Car connection

app/build.gradle

@@ -593,6 +593,9 @@ dependencies {
     // https://mvnrepository.com/artifact/com.github.seancfoley/ipaddress
     implementation "com.github.seancfoley:ipaddress:$ipaddress_version"
 
+    // https://mvnrepository.com/artifact/androidx.car.app/app?repo=google
+    // implementation "androidx.car.app:app:1.2.0-rc01"
+
     // https://github.com/square/leakcanary
     // https://square.github.io/leakcanary/getting_started/
     // https://mvnrepository.com/artifact/com.squareup.leakcanary/leakcanary-android

app/src/fdroid/AndroidManifest.xml

@@ -97,6 +97,11 @@
         <intent>
             <action android:name="android.intent.action.TTS_SERVICE" />
         </intent>
+
+        <provider
+            android:name="androidx.car.app.connection.provider"
+            android:authorities="androidx.car.app.connection"
+            tools:ignore="MissingClass" />
     </queries>
 
     <application

app/src/github/AndroidManifest.xml

@@ -97,6 +97,11 @@
         <intent>
             <action android:name="android.intent.action.TTS_SERVICE" />
         </intent>
+
+        <provider
+            android:name="androidx.car.app.connection.provider"
+            android:authorities="androidx.car.app.connection"
+            tools:ignore="MissingClass" />
     </queries>
 
     <application

app/src/main/java/androidx/car/app/connection/CarConnection.java

@@ -0,0 +1,112 @@
+  /*
+   * Copyright 2021 The Android Open Source Project
+   *
+   * 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 androidx.car.app.connection;
+
+  import static androidx.annotation.RestrictTo.Scope.LIBRARY;
+  //import static androidx.car.app.utils.CommonUtils.isAutomotiveOS;
+
+  import static java.util.Objects.requireNonNull;
+
+  import android.content.Context;
+
+  import androidx.annotation.IntDef;
+  import androidx.annotation.NonNull;
+  import androidx.annotation.RestrictTo;
+  import androidx.lifecycle.LiveData;
+
+  import java.lang.annotation.ElementType;
+  import java.lang.annotation.Retention;
+  import java.lang.annotation.RetentionPolicy;
+  import java.lang.annotation.Target;
+
+  /**
+   * A class that allows retrieval of information about connection to a car head unit.
+   */
+  public final class CarConnection {
+      /**
+       * Defines current car connection state.
+       *
+       * <p>This is used for communication with the car host's content provider on queries for
+       * connection type.
+       */
+      public static final String CAR_CONNECTION_STATE = "CarConnectionState";
+
+      /**
+       * Broadcast action that notifies that the car connection has changed and needs to be updated.
+       */
+      public static final String ACTION_CAR_CONNECTION_UPDATED =
+              "androidx.car.app.connection.action.CAR_CONNECTION_UPDATED";
+
+      /**
+       * Represents the types of connections that exist to a car head unit.
+       *
+       * @hide
+       */
+      @IntDef({CONNECTION_TYPE_NOT_CONNECTED, CONNECTION_TYPE_NATIVE, CONNECTION_TYPE_PROJECTION})
+      @Retention(RetentionPolicy.SOURCE)
+      @Target({ElementType.TYPE_USE})
+      @RestrictTo(LIBRARY)
+      public @interface ConnectionType {
+      }
+
+      /**
+       * Not connected to any car head unit.z
+       */
+      public static final int CONNECTION_TYPE_NOT_CONNECTED = 0;
+
+      /**
+       * Natively running on a head unit (Android Automotive OS).
+       */
+      public static final int CONNECTION_TYPE_NATIVE = 1;
+
+      /**
+       * Connected to a car head unit by projecting to it.
+       */
+      public static final int CONNECTION_TYPE_PROJECTION = 2;
+
+      private final LiveData<Integer> mConnectionTypeLiveData;
+
+      /**
+       * Constructs a {@link CarConnection} that can be used to get connection information.
+       *
+       * @throws NullPointerException if {@code context} is {@code null}
+       */
+      public CarConnection(@NonNull Context context) {
+          requireNonNull(context);
+          mConnectionTypeLiveData = /*isAutomotiveOS(context)
+                  ? new AutomotiveCarConnectionTypeLiveData()
+                  :*/ new CarConnectionTypeLiveData(context);
+      }
+
+      /**
+       * Returns a {@link LiveData} that can be observed to get current connection type.
+       *
+       * <p>The recommended pattern is to observe the {@link LiveData} with the activity's
+       * lifecycle in order to get updates on the state change throughout the activity's lifetime.
+       *
+       * <p>Connection types are:
+       * <ol>
+       *     <li>{@link #CONNECTION_TYPE_NOT_CONNECTED}
+       *     <li>{@link #CONNECTION_TYPE_NATIVE}
+       *     <li>{@link #CONNECTION_TYPE_PROJECTION}
+       * </ol>
+       */
+      @NonNull
+      public LiveData<@ConnectionType Integer> getType() {
+          return mConnectionTypeLiveData;
+      }
+  }

app/src/main/java/androidx/car/app/connection/CarConnectionTypeLiveData.java

@@ -0,0 +1,120 @@
+/*
+ * Copyright 2021 The Android Open Source Project
+ *
+ * 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 androidx.car.app.connection;
+
+import static androidx.car.app.connection.CarConnection.ACTION_CAR_CONNECTION_UPDATED;
+import static androidx.car.app.connection.CarConnection.CAR_CONNECTION_STATE;
+//import static androidx.car.app.utils.LogTags.TAG_CONNECTION_TO_CAR;
+
+import android.content.AsyncQueryHandler;
+import android.content.BroadcastReceiver;
+import android.content.ContentResolver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.database.Cursor;
+import android.net.Uri;
+import android.util.Log;
+
+import androidx.annotation.VisibleForTesting;
+import androidx.car.app.connection.CarConnection.ConnectionType;
+import androidx.lifecycle.LiveData;
+
+/**
+ * A {@link LiveData} that will query once while being observed and only again if it gets updates
+ * via a broadcast.
+ */
+final class CarConnectionTypeLiveData extends LiveData<@ConnectionType Integer> {
+    @VisibleForTesting
+    static final String CAR_CONNECTION_AUTHORITY = "androidx.car.app.connection";
+
+    private static final int QUERY_TOKEN = 42;
+    private static final Uri PROJECTION_HOST_URI = new Uri.Builder().scheme("content").authority(
+            CAR_CONNECTION_AUTHORITY).build();
+
+    private final Context mContext;
+    private final AsyncQueryHandler mQueryHandler;
+    private final CarConnectionBroadcastReceiver mBroadcastReceiver;
+
+    CarConnectionTypeLiveData(Context context) {
+        mContext = context;
+
+        mQueryHandler = new CarConnectionQueryHandler(
+                context.getContentResolver());
+        mBroadcastReceiver = new CarConnectionBroadcastReceiver();
+    }
+
+    @Override
+    public void onActive() {
+        mContext.registerReceiver(mBroadcastReceiver,
+                new IntentFilter(ACTION_CAR_CONNECTION_UPDATED));
+        queryForState();
+    }
+
+    @Override
+    public void onInactive() {
+        mContext.unregisterReceiver(mBroadcastReceiver);
+        mQueryHandler.cancelOperation(QUERY_TOKEN);
+    }
+
+    void queryForState() {
+        mQueryHandler.startQuery(/* token= */ QUERY_TOKEN, /* cookie= */ null,
+                /* uri */ PROJECTION_HOST_URI,
+                /* projection= */ new String[]{CAR_CONNECTION_STATE}, /* selection= */ null,
+                /* selectionArgs= */ null, /* orderBy= */ null);
+    }
+
+    class CarConnectionQueryHandler extends AsyncQueryHandler {
+        CarConnectionQueryHandler(ContentResolver resolver) {
+            super(resolver);
+        }
+
+        @Override
+        protected void onQueryComplete(int token, Object cookie, Cursor response) {
+            if (response == null) {
+                //Log.w(TAG_CONNECTION_TO_CAR, "Null response from content provider when checking "
+                //        + "connection to the car, treating as disconnected");
+                postValue(CarConnection.CONNECTION_TYPE_NOT_CONNECTED);
+                return;
+            }
+
+            int carConnectionTypeColumn = response.getColumnIndex(CAR_CONNECTION_STATE);
+            if (carConnectionTypeColumn < 0) {
+                //Log.e(TAG_CONNECTION_TO_CAR, "Connection to car response is missing the "
+                //        + "connection type, treating as disconnected");
+                postValue(CarConnection.CONNECTION_TYPE_NOT_CONNECTED);
+                return;
+            }
+
+            if (!response.moveToNext()) {
+                //Log.e(TAG_CONNECTION_TO_CAR, "Connection to car response is empty, treating as "
+                //        + "disconnected");
+                postValue(CarConnection.CONNECTION_TYPE_NOT_CONNECTED);
+                return;
+            }
+
+            postValue(response.getInt(carConnectionTypeColumn));
+        }
+    }
+
+    class CarConnectionBroadcastReceiver extends BroadcastReceiver {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            queryForState();
+        }
+    }
+}