Workarounds to avoid removing all prefs

Removing all prefs causes ugly animations, so avoid it at all cost
and cache all the prefs (while still added) as long as possible.

Bug: 26271353
Change-Id: I33b84d751938b460f4b66c0158057407dd45d974

src/com/android/settings/SettingsPreferenceFragment.java

@@ -34,6 +34,7 @@ import android.support.v7.preference.PreferenceViewHolder;
 import android.support.v7.widget.LinearLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import android.text.TextUtils;
+import android.util.ArrayMap;
 import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.Menu;
@@ -97,6 +98,7 @@ public abstract class SettingsPreferenceFragment extends InstrumentedPreferenceF
     private View mEmptyView;
     private LinearLayoutManager mLayoutManager;
     private HighlightablePreferenceGroupAdapter mAdapter;
+    private ArrayMap<String, Preference> mPreferenceCache;
 
     @Override
     public void onCreate(Bundle icicle) {
@@ -367,6 +369,28 @@ public abstract class SettingsPreferenceFragment extends InstrumentedPreferenceF
         return mAdapter;
     }
 
+    protected void cacheRemoveAllPrefs(PreferenceGroup group) {
+        mPreferenceCache = new ArrayMap<String, Preference>();
+        final int N = group.getPreferenceCount();
+        for (int i = 0; i < N; i++) {
+            Preference p = group.getPreference(i);
+            if (TextUtils.isEmpty(p.getKey())) {
+                continue;
+            }
+            mPreferenceCache.put(p.getKey(), p);
+        }
+    }
+
+    protected Preference getCachedPreference(String key) {
+        return mPreferenceCache != null ? mPreferenceCache.remove(key) : null;
+    }
+
+    protected void removeCachedPrefs(PreferenceGroup group) {
+        for (Preference p : mPreferenceCache.values()) {
+            group.removePreference(p);
+        }
+    }
+
     private void highlightPreference(String key) {
         final int position = canUseListViewForHighLighting(key);
         if (position >= 0) {

src/com/android/settings/bluetooth/BluetoothDevicePreference.java

@@ -84,6 +84,10 @@ public final class BluetoothDevicePreference extends Preference implements
         onDeviceAttributesChanged();
     }
 
+    void rebind() {
+        notifyChanged();
+    }
+
     CachedBluetoothDevice getCachedDevice() {
         return mCachedDevice;
     }

src/com/android/settings/bluetooth/BluetoothSettings.java

@@ -39,7 +39,6 @@ import android.view.MenuInflater;
 import android.view.MenuItem;
 import android.view.View;
 import android.widget.TextView;
-
 import com.android.internal.logging.MetricsLogger;
 import com.android.internal.logging.MetricsProto.MetricsEvent;
 import com.android.settings.LinkifyUtils;
@@ -77,6 +76,8 @@ public final class BluetoothSettings extends DeviceListPreferenceFragment implem
     private static final String BTOPP_ACTION_OPEN_RECEIVED_FILES =
             "android.btopp.intent.action.OPEN_RECEIVED_FILES";
 
+    private static final String KEY_PAIRED_DEVICES = "paired_devices";
+
     private static View mSettingsDialogView = null;
 
     private BluetoothEnabler mBluetoothEnabler;
@@ -154,6 +155,21 @@ public final class BluetoothSettings extends DeviceListPreferenceFragment implem
     void addPreferencesForActivity() {
         addPreferencesFromResource(R.xml.bluetooth_settings);
 
+        mPairedDevicesCategory = new PreferenceCategory(getPrefContext());
+        mPairedDevicesCategory.setKey(KEY_PAIRED_DEVICES);
+        mPairedDevicesCategory.setOrder(1);
+        getPreferenceScreen().addPreference(mPairedDevicesCategory);
+
+        mAvailableDevicesCategory = new BluetoothProgressCategory(getActivity());
+        mAvailableDevicesCategory.setSelectable(false);
+        mAvailableDevicesCategory.setOrder(2);
+        getPreferenceScreen().addPreference(mAvailableDevicesCategory);
+
+        mMyDevicePreference = new Preference(getPrefContext());
+        mMyDevicePreference.setSelectable(false);
+        mMyDevicePreference.setOrder(3);
+        getPreferenceScreen().addPreference(mMyDevicePreference);
+
         setHasOptionsMenu(true);
     }
 
@@ -275,14 +291,15 @@ public final class BluetoothSettings extends DeviceListPreferenceFragment implem
 
     private void addDeviceCategory(PreferenceGroup preferenceGroup, int titleId,
             BluetoothDeviceFilter.Filter filter, boolean addCachedDevices) {
+        cacheRemoveAllPrefs(preferenceGroup);
         preferenceGroup.setTitle(titleId);
-        getPreferenceScreen().addPreference(preferenceGroup);
         setFilter(filter);
         setDeviceListGroup(preferenceGroup);
         if (addCachedDevices) {
             addCachedDevices();
         }
         preferenceGroup.setEnabled(true);
+        removeCachedPrefs(preferenceGroup);
     }
 
     private void updateContent(int bluetoothState) {
@@ -291,8 +308,6 @@ public final class BluetoothSettings extends DeviceListPreferenceFragment implem
 
         switch (bluetoothState) {
             case BluetoothAdapter.STATE_ON:
-                preferenceScreen.removeAll();
-                preferenceScreen.setOrderingAsAdded(true);
                 mDevicePreferenceMap.clear();
 
                 if (isUiRestricted()) {
@@ -301,44 +316,32 @@ public final class BluetoothSettings extends DeviceListPreferenceFragment implem
                 }
 
                 // Paired devices category
-                if (mPairedDevicesCategory == null) {
-                    mPairedDevicesCategory = new PreferenceCategory(getPrefContext());
-                } else {
-                    mPairedDevicesCategory.removeAll();
-                }
                 addDeviceCategory(mPairedDevicesCategory,
                         R.string.bluetooth_preference_paired_devices,
                         BluetoothDeviceFilter.BONDED_DEVICE_FILTER, true);
                 int numberOfPairedDevices = mPairedDevicesCategory.getPreferenceCount();
 
                 if (isUiRestricted() || numberOfPairedDevices <= 0) {
+                    if (preferenceScreen.findPreference(KEY_PAIRED_DEVICES) != null) {
                         preferenceScreen.removePreference(mPairedDevicesCategory);
                     }
+                } else {
+                    if (preferenceScreen.findPreference(KEY_PAIRED_DEVICES) == null) {
+                        preferenceScreen.addPreference(mPairedDevicesCategory);
+                    }
+                }
 
                 // Available devices category
-                if (mAvailableDevicesCategory == null) {
-                    mAvailableDevicesCategory = new BluetoothProgressCategory(getActivity());
-                    mAvailableDevicesCategory.setSelectable(false);
-                } else {
-                    mAvailableDevicesCategory.removeAll();
-                }
                 addDeviceCategory(mAvailableDevicesCategory,
                         R.string.bluetooth_preference_found_devices,
                         BluetoothDeviceFilter.UNBONDED_DEVICE_FILTER, mInitialScanStarted);
-                int numberOfAvailableDevices = mAvailableDevicesCategory.getPreferenceCount();
 
                 if (!mInitialScanStarted) {
                     startScanning();
                 }
 
-                if (mMyDevicePreference == null) {
-                    mMyDevicePreference = new Preference(getPrefContext());
-                }
-
                 mMyDevicePreference.setSummary(getResources().getString(
                             R.string.bluetooth_is_visible_message, mLocalAdapter.getName()));
-                mMyDevicePreference.setSelectable(false);
-                preferenceScreen.addPreference(mMyDevicePreference);
 
                 getActivity().invalidateOptionsMenu();
 

src/com/android/settings/bluetooth/DeviceListPreferenceFragment.java

@@ -176,11 +176,19 @@ public abstract class DeviceListPreferenceFragment extends
             return;
         }
 
-        BluetoothDevicePreference preference = new BluetoothDevicePreference(
+        String key = cachedDevice.getDevice().getAddress();
-                getPrefContext(), cachedDevice);
+        BluetoothDevicePreference preference = (BluetoothDevicePreference) getCachedPreference(key);
+
+        if (preference == null) {
+            preference = new BluetoothDevicePreference(getPrefContext(), cachedDevice);
+            mDeviceListGroup.addPreference(preference);
+        } else {
+            // Tell the preference it is being re-used in case there is new info in the
+            // cached device.
+            preference.rebind();
+        }
 
         initDevicePreference(preference);
-        mDeviceListGroup.addPreference(preference);
         mDevicePreferenceMap.put(cachedDevice, preference);
     }
 

src/com/android/settings/wifi/WifiSettings.java

@@ -649,19 +649,22 @@ public class WifiSettings extends RestrictedSettingsFragment
 
                 boolean hasAvailableAccessPoints = false;
                 int index = 0;
+                cacheRemoveAllPrefs(getPreferenceScreen());
                 for (AccessPoint accessPoint : accessPoints) {
                     // Ignore access points that are out of range.
                     if (accessPoint.getLevel() != -1) {
+                        String key = accessPoint.getBssid();
                         hasAvailableAccessPoints = true;
-                        if (accessPoint.getTag() != null) {
+                        LongPressAccessPointPreference pref = (LongPressAccessPointPreference)
-                            final Preference pref = (Preference) accessPoint.getTag();
+                                getCachedPreference(key);
+                        if (pref != null) {
                             pref.setOrder(index++);
-                            getPreferenceScreen().addPreference(pref);
                             continue;
                         }
                         LongPressAccessPointPreference
                                 preference = new LongPressAccessPointPreference(accessPoint,
                                 getPrefContext(), mUserBadgeCache, false, this);
+                        preference.setKey(key);
                         preference.setOrder(index++);
 
                         if (mOpenSsid != null && mOpenSsid.equals(accessPoint.getSsidStr())
@@ -674,6 +677,7 @@ public class WifiSettings extends RestrictedSettingsFragment
                         accessPoint.setListener(this);
                     }
                 }
+                removeCachedPrefs(getPreferenceScreen());
                 if (!hasAvailableAccessPoints) {
                     setProgressBarVisible(true);
                     Preference pref = new Preference(getContext()) {