Add support for InputEvent::TextAction events

This exposes IME actions via an InputEvent::TextAction event so that
it's possible to recognise when text entry via an input method is
finished.

This adds a `TextInputAction` enum to represent the action key on a soft
keyboard, such as "Done".

For example, this makes it possible to emit Ime::Commit events in Winit.

android-activity/CHANGELOG.md

@@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- input: TextInputAction enum representing action button types on soft keyboards.
+- input: InputEvent::TextAction event for handling action button presses from soft keyboards.
 - The `ndk` and `ndk-sys` crates are now re-exported under `android_activity::ndk` and `android_activity::ndk_sys` ([#194](https://github.com/rust-mobile/android-activity/pull/194))
 
 ### Changed

android-activity/src/game_activity/input.rs

@@ -27,6 +27,7 @@ pub enum InputEvent<'a> {
     MotionEvent(MotionEvent<'a>),
     KeyEvent(KeyEvent<'a>),
     TextEvent(crate::input::TextInputState),
+    TextAction(crate::input::TextInputAction),
 }
 
 /// A motion event.

android-activity/src/game_activity/mod.rs

@@ -21,7 +21,7 @@ use ndk::configuration::Configuration;
 use ndk::native_window::NativeWindow;
 
 use crate::error::InternalResult;
-use crate::input::{Axis, KeyCharacterMap, KeyCharacterMapBinding};
+use crate::input::{Axis, KeyCharacterMap, KeyCharacterMapBinding, TextInputAction};
 use crate::jni_utils::{self, CloneJavaVM};
 use crate::util::{abort_on_panic, forward_stdio_to_logcat, log_panic, try_get_path_from_ptr};
 use crate::{
@@ -174,9 +174,6 @@ impl NativeAppGlue {
             };
             let out_ptr = &mut out_state as *mut TextInputState;
 
-            let app_ptr = self.as_ptr();
-            (*app_ptr).textInputState = 0;
-
             // NEON WARNING:
             //
             // It's not clearly documented but the GameActivity API over the
@@ -204,6 +201,14 @@ impl NativeAppGlue {
         }
     }
 
+    pub fn take_text_input_state(&self) -> TextInputState {
+        unsafe {
+            let app_ptr = self.as_ptr();
+            (*app_ptr).textInputState = 0;
+        }
+        self.text_input_state()
+    }
+
     // TODO: move into a trait
     pub fn set_text_input_state(&self, state: TextInputState) {
         unsafe {
@@ -247,6 +252,18 @@ impl NativeAppGlue {
             ffi::GameActivity_setTextInputState(activity, &ffi_state as *const _);
         }
     }
+
+    pub fn take_pending_editor_action(&self) -> Option<i32> {
+        unsafe {
+            let app_ptr = self.as_ptr();
+            if (*app_ptr).pendingEditorAction {
+                (*app_ptr).pendingEditorAction = false;
+                Some((*app_ptr).editorAction)
+            } else {
+                None
+            }
+        }
+    }
 }
 
 #[derive(Debug)]
@@ -804,7 +821,8 @@ impl<'a> From<Arc<InputReceiver>> for InputIteratorInner<'a> {
             _receiver: receiver,
             buffered,
             native_app,
-            text_event_checked: false,
+            ime_text_input_state_checked: false,
+            ime_editor_action_checked: false,
         }
     }
 }
@@ -821,7 +839,8 @@ pub(crate) struct InputIteratorInner<'a> {
 
     buffered: Option<BufferedEvents<'a>>,
     native_app: NativeAppGlue,
-    text_event_checked: bool,
+    ime_text_input_state_checked: bool,
+    ime_editor_action_checked: bool,
 }
 
 impl InputIteratorInner<'_> {
@@ -841,8 +860,10 @@ impl InputIteratorInner<'_> {
             self.buffered = None;
         }
 
-        if !self.text_event_checked {
-            self.text_event_checked = true;
+        // We make sure any input state changes are sent before we check
+        // for editor actions, so actions will apply to the latest state.
+        if !self.ime_text_input_state_checked {
+            self.ime_text_input_state_checked = true;
             unsafe {
                 let app_ptr = self.native_app.as_ptr();
 
@@ -854,12 +875,21 @@ impl InputIteratorInner<'_> {
                 // the compiler isn't reordering code so this gets flagged
                 // before the java main thread really updates the state.
                 if (*app_ptr).textInputState != 0 {
-                    let state = self.native_app.text_input_state(); // Will clear .textInputState
+                    let state = self.native_app.take_text_input_state(); // Will clear .textInputState
                     let _ = callback(&InputEvent::TextEvent(state));
                     return true;
                 }
             }
         }
+
+        if !self.ime_editor_action_checked {
+            self.ime_editor_action_checked = true;
+            if let Some(action) = self.native_app.take_pending_editor_action() {
+                let _ = callback(&InputEvent::TextAction(TextInputAction::from(action)));
+                return true;
+            }
+        }
+
         false
     }
 }

android-activity/src/input.rs

@@ -907,6 +907,33 @@ pub struct TextInputState {
     pub compose_region: Option<TextSpan>,
 }
 
+// Represents the action button on a soft keyboard.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, num_enum::FromPrimitive, num_enum::IntoPrimitive)]
+#[non_exhaustive]
+#[repr(i32)]
+pub enum TextInputAction {
+    /// Let receiver decide what logical action to perform
+    Unspecified = 0,
+    /// No action - receiver could instead interpret as an "enter" key that inserts a newline character
+    None = 1,
+    /// Navigate to the input location (such as a URL)
+    Go = 2,
+    /// Search based on the input text
+    Search = 3,
+    /// Send the input to the target
+    Send = 4,
+    /// Move to the next input field
+    Next = 5,
+    /// Indicate that input is done
+    Done = 6,
+    /// Move to the previous input field
+    Previous = 7,
+
+    #[doc(hidden)]
+    #[num_enum(catch_all)]
+    __Unknown(i32),
+}
+
 /// An exclusive, lending iterator for input events
 pub struct InputIterator<'a> {
     pub(crate) inner: crate::activity_impl::InputIteratorInner<'a>,

android-activity/src/native_activity/input.rs

@@ -434,4 +434,5 @@ pub enum InputEvent<'a> {
     MotionEvent(self::MotionEvent<'a>),
     KeyEvent(self::KeyEvent<'a>),
     TextEvent(crate::input::TextInputState),
+    TextAction(crate::input::TextInputAction),
 }