Fix Bluetooth device name max length checking.

The Bluetooth device name has a maximum length of 248 bytes in UTF-8
encoding. The settings app previously limited the Bluetooth device
name entered by the user based on the number of characters, which is
incorrect when the name includes non-ASCII characters.

Created a new Utf8ByteLengthFilter class for BluetoothNamePreference
which counts UTF-8 bytes instead of Unicode characters, along with
unit tests.

We can move Utf8ByteLengthFilter into the framework in the future
if it would be useful elsewhere in the system or for applications.

Change-Id: I9debface09659f09d750f3bfe8ad6ddfd34c75c5

tests/src/com/android/settings/tests/SettingsLaunchPerformance.java

@@ -26,7 +26,7 @@ import java.util.Map;
  * Instrumentation class for Settings launch performance testing.
  */
 public class SettingsLaunchPerformance extends LaunchPerformanceBase {
- 
+
     public static final String LOG_TAG = "SettingsLaunchPerformance";
 
     public SettingsLaunchPerformance() {

tests/src/com/android/settings/tests/Utf8ByteLengthFilterTest.java

@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2010 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.tests;
+
+import android.test.AndroidTestCase;
+import android.text.InputFilter;
+import android.text.SpannableStringBuilder;
+
+import com.android.settings.bluetooth.BluetoothNamePreference;
+
+import dalvik.annotation.TestLevel;
+import dalvik.annotation.TestTargetClass;
+import dalvik.annotation.TestTargetNew;
+import dalvik.annotation.TestTargets;
+
+@TestTargetClass(BluetoothNamePreference.Utf8ByteLengthFilter.class)
+public class Utf8ByteLengthFilterTest extends AndroidTestCase {
+
+    @TestTargets({
+        @TestTargetNew(
+            level = TestLevel.COMPLETE,
+            method = "filter",
+            args = {java.lang.CharSequence.class, int.class, int.class, android.text.Spanned.class,
+                    int.class, int.class}
+        ),
+        @TestTargetNew(
+            level = TestLevel.COMPLETE,
+            method = "BluetoothNamePreference.Utf8ByteLengthFilter",
+            args = {int.class}
+        )
+    })
+    public void testFilter() {
+        // Define the variables
+        CharSequence source;
+        SpannableStringBuilder dest;
+        // Constructor to create a LengthFilter
+        BluetoothNamePreference.Utf8ByteLengthFilter lengthFilter = new BluetoothNamePreference.Utf8ByteLengthFilter(10);
+        InputFilter[] filters = {lengthFilter};
+
+        // filter() implicitly invoked. If the total length > filter length, the filter will
+        // cut off the source CharSequence from beginning to fit the filter length.
+        source = "abc";
+        dest = new SpannableStringBuilder("abcdefgh");
+        dest.setFilters(filters);
+
+        dest.insert(1, source);
+        String expectedString1 = "aabbcdefgh";
+        assertEquals(expectedString1, dest.toString());
+
+        dest.replace(5, 8, source);
+        String expectedString2 = "aabbcabcgh";
+        assertEquals(expectedString2, dest.toString());
+
+        dest.insert(2, source);
+        assertEquals(expectedString2, dest.toString());
+
+        dest.delete(1, 3);
+        String expectedString3 = "abcabcgh";
+        assertEquals(expectedString3, dest.toString());
+
+        dest.append("12345");
+        String expectedString4 = "abcabcgh12";
+        assertEquals(expectedString4, dest.toString());
+
+        source = "\u60a8\u597d";  // 2 Chinese chars == 6 bytes in UTF-8
+        dest.replace(8, 10, source);
+        assertEquals(expectedString3, dest.toString());
+
+        dest.replace(0, 1, source);
+        String expectedString5 = "\u60a8bcabcgh";
+        assertEquals(expectedString5, dest.toString());
+
+        dest.replace(0, 4, source);
+        String expectedString6 = "\u60a8\u597dbcgh";
+        assertEquals(expectedString6, dest.toString());
+
+        source = "\u00a3\u00a5";  // 2 Latin-1 chars == 4 bytes in UTF-8
+        dest.delete(2, 6);
+        dest.insert(0, source);
+        String expectedString7 = "\u00a3\u00a5\u60a8\u597d";
+        assertEquals(expectedString7, dest.toString());
+
+        dest.replace(2, 3, source);
+        String expectedString8 = "\u00a3\u00a5\u00a3\u597d";
+        assertEquals(expectedString8, dest.toString());
+
+        dest.replace(3, 4, source);
+        String expectedString9 = "\u00a3\u00a5\u00a3\u00a3\u00a5";
+        assertEquals(expectedString9, dest.toString());
+
+        // filter() explicitly invoked
+        dest = new SpannableStringBuilder("abcdefgh");
+        CharSequence beforeFilterSource = "TestLengthFilter";
+        String expectedAfterFilter = "TestLength";
+        CharSequence actualAfterFilter = lengthFilter.filter(beforeFilterSource, 0,
+                beforeFilterSource.length(), dest, 0, dest.length());
+        assertEquals(expectedAfterFilter, actualAfterFilter);
+    }
+}