feat: add macos simple fullscreen (#692)

* feat: add macos simple fullscreen

* move impl to WindowExt

* feedback: remove warning, unused file and rename param

* feedback: combine fullscreen examples into one example

* fix: ensure decorations and maximize do not toggle while in fullscreen

* fix: prevent warning on non-macos platforms

* feedback: make changelog more explicit

* fix: prevent unconditional construction of NSRect

* fix: don't try to set_simple_fullscreen if already using native fullscreen

* fix: ensure set_simple_fullscreen plays nicely with set_fullscreen

* fix: do not enter native fullscreen if simple fullscreen is active

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 - On X11 with a tiling WM, fixed high CPU usage when moving windows across monitors.
 - On X11, fixed panic caused by dropping the window before running the event loop.
+- on macOS, added `WindowExt::set_simple_fullscreen` which does not require a separate space
 - Introduce `WindowBuilderExt::with_app_id` to allow setting the application ID on Wayland.
 - On Windows, catch panics in event loop child thread and forward them to the parent thread. This prevents an invocation of undefined behavior due to unwinding into foreign code.
 - On Windows, fix issue where resizing or moving window combined with grabbing the cursor would freeze program.

examples/fullscreen.rs

@@ -6,35 +6,46 @@ use winit::{ControlFlow, Event, WindowEvent};
 fn main() {
     let mut events_loop = winit::EventsLoop::new();
 
-    // enumerating monitors
+    #[cfg(target_os = "macos")]
+    let mut macos_use_simple_fullscreen = false;
+
     let monitor = {
-        for (num, monitor) in events_loop.get_available_monitors().enumerate() {
-            println!("Monitor #{}: {:?}", num, monitor.get_name());
+        // On macOS there are two fullscreen modes "native" and "simple"
+        #[cfg(target_os = "macos")]
+        {
+            print!("Please choose the fullscreen mode: (1) native, (2) simple: ");
+            io::stdout().flush().unwrap();
+
+            let mut num = String::new();
+            io::stdin().read_line(&mut num).unwrap();
+            let num = num.trim().parse().ok().expect("Please enter a number");
+            match num {
+                2 => macos_use_simple_fullscreen = true,
+                _ => {}
+            }
+
+            // Prompt for monitor when using native fullscreen
+            if !macos_use_simple_fullscreen {
+                Some(prompt_for_monitor(&events_loop))
+            } else {
+                None
+            }
         }
 
-        print!("Please write the number of the monitor to use: ");
-        io::stdout().flush().unwrap();
-
-        let mut num = String::new();
-        io::stdin().read_line(&mut num).unwrap();
-        let num = num.trim().parse().ok().expect("Please enter a number");
-        let monitor = events_loop.get_available_monitors().nth(num).expect("Please enter a valid ID");
-
-        println!("Using {:?}", monitor.get_name());
-
-        monitor
+        #[cfg(not(target_os = "macos"))]
+        Some(prompt_for_monitor(&events_loop))
     };
 
+    let mut is_fullscreen = monitor.is_some();
+    let mut is_maximized = false;
+    let mut decorations = true;
+
     let window = winit::WindowBuilder::new()
         .with_title("Hello world!")
-        .with_fullscreen(Some(monitor))
+        .with_fullscreen(monitor)
         .build(&events_loop)
         .unwrap();
 
-    let mut is_fullscreen = true;
-    let mut is_maximized = false;
-    let mut decorations = true;
-
     events_loop.run_forever(|event| {
         println!("{:?}", event);
 
@@ -52,6 +63,18 @@ fn main() {
                 } => match (virtual_code, state) {
                     (winit::VirtualKeyCode::Escape, _) => return ControlFlow::Break,
                     (winit::VirtualKeyCode::F, winit::ElementState::Pressed) => {
+                        #[cfg(target_os = "macos")]
+                        {
+                            if macos_use_simple_fullscreen {
+                                use winit::os::macos::WindowExt;
+                                if WindowExt::set_simple_fullscreen(&window, !is_fullscreen) {
+                                    is_fullscreen = !is_fullscreen;
+                                }
+
+                                return ControlFlow::Continue;
+                            }
+                        }
+
                         is_fullscreen = !is_fullscreen;
                         if !is_fullscreen {
                             window.set_fullscreen(None);
@@ -77,3 +100,22 @@ fn main() {
         ControlFlow::Continue
     });
 }
+
+// Enumerate monitors and prompt user to choose one
+fn prompt_for_monitor(events_loop: &winit::EventsLoop) -> winit::MonitorId {
+    for (num, monitor) in events_loop.get_available_monitors().enumerate() {
+        println!("Monitor #{}: {:?}", num, monitor.get_name());
+    }
+
+    print!("Please write the number of the monitor to use: ");
+    io::stdout().flush().unwrap();
+
+    let mut num = String::new();
+    io::stdin().read_line(&mut num).unwrap();
+    let num = num.trim().parse().ok().expect("Please enter a number");
+    let monitor = events_loop.get_available_monitors().nth(num).expect("Please enter a valid ID");
+
+    println!("Using {:?}", monitor.get_name());
+
+    monitor
+}

src/os/macos.rs

@@ -22,6 +22,15 @@ pub trait WindowExt {
     /// - `false`: the dock icon will only bounce once.
     /// - `true`: the dock icon will bounce until the application is focused.
     fn request_user_attention(&self, is_critical: bool);
+
+    /// Toggles a fullscreen mode that doesn't require a new macOS space.
+    /// Returns a boolean indicating whether the transition was successful (this
+    /// won't work if the window was already in the native fullscreen).
+    ///
+    /// This is how fullscreen used to work on macOS in versions before Lion.
+    /// And allows the user to have a fullscreen window without using another
+    /// space or taking control over the entire monitor.
+    fn set_simple_fullscreen(&self, fullscreen: bool) -> bool;
 }
 
 impl WindowExt for Window {
@@ -39,6 +48,11 @@ impl WindowExt for Window {
     fn request_user_attention(&self, is_critical: bool) {
         self.window.request_user_attention(is_critical)
     }
+
+    #[inline]
+    fn set_simple_fullscreen(&self, fullscreen: bool) -> bool {
+        self.window.set_simple_fullscreen(fullscreen)
+    }
 }
 
 /// Corresponds to `NSApplicationActivationPolicy`.

src/platform/macos/util.rs

@@ -25,6 +25,20 @@ pub unsafe fn set_style_mask(window: id, view: id, mask: NSWindowStyleMask) {
     window.makeFirstResponder_(view);
 }
 
+pub unsafe fn toggle_style_mask(window: id, view: id, mask: NSWindowStyleMask, on: bool) {
+    use cocoa::appkit::NSWindow;
+
+    let current_style_mask = window.styleMask();
+    if on {
+        window.setStyleMask_(current_style_mask | mask);
+    } else {
+        window.setStyleMask_(current_style_mask & (!mask));
+    }
+
+    // If we don't do this, key handling will break. Therefore, never call `setStyleMask` directly!
+    window.makeFirstResponder_(view);
+}
+
 pub unsafe fn create_input_context(view: id) -> IdRef {
     let input_context: id = msg_send![class!(NSTextInputContext), alloc];
     let input_context: id = msg_send![input_context, initWithClient:view];

src/platform/macos/window.rs

@@ -19,6 +19,7 @@ use cocoa::appkit::{
     NSWindowButton,
     NSWindowStyleMask,
     NSApplicationActivationPolicy,
+    NSApplicationPresentationOptions,
 };
 use cocoa::base::{id, nil};
 use cocoa::foundation::{NSAutoreleasePool, NSDictionary, NSPoint, NSRect, NSSize, NSString};
@@ -57,7 +58,9 @@ pub struct DelegateState {
 
     win_attribs: RefCell<WindowAttributes>,
     standard_frame: Cell<Option<NSRect>>,
+    is_simple_fullscreen: Cell<bool>,
     save_style_mask: Cell<Option<NSWindowStyleMask>>,
+    save_presentation_opts: Cell<Option<NSApplicationPresentationOptions>>,
 
     // This is set when WindowBuilder::with_fullscreen was set,
     // see comments of `window_did_fail_to_enter_fullscreen`
@@ -94,22 +97,30 @@ impl DelegateState {
         }
     }
 
+    unsafe fn saved_style_mask(&self, resizable: bool) -> NSWindowStyleMask {
+        let base_mask = self.save_style_mask
+            .take()
+            .unwrap_or_else(|| self.window.styleMask());
+        if resizable {
+            base_mask | NSWindowStyleMask::NSResizableWindowMask
+        } else {
+            base_mask & !NSWindowStyleMask::NSResizableWindowMask
+        }
+    }
+
+    fn saved_standard_frame(&self) -> NSRect {
+        self.standard_frame.get().unwrap_or_else(|| NSRect::new(
+            NSPoint::new(50.0, 50.0),
+            NSSize::new(800.0, 600.0),
+        ))
+    }
+
     fn restore_state_from_fullscreen(&mut self) {
         let maximized = unsafe {
             let mut win_attribs = self.win_attribs.borrow_mut();
             win_attribs.fullscreen = None;
 
-            let mask = {
-                let base_mask = self.save_style_mask
-                    .take()
-                    .unwrap_or_else(|| self.window.styleMask());
-                if win_attribs.resizable {
-                    base_mask | NSWindowStyleMask::NSResizableWindowMask
-                } else {
-                    base_mask & !NSWindowStyleMask::NSResizableWindowMask
-                }
-            };
-
+            let mask = self.saved_style_mask(win_attribs.resizable);
             util::set_style_mask(*self.window, *self.view, mask);
 
             win_attribs.maximized
@@ -151,10 +162,7 @@ impl DelegateState {
                     let screen = NSScreen::mainScreen(nil);
                     NSScreen::visibleFrame(screen)
                 } else {
-                    self.standard_frame.get().unwrap_or(NSRect::new(
-                        NSPoint::new(50.0, 50.0),
-                        NSSize::new(800.0, 600.0),
-                    ))
+                    self.saved_standard_frame()
                 };
 
                 self.window.setFrame_display_(new_rect, 0);
@@ -600,6 +608,68 @@ impl WindowExt for Window2 {
             NSApp().requestUserAttention_(request_type);
         }
     }
+
+    #[inline]
+    fn set_simple_fullscreen(&self, fullscreen: bool) -> bool {
+        let state = &self.delegate.state;
+
+        unsafe {
+            let app = NSApp();
+            let win_attribs = state.win_attribs.borrow_mut();
+            let is_native_fullscreen = win_attribs.fullscreen.is_some();
+            let is_simple_fullscreen = state.is_simple_fullscreen.get();
+
+            // Do nothing if native fullscreen is active.
+            if is_native_fullscreen || (fullscreen && is_simple_fullscreen) || (!fullscreen && !is_simple_fullscreen) {
+                return false;
+            }
+
+            if fullscreen {
+                // Remember the original window's settings
+                state.standard_frame.set(Some(NSWindow::frame(*self.window)));
+                state.save_style_mask.set(Some(self.window.styleMask()));
+                state.save_presentation_opts.set(Some(app.presentationOptions_()));
+
+                // Tell our window's state that we're in fullscreen
+                state.is_simple_fullscreen.set(true);
+
+                // Simulate pre-Lion fullscreen by hiding the dock and menu bar
+                let presentation_options =
+                    NSApplicationPresentationOptions::NSApplicationPresentationAutoHideDock |
+                    NSApplicationPresentationOptions::NSApplicationPresentationAutoHideMenuBar;
+                app.setPresentationOptions_(presentation_options);
+
+                // Hide the titlebar
+                util::toggle_style_mask(*self.window, *self.view, NSWindowStyleMask::NSTitledWindowMask, false);
+
+                // Set the window frame to the screen frame size
+                let screen = self.window.screen();
+                let screen_frame = NSScreen::frame(screen);
+                NSWindow::setFrame_display_(*self.window, screen_frame, YES);
+
+                // Fullscreen windows can't be resized, minimized, or moved
+                util::toggle_style_mask(*self.window, *self.view, NSWindowStyleMask::NSMiniaturizableWindowMask, false);
+                util::toggle_style_mask(*self.window, *self.view, NSWindowStyleMask::NSResizableWindowMask, false);
+                NSWindow::setMovable_(*self.window, NO);
+
+                true
+            } else {
+                let saved_style_mask = state.saved_style_mask(win_attribs.resizable);
+                util::set_style_mask(*self.window, *self.view, saved_style_mask);
+                state.is_simple_fullscreen.set(false);
+
+                if let Some(presentation_opts) = state.save_presentation_opts.get() {
+                    app.setPresentationOptions_(presentation_opts);
+                }
+
+                let frame = state.saved_standard_frame();
+                NSWindow::setFrame_display_(*self.window, frame, YES);
+                NSWindow::setMovable_(*self.window, YES);
+
+                true
+            }
+        }
+    }
 }
 
 impl Window2 {
@@ -675,7 +745,9 @@ impl Window2 {
             shared,
             win_attribs: RefCell::new(win_attribs.clone()),
             standard_frame: Cell::new(None),
+            is_simple_fullscreen: Cell::new(false),
             save_style_mask: Cell::new(None),
+            save_presentation_opts: Cell::new(None),
             handle_with_fullscreen: win_attribs.fullscreen.is_some(),
             previous_position: None,
             previous_dpi_factor: dpi_factor,
@@ -1086,6 +1158,12 @@ impl Window2 {
     /// in fullscreen mode
     pub fn set_fullscreen(&self, monitor: Option<RootMonitorId>) {
         let state = &self.delegate.state;
+
+        // Do nothing if simple fullscreen is active.
+        if state.is_simple_fullscreen.get() {
+            return
+        }
+
         let current = {
             let win_attribs = state.win_attribs.borrow_mut();