Change Input Settings UI flow.

1. Introduces new UI components as per the new flow
2. Temporarily disables components in the old flow that are to be
   replaced by the new flow. This is done so we can neatly revert
   to the old flow if there are issues with the new flow
3. AvailableVirtualKeyboardActivity now responds to
   android.settings.INPUT_METHOD_SETTINGS intents instead of
   InputMethodAndLanguageSettingsActivity

Bug: 25752812
Change-Id: I728d7ee185827ed328c16cb7abce244557a26518

src/com/android/settings/inputmethod/VirtualKeyboardFragment.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2016 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.inputmethod;
+
+import android.app.Activity;
+import android.app.admin.DevicePolicyManager;
+import android.content.Context;
+import android.os.Bundle;
+import android.support.v7.preference.Preference;
+import android.view.inputmethod.InputMethodInfo;
+import android.view.inputmethod.InputMethodManager;
+
+import com.android.internal.util.Preconditions;
+import com.android.settings.R;
+import com.android.settings.InstrumentedFragment;
+import com.android.settings.SettingsPreferenceFragment;
+
+import java.text.Collator;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+public final class VirtualKeyboardFragment extends SettingsPreferenceFragment {
+
+    private static final String ADD_VIRTUAL_KEYBOARD_SCREEN = "add_virtual_keyboard_screen";
+
+    private final ArrayList<InputMethodPreference> mInputMethodPreferenceList = new ArrayList<>();
+    private InputMethodManager mImm;
+    private DevicePolicyManager mDpm;
+    private Preference mAddVirtualKeyboardScreen;
+
+    @Override
+    public void onCreatePreferences(Bundle bundle, String s) {
+        Activity activity = Preconditions.checkNotNull(getActivity());
+        addPreferencesFromResource(R.xml.virtual_keyboard_settings);
+        mImm = Preconditions.checkNotNull(activity.getSystemService(InputMethodManager.class));
+        mDpm = Preconditions.checkNotNull(activity.getSystemService(DevicePolicyManager.class));
+        mAddVirtualKeyboardScreen = Preconditions.checkNotNull(
+                findPreference(ADD_VIRTUAL_KEYBOARD_SCREEN));
+    }
+
+    @Override
+    public void onResume() {
+        super.onResume();
+        // Refresh internal states in mInputMethodSettingValues to keep the latest
+        // "InputMethodInfo"s and "InputMethodSubtype"s
+        updateInputMethodPreferenceViews();
+    }
+
+    @Override
+    protected int getMetricsCategory() {
+        return InstrumentedFragment.VIRTUAL_KEYBOARDS;
+    }
+
+    private void updateInputMethodPreferenceViews() {
+        // Clear existing "InputMethodPreference"s
+        mInputMethodPreferenceList.clear();
+        List<String> permittedList = mDpm.getPermittedInputMethodsForCurrentUser();
+        final Context context = getPrefContext();
+        final List<InputMethodInfo> imis = mImm.getEnabledInputMethodList();
+        final int N = (imis == null ? 0 : imis.size());
+        for (int i = 0; i < N; ++i) {
+            final InputMethodInfo imi = imis.get(i);
+            final boolean isAllowedByOrganization = permittedList == null
+                    || permittedList.contains(imi.getPackageName());
+            final InputMethodPreference pref = new InputMethodPreference(
+                    context,
+                    imi,
+                    false,  /* isImeEnabler */
+                    isAllowedByOrganization,
+                    null  /* this can be null since isImeEnabler is false */);
+            mInputMethodPreferenceList.add(pref);
+        }
+        final Collator collator = Collator.getInstance();
+        Collections.sort(mInputMethodPreferenceList, new Comparator<InputMethodPreference>() {
+            @Override
+            public int compare(InputMethodPreference lhs, InputMethodPreference rhs) {
+                return lhs.compareTo(rhs, collator);
+            }
+        });
+        getPreferenceScreen().removeAll();
+        for (int i = 0; i < N; ++i) {
+            final InputMethodPreference pref = mInputMethodPreferenceList.get(i);
+            pref.setOrder(i);
+            getPreferenceScreen().addPreference(pref);
+            InputMethodAndSubtypeUtil.removeUnnecessaryNonPersistentPreference(pref);
+            pref.updatePreferenceViews();
+        }
+        mAddVirtualKeyboardScreen.setOrder(N);
+        getPreferenceScreen().addPreference(mAddVirtualKeyboardScreen);
+    }
+}