You signed in with another tab or window. Reload to refresh your session.You signed out in another tab or window. Reload to refresh your session.You switched accounts on another tab or window. Reload to refresh your session.Dismiss alert
`android-activity` provides a "glue" layer for building native Rust
4
11
applications on Android, supporting multiple [`Activity`] base classes.
@@ -22,10 +29,11 @@ applications.
22
29
[ndk-glue]: https://crates.io/crates/ndk-glue
23
30
[agdk]: https://developer.android.com/games/agdk
24
31
25
-
# Example
32
+
##Example
26
33
27
34
Cargo.toml
28
-
```
35
+
36
+
```toml
29
37
[dependencies]
30
38
log = "0.4"
31
39
android_logger = "0.11"
@@ -38,6 +46,7 @@ crate_type = ["cdylib"]
38
46
_Note: that you will need to either specify the **"native-activity"** feature or **"game-activity"** feature to identify which `Activity` base class your application is based on_
See [this collection of examples](https://github.com/rust-mobile/rust-android-examples) (based on both `GameActivity` and `NativeActivity`).
82
91
83
92
Each example is a standalone project that may also be a convenient templates for starting a new project.
84
93
85
94
For the examples based on middleware frameworks (Winit and or Egui) they also aim to demonstrate how it's possible to write portable code that will run on Android and other systems.
86
95
87
-
# Should I use NativeActivity or GameActivity?
96
+
##Should I use NativeActivity or GameActivity?
88
97
89
98
To learn more about the `NativeActivity` class that's shipped with Android see [here](https://developer.android.com/ndk/guides/concepts#naa).
90
99
@@ -96,22 +105,23 @@ It's expected that the `GameActivity` backend will gain more sophisticated input
96
105
97
106
Even if you start out using `NativeActivity` for the convenience, it's likely that most moderately complex applications will eventually need to define their own `Activity` subclass (either subclassing `NativeActivity` or `GameActivity`) which will require compiling at least a small amount of Java or Kotlin code. This is generally due to Android's design which directs numerous events via the `Activity` class which can only be processed by overloading some associated Activity method.
98
107
99
-
# Switching from ndk-glue to android-activity
108
+
## Switching from ndk-glue to android-activity
109
+
110
+
### Winit-based applications
100
111
101
-
## Winit-based applications
102
112
Firstly; if you have a [Winit](https://crates.io/crates/winit) based application and also have an explicit dependency on `ndk-glue` your application will need to remove its dependency on `ndk-glue` for the 0.28 release of Winit which will be based on android-activity (Since glue crates, due to their nature, can't be compatible with alternative glue crates).
103
113
104
114
Winit-based applications can follow the [Android README](https://github.com/rust-windowing/winit#android) guidance for advice on how to switch over. Most Winit-based applications should aim to remove any explicit dependency on a specific glue crate (so not depend directly on `ndk-glue` or `android-activity` and instead rely on Winit to pull in the right glue crate). The main practical change will then be to add a `#[no_mangle]fn android_main(app: AndroidApp)` entry point.
105
115
106
116
See the [Android README](https://github.com/rust-windowing/winit#android) for more details and also see the [Winit-based examples here](https://github.com/rust-mobile/rust-android-examples).
107
117
108
-
## Middleware crates (i.e. not applications)
118
+
###Middleware crates (i.e. not applications)
109
119
110
120
If you have a crate that would be considered a middleware library (for example using JNI to support access to Bluetooth, or Android's Camera APIs) then the crate should almost certainly remove any dependence on a specific glue crate because this imposes a strict compatibility constraint that means the crate can only be used by applications that use that exact same glue crate version.
111
121
112
122
Middleware libraries can instead look at using the [ndk-context](https://crates.io/crates/ndk-context) crate as a means for being able to use JNI without making any assumptions about the applications overall architecture. This way a middleware crate can work with alternative glue crates (including `ndk-glue` and `android-activity`) as well as work with embedded use cases (i.e. non-native applications that may just embed a dynamic library written in Rust to implement certain native functions).
113
123
114
-
## Other, non-Winit-based applications
124
+
###Other, non-Winit-based applications
115
125
116
126
The steps to switch a simple standalone application over from `ndk-glue` to `android-activity` (still based on `NativeActivity`) should be:
117
127
@@ -120,7 +130,7 @@ The steps to switch a simple standalone application over from `ndk-glue` to `and
120
130
3. Optionally add a dependency on `android_logger = "0.11.0"`
121
131
4. Update the `main` entry point to look like this:
122
132
123
-
```
133
+
```rust
124
134
useandroid_activity::AndroidApp;
125
135
126
136
#[no_mangle]
@@ -133,21 +143,18 @@ See this minimal [NativeActivity Mainloop](https://github.com/rust-mobile/androi
133
143
134
144
There is is no `#[ndk_glue::main]` replacement considering that `android_main()` entry point needs to be passed an `AndroidApp` argument which isn't compatible with a traditional `main()` function. Having an Android specific entry point also gives a place to initialize Android logging and handle other Android specific details (such as building an event loop based on the `app` argument)
Prior to working on android-activity, the existing glue crates available for building standalone Rust applications on Android were found to have a number of technical limitations that this crate aimed to solve:
140
149
141
150
1.**Support alternative Activity classes**: Prior glue crates were based on `NativeActivity` and their API precluded supporting alternatives. In particular there was an interest in the [`GameActivity`] class in conjunction with it's [`GameTextInput`] library that can facilitate onscreen keyboard support. This also allows building applications based on the standard [`AppCompatActivity`] base class which isn't possible with `NativeActivity`. Finally there was interest in paving the way towards supporting a first-party `RustActivity` that could be best tailored towards the needs of Rust applications on Android.
142
151
2.**Encapsulate IPC + synchronization between the native thread and the JVM thread**: For example with `ndk-glue` the application itself needs to avoid race conditions between the native and Java thread by following a locking convention) and it wasn't clear how this would extend to support other requests (like state saving) that also require synchronization.
143
152
3.**Avoid static global state**: Keeping in mind the possibility of supporting applications with multiple native activities there was interest in having an API that didn't rely on global statics to track top-level state. Instead of having global getters for state then `android-activity` passes an explicit `app: AndroidApp` argument to the entry point that encapsulates the state connected with a single `Activity`.
We aim to (at least) support stable releases of Rust from the last three months. Rust has a 6 week release cycle which means we will support the last three stable releases.
153
160
For example, when Rust 1.69 is released we would limit our `rust_version` to 1.67.
0 commit comments