Update dark theme to have new screen

The dark theme preference should have it's own screen rather than
being a dialog. This adds some boilerplate code that will be
needed for the illustration as well as converting the current
list preference to open a new screen.

Test: robotests
Bug: 128686189
Change-Id: I5b62276353c0d39ad2ad00d21d2280e76cceb09b

src/com/android/settings/display/DarkUISettings.java

@@ -0,0 +1,145 @@
+/*
+ * Copyright (C) 2019 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.display;
+
+import android.app.UiModeManager;
+import android.app.settings.SettingsEnums;
+import android.content.Context;
+import android.graphics.drawable.Drawable;
+import android.provider.SearchIndexableResource;
+import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
+import com.android.settings.R;
+import com.android.settings.search.BaseSearchIndexProvider;
+import com.android.settings.search.Indexable;
+import com.android.settings.widget.RadioButtonPickerFragment;
+import com.android.settingslib.search.SearchIndexable;
+import com.android.settingslib.widget.CandidateInfo;
+import com.android.settingslib.widget.FooterPreference;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * The screen for selecting the dark theme preference for this device. Automatically updates
+ * the associated footer view with any needed information.
+ */
+@SearchIndexable(forTarget = SearchIndexable.ALL & ~SearchIndexable.ARC)
+public class DarkUISettings extends RadioButtonPickerFragment implements Indexable {
+
+  private DarkUISettingsRadioButtonsController mController;
+  private Preference mFooter;
+
+  @Override
+  protected int getPreferenceScreenResId() {
+      return R.xml.dark_ui_settings;
+  }
+
+  @Override
+  public void onAttach(Context context) {
+      super.onAttach(context);
+      // TODO(b/128686189): add illustration once it is ready
+      setIllustration(0, 0);
+      mFooter = new FooterPreference(context);
+      mFooter.setIcon(android.R.color.transparent);
+      mController = new DarkUISettingsRadioButtonsController(context, mFooter);
+  }
+
+  @Override
+  protected List<? extends CandidateInfo> getCandidates() {
+      final Context context = getContext();
+      final List<CandidateInfo> candidates = new ArrayList<>();
+      candidates.add(new DarkUISettingsCandidateInfo(
+              DarkUISettingsRadioButtonsController.modeToDescription(
+                      context, UiModeManager.MODE_NIGHT_YES),
+              /* summary */ null,
+              DarkUISettingsRadioButtonsController.KEY_DARK,
+              /* enabled */ true));
+      candidates.add(new DarkUISettingsCandidateInfo(
+              DarkUISettingsRadioButtonsController.modeToDescription(
+                      context, UiModeManager.MODE_NIGHT_NO),
+              /* summary */ null,
+              DarkUISettingsRadioButtonsController.KEY_LIGHT,
+              /* enabled */ true));
+      return candidates;
+  }
+
+  @Override
+  protected void addStaticPreferences(PreferenceScreen screen) {
+      screen.addPreference(mFooter);
+  }
+
+  @Override
+  protected String getDefaultKey() {
+      return mController.getDefaultKey();
+  }
+
+  @Override
+  protected boolean setDefaultKey(String key) {
+      return mController.setDefaultKey(key);
+  }
+
+  @Override
+  public int getMetricsCategory() {
+      return SettingsEnums.DARK_UI_SETTINGS;
+  }
+
+  static class DarkUISettingsCandidateInfo extends CandidateInfo {
+
+      private final CharSequence mLabel;
+      private final CharSequence mSummary;
+      private final String mKey;
+
+      DarkUISettingsCandidateInfo(CharSequence label, CharSequence summary, String key,
+              boolean enabled) {
+          super(enabled);
+          mLabel = label;
+          mKey = key;
+          mSummary = summary;
+      }
+
+      @Override
+      public CharSequence loadLabel() {
+          return mLabel;
+      }
+
+      @Override
+      public Drawable loadIcon() {
+          return null;
+      }
+
+      @Override
+      public String getKey() {
+          return mKey;
+      }
+
+      public CharSequence getSummary() {
+          return mSummary;
+      }
+  }
+
+  public static final Indexable.SearchIndexProvider SEARCH_INDEX_DATA_PROVIDER =
+      new BaseSearchIndexProvider() {
+        @Override
+        public List<SearchIndexableResource> getXmlResourcesToIndex(
+            Context context, boolean enabled) {
+          final SearchIndexableResource sir = new SearchIndexableResource(context);
+          sir.xmlResId = R.xml.dark_ui_settings;
+          return Arrays.asList(sir);
+        }
+      };
+}