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/*
* Copyright (C) 2008 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.bluetooth;
import android.app.AlertDialog;
import android.app.Dialog;
import android.bluetooth.BluetoothAdapter;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
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.util.AttributeSet;
import android.widget.Button;
import android.widget.EditText;
/**
* BluetoothNamePreference is the preference type for editing the device's
* Bluetooth name. It asks the user for a name, and persists it via the
* Bluetooth API.
*/
public class BluetoothNamePreference extends EditTextPreference implements TextWatcher {
private static final String TAG = "BluetoothNamePreference";
private static final int BLUETOOTH_NAME_MAX_LENGTH_BYTES = 248;
private LocalBluetoothManager mLocalManager;
private BroadcastReceiver mReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (action.equals(BluetoothAdapter.ACTION_LOCAL_NAME_CHANGED)) {
setSummaryToName();
} else if (action.equals(BluetoothAdapter.ACTION_STATE_CHANGED) &&
(intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, BluetoothAdapter.ERROR) ==
BluetoothAdapter.STATE_ON)) {
setSummaryToName();
}
}
};
public BluetoothNamePreference(Context context, AttributeSet attrs) {
super(context, attrs);
mLocalManager = LocalBluetoothManager.getInstance(context);
setSummaryToName();
}
public void resume() {
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothAdapter.ACTION_STATE_CHANGED);
filter.addAction(BluetoothAdapter.ACTION_LOCAL_NAME_CHANGED);
getContext().registerReceiver(mReceiver, filter);
// Make sure the OK button is disabled (if necessary) after rotation
EditText et = getEditText();
if (et != null) {
et.setFilters(new InputFilter[] {
new Utf8ByteLengthFilter(BLUETOOTH_NAME_MAX_LENGTH_BYTES)
});
et.addTextChangedListener(this);
Dialog d = getDialog();
if (d instanceof AlertDialog) {
Button b = ((AlertDialog) d).getButton(AlertDialog.BUTTON_POSITIVE);
b.setEnabled(et.getText().length() > 0);
}
}
}
public void pause() {
EditText et = getEditText();
if (et != null) {
et.removeTextChangedListener(this);
}
getContext().unregisterReceiver(mReceiver);
}
private void setSummaryToName() {
BluetoothAdapter adapter = mLocalManager.getBluetoothAdapter();
if (adapter.isEnabled()) {
setSummary(adapter.getName());
}
}
@Override
protected boolean persistString(String value) {
BluetoothAdapter adapter = mLocalManager.getBluetoothAdapter();
adapter.setName(value);
return true;
}
@Override
protected void onClick() {
super.onClick();
// The dialog should be created by now
EditText et = getEditText();
if (et != null) {
et.setText(mLocalManager.getBluetoothAdapter().getName());
}
}
// TextWatcher interface
public void afterTextChanged(Editable s) {
Dialog d = getDialog();
if (d instanceof AlertDialog) {
((AlertDialog) d).getButton(AlertDialog.BUTTON_POSITIVE).setEnabled(s.length() > 0);
}
}
// TextWatcher interface
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
// not used
}
// TextWatcher interface
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;
}
}
}
}
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