Q:

Format text in bluetooth printer

actually, I have to implement a module the which connect to a BT termical printer and print in it. I have a simple but functionally example, it works with the printer. The problem is that these text are printed in plain text, and i have to give it format, bold, change the font size and others... How can i do it??. I don't know how... I use this Class: 
/*
 * Copyright (C) 2009 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.edec.aptr;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.UUID;

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothServerSocket;
import android.bluetooth.BluetoothSocket;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;

/**
 * This class does all the work for setting up and managing Bluetooth
 * connections with other devices. It has a thread that listens for incoming
 * connections, a thread for connecting with a device, and a thread for
 * performing data transmissions when connected.
 */
public class BluetoothService {
    // Debugging
    private static final String TAG = "BluetoothService";
    private static final boolean D = true;

    // Name for the SDP record when creating server socket
    private static final String NAME = "BTPrinter";

    // Unique UUID for this application
    private static final UUID MY_UUID = UUID
            .fromString("00001101-0000-1000-8000-00805F9B34FB"); // change by
                                                                    // chongqing
                                                                    // jinou

    // Member fields
    private final BluetoothAdapter mAdapter;
    private final Handler mHandler;
    private AcceptThread mAcceptThread;
    private ConnectThread mConnectThread;
    private ConnectedThread mConnectedThread;
    private int mState;

    // Constants that indicate the current connection state
    public static final int STATE_NONE = 0; // we're doing nothing
    public static final int STATE_LISTEN = 1; // now listening for incoming
                                                // connections
    public static final int STATE_CONNECTING = 2; // now initiating an outgoing
                                                    // connection
    public static final int STATE_CONNECTED = 3; // now connected to a remote
                                                    // device

    /**
     * Constructor. Prepares a new BTPrinter session.
     * 
     * @param context
     *            The UI Activity Context
     * @param handler
     *            A Handler to send messages back to the UI Activity
     */
    public BluetoothService(Context context, Handler handler) {
        mAdapter = BluetoothAdapter.getDefaultAdapter();
        mState = STATE_NONE;
        mHandler = handler;
    }

    /**
     * Set the current state of the connection
     * 
     * @param state
     *            An integer defining the current connection state
     */
    private synchronized void setState(int state) {
        if (D)
            Log.d(TAG, "setState() " + mState + " -> " + state);
        mState = state;

        // Give the new state to the Handler so the UI Activity can update
        mHandler.obtainMessage(amarre.MESSAGE_STATE_CHANGE, state, -1)
                .sendToTarget();
    }

    /**
     * Return the current connection state.
     */
    public synchronized int getState() {
        return mState;
    }

    /**
     * Start the service. Specifically start AcceptThread to begin a session in
     * listening (server) mode. Called by the Activity onResume()
     */
    public synchronized void start() {
        if (D)
            Log.d(TAG, "start");

        // Cancel any thread attempting to make a connection
        if (mConnectThread != null) {
            mConnectThread.cancel();
            mConnectThread = null;
        }

        // Cancel any thread currently running a connection
        if (mConnectedThread != null) {
            mConnectedThread.cancel();
            mConnectedThread = null;
        }

        // Start the thread to listen on a BluetoothServerSocket
        if (mAcceptThread == null) {
            mAcceptThread = new AcceptThread();
            mAcceptThread.start();
        }
        setState(STATE_LISTEN);
    }

    /**
     * Start the ConnectThread to initiate a connection to a remote device.
     * 
     * @param device
     *            The BluetoothDevice to connect
     */
    public synchronized void connect(BluetoothDevice device) {
        if (D)
            Log.d(TAG, "connect to: " + device);

        // Cancel any thread attempting to make a connection
        if (mState == STATE_CONNECTING) {
            if (mConnectThread != null) {
                mConnectThread.cancel();
                mConnectThread = null;
            }
        }

        // Cancel any thread currently running a connection
        if (mConnectedThread != null) {
            mConnectedThread.cancel();
            mConnectedThread = null;
        }

        // Start the thread to connect with the given device
        mConnectThread = new ConnectThread(device);
        mConnectThread.start();
        setState(STATE_CONNECTING);
    }

    /**
     * Start the ConnectedThread to begin managing a Bluetooth connection
     * 
     * @param socket
     *            The BluetoothSocket on which the connection was made
     * @param device
     *            The BluetoothDevice that has been connected
     */
    public synchronized void connected(BluetoothSocket socket,
            BluetoothDevice device) {
        if (D)
            Log.d(TAG, "connected");

        // Cancel the thread that completed the connection
        if (mConnectThread != null) {
            mConnectThread.cancel();
            mConnectThread = null;
        }

        // Cancel any thread currently running a connection
        if (mConnectedThread != null) {
            mConnectedThread.cancel();
            mConnectedThread = null;
        }

        // Cancel the accept thread because we only want to connect to one
        // device
        if (mAcceptThread != null) {
            mAcceptThread.cancel();
            mAcceptThread = null;
        }

        // Start the thread to manage the connection and perform transmissions
        mConnectedThread = new ConnectedThread(socket);
        mConnectedThread.start();

        // Send the name of the connected device back to the UI Activity
        Message msg = mHandler.obtainMessage(amarre.MESSAGE_DEVICE_NAME);
        Bundle bundle = new Bundle();
        bundle.putString(amarre.DEVICE_NAME, device.getName());
        msg.setData(bundle);
        mHandler.sendMessage(msg);

        setState(STATE_CONNECTED);
    }

    /**
     * Stop all threads
     */
    public synchronized void stop() {
        if (D)
            Log.d(TAG, "stop");
        setState(STATE_NONE);
        if (mConnectThread != null) {
            mConnectThread.cancel();
            mConnectThread = null;
        }
        if (mConnectedThread != null) {
            mConnectedThread.cancel();
            mConnectedThread = null;
        }
        if (mAcceptThread != null) {
            mAcceptThread.cancel();
            mAcceptThread = null;
        }
    }

    /**
     * Write to the ConnectedThread in an unsynchronized manner
     * 
     * @param out
     *            The bytes to write
     * @see ConnectedThread#write(byte[])
     */
    public void write(byte[] out) {
        // Create temporary object
        ConnectedThread r;
        // Synchronize a copy of the ConnectedThread
        synchronized (this) {
            if (mState != STATE_CONNECTED)
                return;
            r = mConnectedThread;
        }
        // Perform the write unsynchronized
        r.write(out);
    }

    /**
     * Indicate that the connection attempt failed and notify the UI Activity.
     */
    private void connectionFailed() {
        setState(STATE_LISTEN);

        // Send a failure message back to the Activity
        Message msg = mHandler.obtainMessage(amarre.MESSAGE_TOAST);
        Bundle bundle = new Bundle();
        bundle.putString(
                amarre.TOAST,
                "No se puede conectar al dispostivo, verifique que éste se encuentra encendido y cercano a la tablet");
        msg.setData(bundle);
        mHandler.sendMessage(msg);
    }

    /**
     * Indicate that the connection was lost and notify the UI Activity.
     */
    private void connectionLost() {
        // setState(STATE_LISTEN);

        // Send a failure message back to the Activity
        Message msg = mHandler.obtainMessage(amarre.MESSAGE_TOAST);
        Bundle bundle = new Bundle();
        bundle.putString(amarre.TOAST,
                "La conexión con el dispositivo se ha perdido");
        msg.setData(bundle);
        mHandler.sendMessage(msg);
    }

    /**
     * This thread runs while listening for incoming connections. It behaves
     * like a server-side client. It runs until a connection is accepted (or
     * until cancelled).
     */
    private class AcceptThread extends Thread {
        // The local server socket
        private final BluetoothServerSocket mmServerSocket;

        public AcceptThread() {
            BluetoothServerSocket tmp = null;

            // Create a new listening server socket
            try {
                tmp = mAdapter
                        .listenUsingRfcommWithServiceRecord(NAME, MY_UUID);
            } catch (IOException e) {
                Log.e(TAG, "listen() failed", e);
            }
            mmServerSocket = tmp;
        }

        public void run() {
            if (D)
                Log.d(TAG, "BEGIN mAcceptThread" + this);
            setName("AcceptThread");
            BluetoothSocket socket = null;

            // Listen to the server socket if we're not connected
            while (mState != STATE_CONNECTED) {
                try {
                    // This is a blocking call and will only return on a
                    // successful connection or an exception
                    socket = mmServerSocket.accept();
                } catch (IOException e) {
                    Log.e(TAG, "accept() failed", e);
                    break;
                }

                // If a connection was accepted
                if (socket != null) {
                    synchronized (BluetoothService.this) {
                        switch (mState) {
                        case STATE_LISTEN:
                        case STATE_CONNECTING:
                            // Situation normal. Start the connected thread.
                            connected(socket, socket.getRemoteDevice());
                            break;
                        case STATE_NONE:
                        case STATE_CONNECTED:
                            // Either not ready or already connected. Terminate
                            // new socket.
                            try {
                                socket.close();
                            } catch (IOException e) {
                                Log.e(TAG, "Could not close unwanted socket", e);
                            }
                            break;
                        }
                    }
                }
            }
            if (D)
                Log.i(TAG, "END mAcceptThread");
        }

        public void cancel() {
            if (D)
                Log.d(TAG, "cancel " + this);
            try {
                mmServerSocket.close();
            } catch (IOException e) {
                Log.e(TAG, "close() of server failed", e);
            }
        }
    }

    /**
     * This thread runs while attempting to make an outgoing connection with a
     * device. It runs straight through; the connection either succeeds or
     * fails.
     */
    private class ConnectThread extends Thread {
        private final BluetoothSocket mmSocket;
        private final BluetoothDevice mmDevice;

        public ConnectThread(BluetoothDevice device) {
            mmDevice = device;
            BluetoothSocket tmp = null;

            // Get a BluetoothSocket for a connection with the
            // given BluetoothDevice
            try {
                tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
            } catch (IOException e) {
                Log.e(TAG, "create() failed", e);
            }
            mmSocket = tmp;
        }

        public void run() {
            Log.i(TAG, "BEGIN mConnectThread");
            setName("ConnectThread");

            // Always cancel discovery because it will slow down a connection
            mAdapter.cancelDiscovery();

            // Make a connection to the BluetoothSocket
            try {
                // This is a blocking call and will only return on a
                // successful connection or an exception
                mmSocket.connect();
            } catch (IOException e) {
                connectionFailed();
                // Close the socket
                try {
                    mmSocket.close();
                } catch (IOException e2) {
                    Log.e(TAG,
                            "unable to close() socket during connection failure",
                            e2);
                }
                // Start the service over to restart listening mode
                BluetoothService.this.start();
                return;
            }

            // Reset the ConnectThread because we're done
            synchronized (BluetoothService.this) {
                mConnectThread = null;
            }

            // Start the connected thread
            connected(mmSocket, mmDevice);
        }

        public void cancel() {
            try {
                mmSocket.close();
            } catch (IOException e) {
                Log.e(TAG, "close() of connect socket failed", e);
            }
        }
    }

    /**
     * This thread runs during a connection with a remote device. It handles all
     * incoming and outgoing transmissions.
     */
    private class ConnectedThread extends Thread {
        private final BluetoothSocket mmSocket;
        private final InputStream mmInStream;
        private final OutputStream mmOutStream;

        public ConnectedThread(BluetoothSocket socket) {
            Log.d(TAG, "create ConnectedThread");
            mmSocket = socket;
            InputStream tmpIn = null;
            OutputStream tmpOut = null;

            // Get the BluetoothSocket input and output streams
            try {
                tmpIn = socket.getInputStream();
                tmpOut = socket.getOutputStream();
            } catch (IOException e) {
                Log.e(TAG, "temp sockets not created", e);
            }

            mmInStream = tmpIn;
            mmOutStream = tmpOut;
        }

        public void run() {
            Log.i(TAG, "BEGIN mConnectedThread");
            int bytes;

            // Keep listening to the InputStream while connected
            while (true) {
                try {
                    byte[] buffer = new byte[256];
                    // Read from the InputStream
                    bytes = mmInStream.read(buffer);
                    if (bytes > 0) {
                        // Send the obtained bytes to the UI Activity
                        mHandler.obtainMessage(amarre.MESSAGE_READ, bytes, -1,
                                buffer).sendToTarget();
                    } else {
                        Log.e(TAG, "disconnected");
                        connectionLost();

                        // add by chongqing jinou
                        if (mState != STATE_NONE) {
                            Log.e(TAG, "disconnected");
                            // Start the service over to restart listening mode
                            BluetoothService.this.start();
                        }
                        break;
                    }
                } catch (IOException e) {
                    Log.e(TAG, "disconnected", e);
                    connectionLost();

                    // add by chongqing jinou
                    if (mState != STATE_NONE) {
                        // Start the service over to restart listening mode
                        BluetoothService.this.start();
                    }
                    break;
                }
            }
        }

        /**
         * Write to the connected OutStream.
         * 
         * @param buffer
         *            The bytes to write
         */
        public void write(byte[] buffer) {
            try {
                mmOutStream.write(buffer);
                // Share the sent message back to the UI Activity
                mHandler.obtainMessage(amarre.MESSAGE_WRITE, -1, -1, buffer)
                        .sendToTarget();
            } catch (IOException e) {
                Log.e(TAG, "Exception during write", e);
            }
        }

        public void cancel() {
            try {
                mmSocket.close();
            } catch (IOException e) {
                Log.e(TAG, "close() of connect socket failed", e);
            }
        }
    }
}

I send the data from another class, so:
        byte[] send;
        try {
            send = message.getBytes("GB2312");
        } catch (UnsupportedEncodingException e) {
            send = message.getBytes();

        }

        mService.write(send);

message is a String var.. Then, how can I format the text??, or at least, change font size...

A:

Now I know how to do it. I had to apply reverse engineering and de-compile an .apk from the  market, using dex2jar on Linux and then opening the jar with java de-compiler... Try this...When you write this command:
out.write(str.getBytes(),0,str.getBytes().length);
you are sending to the method a byte[] array. You can modify the format by sending another byte[] array before sending the real byte[] array... 
The default format byte[] array is this:
byte[] arrayOfByte1 = { 27, 33, 0 };
So u can try this:
byte[] format = { 27, 33, 0 };

out.write(format);

out.write(str.getBytes(),0,str.getBytes().length);

These lines will print the default format text, but if you try below code, 
byte[] format = { 27, 33, 0 };

format[2] = ((byte)(0x8 | arrayOfByte1[2]));

out.write(format);

out.write(str.getBytes(),0,str.getBytes().length);

it will print text in bold style... You can try these other format arrays:
// Bold
format[2] = ((byte)(0x8 | arrayOfByte1[2]));

// Height
format[2] = ((byte)(0x10 | arrayOfByte1[2]));

// Width
format[2] = ((byte) (0x20 | arrayOfByte1[2]));

// Underline
format[2] = ((byte)(0x80 | arrayOfByte1[2]));

// Small
format[2] = ((byte)(0x1 | arrayOfByte1[2]));

Also you can combine it, then if you like little and bold text, uncomment these array assignments, for example:
byte[] format = { 27, 33, 0 };

// Bold
format[2] = ((byte)(0x8 | arrayOfByte1[2]));
// Height
format[2] = ((byte)(0x10 | arrayOfByte1[2]));
// Width
format[2] = ((byte) (0x20 | arrayOfByte1[2]));
// Underline
// format[2] = ((byte)(0x80 | arrayOfByte1[2]));
// Small
// format[2] = ((byte)(0x1 | arrayOfByte1[2]));
out.write(format);
out.write(str.getBytes(),0,str.getBytes().length);

This last code prints que biggest text size.

A:

I know this is an old thread but it helped me alot so I decided to share my code for simplified use of Formatting.
Sample usage:
final String message = "Example message\n";
// Default format:
writeWithFormat(message.getBytes(), new Formatter().get(), Formatter.leftAlign());
// Bold format center:
writeWithFormat(message.getBytes(), new Formatter().bold().get(), Formatter.centerAlign());
// Bold underlined format with right alignment:
writeWithFormat(message.getBytes(), new Formatter().bold().underlined().get(), Formatter.rightAlign());

Formatter class with Builder pattern:
/**
 * Class for formatting
 */
public static class Formatter {
    /** The format that is being build on */
    private byte[] mFormat;

    public Formatter() {
        // Default:
        mFormat = new byte[]{27, 33, 0};
    }

    /**
     * Method to get the Build result
     *
     * @return the format
     */
    public byte[] get() {
        return mFormat;
    }

    public Formatter bold() {
        // Apply bold:
        mFormat[2] = ((byte) (0x8 | mFormat[2]));
        return this;
    }

    public Formatter small() {
        mFormat[2] = ((byte) (0x1 | mFormat[2]));
        return this;
    }

    public Formatter height() {
        mFormat[2] = ((byte) (0x10 | mFormat[2]));
        return this;
    }

    public Formatter width() {
        mFormat[2] = ((byte) (0x20 | mFormat[2]));
        return this;
    }

    public Formatter underlined() {
        mFormat[2] = ((byte) (0x80 | mFormat[2]));
        return this;
    }

    public static byte[] rightAlign(){
        return new byte[]{0x1B, 'a', 0x02};
    }

    public static byte[] leftAlign(){
        return new byte[]{0x1B, 'a', 0x00};
    }

    public static byte[] centerAlign(){
        return new byte[]{0x1B, 'a', 0x01};
    }
}

The write method that uses the formatting looks like this:
     /**
     * Method to write with a given format
     *
     * @param buffer     the array of bytes to actually write
     * @param pFormat    The format byte array
     * @param pAlignment The alignment byte array
     * @return true on successful write, false otherwise
     */
    public boolean writeWithFormat(byte[] buffer, final byte[] pFormat, final byte[] pAlignment) {
        try {
            // Notify printer it should be printed with given alignment:
            mOutputStream.write(pAlignment);
            // Notify printer it should be printed in the given format:
            mOutputStream.write(pFormat);
            // Write the actual data:
            mOutputStream.write(buffer, 0, buffer.length);

            // Share the sent message back to the UI Activity
            App.getInstance().getHandler().obtainMessage(MESSAGE_WRITE, buffer.length, -1, buffer).sendToTarget();
            return true;
        } catch (IOException e) {
            Log.e(TAG, "Exception during write", e);
            return false;
        }
    }

