Use InputMethodManager#showSoftInput to show_soft_input

This updates `AndroidApp::show/hide_soft_input` to be implemented
manually with JNI (instead of `ANativeActivity_show/hideSoftInput`) so
that we can pass the root, decor view to
`InputMethodManager.showSoftInput` instead of the private
`mNativeContentView` created by `NativeActivity`.

Unlike the private `mNativeContentView`, the root decor view is
considered to be the current "served" view for a vanilla
`NativeActivity`-based application.

Co-authored-by: Robert Bragg <robert@sixbynine.org>

android-activity/CHANGELOG.md

@@ -61,6 +61,7 @@ fn android_on_create(state: &OnCreateState) {
 - *Safety* The `native-activity` backend clears its `ANativeActivity` ptr after `onDestroy` and `AndroidApp` remains safe to access after `android_main()` returns ([#234](https://github.com/rust-mobile/android-activity/pull/234))
 - *Safety* `AndroidApp::activity_as_ptr()` returns a pointer to a global reference that remains valid until `AndroidApp` is dropped, instead of the `ANativeActivity`'s `clazz` pointer which is only guaranteed to be valid until `onDestroy` returns (`native-activity` backend) ([#234](https://github.com/rust-mobile/android-activity/pull/234))
 - *Safety* The `game-activity` backend clears its `android_app` ptr after `onDestroy` and `AndroidApp` remains safe to access after `android_main()` returns ([#236](https://github.com/rust-mobile/android-activity/pull/236))
+- Support for `AndroidApp::show/hide_soft_input()` APIs in the `native-activity` backend ([#178](https://github.com/rust-mobile/android-activity/pull/178))
 
 ## [0.6.0] - 2024-04-26
 

android-activity/src/game_activity/mod.rs

@@ -128,7 +128,7 @@ impl AndroidApp {
     ) -> Self {
         // We attach to the thread before creating the AndroidApp
         jvm.with_local_frame(10, |env| -> jni::errors::Result<_> {
-            if let Err(err) = crate::input::jni_init(env) {
+            if let Err(err) = crate::sdk::jni_init(env) {
                 panic!("Failed to init JNI bindings: {err:?}");
             };
 

android-activity/src/input/sdk.rs

@@ -107,8 +107,7 @@ impl AKeyCharacterMap<'_> {
 }
 
 jni::bind_java_type! {
-    rust_type = AInputDevice,
-    java_type = "android.view.InputDevice",
+    pub(crate) AInputDevice => "android.view.InputDevice",
     type_map {
         AKeyCharacterMap => "android.view.KeyCharacterMap",
     },
@@ -118,14 +117,6 @@ jni::bind_java_type! {
     }
 }
 
-// Explicitly initialize the JNI bindings so we can get and early, upfront,
-// error if something is wrong.
-pub fn jni_init(env: &jni::Env) -> jni::errors::Result<()> {
-    let _ = AKeyCharacterMapAPI::get(env, &Default::default())?;
-    let _ = AInputDeviceAPI::get(env, &Default::default())?;
-    Ok(())
-}
-
 /// Describes the keys provided by a keyboard device and their associated labels.
 #[derive(Debug)]
 pub struct KeyCharacterMap {

android-activity/src/lib.rs

@@ -395,6 +395,8 @@ mod util;
 
 mod jni_utils;
 
+mod sdk;
+
 mod waker;
 pub use waker::AndroidAppWaker;
 

android-activity/src/native_activity/mod.rs

@@ -14,6 +14,7 @@ use ndk::{asset::AssetManager, native_window::NativeWindow};
 
 use crate::error::InternalResult;
 use crate::main_callbacks::MainCallbacks;
+use crate::sdk::{Activity, Context, InputMethodManager};
 use crate::{
     util, AndroidApp, AndroidAppWaker, ConfigurationRef, InputStatus, MainEvent, PollEvent, Rect,
     WindowManagerFlags,
@@ -72,7 +73,7 @@ impl AndroidApp {
         jni_activity: &JObject,
     ) -> Self {
         jvm.with_local_frame(10, |env| -> jni::errors::Result<_> {
-            if let Err(err) = crate::input::jni_init(env) {
+            if let Err(err) = crate::sdk::jni_init(env) {
                 panic!("Failed to init JNI bindings: {err:?}");
             };
 
@@ -368,13 +369,29 @@ impl AndroidAppInner {
             log::error!("Can't show soft input after NativeActivity has been destroyed");
             return;
         }
-        unsafe {
-            let flags = if show_implicit {
-                ndk_sys::ANATIVEACTIVITY_SHOW_SOFT_INPUT_IMPLICIT
-            } else {
-                0
-            };
-            ndk_sys::ANativeActivity_showSoftInput(na as *mut _, flags);
+
+        // Note: `.attach_current_thread()` will also handle catching any Java exceptions that
+        // might be thrown by the JNI calls we make.
+        let res = self
+            .jvm
+            .attach_current_thread(|env| -> jni::errors::Result<()> {
+                let activity = env.as_cast::<Activity>(self.activity.as_ref())?;
+
+                let ims = Context::INPUT_METHOD_SERVICE(env)?;
+                let im_manager = activity.as_context().get_system_service(env, ims)?;
+                let im_manager = InputMethodManager::cast_local(env, im_manager)?;
+                let jni_window = activity.get_window(env)?;
+                let view = jni_window.get_decor_view(env)?;
+                let flags = if show_implicit {
+                    ndk_sys::ANATIVEACTIVITY_SHOW_SOFT_INPUT_IMPLICIT as i32
+                } else {
+                    0
+                };
+                im_manager.show_soft_input(env, view, flags)?;
+                Ok(())
+            });
+        if let Err(err) = res {
+            log::warn!("Failed to show soft input: {err:?}");
         }
     }
 
@@ -386,13 +403,31 @@ impl AndroidAppInner {
             log::error!("Can't hide soft input after NativeActivity has been destroyed");
             return;
         }
-        unsafe {
-            let flags = if hide_implicit_only {
-                ndk_sys::ANATIVEACTIVITY_HIDE_SOFT_INPUT_IMPLICIT_ONLY
-            } else {
-                0
-            };
-            ndk_sys::ANativeActivity_hideSoftInput(na as *mut _, flags);
+
+        // Note: `.attach_current_thread()` will also handle catching any Java exceptions that
+        // might be thrown by the JNI calls we make.
+        let res = self
+            .jvm
+            .attach_current_thread(|env| -> jni::errors::Result<()> {
+                let activity = env.as_cast::<Activity>(self.activity.as_ref())?;
+
+                let ims = Context::INPUT_METHOD_SERVICE(env)?;
+                let imm_obj = activity.as_context().get_system_service(env, ims)?;
+                let imm = InputMethodManager::cast_local(env, imm_obj)?;
+
+                let window = activity.get_window(env)?;
+                let decor = window.get_decor_view(env)?;
+                let token = decor.get_window_token(env)?;
+
+                // HIDE_IMPLICIT_ONLY == 1, HIDE_NOT_ALWAYS == 2
+                let flags = if hide_implicit_only { 1 } else { 0 };
+
+                let _hidden = imm.hide_soft_input_from_window(env, token, flags)?;
+                Ok(())
+            });
+
+        if let Err(err) = res {
+            error!("Failed to hide soft input: {err:?}");
         }
     }
 

android-activity/src/sdk.rs

@@ -0,0 +1,67 @@
+jni::bind_java_type! { pub(crate) IBinder => "android.os.IBinder" }
+jni::bind_java_type! {
+    pub(crate) View => "android.view.View",
+    type_map {
+        IBinder => "android.os.IBinder",
+    },
+    methods {
+        fn get_window_token() -> IBinder,
+    }
+}
+jni::bind_java_type! {
+    pub(crate) InputMethodManager => "android.view.inputmethod.InputMethodManager",
+    type_map {
+        View => "android.view.View",
+        IBinder => "android.os.IBinder",
+    },
+    methods {
+        fn show_soft_input(view: View, flags: i32) -> bool,
+        fn hide_soft_input_from_window(window_token: IBinder, flags: i32) -> bool,
+    }
+}
+jni::bind_java_type! {
+    pub(crate) Context => "android.content.Context",
+    fields {
+        #[allow(non_snake_case)]
+        static INPUT_METHOD_SERVICE: JString
+    },
+    methods {
+        fn get_system_service(service_name: JString) -> JObject,
+    }
+}
+jni::bind_java_type! {
+    pub(crate) Window => "android.view.Window",
+    type_map {
+        View => "android.view.View",
+    },
+    methods {
+        fn get_decor_view() -> View,
+    }
+}
+jni::bind_java_type! {
+    pub(crate) Activity => "android.app.Activity",
+    type_map {
+        Context => "android.content.Context",
+        Window => "android.view.Window",
+    },
+    is_instance_of {
+        context: Context
+    },
+    methods {
+        fn get_window() -> Window,
+    }
+}
+
+// Explicitly initialize the JNI bindings so we can get and early, upfront,
+// error if something is wrong.
+pub(crate) fn jni_init(env: &jni::Env) -> jni::errors::Result<()> {
+    let _ = IBinderAPI::get(env, &Default::default())?;
+    let _ = ViewAPI::get(env, &Default::default())?;
+    let _ = InputMethodManagerAPI::get(env, &Default::default())?;
+    let _ = ContextAPI::get(env, &Default::default())?;
+    let _ = WindowAPI::get(env, &Default::default())?;
+    let _ = ActivityAPI::get(env, &Default::default())?;
+    let _ = crate::input::AKeyCharacterMapAPI::get(env, &Default::default())?;
+    let _ = crate::input::AInputDeviceAPI::get(env, &Default::default())?;
+    Ok(())
+}