diff options
Diffstat (limited to 'src/com/android/settings/bluetooth/BluetoothNamePreference.java')
| -rw-r--r-- | src/com/android/settings/bluetooth/BluetoothNamePreference.java | 74 |
1 files changed, 70 insertions, 4 deletions
diff --git a/src/com/android/settings/bluetooth/BluetoothNamePreference.java b/src/com/android/settings/bluetooth/BluetoothNamePreference.java index 7a9a0c1..c99ab4c 100644 --- a/src/com/android/settings/bluetooth/BluetoothNamePreference.java +++ b/src/com/android/settings/bluetooth/BluetoothNamePreference.java @@ -27,8 +27,8 @@ import android.content.IntentFilter; import android.preference.EditTextPreference; import android.text.Editable; import android.text.InputFilter; +import android.text.Spanned; import android.text.TextWatcher; -import android.text.InputFilter.LengthFilter; import android.util.AttributeSet; import android.widget.Button; import android.widget.EditText; @@ -40,8 +40,7 @@ import android.widget.EditText; */ public class BluetoothNamePreference extends EditTextPreference implements TextWatcher { private static final String TAG = "BluetoothNamePreference"; - // TODO(): Investigate bluetoothd/dbus crash when length is set to 248, limit as per spec. - private static final int BLUETOOTH_NAME_MAX_LENGTH = 200; + private static final int BLUETOOTH_NAME_MAX_LENGTH_BYTES = 248; private LocalBluetoothManager mLocalManager; @@ -75,8 +74,11 @@ public class BluetoothNamePreference extends EditTextPreference implements TextW // Make sure the OK button is disabled (if necessary) after rotation EditText et = getEditText(); - et.setFilters(new InputFilter[] {new LengthFilter(BLUETOOTH_NAME_MAX_LENGTH)}); if (et != null) { + et.setFilters(new InputFilter[] { + new Utf8ByteLengthFilter(BLUETOOTH_NAME_MAX_LENGTH_BYTES) + }); + et.addTextChangedListener(this); Dialog d = getDialog(); if (d instanceof AlertDialog) { @@ -136,4 +138,68 @@ public class BluetoothNamePreference extends EditTextPreference implements TextW public void onTextChanged(CharSequence s, int start, int before, int count) { // not used } + + /** + * This filter will constrain edits so that the text length is not + * greater than the specified number of bytes using UTF-8 encoding. + * <p>The JNI method used by {@link android.server.BluetoothService} + * to convert UTF-16 to UTF-8 doesn't support surrogate pairs, + * therefore code points outside of the basic multilingual plane + * (0000-FFFF) will be encoded as a pair of 3-byte UTF-8 characters, + * rather than a single 4-byte UTF-8 encoding. Dalvik implements this + * conversion in {@code convertUtf16ToUtf8()} in + * {@code dalvik/vm/UtfString.c}. + * <p>This JNI method is unlikely to change in the future due to + * backwards compatibility requirements. It's also unclear whether + * the installed base of Bluetooth devices would correctly handle the + * encoding of surrogate pairs in UTF-8 as 4 bytes rather than 6. + * However, this filter will still work in scenarios where surrogate + * pairs are encoded as 4 bytes, with the caveat that the maximum + * length will be constrained more conservatively than necessary. + */ + public static class Utf8ByteLengthFilter implements InputFilter { + private int mMaxBytes; + + public Utf8ByteLengthFilter(int maxBytes) { + mMaxBytes = maxBytes; + } + + public CharSequence filter(CharSequence source, int start, int end, + Spanned dest, int dstart, int dend) { + int srcByteCount = 0; + // count UTF-8 bytes in source substring + for (int i = start; i < end; i++) { + char c = source.charAt(i); + srcByteCount += (c < 0x0080) ? 1 : (c < 0x0800 ? 2 : 3); + } + int destLen = dest.length(); + int destByteCount = 0; + // count UTF-8 bytes in destination excluding replaced section + for (int i = 0; i < destLen; i++) { + if (i < dstart || i >= dend) { + char c = dest.charAt(i); + destByteCount += (c < 0x0080) ? 1 : (c < 0x0800 ? 2 : 3); + } + } + int keepBytes = mMaxBytes - destByteCount; + if (keepBytes <= 0) { + return ""; + } else if (keepBytes >= srcByteCount) { + return null; // use original dest string + } else { + // find end position of largest sequence that fits in keepBytes + for (int i = start; i < end; i++) { + char c = source.charAt(i); + keepBytes -= (c < 0x0080) ? 1 : (c < 0x0800 ? 2 : 3); + if (keepBytes < 0) { + return source.subSequence(start, i); + } + } + // If the entire substring fits, we should have returned null + // above, so this line should not be reached. If for some + // reason it is, return null to use the original dest string. + return null; + } + } + } } |