,6 +569,11 @@ impl Window {
     false
   }
 
+  pub fn is_always_on_top(&self) -> bool {
+    log::warn!("`Window::is_always_on_top` is ignored on Android");
+    false
+  }
+
   pub fn set_resizable(&self, _resizeable: bool) {
     warn!("`Window::set_resizable` is ignored on Android")
   }

src/platform_impl/ios/window.rs

@@ -77,6 +77,11 @@ impl Inner {
     false
   }
 
+  pub fn is_always_on_top(&self) -> bool {
+    log::warn!("`Window::is_always_on_top` is ignored on iOS");
+    false
+  }
+
   pub fn request_redraw(&self) {
     unsafe {
       if self.gl_or_metal_backed {

src/platform_impl/linux/window.rs

@@ -60,6 +60,7 @@ pub struct Window {
   position: Rc<(AtomicI32, AtomicI32)>,
   size: Rc<(AtomicI32, AtomicI32)>,
   maximized: Rc<AtomicBool>,
+  is_always_on_top: Rc<AtomicBool>,
   minimized: Rc<AtomicBool>,
   fullscreen: RefCell<Option<Fullscreen>>,
   inner_size_constraints: RefCell<WindowSizeConstraints>,
@@ -258,11 +259,14 @@ impl Window {
     let max_clone = maximized.clone();
     let minimized = Rc::new(AtomicBool::new(false));
     let minimized_clone = minimized.clone();
+    let is_always_on_top = Rc::new(AtomicBool::new(attributes.always_on_top));
+    let is_always_on_top_clone = is_always_on_top.clone();
 
     window.connect_window_state_event(move |_, event| {
       let state = event.new_window_state();
       max_clone.store(state.contains(WindowState::MAXIMIZED), Ordering::Release);
       minimized_clone.store(state.contains(WindowState::ICONIFIED), Ordering::Release);
+      is_always_on_top_clone.store(state.contains(WindowState::ABOVE), Ordering::Release);
       glib::Propagation::Proceed
     });
 
@@ -304,6 +308,7 @@ impl Window {
       size,
       maximized,
       minimized,
+      is_always_on_top,
       fullscreen: RefCell::new(attributes.fullscreen),
       inner_size_constraints: RefCell::new(attributes.inner_size_constraints),
       preferred_theme: RefCell::new(preferred_theme),
@@ -354,11 +359,14 @@ impl Window {
     let max_clone = maximized.clone();
     let minimized = Rc::new(AtomicBool::new(false));
     let minimized_clone = minimized.clone();
+    let is_always_on_top = Rc::new(AtomicBool::new(false));
+    let is_always_on_top_clone = is_always_on_top.clone();
 
     window.connect_window_state_event(move |_, event| {
       let state = event.new_window_state();
       max_clone.store(state.contains(WindowState::MAXIMIZED), Ordering::Release);
       minimized_clone.store(state.contains(WindowState::ICONIFIED), Ordering::Release);
+      is_always_on_top_clone.store(state.contains(WindowState::ABOVE), Ordering::Release);
       glib::Propagation::Proceed
     });
 
@@ -383,6 +391,7 @@ impl Window {
       size,
       maximized,
       minimized,
+      is_always_on_top,
       fullscreen: RefCell::new(None),
       inner_size_constraints: RefCell::new(WindowSizeConstraints::default()),
       preferred_theme: RefCell::new(None),
@@ -577,6 +586,10 @@ impl Window {
     }
   }
 
+  pub fn is_always_on_top(&self) -> bool {
+    self.is_always_on_top.load(Ordering::Acquire)
+  }
+
   pub fn is_maximized(&self) -> bool {
     self.maximized.load(Ordering::Acquire)
   }

src/platform_impl/macos/window.rs

@@ -990,6 +990,11 @@ impl UnownedWindow {
     is_visible == YES
   }
 
+  #[inline]
+  pub fn is_always_on_top(&self) -> bool {
+    unsafe { self.ns_window.level() == ffi::kCGFloatingWindowLevelKey }
+  }
+
   #[inline]
   pub fn is_maximized(&self) -> bool {
     self.is_zoomed()

src/platform_impl/windows/window.rs

@@ -583,6 +583,14 @@ impl Window {
     window_state.window_flags.contains(WindowFlags::MAXIMIZED)
   }
 
+  #[inline]
+  pub fn is_always_on_top(&self) -> bool {
+    let window_state = self.window_state.lock();
+    window_state
+      .window_flags
+      .contains(WindowFlags::ALWAYS_ON_TOP)
+  }
+
   #[inline]
   pub fn is_minimized(&self) -> bool {
     unsafe { IsIconic(self.hwnd()) }.as_bool()

src/window.rs

@@ -809,6 +809,16 @@ impl Window {
     self.window.is_focused()
   }
 
+  /// Indicates whether the window is always on top of other windows.
+  ///
+  /// ## Platform-specific
+  ///
+  /// - **iOS / Android:** Unsupported.
+  #[inline]
+  pub fn is_always_on_top(&self) -> bool {
+    self.window.is_always_on_top()
+  }
+
   /// Sets whether the window is resizable or not.
   ///
   /// Note that making the window unresizable doesn't exempt you from handling `Resized`, as that event can still be