Add minimal Cpal audio library example

Based on the android example that's in the cpal repo, this test plays
a 440hz sine wave and is based on GameActivity

Note: this requires a workaround branch for cpal that comments out
a dev-dependency on ndk-glue that cpal has for its android example.
This is needed because Cargo is spuriously propagating this dev
dependency outside of the cpal package (which leads to a crash)

Cargo.toml

@@ -8,6 +8,7 @@ exclude = [
     "examples/agdk-winit-wgpu",
     "examples/agdk-egui",
     "examples/agdk-oboe",
+    "examples/agdk-cpal",
     "examples/na-mainloop",
     "examples/na-winit-wgpu",
     "examples/na-subclass-jni"

examples/agdk-cpal/.gitignore

@@ -0,0 +1,21 @@
+*.iml
+.gradle
+/local.properties
+/.idea/caches
+/.idea/libraries
+/.idea/modules.xml
+/.idea/workspace.xml
+/.idea/navEditor.xml
+/.idea/assetWizardSettings.xml
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+.cxx
+local.properties
+*.so
+
+# Added by cargo
+
+/target
+Cargo.lock

examples/agdk-cpal/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "agdk-cpal"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+log = "0.4"
+android_logger = "0.11.0"
+android-activity = { path="../../android-activity", features = ["game-activity"] }
+cpal = { version = "0.13" }
+atomic_float = "0.1"
+anyhow = "1"
+
+[patch.crates-io]
+cpal = { git = "https://github.com/rib/cpal", branch = "no-ndk-glue-dev-dependency" }
+
+[lib]
+name="main"
+crate_type=["cdylib"]

examples/agdk-cpal/README.md

@@ -0,0 +1,16 @@
+This is a minimal test application based on `GameActivity` that just
+runs a mainloop based on android_activity::poll_events() and plays a
+sine wave audio test using the Cpal audio library.
+
+```
+export ANDROID_NDK_HOME="path/to/ndk"
+export ANDROID_HOME="path/to/sdk"
+
+rustup target add aarch64-linux-android
+cargo install cargo-ndk
+
+cargo ndk -t arm64-v8a -o app/src/main/jniLibs/  build
+./gradlew build
+./gradlew installDebug
+adb shell am start -n co.realfit.agdkcpal/.MainActivity
+```

examples/agdk-cpal/app/.gitignore

@@ -0,0 +1 @@
+/build

examples/agdk-cpal/app/build.gradle

@@ -0,0 +1,61 @@
+plugins {
+    id 'com.android.application'
+}
+
+android {
+    compileSdk 31
+
+    defaultConfig {
+        applicationId "co.realfit.agdkcpal"
+        minSdk 28
+        targetSdk 31
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+        debug {
+            minifyEnabled false
+            //packagingOptions {
+            //    doNotStrip '**/*.so'
+            //}
+            //debuggable true
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+}
+
+dependencies {
+
+    implementation 'androidx.appcompat:appcompat:1.4.1'
+    implementation 'com.google.android.material:material:1.5.0'
+    implementation 'androidx.constraintlayout:constraintlayout:2.1.3'
+    testImplementation 'junit:junit:4.13.2'
+    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
+
+    // To use the Android Frame Pacing library
+    //implementation "androidx.games:games-frame-pacing:1.9.1"
+
+    // To use the Android Performance Tuner
+    //implementation "androidx.games:games-performance-tuner:1.5.0"
+
+    // To use the Games Activity library
+    implementation "androidx.games:games-activity:1.1.0"
+
+    // To use the Games Controller Library
+    //implementation "androidx.games:games-controller:1.1.0"
+
+    // To use the Games Text Input Library
+    //implementation "androidx.games:games-text-input:1.1.0"
+}
+

examples/agdk-cpal/app/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

examples/agdk-cpal/app/src/main/AndroidManifest.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="co.realfit.agdkcpal">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="AGDK Cpal"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.RustTemplate">
+        <activity
+            android:name=".MainActivity"
+            android:configChanges="orientation|screenSize|screenLayout|keyboardHidden"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+
+            <meta-data android:name="android.app.lib_name" android:value="main" />
+        </activity>
+    </application>
+
+</manifest>

examples/agdk-cpal/app/src/main/java/co/realfit/agdkcpal/MainActivity.java

@@ -0,0 +1,70 @@
+package co.realfit.agdkcpal;
+
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.core.view.WindowCompat;
+import androidx.core.view.WindowInsetsCompat;
+import androidx.core.view.WindowInsetsControllerCompat;
+
+import com.google.androidgamesdk.GameActivity;
+
+import android.os.Bundle;
+import android.content.pm.PackageManager;
+import android.os.Build.VERSION;
+import android.os.Build.VERSION_CODES;
+import android.os.Bundle;
+import android.view.View;
+import android.view.WindowManager;
+
+public class MainActivity extends GameActivity {
+
+    static {
+        // Load the STL first to workaround issues on old Android versions:
+        // "if your app targets a version of Android earlier than Android 4.3
+        // (Android API level 18),
+        // and you use libc++_shared.so, you must load the shared library before any other
+        // library that depends on it."
+        // See https://developer.android.com/ndk/guides/cpp-support#shared_runtimes
+        //System.loadLibrary("c++_shared");
+
+        // Load the native library.
+        // The name "android-game" depends on your CMake configuration, must be
+        // consistent here and inside AndroidManifect.xml
+        System.loadLibrary("main");
+    }
+
+    private void hideSystemUI() {
+        // This will put the game behind any cutouts and waterfalls on devices which have
+        // them, so the corresponding insets will be non-zero.
+        if (VERSION.SDK_INT >= VERSION_CODES.P) {
+            getWindow().getAttributes().layoutInDisplayCutoutMode
+                    = WindowManager.LayoutParams.LAYOUT_IN_DISPLAY_CUTOUT_MODE_ALWAYS;
+        }
+        // From API 30 onwards, this is the recommended way to hide the system UI, rather than
+        // using View.setSystemUiVisibility.
+        View decorView = getWindow().getDecorView();
+        WindowInsetsControllerCompat controller = new WindowInsetsControllerCompat(getWindow(),
+                decorView);
+        controller.hide(WindowInsetsCompat.Type.systemBars());
+        controller.hide(WindowInsetsCompat.Type.displayCutout());
+        controller.setSystemBarsBehavior(
+                WindowInsetsControllerCompat.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE);
+    }
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        // When true, the app will fit inside any system UI windows.
+        // When false, we render behind any system UI windows.
+        WindowCompat.setDecorFitsSystemWindows(getWindow(), false);
+        hideSystemUI();
+        // You can set IME fields here or in native code using GameActivity_setImeEditorInfoFields.
+        // We set the fields in native_engine.cpp.
+        // super.setImeEditorInfoFields(InputType.TYPE_CLASS_TEXT,
+        //     IME_ACTION_NONE, IME_FLAG_NO_FULLSCREEN );
+        super.onCreate(savedInstanceState);
+    }
+
+    public boolean isGooglePlayGames() {
+        PackageManager pm = getPackageManager();
+        return pm.hasSystemFeature("com.google.android.play.feature.HPE_EXPERIENCE");
+    }
+}

examples/agdk-cpal/app/src/main/res/drawable-v24/ic_launcher_foreground.xml

@@ -0,0 +1,30 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path android:pathData="M31,63.928c0,0 6.4,-11 12.1,-13.1c7.2,-2.6 26,-1.4 26,-1.4l38.1,38.1L107,108.928l-32,-1L31,63.928z">
+        <aapt:attr name="android:fillColor">
+            <gradient
+                android:endX="85.84757"
+                android:endY="92.4963"
+                android:startX="42.9492"
+                android:startY="49.59793"
+                android:type="linear">
+                <item
+                    android:color="#44000000"
+                    android:offset="0.0" />
+                <item
+                    android:color="#00000000"
+                    android:offset="1.0" />
+            </gradient>
+        </aapt:attr>
+    </path>
+    <path
+        android:fillColor="#FFFFFF"
+        android:fillType="nonZero"
+        android:pathData="M65.3,45.828l3.8,-6.6c0.2,-0.4 0.1,-0.9 -0.3,-1.1c-0.4,-0.2 -0.9,-0.1 -1.1,0.3l-3.9,6.7c-6.3,-2.8 -13.4,-2.8 -19.7,0l-3.9,-6.7c-0.2,-0.4 -0.7,-0.5 -1.1,-0.3C38.8,38.328 38.7,38.828 38.9,39.228l3.8,6.6C36.2,49.428 31.7,56.028 31,63.928h46C76.3,56.028 71.8,49.428 65.3,45.828zM43.4,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2c-0.3,-0.7 -0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C45.3,56.528 44.5,57.328 43.4,57.328L43.4,57.328zM64.6,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2s-0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C66.5,56.528 65.6,57.328 64.6,57.328L64.6,57.328z"
+        android:strokeWidth="1"
+        android:strokeColor="#00000000" />
+</vector>