Move Android backend to winit-android (#4250)

.github/CODEOWNERS

@@ -1,6 +1,5 @@
 # Android
-/src/platform/android.rs            @MarijnS95
-/src/platform_impl/android          @MarijnS95
+/winit-android                      @MarijnS95
 
 # Apple (AppKit + UIKit)
 /src/platform/ios.rs                @madsmtm

.github/workflows/ci.yml

@@ -182,6 +182,10 @@ jobs:
     - name: Test winit core
       run: cargo test -p winit-core
 
+    - name: Test winit Android
+      if: contains(matrix.platform.target, 'android')
+      run: cargo $CMD test -p winit-android --target=${{ matrix.platform.target }} --features native-activity --no-run
+
     - name: Test winit Orbital
       if: contains(matrix.platform.target, 'redox')
       run: cargo test -p winit-orbital

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-members = ["dpi", "winit-core", "winit-orbital"]
+members = ["dpi", "winit-*"]
 resolver = "2"
 
 [workspace.package]
@@ -12,6 +12,7 @@ rust-version = "1.80"
 # Workspace dependencies.
 # `winit` has no version here to allow using it in dev deps for docs.
 winit = { path = "." }
+winit-android = { version = "0.0.0", path = "winit-android" }
 winit-core = { version = "0.0.0", path = "winit-core" }
 winit-orbital = { version = "0.0.0", path = "winit-orbital" }
 
@@ -149,9 +150,10 @@ targets = [
 
 # Features are documented in either `lib.rs` or under `winit::platform`.
 [features]
-android-game-activity = ["android-activity/game-activity"]
-android-native-activity = ["android-activity/native-activity"]
 default = ["x11", "wayland", "wayland-dlopen", "wayland-csd-adwaita"]
+
+android-game-activity = ["winit-android/game-activity"]
+android-native-activity = ["winit-android/native-activity"]
 mint = ["dpi/mint"]
 serde = [
     "dep:serde",
@@ -197,10 +199,8 @@ tracing-subscriber = { workspace = true, features = ["env-filter"] }
 [target.'cfg(not(target_os = "android"))'.dev-dependencies]
 softbuffer.workspace = true
 
-# Android
 [target.'cfg(target_os = "android")'.dependencies]
-android-activity.workspace = true
-ndk.workspace = true
+winit-android.workspace = true
 
 # AppKit or UIKit
 [target.'cfg(target_vendor = "apple")'.dependencies]

src/event_loop.rs

@@ -328,6 +328,26 @@ impl winit_core::event_loop::run_on_demand::EventLoopExtRunOnDemand for EventLoo
     }
 }
 
+#[cfg(android_platform)]
+impl winit_android::EventLoopExtAndroid for EventLoop {
+    fn android_app(&self) -> &winit_android::activity::AndroidApp {
+        &self.event_loop.android_app
+    }
+}
+
+#[cfg(android_platform)]
+impl winit_android::EventLoopBuilderExtAndroid for EventLoopBuilder {
+    fn with_android_app(&mut self, app: winit_android::activity::AndroidApp) -> &mut Self {
+        self.platform_specific.android_app = Some(app);
+        self
+    }
+
+    fn handle_volume_keys(&mut self) -> &mut Self {
+        self.platform_specific.ignore_volume_keys = false;
+        self
+    }
+}
+
 /// ```compile_error
 /// use winit::event_loop::run_on_demand::EventLoopExtRunOnDemand;
 /// use winit::event_loop::EventLoop;

src/platform/mod.rs

@@ -3,7 +3,7 @@
 //! Only the modules corresponding to the platform you're compiling to will be available.
 
 #[cfg(android_platform)]
-pub mod android;
+pub use winit_android as android;
 #[cfg(ios_platform)]
 pub mod ios;
 #[cfg(macos_platform)]

src/platform_impl/mod.rs

@@ -1,5 +1,5 @@
 #[cfg(android_platform)]
-mod android;
+pub(crate) use winit_android as platform;
 #[cfg(target_vendor = "apple")]
 mod apple;
 #[cfg(any(x11_platform, wayland_platform))]
@@ -11,8 +11,6 @@ mod web;
 #[cfg(windows_platform)]
 mod windows;
 
-#[cfg(android_platform)]
-use self::android as platform;
 #[cfg(target_vendor = "apple")]
 use self::apple as platform;
 #[cfg(any(x11_platform, wayland_platform))]

winit-android/Cargo.toml

@@ -0,0 +1,35 @@
+[package]
+description = "Winit's Android backend"
+documentation = "https://docs.rs/winit-android"
+edition.workspace = true
+license.workspace = true
+name = "winit-android"
+repository.workspace = true
+rust-version.workspace = true
+version = "0.0.0"
+
+[features]
+game-activity = ["android-activity/game-activity"]
+native-activity = ["android-activity/native-activity"]
+serde = ["dep:serde", "bitflags/serde", "smol_str/serde", "dpi/serde", "winit-core/serde"]
+
+[dependencies]
+bitflags.workspace = true
+dpi.workspace = true
+rwh_06.workspace = true
+serde = { workspace = true, optional = true }
+smol_str.workspace = true
+tracing.workspace = true
+winit-core.workspace = true
+
+# Platform-specific
+[target.'cfg(target_os = "android")'.dependencies]
+android-activity.workspace = true
+ndk.workspace = true
+
+[dev-dependencies]
+winit.workspace = true
+
+[package.metadata.docs.rs]
+features = ["serde", "native-activity"]
+targets = ["aarch64-linux-android"]

winit-android/README.md

@@ -0,0 +1 @@
+../README.md

winit-android/src/event_loop.rs

@@ -1,4 +1,5 @@
 use std::cell::Cell;
+use std::fmt;
 use std::hash::Hash;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex};
@@ -26,7 +27,7 @@ use winit_core::window::{
     WindowAttributes, WindowButtons, WindowId, WindowLevel,
 };
 
-mod keycodes;
+use crate::keycodes;
 
 static HAS_FOCUS: AtomicBool = AtomicBool::new(true);
 
@@ -42,7 +43,7 @@ struct SharedFlagSetter {
     flag: Arc<AtomicBool>,
 }
 impl SharedFlagSetter {
-    pub fn set(&self) -> bool {
+    fn set(&self) -> bool {
         self.flag.compare_exchange(false, true, Ordering::AcqRel, Ordering::Relaxed).is_ok()
     }
 }
@@ -57,21 +58,21 @@ struct SharedFlag {
 // we just need to know at the start of a main loop iteration if a redraw
 // was queued and be able to read and clear the state atomically)
 impl SharedFlag {
-    pub fn new() -> Self {
+    fn new() -> Self {
         Self { flag: Arc::new(AtomicBool::new(false)) }
     }
 
-    pub fn setter(&self) -> SharedFlagSetter {
+    fn setter(&self) -> SharedFlagSetter {
         SharedFlagSetter { flag: self.flag.clone() }
     }
 
-    pub fn get_and_reset(&self) -> bool {
+    fn get_and_reset(&self) -> bool {
         self.flag.swap(false, std::sync::atomic::Ordering::AcqRel)
     }
 }
 
 #[derive(Clone)]
-pub struct RedrawRequester {
+struct RedrawRequester {
     flag: SharedFlagSetter,
     waker: AndroidAppWaker,
 }
@@ -87,7 +88,7 @@ impl RedrawRequester {
         RedrawRequester { flag: flag.setter(), waker }
     }
 
-    pub fn request_redraw(&self) {
+    fn request_redraw(&self) {
         if self.flag.set() {
             // Only explicitly try to wake up the main loop when the flag
             // value changes
@@ -98,7 +99,7 @@ impl RedrawRequester {
 
 #[derive(Debug)]
 pub struct EventLoop {
-    pub(crate) android_app: AndroidApp,
+    pub android_app: AndroidApp,
     window_target: ActiveEventLoop,
     redraw_flag: SharedFlag,
     loop_running: bool, // Dispatched `NewEvents<Init>`
@@ -111,9 +112,9 @@ pub struct EventLoop {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub(crate) struct PlatformSpecificEventLoopAttributes {
-    pub(crate) android_app: Option<AndroidApp>,
-    pub(crate) ignore_volume_keys: bool,
+pub struct PlatformSpecificEventLoopAttributes {
+    pub android_app: Option<AndroidApp>,
+    pub ignore_volume_keys: bool,
 }
 
 impl Default for PlatformSpecificEventLoopAttributes {
@@ -126,9 +127,7 @@ impl Default for PlatformSpecificEventLoopAttributes {
 const GLOBAL_WINDOW: WindowId = WindowId::from_raw(0);
 
 impl EventLoop {
-    pub(crate) fn new(
-        attributes: &PlatformSpecificEventLoopAttributes,
-    ) -> Result<Self, EventLoopError> {
+    pub fn new(attributes: &PlatformSpecificEventLoopAttributes) -> Result<Self, EventLoopError> {
         let android_app = attributes.android_app.as_ref().expect(
             "An `AndroidApp` as passed to android_main() is required to create an `EventLoop` on \
              Android",
@@ -158,7 +157,7 @@ impl EventLoop {
         })
     }
 
-    pub(crate) fn window_target(&self) -> &dyn RootActiveEventLoop {
+    pub fn window_target(&self) -> &dyn RootActiveEventLoop {
         &self.window_target
     }
 
@@ -751,7 +750,7 @@ impl rwh_06::HasDisplayHandle for OwnedDisplayHandle {
 pub struct PlatformSpecificWindowAttributes;
 
 #[derive(Debug)]
-pub(crate) struct Window {
+pub struct Window {
     app: AndroidApp,
     redraw_requester: RedrawRequester,
 }
@@ -766,11 +765,11 @@ impl Window {
         Ok(Self { app: el.app.clone(), redraw_requester: el.redraw_requester.clone() })
     }
 
-    pub fn config(&self) -> ConfigurationRef {
+    pub(crate) fn config(&self) -> ConfigurationRef {
         self.app.config()
     }
 
-    pub fn content_rect(&self) -> Rect {
+    pub(crate) fn content_rect(&self) -> Rect {
         self.app.content_rect()
     }
 
@@ -999,16 +998,6 @@ impl CoreWindow for Window {
     }
 }
 
-#[derive(Default, Clone, Debug)]
-pub struct OsError;
-
-use std::fmt::{self, Display, Formatter};
-impl Display for OsError {
-    fn fmt(&self, fmt: &mut Formatter<'_>) -> Result<(), fmt::Error> {
-        write!(fmt, "Android OS Error")
-    }
-}
-
 fn screen_size(app: &AndroidApp) -> PhysicalSize<u32> {
     if let Some(native_window) = app.native_window() {
         PhysicalSize::new(native_window.width() as _, native_window.height() as _)

winit-android/src/lib.rs

@@ -69,10 +69,19 @@
 //!    logging as above).
 //! 4. Pass a clone of the `AndroidApp` that your application receives to Winit when building your
 //!    event loop (as shown above).
+#![cfg(target_os = "android")]
+
+mod event_loop;
+mod keycodes;
+
+use winit_core::event_loop::ActiveEventLoop as CoreActiveEventLoop;
+use winit_core::window::Window as CoreWindow;
 
 use self::activity::{AndroidApp, ConfigurationRef, Rect};
-use crate::event_loop::{ActiveEventLoop, EventLoop, EventLoopBuilder};
-use crate::window::Window;
+pub use crate::event_loop::{
+    ActiveEventLoop, EventLoop, EventLoopProxy, PlatformSpecificEventLoopAttributes,
+    PlatformSpecificWindowAttributes, Window,
+};
 
 /// Additional methods on [`EventLoop`] that are specific to Android.
 pub trait EventLoopExtAndroid {
@@ -80,12 +89,6 @@ pub trait EventLoopExtAndroid {
     fn android_app(&self) -> &AndroidApp;
 }
 
-impl EventLoopExtAndroid for EventLoop {
-    fn android_app(&self) -> &AndroidApp {
-        &self.event_loop.android_app
-    }
-}
-
 /// Additional methods on [`ActiveEventLoop`] that are specific to Android.
 pub trait ActiveEventLoopExtAndroid {
     /// Get the [`AndroidApp`] which was used to create this event loop.
@@ -99,21 +102,21 @@ pub trait WindowExtAndroid {
     fn config(&self) -> ConfigurationRef;
 }
 
-impl WindowExtAndroid for dyn Window + '_ {
+impl WindowExtAndroid for dyn CoreWindow + '_ {
     fn content_rect(&self) -> Rect {
-        let window = self.cast_ref::<crate::platform_impl::Window>().unwrap();
+        let window = self.cast_ref::<Window>().unwrap();
         window.content_rect()
     }
 
     fn config(&self) -> ConfigurationRef {
-        let window = self.cast_ref::<crate::platform_impl::Window>().unwrap();
+        let window = self.cast_ref::<Window>().unwrap();
         window.config()
     }
 }
 
-impl ActiveEventLoopExtAndroid for dyn ActiveEventLoop + '_ {
+impl ActiveEventLoopExtAndroid for dyn CoreActiveEventLoop + '_ {
     fn android_app(&self) -> &AndroidApp {
-        let event_loop = self.cast_ref::<crate::platform_impl::ActiveEventLoop>().unwrap();
+        let event_loop = self.cast_ref::<ActiveEventLoop>().unwrap();
         &event_loop.app
     }
 }
@@ -130,18 +133,6 @@ pub trait EventLoopBuilderExtAndroid {
     fn handle_volume_keys(&mut self) -> &mut Self;
 }
 
-impl EventLoopBuilderExtAndroid for EventLoopBuilder {
-    fn with_android_app(&mut self, app: AndroidApp) -> &mut Self {
-        self.platform_specific.android_app = Some(app);
-        self
-    }
-
-    fn handle_volume_keys(&mut self) -> &mut Self {
-        self.platform_specific.ignore_volume_keys = false;
-        self
-    }
-}
-
 /// Re-export of the `android_activity` API
 ///
 /// Winit re-exports the `android_activity` API for convenience so that most
@@ -170,16 +161,5 @@ pub mod activity {
     // feature enabled, so we avoid inlining it so that they're forced to view
     // it on the crate's own docs.rs page.
     #[doc(no_inline)]
-    #[cfg(android_platform)]
     pub use android_activity::*;
-
-    #[cfg(not(android_platform))]
-    #[doc(hidden)]
-    pub struct Rect;
-    #[cfg(not(android_platform))]
-    #[doc(hidden)]
-    pub struct ConfigurationRef;
-    #[cfg(not(android_platform))]
-    #[doc(hidden)]
-    pub struct AndroidApp;
 }