Internal change

android_env/apps/java/com/google/androidenv/MODULE.bazel

@@ -0,0 +1,43 @@
+// Copyright 2025 DeepMind Technologies Limited.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+module(
+    name = "catch",
+    version = "0.1.0",
+)
+
+bazel_dep(name = "rules_kotlin", version = "2.1.8")
+bazel_dep(name = "rules_jvm_external", version = "6.8")
+
+maven = use_extension("@rules_jvm_external//:extensions.bzl", "maven")
+maven.install(
+    artifacts = [
+        "joda-time:joda-time:2.12.7",
+    ],
+    repositories = [
+        "https://repo1.maven.org/maven2",
+    ],
+)
+use_repo(maven, "maven")
+
+bazel_dep(name = "rules_android", version = "0.6.6")
+
+remote_android_extensions = use_extension(
+    "@rules_android//bzlmod_extensions:android_extensions.bzl",
+    "remote_android_tools_extensions",
+)
+use_repo(remote_android_extensions, "android_tools")
+
+android_sdk_repository_extension = use_extension("@rules_android//rules/android_sdk_repository:rule.bzl", "android_sdk_repository_extension")
+use_repo(android_sdk_repository_extension, "androidsdk")

android_env/apps/java/com/google/androidenv/catch/AndroidManifest.xml

@@ -0,0 +1,38 @@
+// Copyright 2025 DeepMind Technologies Limited.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    package="com.google.androidenv.catch">
+    <uses-sdk android:minSdkVersion="26"
+      android:targetSdkVersion="35"/>
+    <application
+        android:allowBackup="false"
+        android:label="@string/app_name"
+        android:supportsRtl="false"
+        android:taskAffinity=""
+        tools:ignore="AllowBackup">
+        <activity
+            android:name=".MainActivity"
+            android:configChanges="orientation|keyboardHidden|screenSize"
+            android:exported="true"
+            android:hardwareAccelerated="true">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+</manifest>

android_env/apps/java/com/google/androidenv/catch/BUILD.bazel

@@ -0,0 +1,78 @@
+// Copyright 2025 DeepMind Technologies Limited.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+# Classic RL task implemented as an Android app.
+
+load("@rules_android//rules:rules.bzl", "android_binary")
+load("@rules_kotlin//kotlin:android.bzl", "kt_android_library")
+
+package(
+    default_applicable_licenses = ["//third_party/py/android_env:license"],
+    default_visibility = ["//catch:__subpackages__"],
+)
+
+licenses(["notice"])
+
+# Build targets will slowly be added to this project and ultimately we'll have
+# an android_binary() target that'll contain the app.
+kt_android_library(
+    name = "GameLogic",
+    srcs = ["GameLogic.kt"],
+    deps = [
+        "//catch/sprite:Background",
+        "//catch/sprite:Ball",
+        "//catch/sprite:LineSegment",
+        "//catch/sprite:Paddle",
+        "@maven//:joda_time_joda_time",
+    ],
+)
+
+kt_android_library(
+    name = "RenderThread",
+    srcs = ["RenderThread.kt"],
+    deps = [
+        ":GameLogic",
+        "@maven//:joda_time_joda_time",
+    ],
+)
+
+kt_android_library(
+    name = "MainActivity",
+    srcs = ["MainActivity.kt"],
+    manifest = "AndroidManifest.xml",
+    resource_files = glob(["res/**"]),
+    deps = [
+        ":GameLogic",
+        ":GameLogicThread",
+        ":RenderThread",
+        "//catch/sprite:Background",
+        "//catch/sprite:Ball",
+        "//catch/sprite:Paddle",
+    ],
+)
+
+android_binary(
+    name = "app",
+    manifest = "AndroidManifest.xml",
+    multidex = "native",
+    deps = [":MainActivity"],
+)
+
+kt_android_library(
+    name = "GameLogicThread",
+    srcs = ["GameLogicThread.kt"],
+    deps = [
+        ":GameLogic",
+    ],
+)

android_env/apps/java/com/google/androidenv/catch/GameLogic.kt

@@ -0,0 +1,76 @@
+// Copyright 2025 DeepMind Technologies Limited.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.androidenv.catch
+
+import android.graphics.Canvas
+import android.view.MotionEvent
+import com.google.androidenv.catch.sprite.Background
+import com.google.androidenv.catch.sprite.Ball
+import com.google.androidenv.catch.sprite.LineSegment
+import com.google.androidenv.catch.sprite.Paddle
+import kotlin.random.Random
+import org.joda.time.Duration
+import org.joda.time.Instant
+
+/** The class that contains the game logic. */
+open class GameLogic(
+  // Expected number of frames per second.
+  fps: Int = 60,
+  // Pseudo random number generator.
+  private val rand: Random = Random.Default,
+  // Width and height of the game in pixels.
+  private val width: Int,
+  private val height: Int,
+  // UI objects in the game.
+  private var background: Background = Background(),
+  private var ball: Ball = Ball(maxX = width, maxY = height, rand = rand),
+  private var paddle: Paddle = Paddle(maxX = width, y = height),
+) {
+
+  private val sleepTime: Duration = Duration.millis((1000.0 / fps).toLong())
+
+  /** Reinitializes the state of the game. */
+  // Need to make this open to allow for testing.
+  open fun reset() {
+    this.ball.reset()
+  }
+
+  /** Runs one "throw" of a [ball] that needs to be caught by the [paddle]. */
+  // Need to make this open to allow for testing.
+  open fun run(): Boolean {
+    var lastTimestamp = Instant.now()
+    do {
+      Thread.sleep(sleepTime.millis)
+      val now = Instant.now()
+      val interval = Duration(lastTimestamp, now)
+      lastTimestamp = now
+      ball.update(interval)
+    } while (!ball.isOutOfBounds())
+
+    return ball.intersects(LineSegment(paddle.topLeft(), paddle.topRight()))
+  }
+
+  /** Processes a user event (e.g. a touchscreen event) and updates the [paddle] accordingly. */
+  fun handleTouch(event: MotionEvent) {
+    paddle.x = event.x.toInt()
+  }
+
+  /** Renders the game on [c]. */
+  open fun render(c: Canvas) {
+    background.draw(c)
+    ball.draw(c)
+    paddle.draw(c)
+  }
+}

android_env/apps/java/com/google/androidenv/catch/GameLogicThread.kt

@@ -0,0 +1,45 @@
+// Copyright 2025 DeepMind Technologies Limited.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.androidenv.catch
+
+import android.util.Log
+
+/** A thread that continuously runs the game logic, resetting after each internal [run()]. */
+class GameLogicThread(private val game: GameLogic, private val loggingTag: String) : Thread() {
+
+  /** Whether this thread should continuously run. */
+  private var shouldRun: Boolean = true
+  /** A counter of game runs. */
+  private var counter: Int = 0
+
+  /**
+   * Lets the current [run()] iteration complete then break exit this [Thread].
+   *
+   * Notice that [shouldRun] cannot have a private getter with a public setter (please see
+   * https://youtrack.jetbrains.com/issue/KT-3110 for details), hence this public function. Also
+   * notice that we cannot call this function [stop()] since it would shadow [Thread.stop()].
+   */
+  public fun finish() {
+    shouldRun = false
+  }
+
+  /** Continuously runs the [game] until [finish()] is called. */
+  public override fun run() {
+    while (shouldRun) {
+      game.reset()
+      Log.i(loggingTag, "${counter++} - ${game.run()}")
+    }
+  }
+}