Use fragment for input preference screen

This CL introduces a common abstract class, SunScreenFragment, for
PreferenceFragment that implements a PreferenceScreen of the main
settings preference screen.

Bug: 16522808
Change-Id: I11fba71b5e9f96208b261e0c0314de8a41720d0f

1 files changed, 118 insertions, 0 deletions

diff --git a/java/src/com/android/inputmethod/latin/settings/SubScreenFragment.java b/java/src/com/android/inputmethod/latin/settings/SubScreenFragment.java
new file mode 100644
index 000000000..c70bf2997
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/settings/SubScreenFragment.java
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2014 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.inputmethod.latin.settings;
+
+import android.app.backup.BackupManager;
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
+import android.os.Bundle;
+import android.preference.ListPreference;
+import android.preference.Preference;
+import android.preference.PreferenceFragment;
+import android.preference.PreferenceScreen;
+import android.util.Log;
+
+/**
+ * A base abstract class for a {@link PreferenceFragment} that implements a nested
+ * {@link PreferenceScreen} of the main preference screen.
+ */
+abstract class SubScreenFragment extends PreferenceFragment
+        implements OnSharedPreferenceChangeListener {
+    private OnSharedPreferenceChangeListener mSharedPreferenceChangeListener;
+
+    static void setPreferenceEnabled(final String prefKey, final boolean enabled,
+            final PreferenceScreen screen) {
+        final Preference preference = screen.findPreference(prefKey);
+        if (preference != null) {
+            preference.setEnabled(enabled);
+        }
+    }
+
+    static void removePreference(final String prefKey, final PreferenceScreen screen) {
+        final Preference preference = screen.findPreference(prefKey);
+        if (preference != null) {
+            screen.removePreference(preference);
+        }
+    }
+
+    static void updateListPreferenceSummaryToCurrentValue(final String prefKey,
+            final PreferenceScreen screen) {
+        // Because the "%s" summary trick of {@link ListPreference} doesn't work properly before
+        // KitKat, we need to update the summary programmatically.
+        final ListPreference listPreference = (ListPreference)screen.findPreference(prefKey);
+        if (listPreference == null) {
+            return;
+        }
+        final CharSequence entries[] = listPreference.getEntries();
+        final int entryIndex = listPreference.findIndexOfValue(listPreference.getValue());
+        listPreference.setSummary(entryIndex < 0 ? null : entries[entryIndex]);
+    }
+
+    final void setPreferenceEnabled(final String prefKey, final boolean enabled) {
+        setPreferenceEnabled(prefKey, enabled, getPreferenceScreen());
+    }
+
+    final void removePreference(final String prefKey) {
+        removePreference(prefKey, getPreferenceScreen());
+    }
+
+    final void updateListPreferenceSummaryToCurrentValue(final String prefKey) {
+        updateListPreferenceSummaryToCurrentValue(prefKey, getPreferenceScreen());
+    }
+
+    final SharedPreferences getSharedPreferences() {
+        return getPreferenceManager().getSharedPreferences();
+    }
+
+    @Override
+    public void addPreferencesFromResource(final int preferencesResId) {
+        super.addPreferencesFromResource(preferencesResId);
+        TwoStatePreferenceHelper.replaceCheckBoxPreferencesBySwitchPreferences(
+                getPreferenceScreen());
+    }
+
+    @Override
+    public void onCreate(final Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        mSharedPreferenceChangeListener = new OnSharedPreferenceChangeListener() {
+            @Override
+            public void onSharedPreferenceChanged(final SharedPreferences prefs, final String key) {
+                final SubScreenFragment fragment = SubScreenFragment.this;
+                final Context context = fragment.getActivity();
+                if (context == null || fragment.getPreferenceScreen() == null) {
+                    final String tag = fragment.getClass().getSimpleName();
+                    // TODO: Introduce a static function to register this class and ensure that
+                    // onCreate must be called before "onSharedPreferenceChanged" is called.
+                    Log.w(tag, "onSharedPreferenceChanged called before activity starts.");
+                    return;
+                }
+                new BackupManager(context).dataChanged();
+                fragment.onSharedPreferenceChanged(prefs, key);
+            }
+        };
+        getSharedPreferences().registerOnSharedPreferenceChangeListener(
+                mSharedPreferenceChangeListener);
+    }
+
+    @Override
+    public void onDestroy() {
+        getSharedPreferences().unregisterOnSharedPreferenceChangeListener(
+                mSharedPreferenceChangeListener);
+        super.onDestroy();
+    }
+}