[Settings] Avoid rendering hidden preferences

Under dashboards with expand button, preferences are renderred even
not been expanded.
Avoid from rendering un-expanded preference can improve the performance
of dashboard display.

Bug: 141833767
Test: manual
Change-Id: I00c6f827a0b7b7cec6a6fd8c809b94ca1dce88bb

src/com/android/settings/SettingsPreferenceFragment.java

@@ -258,6 +258,18 @@ public abstract class SettingsPreferenceFragment extends InstrumentedPreferenceF
         return 0;
     }
 
+    /**
+     * Whether preference is allowing to be displayed to the user.
+     *
+     * @param preference to check if it can be displayed to the user (not hidding in expand area).
+     * @return {@code true} when preference is allowing to be displayed to the user.
+     * {@code false} when preference is hidden in expand area and not been displayed to the user.
+     */
+    protected boolean isPreferenceExpanded(Preference preference) {
+        return ((mAdapter == null)
+                || (mAdapter.getPreferenceAdapterPosition(preference) != RecyclerView.NO_POSITION));
+    }
+
     protected void onDataSetChanged() {
         highlightPreferenceIfNeeded();
         updateEmptyView();

src/com/android/settings/dashboard/DashboardFragment.java

@@ -319,6 +319,13 @@ public abstract class DashboardFragment extends SettingsPreferenceFragment
         return false;
     }
 
+    /**
+     * Get current PreferenceController(s)
+     */
+    protected Collection<List<AbstractPreferenceController>> getPreferenceControllers() {
+        return mPreferenceControllers.values();
+    }
+
     /**
      * Update state of each preference managed by PreferenceController.
      */

src/com/android/settings/network/telephony/MobileNetworkSettings.java

@@ -33,6 +33,7 @@ import android.view.MenuItem;
 
 import androidx.annotation.VisibleForTesting;
 import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
 
 import com.android.settings.R;
 import com.android.settings.dashboard.RestrictedDashboardFragment;
@@ -47,7 +48,9 @@ import com.android.settings.widget.PreferenceCategoryController;
 import com.android.settingslib.core.AbstractPreferenceController;
 import com.android.settingslib.search.SearchIndexable;
 
+import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.List;
 
 @SearchIndexable(forTarget = SearchIndexable.ALL & ~SearchIndexable.ARC)
@@ -72,6 +75,8 @@ public class MobileNetworkSettings extends RestrictedDashboardFragment {
     private UserManager mUserManager;
     private String mClickedPrefKey;
 
+    private List<AbstractPreferenceController> mHiddenControllerList;
+
     public MobileNetworkSettings() {
         super(UserManager.DISALLOW_CONFIG_MOBILE_NETWORKS);
     }
@@ -113,13 +118,13 @@ public class MobileNetworkSettings extends RestrictedDashboardFragment {
                 MobileNetworkUtils.getSearchableSubscriptionId(context));
         Log.i(LOG_TAG, "display subId: " + mSubId);
 
-        if (mSubId != SubscriptionManager.INVALID_SUBSCRIPTION_ID) {
+        if (!SubscriptionManager.isValidSubscriptionId(mSubId)) {
+            return Arrays.asList();
+        }
         return Arrays.asList(
                 new DataUsageSummaryPreferenceController(getActivity(), getSettingsLifecycle(),
                         this, mSubId));
     }
-        return Arrays.asList();
-    }
 
     @Override
     public void onAttach(Context context) {
@@ -187,6 +192,50 @@ public class MobileNetworkSettings extends RestrictedDashboardFragment {
         onRestoreInstance(icicle);
     }
 
+    @Override
+    public void onExpandButtonClick() {
+        final PreferenceScreen screen = getPreferenceScreen();
+        mHiddenControllerList.stream()
+                .filter(controller -> controller.isAvailable())
+                .forEach(controller -> {
+                    final String key = controller.getPreferenceKey();
+                    final Preference preference = screen.findPreference(key);
+                    controller.updateState(preference);
+                });
+        super.onExpandButtonClick();
+    }
+
+    /*
+     * Replace design within {@link DashboardFragment#updatePreferenceStates()}
+     */
+    @Override
+    protected void updatePreferenceStates() {
+        mHiddenControllerList = new ArrayList<AbstractPreferenceController>();
+
+        final PreferenceScreen screen = getPreferenceScreen();
+        final Collection<List<AbstractPreferenceController>> controllerLists =
+                getPreferenceControllers();
+        controllerLists.stream().flatMap(Collection::stream)
+                .forEach(controller -> {
+                    final String key = controller.getPreferenceKey();
+                    if (TextUtils.isEmpty(key)) {
+                        return;
+                    }
+                    final Preference preference = screen.findPreference(key);
+                    if (preference == null) {
+                        return;
+                    }
+                    if (!isPreferenceExpanded(preference)) {
+                        mHiddenControllerList.add(controller);
+                        return;
+                    }
+                    if (!controller.isAvailable()) {
+                        return;
+                    }
+                    controller.updateState(preference);
+                });
+    }
+
     @VisibleForTesting
     void onRestoreInstance(Bundle icicle) {
         if (icicle != null) {
@@ -238,7 +287,7 @@ public class MobileNetworkSettings extends RestrictedDashboardFragment {
 
     @Override
     public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
-        if (mSubId != SubscriptionManager.INVALID_SUBSCRIPTION_ID) {
+        if (SubscriptionManager.isValidSubscriptionId(mSubId)) {
             final MenuItem item = menu.add(Menu.NONE, R.id.edit_sim_name, Menu.NONE,
                     R.string.mobile_network_sim_name);
             item.setIcon(com.android.internal.R.drawable.ic_mode_edit);
@@ -249,7 +298,7 @@ public class MobileNetworkSettings extends RestrictedDashboardFragment {
 
     @Override
     public boolean onOptionsItemSelected(MenuItem menuItem) {
-        if (mSubId != SubscriptionManager.INVALID_SUBSCRIPTION_ID) {
+        if (SubscriptionManager.isValidSubscriptionId(mSubId)) {
             if (menuItem.getItemId() == R.id.edit_sim_name) {
                 RenameMobileNetworkDialogFragment.newInstance(mSubId).show(
                         getFragmentManager(), RenameMobileNetworkDialogFragment.TAG);