Initial android support.

Author: dvc94ch

Cargo.toml

@@ -10,3 +10,13 @@ flutter-engine = { git = "https://github.com/flutter-rs/flutter-rs" }
 flutter-winit = { git = "https://github.com/flutter-rs/flutter-rs" }
 glutin = { git = "https://github.com/dvc94ch/glutin", branch = "android" }
 log = "0.4.8"
+
+[target.'cfg(target_os = "android")'.dependencies]
+android_glue = { git = "https://github.com/rust-windowing/android-rs-glue" }
+android_logger = "0.8.6"
+android-ndk = { git = "https://github.com/rust-windowing/android-ndk-rs" }
+jni-glue = "0.0.10"
+
+[target.'cfg(target_os = "android")'.dependencies.jni-android-sys]
+version = "0.0.10"
+features = ["api-level-18", "android-content-Context", "android-content-pm-ApplicationInfo"]

src/main.rs

@@ -2,6 +2,7 @@ use flutter_winit::FlutterWindow;
 use glutin::window::WindowBuilder;
 use std::path::Path;
 
+#[cfg(not(target_os = "android"))]
 fn main() {
     env_logger::init();
 
@@ -23,3 +24,69 @@ fn main() {
 
     flutter.run();
 }
+
+#[cfg(target_os = "android")]
+fn main() {
+    use android_logger::Config;
+    use android_ndk::android_app::AndroidApp;
+    use jni_android_sys::android::content::Context;
+    use log::Level;
+    use std::ffi::OsStr;
+    use std::os::unix::ffi::OsStrExt;
+    use std::path::PathBuf;
+
+    android_logger::init_once(
+        Config::default()
+            .with_min_level(Level::Debug)
+            .with_tag("flutter_app_template"),
+    );
+
+    let android_app = unsafe { AndroidApp::from_ptr(android_glue::get_android_app()) };
+
+    let assets_dir = PathBuf::from(OsStr::from_bytes(
+        android_app.activity().internal_data_path().to_bytes(),
+    ));
+
+    let mut args = Vec::with_capacity(1);
+
+    let vm = unsafe { jni_glue::VM::from_jni_local(&*android_app.activity().vm()) };
+
+    let snapshot = vm.with_env(|env| {
+        let context = Context::new(env).unwrap();
+        let info = context.getApplicationInfo().unwrap().unwrap();
+        let lib_dir = info.nativeLibraryDir().unwrap().to_string().unwrap();
+        Path::new(&lib_dir).join("app.so")
+    });
+
+    if snapshot.exists() {
+        args.push(format!("--aot-shared-library-name={}", snapshot.display()));
+    } else {
+        std::fs::create_dir_all(&assets_dir).unwrap();
+        copy_asset(
+            &android_app.activity().asset_manager(),
+            b"kernel_blob.bin\0",
+            &assets_dir.join("kernel_blob.bin"),
+        );
+    }
+
+    let window = WindowBuilder::new().with_title("Flutter App Demo");
+    let flutter = FlutterWindow::new(window).unwrap();
+
+    flutter.start_engine(Path::new(&assets_dir), &args).unwrap();
+
+    flutter.run();
+}
+
+#[cfg(target_os = "android")]
+fn copy_asset(asset_manager: &android_ndk::asset::AssetManager, asset: &[u8], path: &Path) {
+    use std::ffi::CStr;
+    use std::io::Read;
+
+    let bytes: Vec<u8> = asset_manager
+        .open(CStr::from_bytes_with_nul(asset).unwrap())
+        .unwrap()
+        .bytes()
+        .collect::<Result<_, _>>()
+        .unwrap();
+    std::fs::write(path, bytes).unwrap();
+}