Support two pane design in the Settings app.

1. Only enable this feature when the flag is on and library is supported
in this device.
2. Add a placeholder rule for home menu.
Network page will be shown to the right pane by default.
3. Add a rule for most sub settings pages.

Known issues:
1. Transition animation seems wrong in this cl.
2. App is closed if user taps back key on the second layer page in fold
state.

Test: Run the apk on large screen device and regular phone. No crash
happens
Bug: 197716926

Change-Id: I089717e84c5e92c6e5b02d9770a24376e250fea2

src/com/android/settings/activityembedding/ActivityEmbeddingRulesController.java

@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 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 com.android.settings.activityembedding;
+
+import android.app.Activity;
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.util.LayoutDirection;
+import android.util.Log;
+
+import androidx.annotation.NonNull;
+import androidx.window.embedding.ActivityFilter;
+import androidx.window.embedding.SplitController;
+import androidx.window.embedding.SplitPairFilter;
+import androidx.window.embedding.SplitPairRule;
+import androidx.window.embedding.SplitPlaceholderRule;
+
+import com.android.settings.Settings;
+import com.android.settings.SubSettings;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/** A class to initialize split rules for activity embedding. */
+public class ActivityEmbeddingRulesController {
+
+    private static final String TAG = "ActivityEmbeddingCtrl ";
+    private final Context mContext;
+    private final SplitController mSplitController;
+
+    public ActivityEmbeddingRulesController(Context context) {
+        mContext = context;
+        mSplitController = new SplitController(context);
+    }
+
+    /**
+     * Set up embedding rules to place activities to the right pane.
+     */
+    public void initRules() {
+        if (!ActivityEmbeddingUtils.isEmbeddingActivityEnabled(mContext)) {
+            Log.d(TAG, "Not support this feature now");
+            return;
+        }
+
+        mSplitController.clearRegisteredRules();
+
+        // Set a placeholder for home page.
+        mSplitController.registerRule(getHomepagePlaceholderRule());
+        // Set subsettings rule.
+        mSplitController.registerRule(getSubSettingsPairRule());
+    }
+
+    private SplitPlaceholderRule getHomepagePlaceholderRule() {
+        final Set<ActivityFilter> activityFilters = new HashSet<>();
+        activityFilters.add(new ActivityFilter(getComponentName(Settings.class)));
+        final Intent intent = new Intent();
+        intent.setComponent(getComponentName(Settings.NetworkDashboardActivity.class));
+        final SplitPlaceholderRule placeholderRule = new SplitPlaceholderRule(
+                activityFilters,
+                intent,
+                ActivityEmbeddingUtils.getMinCurrentScreenSplitWidthPx(mContext),
+                ActivityEmbeddingUtils.getMinSmallestScreenSplitWidthPx(mContext),
+                ActivityEmbeddingUtils.SPLIT_RATIO,
+                LayoutDirection.LOCALE);
+
+        return placeholderRule;
+    }
+
+    private SplitPairRule getSubSettingsPairRule() {
+        final Set<SplitPairFilter> pairFilters = new HashSet<>();
+        pairFilters.add(new SplitPairFilter(
+                getComponentName(Settings.class),
+                getComponentName(SubSettings.class),
+                null /* secondaryActivityIntentAction */,
+                null /* secondaryActivityIntentCategory */));
+        final SplitPairRule rule = new SplitPairRule(
+                pairFilters,
+                true /* finishPrimaryWithSecondary */,
+                true /* finishSecondaryWithPrimary */,
+                true /* clearTop */,
+                ActivityEmbeddingUtils.getMinCurrentScreenSplitWidthPx(mContext),
+                ActivityEmbeddingUtils.getMinSmallestScreenSplitWidthPx(mContext),
+                ActivityEmbeddingUtils.SPLIT_RATIO,
+                LayoutDirection.LOCALE);
+
+        return rule;
+    }
+
+    @NonNull
+    private ComponentName getComponentName(Class<? extends Activity> activityClass) {
+        return new ComponentName(mContext.getPackageName(), activityClass.getName());
+    }
+}