Make the safe area on iOS track the soft keyboard as well

winit-core/src/window.rs

@@ -752,10 +752,11 @@ pub trait Window: AsAny + Send + Sync + fmt::Debug {
     /// The inset area of the surface that is unobstructed.
     ///
     /// On some devices, especially mobile devices, the screen is not a perfect rectangle, and may
-    /// have rounded corners, notches, bezels, and so on. When drawing your content, you usually
-    /// want to draw your background and other such unimportant content on the entire surface, while
-    /// you will want to restrict important content such as text, interactable or visual indicators
-    /// to the part of the screen that is actually visible; for this, you use the safe area.
+    /// have rounded corners, notches, bezels, and so on. Additionally, a soft keyboard may be open.
+    /// When drawing your content, you usually want to draw your background and other such
+    /// unimportant content on the entire surface, while you will want to restrict important content
+    /// such as text, interactable or visual indicators to the part of the screen that is actually
+    /// visible; for this, you use the safe area.
     ///
     /// The safe area is a rectangle that is defined relative to the origin at the top-left corner
     /// of the surface, and the size extending downwards to the right. The area will not extend

winit-uikit/Cargo.toml

@@ -32,6 +32,7 @@ objc2-core-foundation = { workspace = true, features = [
     "CFRunLoop",
     "CFString",
 ] }
+objc2-core-graphics = { workspace = true, features = ["std", "CGGeometry"] }
 objc2-foundation = { workspace = true, features = [
     "std",
     "block2",
@@ -47,14 +48,13 @@ objc2-foundation = { workspace = true, features = [
 ] }
 objc2-ui-kit = { workspace = true, features = [
     "std",
+    "block2",
     "objc2-core-foundation",
     "UIApplication",
     "UIDevice",
     "UIEvent",
     "UIGeometry",
     "UIGestureRecognizer",
-    "UITextInput",
-    "UITextInputTraits",
     "UIOrientation",
     "UIPanGestureRecognizer",
     "UIPinchGestureRecognizer",
@@ -63,10 +63,14 @@ objc2-ui-kit = { workspace = true, features = [
     "UIScreen",
     "UIScreenMode",
     "UITapGestureRecognizer",
+    "UITextInput",
+    "UITextInputTraits",
     "UITouch",
     "UITraitCollection",
     "UIView",
+    "UIViewAnimating",
     "UIViewController",
+    "UIViewPropertyAnimator",
     "UIWindow",
 ] }
 winit-common = { workspace = true, features = ["core-foundation", "event-handler"] }

winit-uikit/src/app_state.rs

@@ -309,7 +309,7 @@ pub(crate) fn handle_nonuser_events<I: IntoIterator<Item = EventWrapper>>(
 
     for event in events {
         if !processing_redraws && event.is_redraw() {
-            tracing::info!("processing `RedrawRequested` during the main event loop");
+            // tracing::info!("processing `RedrawRequested` during the main event loop");
         } else if processing_redraws && !event.is_redraw() {
             tracing::warn!(
                 "processing non `RedrawRequested` event after the main event loop: {:#?}",
@@ -327,7 +327,7 @@ pub(crate) fn handle_nonuser_events<I: IntoIterator<Item = EventWrapper>>(
 
         for event in queued_events {
             if !processing_redraws && event.is_redraw() {
-                tracing::info!("processing `RedrawRequested` during the main event loop");
+                // tracing::info!("processing `RedrawRequested` during the main event loop");
             } else if processing_redraws && !event.is_redraw() {
                 tracing::warn!(
                     "processing non-`RedrawRequested` event after the main event loop: {:#?}",

winit-uikit/src/view.rs

@@ -124,7 +124,7 @@ define_class!(
 
         #[unsafe(method(safeAreaInsetsDidChange))]
         fn safe_area_changed(&self) {
-            debug!("safeAreaInsetsDidChange was called, requesting redraw");
+            println!("safeAreaInsetsDidChange was called, requesting redraw");
             // When the safe area changes we want to make sure to emit a redraw event
             self.setNeedsDisplay();
         }

winit-uikit/src/view_controller.rs

@@ -1,13 +1,26 @@
 use std::cell::Cell;
 
-use objc2::rc::Retained;
-use objc2::{DefinedClass, MainThreadMarker, available, define_class, msg_send};
-use objc2_foundation::NSObject;
+use block2::RcBlock;
+use objc2::rc::{Retained, Weak};
+use objc2::runtime::ProtocolObject;
+use objc2::{
+    DefinedClass, MainThreadMarker, MainThreadOnly, Message, available, define_class, msg_send,
+};
+use objc2_core_foundation::{CFTimeInterval, CGRect};
+use objc2_core_graphics::CGRectIntersection;
+use objc2_foundation::{
+    NSNotification, NSNotificationCenter, NSNumber, NSObject, NSObjectProtocol, NSValue,
+};
 use objc2_ui_kit::{
-    UIDevice, UIInterfaceOrientationMask, UIRectEdge, UIResponder, UIStatusBarStyle,
-    UIUserInterfaceIdiom, UIView, UIViewController,
+    UICoordinateSpace, UIDevice, UIEdgeInsets, UIInterfaceOrientationMask,
+    UIKeyboardAnimationCurveUserInfoKey, UIKeyboardAnimationDurationUserInfoKey,
+    UIKeyboardFrameBeginUserInfoKey, UIKeyboardFrameEndUserInfoKey,
+    UIKeyboardWillChangeFrameNotification, UIRectEdge, UIResponder, UIScreen, UIStatusBarStyle,
+    UIUserInterfaceIdiom, UIView, UIViewAnimating, UIViewAnimationCurve, UIViewAnimationOptions,
+    UIViewController, UIViewPropertyAnimator,
 };
 
+use crate::notification_center::create_observer;
 use crate::{ScreenEdge, StatusBarStyle, ValidOrientations, WindowAttributesIos};
 
 pub struct ViewControllerState {
@@ -16,6 +29,9 @@ pub struct ViewControllerState {
     prefers_home_indicator_auto_hidden: Cell<bool>,
     supported_orientations: Cell<UIInterfaceOrientationMask>,
     preferred_screen_edges_deferring_system_gestures: Cell<UIRectEdge>,
+    // Keep observer around (deallocating it stops notifications being posted).
+    keyboard_will_change_frame_observer:
+        Cell<Option<Retained<ProtocolObject<dyn NSObjectProtocol>>>>,
 }
 
 define_class!(
@@ -138,6 +154,7 @@ impl WinitViewController {
             prefers_home_indicator_auto_hidden: Cell::new(false),
             supported_orientations: Cell::new(UIInterfaceOrientationMask::All),
             preferred_screen_edges_deferring_system_gestures: Cell::new(UIRectEdge::empty()),
+            keyboard_will_change_frame_observer: Cell::new(None),
         });
         let this: Retained<Self> = unsafe { msg_send![super(this), init] };
 
@@ -153,8 +170,115 @@ impl WinitViewController {
             ios_attributes.preferred_screen_edges_deferring_system_gestures,
         );
 
+        let center = NSNotificationCenter::defaultCenter();
+
         this.setView(Some(view));
 
+        // Set up an observer that will make the `safeAreaRect` of the view update based on the soft
+        // keyboard's presence (in addition to everything else that the safe area depends on).
+        let controller_weak = Weak::from_retained(&this);
+        this.ivars().keyboard_will_change_frame_observer.set(Some(create_observer(
+            &center,
+            unsafe { UIKeyboardWillChangeFrameNotification },
+            move |notification| {
+                eprintln!("UIKeyboardWillChangeFrameNotification");
+                if let Some(controller) = controller_weak.load() {
+                    keyboard_will_change_frame(&controller, notification);
+                }
+            },
+        )));
+
         this
     }
+
+    /// The current keyboard frame, in the view's coordinate space.
+    pub(crate) fn current_keyboard_frame(&self) -> CGRect {
+        // TODO: Combine start_frame and end_frame with `animator.fractionComplete()` to produce
+        // current frame
+
+        // Convert keyboard frame to view coordinates.
+        let keyboard_frame = self
+            .view()
+            .unwrap()
+            .convertRect_fromCoordinateSpace(frame, &keyboard_screen.coordinateSpace());
+        todo!()
+    }
+}
+
+fn keyboard_will_change_frame(controller: &WinitViewController, notification: &NSNotification) {
+    let mtm = controller.mtm();
+    let controller = controller.retain();
+    let view = controller.view().unwrap();
+
+    // The notification's object is the screen the keyboard appears on (since iOS 16).
+    let keyboard_screen = notification
+        .object()
+        .map(|s| s.downcast::<UIScreen>().unwrap())
+        .unwrap_or_else(|| view.window().unwrap().screen());
+
+    let user_info = notification.userInfo().unwrap();
+    let begin_frame = user_info
+        .objectForKey(unsafe { UIKeyboardFrameBeginUserInfoKey })
+        .unwrap()
+        .downcast::<NSValue>()
+        .unwrap()
+        .get_rect()
+        .unwrap();
+    let end_frame = user_info
+        .objectForKey(unsafe { UIKeyboardFrameEndUserInfoKey })
+        .unwrap()
+        .downcast::<NSValue>()
+        .unwrap()
+        .get_rect()
+        .unwrap();
+    let duration: CFTimeInterval = user_info
+        .objectForKey(unsafe { UIKeyboardAnimationDurationUserInfoKey })
+        .unwrap()
+        .downcast::<NSNumber>()
+        .unwrap()
+        .doubleValue();
+    let curve_raw = user_info
+        .objectForKey(unsafe { UIKeyboardAnimationCurveUserInfoKey })
+        .unwrap()
+        .downcast::<NSNumber>()
+        .unwrap()
+        .integerValue();
+    let curve = UIViewAnimationCurve(curve_raw);
+
+    // If OS version is high enough, set up a `UIViewPropertyAnimator` to track the position of the
+    // keyboard.
+    if available!(ios = 10.0, tvos = 10.0, visionos = 1.0) {
+        let animator = UIViewPropertyAnimator::initWithDuration_curve_animations(
+            UIViewPropertyAnimator::alloc(mtm),
+            duration,
+            curve,
+            None,
+        );
+
+        animator.addCompletion(&RcBlock::new(move |_| {
+            controller.setAdditionalSafeAreaInsets(todo!());
+            // TODO: Might need to do further work to update the safe area when we
+            // move the view?
+
+            view.layoutIfNeeded();
+            // Safe area changed -> request redraw.
+            view.setNeedsDisplay();
+        }));
+
+        animator.startAnimation();
+    } else {
+        // Update immediately.
+        todo!()
+    }
+
+    // Not sufficient, `setAdditionalSafeAreaInsets` only updates at the start, it doesn't change
+    // `safeAreaInsets` continously during the keyboard open animation.
+    //
+    // UIView::animateWithDuration_delay_options_animations_completion(
+    //     duration,
+    //     0.0,
+    //     options,
+    //     None,
+    //     mtm,
+    // );
 }

winit-uikit/src/window.rs

@@ -11,6 +11,7 @@ use dpi::{
 use objc2::rc::Retained;
 use objc2::{MainThreadMarker, available, class, define_class, msg_send};
 use objc2_core_foundation::{CGFloat, CGPoint, CGRect, CGSize};
+use objc2_core_graphics::CGRectIntersection;
 use objc2_foundation::{NSObject, NSObjectProtocol};
 use objc2_ui_kit::{
     UIApplication, UICoordinateSpace, UIEdgeInsets, UIResponder, UIScreen,
@@ -202,7 +203,7 @@ impl Inner {
     }
 
     pub fn safe_area(&self) -> PhysicalInsets<u32> {
-        let insets = if available!(ios = 11.0, tvos = 11.0, visionos = 1.0) {
+        let device_insets = if available!(ios = 11.0, tvos = 11.0, visionos = 1.0) {
             self.view.safeAreaInsets()
         } else {
             // Assume the status bar frame is the only thing that obscures the view
@@ -211,7 +212,17 @@ impl Inner {
             let status_bar_frame = app.statusBarFrame();
             UIEdgeInsets { top: status_bar_frame.size.height, left: 0.0, bottom: 0.0, right: 0.0 }
         };
-        let insets = LogicalInsets::new(insets.top, insets.left, insets.bottom, insets.right);
+
+        let keyboard_frame = self.view_controller.current_keyboard_frame();
+        let intersection = CGRectIntersection(self.view.bounds(), keyboard_frame);
+
+        let insets = LogicalInsets::new(
+            device_insets.top,
+            device_insets.left,
+            // Assume that the keyboard appears from the bottom.
+            device_insets.bottom + intersection.size.height,
+            device_insets.right,
+        );
         insets.to_physical(self.scale_factor())
     }
 

winit/examples/window.rs

@@ -2,12 +2,16 @@
 
 use std::error::Error;
 
+use dpi::PhysicalInsets;
 use winit::application::ApplicationHandler;
 use winit::event::WindowEvent;
 use winit::event_loop::{ActiveEventLoop, EventLoop};
 #[cfg(web_platform)]
 use winit::platform::web::WindowAttributesWeb;
-use winit::window::{Window, WindowAttributes, WindowId};
+use winit::window::{
+    ImeCapabilities, ImeEnableRequest, ImeRequest, ImeRequestData, Window, WindowAttributes,
+    WindowId,
+};
 
 #[path = "util/fill.rs"]
 mod fill;
@@ -17,6 +21,7 @@ mod tracing;
 #[derive(Default, Debug)]
 struct App {
     window: Option<Box<dyn Window>>,
+    prev_safe_area: PhysicalInsets<u32>,
 }
 
 impl ApplicationHandler for App {
@@ -33,11 +38,24 @@ impl ApplicationHandler for App {
                 event_loop.exit();
                 return;
             },
-        }
+        };
+
+        // Allow IME out of the box.
+        let enable_request =
+            ImeEnableRequest::new(ImeCapabilities::new(), ImeRequestData::default()).unwrap();
+        let enable_ime = ImeRequest::Enable(enable_request);
+
+        // Initial update
+        self.window.as_ref().unwrap().request_ime_update(enable_ime).unwrap();
     }
 
     fn window_event(&mut self, event_loop: &dyn ActiveEventLoop, _: WindowId, event: WindowEvent) {
-        println!("{event:?}");
+        let current_safe_area = self.window.as_ref().unwrap().safe_area();
+        if self.prev_safe_area != current_safe_area {
+            println!("safe area changed from {:?} to {:?}", self.prev_safe_area, current_safe_area);
+            self.prev_safe_area = current_safe_area;
+        }
+
         match event {
             WindowEvent::CloseRequested => {
                 println!("Close was requested; stopping");
@@ -47,6 +65,7 @@ impl ApplicationHandler for App {
                 self.window.as_ref().expect("resize event without a window").request_redraw();
             },
             WindowEvent::RedrawRequested => {
+                println!("redraw");
                 // Redraw the application.
                 //
                 // It's preferable for applications that do not render continuously to render in
@@ -64,9 +83,16 @@ impl ApplicationHandler for App {
                 // For contiguous redraw loop you can request a redraw from here.
                 // window.request_redraw();
             },
-            _ => (),
+            _ => {
+                println!("{event:?}");
+            },
         }
     }
+
+    fn about_to_wait(&mut self, event_loop: &dyn ActiveEventLoop) {
+        let window = self.window.as_ref().expect("redraw request without a window");
+        // window.request_redraw();
+    }
 }
 
 fn main() -> Result<(), Box<dyn Error>> {