add a set of base classes for creating Fragment-based preference UI

src/com/android/settings/ext/BoolSettingFragment.java

@@ -0,0 +1,128 @@
+package com.android.settings.ext;
+
+import android.content.Context;
+import android.ext.settings.BoolSetting;
+import android.os.Bundle;
+
+import androidx.preference.PreferenceScreen;
+import androidx.preference.SwitchPreference;
+
+import com.android.settings.dashboard.DashboardFragment;
+import com.android.settingslib.widget.FooterPreference;
+
+public abstract class BoolSettingFragment extends DashboardFragment implements ExtSettingPrefController<BoolSetting> {
+
+    private static final String TAG = BoolSettingFragment.class.getSimpleName();
+
+    protected SwitchPreference mainSwitch;
+
+    private ExtSettingControllerHelper<BoolSetting> helper;
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        helper = new ExtSettingControllerHelper<>(requireContext(), getSetting());
+
+        getActivity().setTitle(getTitle());
+
+        Context ctx = requireContext();
+
+        PreferenceScreen screen = getPreferenceManager().createPreferenceScreen(ctx);
+
+        var mainSwitch = new SwitchPreference(ctx);
+        mainSwitch.setTitle(getMainSwitchTitle());
+
+        this.mainSwitch = mainSwitch;
+        refreshMainSwitch();
+
+        mainSwitch.setOnPreferenceChangeListener((preference, newValue) -> {
+            boolean state = (boolean) newValue;
+
+            if (!getSetting().put(requireContext(), state)) {
+                return false;
+            }
+
+            onMainSwitchChanged(state);
+
+            return true;
+        });
+
+        screen.addPreference(mainSwitch);
+
+        addExtraPrefs(screen);
+
+        FooterPreference footer = makeFooterPref(new FooterPreference.Builder(ctx));
+
+        if (footer != null) {
+            screen.addPreference(footer);
+        }
+
+        setPreferenceScreen(screen);
+    }
+
+    protected abstract BoolSetting getSetting();
+
+    protected abstract CharSequence getTitle();
+
+    protected abstract CharSequence getMainSwitchTitle();
+
+    protected CharSequence getMainSwitchSummary() {
+        return null;
+    }
+
+    protected void addExtraPrefs(PreferenceScreen screen) {}
+
+    protected FooterPreference makeFooterPref(FooterPreference.Builder builder) {
+        return null;
+    }
+
+    protected void onMainSwitchChanged(boolean state) {}
+
+    private void refreshMainSwitch() {
+        mainSwitch.setChecked(getSetting().get(requireContext()));
+
+        CharSequence mainSwitchSummary = getMainSwitchSummary();
+        if (mainSwitchSummary != null) {
+            mainSwitch.setSummary(mainSwitchSummary);
+        }
+    }
+
+    @Override
+    public void onResume() {
+        super.onResume();
+
+        helper.onResume(this);
+    }
+
+    @Override
+    public void onPause() {
+        super.onPause();
+
+        helper.onPause(this);
+    }
+
+    @Override
+    public void accept(BoolSetting setting) {
+        refreshMainSwitch();
+    }
+
+    @Override
+    public int getMetricsCategory() {
+        return METRICS_CATEGORY_UNKNOWN;
+    }
+
+    @Override
+    protected int getPreferenceScreenResId() {
+        return 0;
+    }
+
+    @Override
+    protected String getLogTag() {
+        return TAG;
+    }
+
+    protected final CharSequence resText(int res) {
+        return requireContext().getText(res);
+    }
+}

src/com/android/settings/ext/BoolSettingFragmentPrefController.java

@@ -0,0 +1,19 @@
+package com.android.settings.ext;
+
+import android.content.Context;
+import android.ext.settings.BoolSetting;
+
+public abstract class BoolSettingFragmentPrefController extends ExtSettingFragmentPrefController<BoolSetting> {
+
+    protected BoolSettingFragmentPrefController(Context ctx, String key, BoolSetting setting) {
+        super(ctx, key, setting);
+    }
+
+    @Override
+    public CharSequence getSummary() {
+        return setting.get(mContext) ? getSummaryOn() : getSummaryOff();
+    }
+
+    protected abstract CharSequence getSummaryOn();
+    protected abstract CharSequence getSummaryOff();
+}

src/com/android/settings/ext/ExtSettingFragmentPrefController.java

@@ -0,0 +1,42 @@
+package com.android.settings.ext;
+
+import android.content.Context;
+import android.ext.settings.Setting;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.LifecycleOwner;
+
+public abstract class ExtSettingFragmentPrefController<T extends Setting> extends FragmentPrefController
+        implements ExtSettingPrefController<T> {
+    protected final T setting;
+    protected final ExtSettingControllerHelper<T> helper;
+
+    protected ExtSettingFragmentPrefController(Context ctx, String key, T setting) {
+        super(ctx, key);
+        this.setting = setting;
+        helper = new ExtSettingControllerHelper<T>(ctx, setting);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return helper.getAvailabilityStatus();
+    }
+
+    @Override
+    public void onResume(@NonNull LifecycleOwner owner) {
+        helper.onResume(this);
+    }
+
+    @Override
+    public void onPause(@NonNull LifecycleOwner owner) {
+        helper.onPause(this);
+    }
+
+    // called by the setting observer
+    @Override
+    public void accept(T setting) {
+        if (preference != null) {
+            updateState(preference);
+        }
+    }
+}

src/com/android/settings/ext/FragmentPrefController.java

@@ -0,0 +1,36 @@
+package com.android.settings.ext;
+
+import android.content.Context;
+
+import androidx.annotation.Nullable;
+import androidx.preference.Preference;
+import androidx.preference.PreferenceFragmentCompat;
+
+import com.android.settings.core.BasePreferenceController;
+
+public abstract class FragmentPrefController<FragmentType extends PreferenceFragmentCompat>
+        extends BasePreferenceController {
+
+    protected FragmentPrefController(Context ctx, String key) {
+        super(ctx, key);
+    }
+
+    @Nullable
+    protected Preference preference;
+
+    @Override
+    public void updateState(Preference preference) {
+        super.updateState(preference);
+
+        if (preference != this.preference) {
+            preference.setSingleLineTitle(false);
+            preference.setPersistent(false);
+
+            this.preference = preference;
+        }
+    }
+
+    protected final CharSequence resText(int res) {
+        return mContext.getText(res);
+    }
+}