Add support for statusBarHidden(:)

Sources/SkipUI/SkipUI/System/SystemOverlays.swift

@@ -0,0 +1,111 @@
+// Copyright 2023–2026 Skip
+// SPDX-License-Identifier: MPL-2.0
+#if SKIP
+import android.os.Build
+import android.view.ViewTreeObserver
+import androidx.core.view.WindowCompat
+import androidx.core.view.WindowInsetsAnimationControlListenerCompat
+import androidx.core.view.WindowInsetsAnimationControllerCompat
+import androidx.core.view.WindowInsetsControllerCompat
+
+private let statusBarInsetTypes: Int = 1 // WindowInsetsCompat.Type.STATUS_BARS
+
+/*
+Our goal here is to use a `WindowInsetsAnimationControllerCompat` (an `animationController`) to hide/show the status bar and/or the home indicator bar.
+
+We're not just using `WindowInsetsControllerCompat` hide/show, because that uses a really ugly animation by default. (The status bar first fades to transparent for a full second, and then disappears, without animation, causing a layout shift).
+
+We get an animation controller via `WindowInsetsControllerCompat.controlWindowInsetsAnimation`, in the `onReady` callback.
+
+The system can choose to "cancel" our animation controller at any time, notifying us in an `onCancelled` callback. For example, our animation controller will be cancelled if the window loses focus (e.g. if you open the overview/recents app-switcher screen). When we regain focus, we have to re-hide the status bar.
+
+If you call `controlWindowInsetsAnimation` "too early", it might call `onCancelled` instantly, or, worse, it might just never call you back at all. (The documentation says that you're supposed to use addOnControllableInsetsChangedListener and wait for that to call you back, but I found that it wasn't working. Even when I got the callback saying that the status bars are controllable, when I called `controlWindowInsetsAnimation` immediately afterward, I never got a callback.)
+
+So: we attempt to request a controller ASAP during UIApplication.launch, but that probably won't succeed. Eventually, if the code calls `setStatusBarHidden`, _that_ will request a controller again, which normally succeeds.
+
+We also listen for window focus changes on the window; if we just regained focus, we request a new controller and then reassert our preferred status bar state.
+*/
+
+class SkipUISystemOverlaysCoordinator: WindowInsetsAnimationControlListenerCompat, ViewTreeObserver.OnWindowFocusChangeListener {
+    private var animationController: WindowInsetsAnimationControllerCompat?
+    private var pendingStatusBarHidden = false
+
+    private var activity: androidx.activity.ComponentActivity? { UIApplication.shared.androidActivity }
+    private var viewTreeObserver: ViewTreeObserver? { activity?.window.decorView.viewTreeObserver }
+
+    public func register() {
+        if let viewTreeObserver, viewTreeObserver.isAlive {
+            viewTreeObserver.addOnWindowFocusChangeListener(self)
+        }
+        requestAnimationController()
+    }
+
+    public func requestAnimationController() {
+        guard Build.VERSION.SDK_INT >= 30, let activity else { return }
+        activity.window.decorView.post {
+            guard let activity, animationController?.isReady != true,
+                  let decor = activity.window.decorView, decor.hasWindowFocus()
+            else { return }
+            let wicc = WindowCompat.getInsetsController(activity.window, decor)
+            wicc.controlWindowInsetsAnimation(statusBarInsetTypes, -1, nil, nil, self)
+        }
+    }
+
+    public func unregister() {
+        if let viewTreeObserver {
+            viewTreeObserver.removeOnWindowFocusChangeListener(self)
+        }
+        animationController?.finish(true)
+        animationController = nil
+        pendingStatusBarHidden = false
+    }
+
+    public func setStatusBarHidden(_ hidden: Bool) {
+        pendingStatusBarHidden = hidden
+        // API 30+ uses `WindowInsetsControllerCompat.controlWindowInsetsAnimation` when available; below 30 uses hide/show.
+        if Build.VERSION.SDK_INT < 30 {
+            guard let activity else { return }
+            let wicc = WindowCompat.getInsetsController(activity.window, activity.window.decorView)
+            if hidden {
+                wicc.hide(statusBarInsetTypes)
+            } else {
+                wicc.show(statusBarInsetTypes)
+            }
+        } else {
+            if animationController?.isReady == true {
+                applyPendingInsets()
+            } else {
+                requestAnimationController()
+            }
+        }
+    }
+
+    private func applyPendingInsets() {
+        guard let c = animationController, c.isReady else { return }
+        let insets = pendingStatusBarHidden ? c.hiddenStateInsets : c.shownStateInsets
+        c.setInsetsAndAlpha(insets, c.currentAlpha, Float(1.0))
+    }
+
+    override func onWindowFocusChanged(hasFocus: Bool) {
+        guard hasFocus, let viewTreeObserver, viewTreeObserver.isAlive else { return }
+        if Build.VERSION.SDK_INT < 30 {
+            setStatusBarHidden(pendingStatusBarHidden)
+        } else {
+            requestAnimationController()
+        }
+    }
+
+    override func onReady(controller: WindowInsetsAnimationControllerCompat, types: Int) {
+        animationController = controller
+        applyPendingInsets()
+    }
+
+    override func onFinished(controller: WindowInsetsAnimationControllerCompat) {}
+
+    override func onCancelled(controller: WindowInsetsAnimationControllerCompat?) {
+        animationController = nil
+        requestAnimationController()
+    }
+}
+
+#endif

Sources/SkipUI/SkipUI/UIKit/UIApplication.swift

@@ -36,6 +36,7 @@ let logger: Logger = Logger(subsystem: "skip.ui", category: "SkipUI") // adb log
     #if SKIP
     private var requestPermissionLauncher: ActivityResultLauncher<String>?
     private let waitingContinuations: MutableList<Continuation<Bool>> = mutableListOf<Continuation<Bool>>()
+    private var systemOverlaysCoordinator: SkipUISystemOverlaysCoordinator?
     #endif
 
     private init() {
@@ -91,14 +92,22 @@ let logger: Logger = Logger(subsystem: "skip.ui", category: "SkipUI") // adb log
             } catch {
                 android.util.Log.w("SkipUI", "error initializing permission launcher", error as? Throwable)
             }
+            shared.systemOverlaysCoordinator = SkipUISystemOverlaysCoordinator()
+            shared.systemOverlaysCoordinator?.register()
         }
     }
 
     func onActivityDestroy() {
+        systemOverlaysCoordinator?.unregister()
+        systemOverlaysCoordinator = nil
         // The permission launcher appears to hold a strong reference to the activity, so we must nil it to avoid memory leaks
         self.requestPermissionLauncher = nil
     }
 
+    public func setStatusBarHidden(_ hidden: Bool) {
+        systemOverlaysCoordinator?.setStatusBarHidden(hidden)
+    }
+
     /// Requests the given permission.
     /// - Parameters:
     ///   - permission: the name of the permission, such as `android.permission.POST_NOTIFICATIONS`

Sources/SkipUI/SkipUI/View/AdditionalViewModifiers.swift

@@ -1276,9 +1276,23 @@ extension View {
         #endif
     }
 
-    @available(*, unavailable)
-    public func statusBarHidden(_ hidden: Bool = true) -> some View {
+    // SKIP @bridge
+    public func statusBarHidden(_ hidden: Bool = true) -> any View {
+        #if SKIP
+        return ModifiedContent(content: self, modifier: SideEffectModifier { _ in
+            DisposableEffect(hidden) {
+                UIApplication.shared.setStatusBarHidden(hidden)
+                onDispose {
+                    if hidden {
+                        UIApplication.shared.setStatusBarHidden(false)
+                    }
+                }
+            }
+            return ComposeResult.ok
+        })
+        #else
         return self
+        #endif
     }
 
     @available(*, unavailable)