feat(winit): client-side resize drag support

src/window/settings.rs

@@ -8,6 +8,9 @@ pub struct Settings {
     /// The initial size of the window.
     pub size: (u32, u32),
 
+    /// The border area for the drag resize handle.
+    pub resize_border: u32,
+
     /// The initial position of the window.
     pub position: Position,
 
@@ -43,6 +46,7 @@ impl Default for Settings {
     fn default() -> Settings {
         Settings {
             size: (1024, 768),
+            resize_border: 8,
             position: Position::default(),
             min_size: None,
             max_size: None,
@@ -61,6 +65,7 @@ impl From<Settings> for iced_winit::settings::Window {
     fn from(settings: Settings) -> Self {
         Self {
             size: settings.size,
+            resize_border: settings.resize_border,
             position: iced_winit::Position::from(settings.position),
             min_size: settings.min_size,
             max_size: settings.max_size,

winit/src/application.rs

@@ -1,4 +1,5 @@
 //! Create interactive, native cross-platform applications.
+mod drag_resize;
 #[cfg(feature = "trace")]
 mod profiler;
 mod state;
@@ -125,6 +126,8 @@ where
     let mut debug = Debug::new();
     debug.startup_started();
 
+    let resize_border = settings.window.resize_border;
+
     #[cfg(feature = "trace")]
     let _ = info_span!("Application", "RUN").entered();
 
@@ -212,6 +215,7 @@ where
             window,
             should_be_visible,
             settings.exit_on_close_request,
+            resize_border,
         );
 
         #[cfg(feature = "trace")]
@@ -279,6 +283,7 @@ async fn run_instance<A, E, C>(
     window: winit::window::Window,
     should_be_visible: bool,
     exit_on_close_request: bool,
+    resize_border: u32,
 ) where
     A: Application + 'static,
     E: Executor + 'static,
@@ -331,6 +336,12 @@ async fn run_instance<A, E, C>(
         &mut debug,
     ));
 
+    // Creates closure for handling the window drag resize state with winit.
+    let mut drag_resize_window_func = drag_resize::event_func(
+        &window,
+        resize_border as f64 * window.scale_factor(),
+    );
+
     let mut mouse_interaction = mouse::Interaction::default();
     let mut events = Vec::new();
     let mut messages = Vec::new();
@@ -562,6 +573,13 @@ async fn run_instance<A, E, C>(
                 event: window_event,
                 ..
             } => {
+                // Initiates a drag resize window state when found.
+                if let Some(func) = drag_resize_window_func.as_mut() {
+                    if func(&window, &window_event) {
+                        continue;
+                    }
+                }
+
                 if requests_exit(&window_event, state.modifiers())
                     && exit_on_close_request
                 {

winit/src/application/drag_resize.rs

@@ -0,0 +1,132 @@
+use winit::window::{CursorIcon, ResizeDirection};
+
+/// If supported by winit, returns a closure that implements cursor resize support.
+pub fn event_func(
+    window: &winit::window::Window,
+    border_size: f64,
+) -> Option<
+    impl FnMut(&winit::window::Window, &winit::event::WindowEvent<'_>) -> bool,
+> {
+    if window.drag_resize_window(ResizeDirection::East).is_ok() {
+        // Keep track of cursor when it is within a resizeable border.
+        let mut cursor_prev_resize_direction = None;
+
+        Some(
+            move |window: &winit::window::Window,
+                  window_event: &winit::event::WindowEvent<'_>|
+                  -> bool {
+                // Keep track of border resize state and set cursor icon when in range
+                match window_event {
+                    winit::event::WindowEvent::CursorMoved {
+                        position, ..
+                    } => {
+                        if !window.is_decorated() {
+                            let location = cursor_resize_direction(
+                                window.inner_size(),
+                                *position,
+                                border_size,
+                            );
+                            if location != cursor_prev_resize_direction {
+                                window.set_cursor_icon(
+                                    resize_direction_cursor_icon(location),
+                                );
+                                cursor_prev_resize_direction = location;
+                                return true;
+                            }
+                        }
+                    }
+                    winit::event::WindowEvent::MouseInput {
+                        state: winit::event::ElementState::Pressed,
+                        button: winit::event::MouseButton::Left,
+                        ..
+                    } => {
+                        if let Some(direction) = cursor_prev_resize_direction {
+                            let _res = window.drag_resize_window(direction);
+                            return true;
+                        }
+                    }
+                    _ => (),
+                }
+
+                false
+            },
+        )
+    } else {
+        None
+    }
+}
+
+/// Get the cursor icon that corresponds to the resize direction.
+fn resize_direction_cursor_icon(
+    resize_direction: Option<ResizeDirection>,
+) -> CursorIcon {
+    match resize_direction {
+        Some(resize_direction) => match resize_direction {
+            ResizeDirection::East => CursorIcon::EResize,
+            ResizeDirection::North => CursorIcon::NResize,
+            ResizeDirection::NorthEast => CursorIcon::NeResize,
+            ResizeDirection::NorthWest => CursorIcon::NwResize,
+            ResizeDirection::South => CursorIcon::SResize,
+            ResizeDirection::SouthEast => CursorIcon::SeResize,
+            ResizeDirection::SouthWest => CursorIcon::SwResize,
+            ResizeDirection::West => CursorIcon::WResize,
+        },
+        None => CursorIcon::Default,
+    }
+}
+
+/// Identifies resize direction based on cursor position and window dimensions.
+#[allow(clippy::similar_names)]
+fn cursor_resize_direction(
+    win_size: winit::dpi::PhysicalSize<u32>,
+    position: winit::dpi::PhysicalPosition<f64>,
+    border_size: f64,
+) -> Option<ResizeDirection> {
+    enum XDirection {
+        West,
+        East,
+        Default,
+    }
+
+    enum YDirection {
+        North,
+        South,
+        Default,
+    }
+
+    let xdir = if position.x < border_size {
+        XDirection::West
+    } else if position.x > (win_size.width as f64 - border_size) {
+        XDirection::East
+    } else {
+        XDirection::Default
+    };
+
+    let ydir = if position.y < border_size {
+        YDirection::North
+    } else if position.y > (win_size.height as f64 - border_size) {
+        YDirection::South
+    } else {
+        YDirection::Default
+    };
+
+    Some(match xdir {
+        XDirection::West => match ydir {
+            YDirection::North => ResizeDirection::NorthWest,
+            YDirection::South => ResizeDirection::SouthWest,
+            YDirection::Default => ResizeDirection::West,
+        },
+
+        XDirection::East => match ydir {
+            YDirection::North => ResizeDirection::NorthEast,
+            YDirection::South => ResizeDirection::SouthEast,
+            YDirection::Default => ResizeDirection::East,
+        },
+
+        XDirection::Default => match ydir {
+            YDirection::North => ResizeDirection::North,
+            YDirection::South => ResizeDirection::South,
+            YDirection::Default => return None,
+        },
+    })
+}

winit/src/settings.rs

@@ -65,6 +65,9 @@ pub struct Window {
     /// The size of the window.
     pub size: (u32, u32),
 
+    /// The border area for the drag resize handle.
+    pub resize_border: u32,
+
     /// The position of the window.
     pub position: Position,
 
@@ -100,6 +103,7 @@ impl fmt::Debug for Window {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("Window")
             .field("size", &self.size)
+            .field("resize_border", &self.resize_border)
             .field("position", &self.position)
             .field("min_size", &self.min_size)
             .field("max_size", &self.max_size)
@@ -226,6 +230,7 @@ impl Default for Window {
     fn default() -> Window {
         Window {
             size: (1024, 768),
+            resize_border: 8,
             position: Position::default(),
             min_size: None,
             max_size: None,