refactor!: Simplify the core Android adapter API

platforms/android/Cargo.toml

@@ -19,5 +19,3 @@ accesskit = { version = "0.18.0", path = "../../common" }
 accesskit_consumer = { version = "0.27.0", path = "../../consumer" }
 jni = "0.21.1"
 log = "0.4.17"
-once_cell = "1.17.1"
-

platforms/android/src/action.rs

@@ -0,0 +1,69 @@
+// Copyright 2025 The AccessKit Authors. All rights reserved.
+// Licensed under the Apache License, Version 2.0 (found in
+// the LICENSE-APACHE file) or the MIT license (found in
+// the LICENSE-MIT file), at your option.
+
+use jni::{objects::JObject, sys::jint, JNIEnv};
+
+use crate::util::*;
+
+pub(crate) enum PlatformActionInner {
+    Simple {
+        action: jint,
+    },
+    SetTextSelection {
+        anchor: jint,
+        focus: jint,
+    },
+    CollapseTextSelection,
+    TraverseText {
+        granularity: jint,
+        forward: bool,
+        extend_selection: bool,
+    },
+}
+
+pub struct PlatformAction(pub(crate) PlatformActionInner);
+
+impl PlatformAction {
+    pub fn from_java(env: &mut JNIEnv, action: jint, arguments: &JObject) -> Option<Self> {
+        match action {
+            ACTION_SET_SELECTION => {
+                if !(!arguments.is_null()
+                    && bundle_contains_key(env, arguments, ACTION_ARGUMENT_SELECTION_START_INT)
+                    && bundle_contains_key(env, arguments, ACTION_ARGUMENT_SELECTION_END_INT))
+                {
+                    return Some(Self(PlatformActionInner::CollapseTextSelection));
+                }
+                let anchor = bundle_get_int(env, arguments, ACTION_ARGUMENT_SELECTION_START_INT);
+                let focus = bundle_get_int(env, arguments, ACTION_ARGUMENT_SELECTION_END_INT);
+                Some(Self(PlatformActionInner::SetTextSelection {
+                    anchor,
+                    focus,
+                }))
+            }
+            ACTION_NEXT_AT_MOVEMENT_GRANULARITY | ACTION_PREVIOUS_AT_MOVEMENT_GRANULARITY => {
+                if arguments.is_null()
+                    || !bundle_contains_key(
+                        env,
+                        arguments,
+                        ACTION_ARGUMENT_MOVEMENT_GRANULARITY_INT,
+                    )
+                {
+                    return None;
+                }
+                let granularity =
+                    bundle_get_int(env, arguments, ACTION_ARGUMENT_MOVEMENT_GRANULARITY_INT);
+                let forward = action == ACTION_NEXT_AT_MOVEMENT_GRANULARITY;
+                let extend_selection =
+                    bundle_get_bool(env, arguments, ACTION_ARGUMENT_EXTEND_SELECTION_BOOLEAN);
+                Some(Self(PlatformActionInner::TraverseText {
+                    granularity,
+                    forward,
+                    extend_selection,
+                }))
+            }
+            _ => Some(Self(PlatformActionInner::Simple { action })),
+        }
+    }
+}