Highlight row (instead of ripple) when come from search.

- Moved HighlightableAdapter to its own class
- Replaced ripple with blue background
- Bluebackground only stays for 5 seconds. After that it's replaced by
  ?attr/selectableBackground

Misc fixes.

- Fix NPE in UserSettings
- Update char limit on a new string

Change-Id: I4687e54e71fd7b9243f520b7630563df58be23d4
Fixes: 71715698
Fixes: 72761974
Test: robotests

src/com/android/settings/widget/HighlightablePreferenceGroupAdapter.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2018 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.widget;
+
+import android.content.Context;
+import android.support.annotation.VisibleForTesting;
+import android.support.v7.preference.PreferenceGroup;
+import android.support.v7.preference.PreferenceGroupAdapter;
+import android.support.v7.preference.PreferenceViewHolder;
+import android.support.v7.widget.RecyclerView;
+import android.text.TextUtils;
+import android.util.TypedValue;
+import android.view.View;
+
+import com.android.settings.R;
+
+public class HighlightablePreferenceGroupAdapter extends PreferenceGroupAdapter {
+
+    @VisibleForTesting
+    static final long DELAY_HIGHLIGHT_DURATION_MILLIS = 600L;
+    private static final long HIGHLIGHT_DURATION = 5000L;
+
+    private final int mHighlightColor;
+    private final int mNormalBackgroundRes;
+    private final String mHighlightKey;
+
+    private boolean mHighlightRequested;
+    private int mHighlightPosition = RecyclerView.NO_POSITION;
+
+    public HighlightablePreferenceGroupAdapter(PreferenceGroup preferenceGroup, String key,
+            boolean highlightRequested) {
+        super(preferenceGroup);
+        mHighlightKey = key;
+        mHighlightRequested = highlightRequested;
+        final Context context = preferenceGroup.getContext();
+        final TypedValue outValue = new TypedValue();
+        context.getTheme().resolveAttribute(android.R.attr.selectableItemBackground,
+                outValue, true /* resolveRefs */);
+        mNormalBackgroundRes = outValue.resourceId;
+        mHighlightColor = context.getColor(R.color.preference_highligh_color);
+    }
+
+    @Override
+    public void onBindViewHolder(PreferenceViewHolder holder, int position) {
+        super.onBindViewHolder(holder, position);
+        updateBackground(holder, position);
+    }
+
+    @VisibleForTesting
+    void updateBackground(PreferenceViewHolder holder, int position) {
+        View v = holder.itemView;
+        if (position == mHighlightPosition) {
+            v.setBackgroundColor(mHighlightColor);
+            v.setTag(R.id.preference_highlighted, true);
+            v.postDelayed(() -> {
+                mHighlightPosition = RecyclerView.NO_POSITION;
+                removeHighlightBackground(v);
+            }, HIGHLIGHT_DURATION);
+        } else if (Boolean.TRUE.equals(v.getTag(R.id.preference_highlighted))) {
+            removeHighlightBackground(v);
+        }
+    }
+
+    public void requestHighlight(View root, RecyclerView recyclerView) {
+        if (mHighlightRequested || recyclerView == null || TextUtils.isEmpty(mHighlightKey)) {
+            return;
+        }
+        root.postDelayed(() -> {
+            final int position = getPreferenceAdapterPosition(mHighlightKey);
+            if (position < 0) {
+                return;
+            }
+            mHighlightRequested = true;
+            recyclerView.getLayoutManager().scrollToPosition(position);
+            mHighlightPosition = position;
+            notifyItemChanged(position);
+        }, DELAY_HIGHLIGHT_DURATION_MILLIS);
+    }
+
+    public boolean isHighlightRequested() {
+        return mHighlightRequested;
+    }
+
+    private void removeHighlightBackground(View v) {
+        v.setBackgroundResource(mNormalBackgroundRes);
+        v.setTag(R.id.preference_highlighted, false);
+    }
+}