Android: rework backend to use android_activity crate

This updates the Android backend to use the android_activity crate instead
of ndk-glue. This solves a few issues:
1. The backend is agnostic of the application's choice of Activity base
   class
2. Winit is no longer responsible for handling any Java synchronization
   details, since these are encapsulated by the design of
   android_activity
3. The backend no longer depends on global / static getters for state
   such as the native_window() which puts it in a better position to
   support running multiple activities within a single Android process.
4. Redraw requests are flagged, not queued, in a way that avoids taking
   priority over user events (resolves rust-windowing#2299)

Addresses: PR rust-windowing#1892
Addresses: PR rust-windowing#2307
Addresses: PR rust-windowing#2343

Addresses: rust-windowing#2293
Resolves: rust-windowing#2299

Cargo.toml

@@ -58,7 +58,7 @@ simple_logger = "2.1.0"
 [target.'cfg(target_os = "android")'.dependencies]
 # Coordinate the next winit release with android-ndk-rs: https://github.com/rust-windowing/winit/issues/1995
 ndk = "0.7.0"
-ndk-glue = "0.7.0"
+android-activity = "0.2"
 
 [target.'cfg(any(target_os = "ios", target_os = "macos"))'.dependencies]
 objc = "0.2.7"

src/event_loop.rs

@@ -97,8 +97,18 @@ impl<T> EventLoopBuilder<T> {
     ///   `WINIT_UNIX_BACKEND`. Legal values are `x11` and `wayland`.
     ///   If it is not set, winit will try to connect to a Wayland connection, and if that fails,
     ///   will fall back on X11. If this variable is set with any other value, winit will panic.
+    /// - **Android:** Must be configured with an `AndroidApp` from `android_main()` by calling
+    ///     [`.with_android_app(app)`] before calling `.build()`.
     ///
     /// [`platform`]: crate::platform
+    #[cfg_attr(
+        target_os = "android",
+        doc = "[`.with_android_app(app)`]: crate::platform::android::EventLoopBuilderExtAndroid::with_android_app"
+    )]
+    #[cfg_attr(
+        not(target_os = "android"),
+        doc = "[`.with_android_app(app)`]: #only-available-on-android"
+    )]
     #[inline]
     pub fn build(&mut self) -> EventLoop<T> {
         static EVENT_LOOP_CREATED: OnceCell<()> = OnceCell::new();

src/platform/android.rs

@@ -1,11 +1,11 @@
 #![cfg(any(target_os = "android"))]
 
 use crate::{
-    event_loop::{EventLoop, EventLoopWindowTarget},
+    event_loop::{EventLoop, EventLoopBuilder, EventLoopWindowTarget},
     window::{Window, WindowBuilder},
 };
-use ndk::configuration::Configuration;
-use ndk_glue::Rect;
+
+use android_activity::{AndroidApp, ConfigurationRef, Rect};
 
 /// Additional methods on [`EventLoop`] that are specific to Android.
 pub trait EventLoopExtAndroid {}
@@ -19,15 +19,15 @@ pub trait EventLoopWindowTargetExtAndroid {}
 pub trait WindowExtAndroid {
     fn content_rect(&self) -> Rect;
 
-    fn config(&self) -> Configuration;
+    fn config(&self) -> ConfigurationRef;
 }
 
 impl WindowExtAndroid for Window {
     fn content_rect(&self) -> Rect {
         self.window.content_rect()
     }
 
-    fn config(&self) -> Configuration {
+    fn config(&self) -> ConfigurationRef {
         self.window.config()
     }
 }
@@ -38,3 +38,17 @@ impl<T> EventLoopWindowTargetExtAndroid for EventLoopWindowTarget<T> {}
 pub trait WindowBuilderExtAndroid {}
 
 impl WindowBuilderExtAndroid for WindowBuilder {}
+
+pub trait EventLoopBuilderExtAndroid {
+    /// Associates the `AndroidApp` that was passed to `android_main()` with the event loop
+    ///
+    /// This must be called on Android since the `AndroidApp` is not global state.
+    fn with_android_app(&mut self, app: AndroidApp) -> &mut Self;
+}
+
+impl<T> EventLoopBuilderExtAndroid for EventLoopBuilder<T> {
+    fn with_android_app(&mut self, app: AndroidApp) -> &mut Self {
+        self.platform_specific.android_app = Some(app);
+        self
+    }
+}