eframe: ask if the window is minimized or maximized (#2672)

* eframe: ask if the window is minimized or maximized

* Improve note

crates/eframe/src/epi.rs

@@ -841,6 +841,12 @@ pub struct WindowInfo {
     /// Are we in fullscreen mode?
     pub fullscreen: bool,
 
+    /// Are we minimized?
+    pub minimized: bool,
+
+    /// Are we maximized?
+    pub maximized: bool,
+
     /// Window inner size in egui points (logical pixels).
     pub size: egui::Vec2,
 

crates/eframe/src/native/epi_integration.rs

@@ -12,6 +12,14 @@ use egui_winit::{native_pixels_per_point, EventResponse, WindowSettings};
 
 use crate::{epi, Theme, WindowInfo};
 
+#[derive(Default)]
+pub struct WindowState {
+    // We cannot simply call `winit::Window::is_minimized/is_maximized`
+    // because that deadlocks on mac.
+    pub minimized: bool,
+    pub maximized: bool,
+}
+
 pub fn points_to_size(points: egui::Vec2) -> winit::dpi::LogicalSize<f64> {
     winit::dpi::LogicalSize {
         width: points.x as f64,
@@ -19,7 +27,11 @@ pub fn points_to_size(points: egui::Vec2) -> winit::dpi::LogicalSize<f64> {
     }
 }
 
-pub fn read_window_info(window: &winit::window::Window, pixels_per_point: f32) -> WindowInfo {
+pub fn read_window_info(
+    window: &winit::window::Window,
+    pixels_per_point: f32,
+    window_state: &WindowState,
+) -> WindowInfo {
     let position = window
         .outer_position()
         .ok()
@@ -38,9 +50,13 @@ pub fn read_window_info(window: &winit::window::Window, pixels_per_point: f32) -
         .inner_size()
         .to_logical::<f32>(pixels_per_point.into());
 
+    // NOTE: calling window.is_minimized() or window.is_maximized() deadlocks on Mac.
+
     WindowInfo {
         position,
         fullscreen: window.fullscreen().is_some(),
+        minimized: window_state.minimized,
+        maximized: window_state.maximized,
         size: egui::Vec2 {
             x: size.width,
             y: size.height,
@@ -198,6 +214,7 @@ pub fn handle_app_output(
     window: &winit::window::Window,
     current_pixels_per_point: f32,
     app_output: epi::backend::AppOutput,
+    window_state: &mut WindowState,
 ) {
     let epi::backend::AppOutput {
         close: _,
@@ -257,10 +274,12 @@ pub fn handle_app_output(
 
     if let Some(minimized) = minimized {
         window.set_minimized(minimized);
+        window_state.minimized = minimized;
     }
 
     if let Some(maximized) = maximized {
         window.set_maximized(maximized);
+        window_state.maximized = maximized;
     }
 }
 
@@ -287,6 +306,7 @@ pub struct EpiIntegration {
     /// When set, it is time to close the native window.
     close: bool,
     can_drag_window: bool,
+    window_state: WindowState,
 }
 
 impl EpiIntegration {
@@ -306,12 +326,17 @@ impl EpiIntegration {
 
         let native_pixels_per_point = window.scale_factor() as f32;
 
+        let window_state = WindowState {
+            minimized: window.is_minimized().unwrap_or(false),
+            maximized: window.is_maximized(),
+        };
+
         let frame = epi::Frame {
             info: epi::IntegrationInfo {
                 system_theme,
                 cpu_usage: None,
                 native_pixels_per_point: Some(native_pixels_per_point),
-                window_info: read_window_info(window, egui_ctx.pixels_per_point()),
+                window_info: read_window_info(window, egui_ctx.pixels_per_point(), &window_state),
             },
             output: epi::backend::AppOutput {
                 visible: Some(true),
@@ -336,6 +361,7 @@ impl EpiIntegration {
             pending_full_output: Default::default(),
             close: false,
             can_drag_window: false,
+            window_state,
         }
     }
 
@@ -417,12 +443,16 @@ impl EpiIntegration {
     ) -> egui::FullOutput {
         let frame_start = std::time::Instant::now();
 
-        self.frame.info.window_info = read_window_info(window, self.egui_ctx.pixels_per_point());
+        self.frame.info.window_info =
+            read_window_info(window, self.egui_ctx.pixels_per_point(), &self.window_state);
         let raw_input = self.egui_winit.take_egui_input(window);
+
+        // Run user code:
         let full_output = self.egui_ctx.run(raw_input, |egui_ctx| {
             crate::profile_scope!("App::update");
             app.update(egui_ctx, &mut self.frame);
         });
+
         self.pending_full_output.append(full_output);
         let full_output = std::mem::take(&mut self.pending_full_output);
 
@@ -435,7 +465,12 @@ impl EpiIntegration {
                 tracing::debug!("App::on_close_event returned {}", self.close);
             }
             self.frame.output.visible = app_output.visible; // this is handled by post_present
-            handle_app_output(window, self.egui_ctx.pixels_per_point(), app_output);
+            handle_app_output(
+                window,
+                self.egui_ctx.pixels_per_point(),
+                app_output,
+                &mut self.window_state,
+            );
         }
 
         let frame_time = frame_start.elapsed().as_secs_f64() as f32;

examples/custom_window_frame/src/main.rs

@@ -22,9 +22,7 @@ fn main() -> Result<(), eframe::Error> {
 }
 
 #[derive(Default)]
-struct MyApp {
-    maximized: bool,
-}
+struct MyApp {}
 
 impl eframe::App for MyApp {
     fn clear_color(&self, _visuals: &egui::Visuals) -> [f32; 4] {
@@ -32,7 +30,7 @@ impl eframe::App for MyApp {
     }
 
     fn update(&mut self, ctx: &egui::Context, frame: &mut eframe::Frame) {
-        custom_window_frame(self, ctx, frame, "egui with custom frame", |ui| {
+        custom_window_frame(ctx, frame, "egui with custom frame", |ui| {
             ui.label("This is just the contents of the window");
             ui.horizontal(|ui| {
                 ui.label("egui theme:");
@@ -43,7 +41,6 @@ impl eframe::App for MyApp {
 }
 
 fn custom_window_frame(
-    app: &mut MyApp,
     ctx: &egui::Context,
     frame: &mut eframe::Frame,
     title: &str,
@@ -55,6 +52,8 @@ fn custom_window_frame(
     // Height of the title bar
     let height = 28.0;
 
+    let button_height = 16.0;
+
     CentralPanel::default()
         .frame(Frame::none())
         .show(ctx, |ui| {
@@ -97,46 +96,47 @@ fn custom_window_frame(
                 ui.interact(title_bar_rect, Id::new("title_bar"), Sense::click());
 
             if title_bar_response.double_clicked() {
-                app.maximized = !app.maximized;
-                frame.set_maximized(app.maximized);
+                frame.set_maximized(!frame.info().window_info.maximized);
             } else if title_bar_response.is_pointer_button_down_on() {
                 frame.drag_window();
             }
 
-            // Add the close button:
-            let close_response = ui.put(
-                Rect::from_min_size(rect.left_top(), Vec2::splat(height)),
-                Button::new(RichText::new("❌").size(height - 4.0)).frame(false),
-            );
-            if close_response.clicked() {
-                frame.close();
-            }
-
-            let minimized_response = ui.put(
-                Rect::from_min_size(
-                    rect.left_top() + vec2((height - 4.0) * 1.0, 0.0),
-                    Vec2::splat(height),
-                ),
-                Button::new(RichText::new("🗕").size(height - 4.0)).frame(false),
-            );
-            if minimized_response.clicked() {
-                frame.set_minimized(true);
-            }
-
-            let maximized_response = ui.put(
-                Rect::from_min_size(
-                    rect.left_top() + vec2((height - 4.0) * 2.0, 0.0),
-                    Vec2::splat(height),
-                ),
-                Button::new(
-                    RichText::new(if app.maximized { "🗗" } else { "🗖" }).size(height - 4.0),
-                )
-                .frame(false),
-            );
-            if maximized_response.clicked() {
-                app.maximized = !app.maximized;
-                frame.set_maximized(app.maximized);
-            }
+            ui.allocate_ui_at_rect(title_bar_rect, |ui| {
+                ui.horizontal_centered(|ui| {
+                    ui.spacing_mut().item_spacing.x = 0.0;
+                    ui.visuals_mut().button_frame = false;
+
+                    let close_response = ui
+                        .add(Button::new(RichText::new("❌").size(button_height)))
+                        .on_hover_text("Close the window");
+                    if close_response.clicked() {
+                        frame.close();
+                    }
+
+                    let minimized_response = ui
+                        .add(Button::new(RichText::new("🗕").size(button_height)))
+                        .on_hover_text("Minimize the window");
+                    if minimized_response.clicked() {
+                        frame.set_minimized(true);
+                    }
+
+                    if frame.info().window_info.maximized {
+                        let maximized_response = ui
+                            .add(Button::new(RichText::new("🗖").size(button_height)))
+                            .on_hover_text("Restore window");
+                        if maximized_response.clicked() {
+                            frame.set_maximized(false);
+                        }
+                    } else {
+                        let maximized_response = ui
+                            .add(Button::new(RichText::new("🗗").size(button_height)))
+                            .on_hover_text("Maximize window");
+                        if maximized_response.clicked() {
+                            frame.set_maximized(true);
+                        }
+                    }
+                });
+            });
 
             // Add the contents:
             let content_rect = {