Fix unresponsive UI during scan and display of "No Bluetooth devices"

- When there are no available Bluetooth devices, we show
  "No Bluetooth devices were found nearby" as a preference item after
  the scan completes. Update the layout for this Preference item so
  that the text is centered and doesn't highlight when touched.

- Fix slow responsiveness on scanning caused by repeated removal of
  "No Bluetooth devices were found" preference item on every call to
  onBindView().

- If no devices are paired, don't restart the scan on every rotation.

Bug: 5173935
Bug: 5055460
Change-Id: I52fb2d52f315c5e793f08499146842d54c5c3ead

1 files changed, 30 insertions, 0 deletions

diff --git a/res/layout/preference_empty_list.xml b/res/layout/preference_empty_list.xml
new file mode 100644
index 0000000..1c721ac
--- /dev/null
+++ b/res/layout/preference_empty_list.xml
@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2011 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.
+-->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:minHeight="48dip"
+    android:background="@android:color/transparent">
+
+    <TextView
+        android:id="@+android:id/title"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:padding="@*android:dimen/preference_fragment_padding_side"
+        android:gravity="center" />
+
+</LinearLayout>