Replace set_decorations with set_prefers_status_bar_hidden on iOS (#1092)

CHANGELOG.md

@@ -19,7 +19,9 @@
 - On iOS, disable overscan compensation for external displays (removes black
   bars surrounding the image).
 - On Linux, the functions `is_wayland`, `is_x11`, `xlib_xconnection` and `wayland_display` have been moved to a new `EventLoopWindowTargetExtUnix` trait.
-
+- On iOS, add `set_prefers_status_bar_hidden` extension function instead of
+  hijacking `set_decorations` for this purpose.
+  
 # 0.20.0 Alpha 2 (2019-07-09)
 
 - On X11, non-resizable windows now have maximize explicitly disabled.

FEATURES.md

@@ -140,6 +140,7 @@ If your PR makes notable changes to Winit's features, please update this section
 * Setting the `UIView` hidpi factor
 * Valid orientations
 * Home indicator visibility
+* Status bar visibility
 * Deferrring system gestures
 * Support for custom `UIView` derived class
 * Getting the device idiom
@@ -164,8 +165,8 @@ Legend:
 |Window initialization            |✔️     |✔️     |▢[#5]      |✔️             |▢[#33]|▢[#33] |❓        |
 |Providing pointer to init OpenGL |✔️     |✔️     |✔️         |✔️             |✔️     |✔️    |❓        |
 |Providing pointer to init Vulkan |✔️     |✔️     |✔️         |✔️             |✔️     |❓     |**N/A**   |
-|Window decorations               |✔️     |✔️     |✔️         |▢[#306]        |**N/A**|✔️     |**N/A**   |
-|Window decorations toggle        |✔️     |✔️     |✔️         |✔️             |**N/A**|✔️     |**N/A**   |
+|Window decorations               |✔️     |✔️     |✔️         |▢[#306]        |**N/A**|**N/A**|**N/A**   |
+|Window decorations toggle        |✔️     |✔️     |✔️         |✔️             |**N/A**|**N/A**|**N/A**   |
 |Window resizing                  |✔️     |▢[#219]|✔️         |▢[#306]        |**N/A**|**N/A**|❓        |
 |Window resize increments         |❌     |❌     |❌         |❌             |❌    |❌     |❌        |
 |Window transparency              |✔️     |✔️     |✔️         |✔️             |**N/A**|**N/A**|**N/A**   |

src/platform/ios.rs

@@ -80,6 +80,16 @@ pub trait WindowExtIOS {
     /// and then calls
     /// [`-[UIViewController setNeedsUpdateOfScreenEdgesDeferringSystemGestures]`](https://developer.apple.com/documentation/uikit/uiviewcontroller/2887507-setneedsupdateofscreenedgesdefer?language=objc).
     fn set_preferred_screen_edges_deferring_system_gestures(&self, edges: ScreenEdge);
+
+    /// Sets whether the [`Window`] prefers the status bar hidden.
+    ///
+    /// The default is to prefer showing the status bar.
+    ///
+    /// This changes the value returned by
+    /// [`-[UIViewController prefersStatusBarHidden]`](https://developer.apple.com/documentation/uikit/uiviewcontroller/1621440-prefersstatusbarhidden?language=objc),
+    /// and then calls
+    /// [`-[UIViewController setNeedsStatusBarAppearanceUpdate]`](https://developer.apple.com/documentation/uikit/uiviewcontroller/1621354-setneedsstatusbarappearanceupdat?language=objc).
+    fn set_prefers_status_bar_hidden(&self, hidden: bool);
 }
 
 impl WindowExtIOS for Window {
@@ -118,6 +128,11 @@ impl WindowExtIOS for Window {
         self.window
             .set_preferred_screen_edges_deferring_system_gestures(edges)
     }
+
+    #[inline]
+    fn set_prefers_status_bar_hidden(&self, hidden: bool) {
+        self.window.set_prefers_status_bar_hidden(hidden)
+    }
 }
 
 /// Additional methods on [`WindowBuilder`] that are specific to iOS.
@@ -163,6 +178,14 @@ pub trait WindowBuilderExtIOS {
         self,
         edges: ScreenEdge,
     ) -> WindowBuilder;
+
+    /// Sets whether the [`Window`] prefers the status bar hidden.
+    ///
+    /// The default is to prefer showing the status bar.
+    ///
+    /// This sets the initial value returned by
+    /// [`-[UIViewController prefersStatusBarHidden]`](https://developer.apple.com/documentation/uikit/uiviewcontroller/1621440-prefersstatusbarhidden?language=objc).
+    fn with_prefers_status_bar_hidden(self, hidden: bool) -> WindowBuilder;
 }
 
 impl WindowBuilderExtIOS for WindowBuilder {
@@ -199,6 +222,12 @@ impl WindowBuilderExtIOS for WindowBuilder {
             .preferred_screen_edges_deferring_system_gestures = edges;
         self
     }
+
+    #[inline]
+    fn with_prefers_status_bar_hidden(mut self, hidden: bool) -> WindowBuilder {
+        self.platform_specific.prefers_status_bar_hidden = hidden;
+        self
+    }
 }
 
 /// Additional methods on [`MonitorHandle`] that are specific to iOS.

src/platform_impl/ios/view.rs

@@ -331,7 +331,7 @@ pub unsafe fn create_view(
 
 // requires main thread
 pub unsafe fn create_view_controller(
-    window_attributes: &WindowAttributes,
+    _window_attributes: &WindowAttributes,
     platform_attributes: &PlatformSpecificWindowBuilderAttributes,
     view: id,
 ) -> id {
@@ -347,10 +347,10 @@ pub unsafe fn create_view_controller(
         !view_controller.is_null(),
         "Failed to initialize `UIViewController` instance"
     );
-    let status_bar_hidden = if window_attributes.decorations {
-        NO
-    } else {
+    let status_bar_hidden = if platform_attributes.prefers_status_bar_hidden {
         YES
+    } else {
+        NO
     };
     let idiom = event_loop::get_idiom();
     let supported_orientations = UIInterfaceOrientationMask::from_valid_orientations_idiom(

src/platform_impl/ios/window.rs

@@ -214,14 +214,8 @@ impl Inner {
         }
     }
 
-    pub fn set_decorations(&self, decorations: bool) {
-        unsafe {
-            let status_bar_hidden = if decorations { NO } else { YES };
-            let () = msg_send![
-                self.view_controller,
-                setPrefersStatusBarHidden: status_bar_hidden
-            ];
-        }
+    pub fn set_decorations(&self, _decorations: bool) {
+        warn!("`Window::set_decorations` is ignored on iOS")
     }
 
     pub fn set_always_on_top(&self, _always_on_top: bool) {
@@ -414,6 +408,16 @@ impl Inner {
             ];
         }
     }
+
+    pub fn set_prefers_status_bar_hidden(&self, hidden: bool) {
+        unsafe {
+            let status_bar_hidden = if hidden { YES } else { NO };
+            let () = msg_send![
+                self.view_controller,
+                setPrefersStatusBarHidden: status_bar_hidden
+            ];
+        }
+    }
 }
 
 impl Inner {
@@ -536,6 +540,7 @@ pub struct PlatformSpecificWindowBuilderAttributes {
     pub hidpi_factor: Option<f64>,
     pub valid_orientations: ValidOrientations,
     pub prefers_home_indicator_hidden: bool,
+    pub prefers_status_bar_hidden: bool,
     pub preferred_screen_edges_deferring_system_gestures: ScreenEdge,
 }
 
@@ -546,6 +551,7 @@ impl Default for PlatformSpecificWindowBuilderAttributes {
             hidpi_factor: None,
             valid_orientations: Default::default(),
             prefers_home_indicator_hidden: false,
+            prefers_status_bar_hidden: false,
             preferred_screen_edges_deferring_system_gestures: Default::default(),
         }
     }

src/window.rs

@@ -585,10 +585,7 @@ impl Window {
     ///
     /// ## Platform-specific
     ///
-    /// - **iOS:** Can only be called on the main thread. Controls whether the status bar is hidden
-    ///   via [`setPrefersStatusBarHidden`].
-    ///
-    /// [`setPrefersStatusBarHidden`]: https://developer.apple.com/documentation/uikit/uiviewcontroller/1621440-prefersstatusbarhidden?language=objc
+    /// - **iOS:** Has no effect.
     #[inline]
     pub fn set_decorations(&self, decorations: bool) {
         self.window.set_decorations(decorations)