Experimental Android support for eframe

Cargo.lock

@@ -188,6 +188,23 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e999941b234f3131b00bc13c22d06e8c5ff726d1b6318ac7eb276997bbb4fef0"
 
+[[package]]
+name = "android_log-sys"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5ecc8056bf6ab9892dcd53216c83d1597487d7dacac16c8df6b877d127df9937"
+
+[[package]]
+name = "android_logger"
+version = "0.14.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "05b07e8e73d720a1f2e4b6014766e6039fd2e96a4fa44e2a78d0e1fa2ff49826"
+dependencies = [
+ "android_log-sys",
+ "env_filter",
+ "log",
+]
+
 [[package]]
 name = "android_system_properties"
 version = "0.1.5"
@@ -1477,6 +1494,16 @@ dependencies = [
  "syn 2.0.48",
 ]
 
+[[package]]
+name = "env_filter"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4f2c92ceda6ceec50f43169f9ee8424fe2db276791afde7b2cd8bc084cb376ab"
+dependencies = [
+ "log",
+ "regex",
+]
+
 [[package]]
 name = "env_logger"
 version = "0.10.0"
@@ -2091,6 +2118,17 @@ version = "0.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "95505c38b4572b2d910cecb0281560f54b440a19336cbbcb27bf6ce6adc6f5a8"
 
+[[package]]
+name = "hello_android"
+version = "0.1.0"
+dependencies = [
+ "android_logger",
+ "eframe",
+ "egui_extras",
+ "log",
+ "winit",
+]
+
 [[package]]
 name = "hello_world"
 version = "0.1.0"

crates/eframe/src/epi.rs

@@ -364,6 +364,16 @@ pub struct NativeOptions {
     ///
     /// Defaults to true.
     pub dithering: bool,
+
+    /// Android application for `winit`'s event loop.
+    ///
+    /// This value is required on Android to correctly create the event loop. See
+    /// [`EventLoopBuilder::build`] and [`with_android_app`] for details.
+    ///
+    /// [`EventLoopBuilder::build`]: winit::event_loop::EventLoopBuilder::build
+    /// [`with_android_app`]: winit::platform::android::EventLoopBuilderExtAndroid::with_android_app
+    #[cfg(target_os = "android")]
+    pub android_app: Option<winit::platform::android::activity::AndroidApp>,
 }
 
 #[cfg(not(target_arch = "wasm32"))]
@@ -383,6 +393,9 @@ impl Clone for NativeOptions {
 
             persistence_path: self.persistence_path.clone(),
 
+            #[cfg(target_os = "android")]
+            android_app: self.android_app.clone(),
+
             ..*self
         }
     }
@@ -424,6 +437,9 @@ impl Default for NativeOptions {
             persistence_path: None,
 
             dithering: true,
+
+            #[cfg(target_os = "android")]
+            android_app: None,
         }
     }
 }

crates/eframe/src/native/run.rs

@@ -17,9 +17,20 @@ use crate::{
 
 // ----------------------------------------------------------------------------
 fn create_event_loop(native_options: &mut epi::NativeOptions) -> Result<EventLoop<UserEvent>> {
+    #[cfg(target_os = "android")]
+    use winit::platform::android::EventLoopBuilderExtAndroid as _;
+
     crate::profile_function!();
     let mut builder = winit::event_loop::EventLoop::with_user_event();
 
+    #[cfg(target_os = "android")]
+    let mut builder =
+        builder.with_android_app(native_options.android_app.take().ok_or_else(|| {
+            crate::Error::AppCreation(Box::from(
+                "`NativeOptions` is missing required `android_app`",
+            ))
+        })?);
+
     if let Some(hook) = std::mem::take(&mut native_options.event_loop_builder) {
         hook(&mut builder);
     }

examples/hello_android/Cargo.toml

@@ -0,0 +1,32 @@
+[package]
+name = "hello_android"
+version = "0.1.0"
+authors = ["Emil Ernerfeldt <[email protected]>"]
+license = "MIT OR Apache-2.0"
+edition = "2021"
+rust-version = "1.76"
+publish = false
+
+# `unsafe_code` is required for `#[no_mangle]`, disable workspace lints to workaround lint error.
+# [lints]
+# workspace = true
+
+[lib]
+crate-type = ["cdylib"]
+
+
+[dependencies]
+eframe = { workspace = true, features = [
+    "default",
+    "android-native-activity",
+] }
+
+# For image support:
+egui_extras = { workspace = true, features = ["default", "image"] }
+
+log = { workspace = true }
+winit = { workspace = true }
+android_logger = "0.14"
+
+[package.metadata.android]
+build_targets = [ "armv7-linux-androideabi", "aarch64-linux-android" ]

examples/hello_android/README.md

@@ -0,0 +1,20 @@
+Hello world example for Android.
+
+Use `cargo-apk` to build and run. Requires a patch to workaround [an upstream bug](https://github.com/rust-mobile/cargo-subcommand/issues/29).
+
+One-time setup:
+
+```sh
+cargo install \
+    --git https://github.com/parasyte/cargo-apk.git \
+    --rev 282639508eeed7d73f2e1eaeea042da2716436d5 \
+    cargo-apk
+```
+
+Build and run:
+
+```sh
+cargo apk run -p hello_android
+```
+
+![](screenshot.png)

examples/hello_android/src/lib.rs

@@ -0,0 +1,65 @@
+#![cfg(target_os = "android")]
+#![allow(rustdoc::missing_crate_level_docs)] // it's an example
+
+use android_logger::Config;
+use eframe::egui;
+use log::LevelFilter;
+use winit::platform::android::activity::AndroidApp;
+
+#[no_mangle]
+fn android_main(app: AndroidApp) {
+    // Log to android output
+    android_logger::init_once(Config::default().with_max_level(LevelFilter::Info));
+
+    let options = eframe::NativeOptions {
+        android_app: Some(app),
+        ..Default::default()
+    };
+    eframe::run_native(
+        "My egui App",
+        options,
+        Box::new(|cc| {
+            // This gives us image support:
+            egui_extras::install_image_loaders(&cc.egui_ctx);
+
+            Ok(Box::<MyApp>::default())
+        }),
+    )
+    .unwrap()
+}
+
+struct MyApp {
+    name: String,
+    age: u32,
+}
+
+impl Default for MyApp {
+    fn default() -> Self {
+        Self {
+            name: "Arthur".to_owned(),
+            age: 42,
+        }
+    }
+}
+
+impl eframe::App for MyApp {
+    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
+        egui::CentralPanel::default().show(ctx, |ui| {
+            ui.heading("My egui Application");
+            ui.horizontal(|ui| {
+                let name_label = ui.label("Your name: ");
+                ui.text_edit_singleline(&mut self.name)
+                    .labelled_by(name_label.id);
+            });
+            ui.add(egui::Slider::new(&mut self.age, 0..=120).text("age"));
+            if ui.button("Increment").clicked() {
+                self.age += 1;
+            }
+            ui.label(format!("Hello '{}', age {}", self.name, self.age));
+
+            ui.image(egui::include_image!(
+                "../../../crates/egui/assets/ferris.png"
+            ));
+        });
+    }
+}