Render to views on Android/iOS

[maxammann]

At some point we want to render to specific android and ios views and not to the whole screen. This is currently unsupported by winit.

Sadly it is not enough to render to a surface provided by the NDK/UIKit/AppKit. We also need to hook into the input handlers of iOS and Android. Maybe we should think about removing the complete winit dependency and handle all gestures in the corresponding SDKs and control the maplibre view from there. This means that the input handlers would be written in Swift/Kotlin/JavaScript instead of Rust.

iOS:

Difficult because winit is bound to the main UIApplicationView

• https://github.com/rust-windowing/winit/blob/cbba00d3600fa49394dac8538be17a438031622a/src/platform_impl/macos/window.rs#L388
• [iOS] Allow setting up a single UIWindow or UIViewController with either metal or glex context rust-windowing/winit#802
• Consider implementing Lifecycle on controller or view. rust-windowing/winit#1281

Android:

Difficult because winit is bound to the main NativeActivity

• SurfaceTexture NDK bindings rust-mobile/ndk#262
• https://github.com/rust-windowing/winit/blob/cbba00d3600fa49394dac8538be17a438031622a/src/platform_impl/android/mod.rs#L783
• use JNA instead of JNI? https://github.com/java-native-access/jna

Gestures

• Here is now pint-to-zoom is handlen on Android: https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/view/ScaleGestureDetector.java

[maxammann]

Take a look at #91 when thinking about adding gesture/input handling.

[maxammann]

This is a relevant update I believe: rust-windowing/winit#3758