Refactor CaptionAppearanceFragment to improve maintainability (4/n)

Root cause: There is a bunch of different logic of preferences in CaptionAppearanceFragment. It’s hard to implement new features and hard to maintain and hard to be testable.
Solution: Move out preset preference logic of CaptionAppearanceFragment into controllers to reduce the complexity of the relationship between preference and fragment.

Bug: 197695932
Test: make RunSettingsRoboTests ROBOTEST_FILTER=CaptionPresetControllerTest CaptionAppearanceFragmentTest
Change-Id: I5409c1e8a6bdfc633abc304d8cf800ea0943de78

src/com/android/settings/accessibility/CaptionAppearanceFragment.java

@@ -17,41 +17,42 @@
 package com.android.settings.accessibility;
 
 import android.app.settings.SettingsEnums;
-import android.content.ContentResolver;
-import android.content.Context;
-import android.content.res.Resources;
 import android.os.Bundle;
+import android.os.Handler;
+import android.os.Looper;
 import android.provider.Settings;
 import android.view.accessibility.CaptioningManager;
+import android.view.accessibility.CaptioningManager.CaptionStyle;
 
+import androidx.annotation.VisibleForTesting;
 import androidx.preference.PreferenceCategory;
 
 import com.android.settings.R;
-import com.android.settings.accessibility.ListDialogPreference.OnValueChangedListener;
 import com.android.settings.dashboard.DashboardFragment;
 import com.android.settings.search.BaseSearchIndexProvider;
 import com.android.settingslib.search.SearchIndexable;
 
+import java.util.Arrays;
+import java.util.List;
+
 /** Settings fragment containing font style of captioning properties. */
 @SearchIndexable(forTarget = SearchIndexable.ALL & ~SearchIndexable.ARC)
-public class CaptionAppearanceFragment extends DashboardFragment
-        implements OnValueChangedListener {
+public class CaptionAppearanceFragment extends DashboardFragment {
 
     private static final String TAG = "CaptionAppearanceFragment";
-    private static final String PREF_PRESET = "captioning_preset";
-    private static final String PREF_CUSTOM = "custom";
+    @VisibleForTesting
+    static final String PREF_CUSTOM = "custom";
+    @VisibleForTesting
+    static final List<String> CAPTIONING_FEATURE_KEYS = Arrays.asList(
+            Settings.Secure.ACCESSIBILITY_CAPTIONING_PRESET
+    );
 
+    private final Handler mHandler = new Handler(Looper.getMainLooper());
+    @VisibleForTesting
+    AccessibilitySettingsContentObserver mSettingsContentObserver;
     private CaptioningManager mCaptioningManager;
-    private CaptionHelper mCaptionHelper;
-
-    // Standard options.
-    private PresetPreference mPreset;
-
-    // Custom options.
     private PreferenceCategory mCustom;
 
-    private boolean mShowingCustom;
-
     @Override
     public int getMetricsCategory() {
         return SettingsEnums.ACCESSIBILITY_CAPTION_APPEARANCE;
@@ -60,14 +61,24 @@ public class CaptionAppearanceFragment extends DashboardFragment
     @Override
     public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
         super.onCreatePreferences(savedInstanceState, rootKey);
-
-        mCaptioningManager = (CaptioningManager) getSystemService(Context.CAPTIONING_SERVICE);
-        mCaptionHelper = new CaptionHelper(getContext());
-
-        initializeAllPreferences();
-        updateAllPreferences();
+        mCaptioningManager = getContext().getSystemService(CaptioningManager.class);
+        mSettingsContentObserver = new AccessibilitySettingsContentObserver(mHandler);
+        mSettingsContentObserver.registerKeysToObserverCallback(CAPTIONING_FEATURE_KEYS,
+                key -> refreshShowingCustom());
+        mCustom = findPreference(PREF_CUSTOM);
         refreshShowingCustom();
-        installUpdateListeners();
+    }
+
+    @Override
+    public void onStart() {
+        super.onStart();
+        mSettingsContentObserver.register(getContext().getContentResolver());
+    }
+
+    @Override
+    public void onStop() {
+        super.onStop();
+        getContext().getContentResolver().unregisterContentObserver(mSettingsContentObserver);
     }
 
     @Override
@@ -80,55 +91,17 @@ public class CaptionAppearanceFragment extends DashboardFragment
         return TAG;
     }
 
-    private void initializeAllPreferences() {
-
-        final Resources res = getResources();
-        final int[] presetValues = res.getIntArray(R.array.captioning_preset_selector_values);
-        final String[] presetTitles = res.getStringArray(R.array.captioning_preset_selector_titles);
-        mPreset = (PresetPreference) findPreference(PREF_PRESET);
-        mPreset.setValues(presetValues);
-        mPreset.setTitles(presetTitles);
-
-        mCustom = (PreferenceCategory) findPreference(PREF_CUSTOM);
-        mShowingCustom = true;
-    }
-
-    private void installUpdateListeners() {
-        mPreset.setOnValueChangedListener(this);
-    }
-
-    private void updateAllPreferences() {
-        final int preset = mCaptioningManager.getRawUserStyle();
-        mPreset.setValue(preset);
-    }
-
-    private void refreshShowingCustom() {
-        final boolean customPreset =
-                mPreset.getValue() == CaptioningManager.CaptionStyle.PRESET_CUSTOM;
-        if (!customPreset && mShowingCustom) {
-            getPreferenceScreen().removePreference(mCustom);
-            mShowingCustom = false;
-        } else if (customPreset && !mShowingCustom) {
-            getPreferenceScreen().addPreference(mCustom);
-            mShowingCustom = true;
-        }
-    }
-
-    @Override
-    public void onValueChanged(ListDialogPreference preference, int value) {
-        final ContentResolver cr = getActivity().getContentResolver();
-        if (mPreset == preference) {
-            Settings.Secure.putInt(cr, Settings.Secure.ACCESSIBILITY_CAPTIONING_PRESET, value);
-            refreshShowingCustom();
-        }
-        mCaptionHelper.setEnabled(true);
-    }
-
     @Override
     public int getHelpResource() {
         return R.string.help_url_caption;
     }
 
+    private void refreshShowingCustom() {
+        final boolean isCustomPreset =
+                mCaptioningManager.getRawUserStyle() == CaptionStyle.PRESET_CUSTOM;
+        mCustom.setVisible(isCustomPreset);
+    }
+
     public static final BaseSearchIndexProvider SEARCH_INDEX_DATA_PROVIDER =
             new BaseSearchIndexProvider(R.xml.captioning_appearance);
 }

src/com/android/settings/accessibility/CaptionHelper.java

@@ -186,4 +186,19 @@ public class CaptionHelper {
         final CaptionStyle attrs = CaptionStyle.getCustomStyle(mContentResolver);
         return attrs.edgeType;
     }
+
+    /**
+     * Sets the caption raw user style.
+     *
+     * @param type The caption raw user style
+     */
+    public void setRawUserStyle(int type) {
+        Settings.Secure.putInt(mContentResolver,
+                Settings.Secure.ACCESSIBILITY_CAPTIONING_PRESET, type);
+    }
+
+    /** Returns the caption raw user style.*/
+    public int getRawUserStyle() {
+        return mCaptioningManager.getRawUserStyle();
+    }
 }

src/com/android/settings/accessibility/CaptionPresetController.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2022 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.accessibility;
+
+import android.content.Context;
+import android.content.res.Resources;
+
+import androidx.preference.PreferenceScreen;
+
+import com.android.settings.R;
+import com.android.settings.core.BasePreferenceController;
+
+/** Preference controller for caption preset. */
+public class CaptionPresetController extends BasePreferenceController
+        implements ListDialogPreference.OnValueChangedListener {
+
+    private final CaptionHelper mCaptionHelper;
+
+    public CaptionPresetController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+        mCaptionHelper = new CaptionHelper(context);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return AVAILABLE;
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        final PresetPreference preference = screen.findPreference(getPreferenceKey());
+        final Resources res = mContext.getResources();
+        final int[] presetValues = res.getIntArray(R.array.captioning_preset_selector_values);
+        final String[] presetTitles = res.getStringArray(R.array.captioning_preset_selector_titles);
+        preference.setTitles(presetTitles);
+        preference.setValues(presetValues);
+        final int preset = mCaptionHelper.getRawUserStyle();
+        preference.setValue(preset);
+        preference.setOnValueChangedListener(this);
+    }
+
+    @Override
+    public void onValueChanged(ListDialogPreference preference, int value) {
+        mCaptionHelper.setRawUserStyle(value);
+        mCaptionHelper.setEnabled(true);
+    }
+}