Printing an Image using a Bluetooth Thermal Printer From an Android App?

Question

I have been trying to get a print of an Image but I have not been successful so far.

The printer is a locally manufactured 2" thermal printer having a printing resolution of 8dots/mm, 384dots/line, 203 dpi.
The printer is based of a board having the "NXP 2388 ARM v7 Microproc." having a Memory FLASH size of 512 KB, RAM: 128 KB & a Receive Buffer Size of 16KB.

I followed this question till now.

Problem: The image I tried printing is of 576x95 res.

The image got printed(with some error LED lighting up and debug buzzer noise :D) but the orientation of the image was vertical instead of getting horizontally printed; that too at the very left side of the page and the top part of the image was cut-off

Assuming here that I din't passed some of the flags(while making the "packet") compatible with the printer that I have.

I have not worked on bluetooth printing before so any help is appreciable :)

My Existing Main Activity:

public class MainActivity extends Activity 
    {
    // will show the statuses
    TextView myLabel;
    // will enable user to enter any text to be printed
    EditText myTextbox;
    EditText devName;
    public TableLayout tl2; 
    String devid;
    String[] pName;
    String[] LODQTY;
    String[] rte;
    String[] stk;
    String[] oQty;
    String[] oVal;
    String[] fQty;

    BitSet dots;
    int mWidth;
    int mHeight;
    String mStatus;
    String TAG = "TAG";

    public String msg;

    // android built in classes for bluetooth operations
    BluetoothAdapter mBluetoothAdapter;
    BluetoothSocket mmSocket;
    BluetoothDevice mmDevice;

    OutputStream mmOutputStream;
    InputStream mmInputStream;
    Thread workerThread;

    byte[] readBuffer;
    int readBufferPosition;
    int counter;
    volatile boolean stopWorker;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        devName = (EditText) findViewById(R.id.etdevice);

        devName.setText("BTprinter0377");

        String[] product_info = new String[6];
        product_info[0] = "CPL400^10^1^0^4^0.4^0";
        product_info[1] = "CPL400^10^1^0^4^0.4^0";
        product_info[2] = "CPL400^10^1^0^4^0.4^0";
        product_info[3] = "CPL400^10^1^0^4^0.4^0";
        product_info[4] = "CPL400^10^1^0^4^0.4^0";
        product_info[5] = "CPL400^10^1^0^4^0.4^0";


        tl2 = (TableLayout) findViewById(R.id.dynSummary);
        LayoutInflater inflater = getLayoutInflater();
    for (int current = 0; current <= (product_info.length - 1); current++) {


            final TableRow row = (TableRow)inflater.inflate(R.layout.table_summary_row, tl2 , false);

            TextView tv1 = (TextView)row.findViewById(R.id.tvSkuName);
            TextView tv2 = (TextView)row.findViewById(R.id.tvOrderQty);
            TextView tv3 = (TextView)row.findViewById(R.id.tvFreeQty);

            TextView tv4 = (TextView)row.findViewById(R.id.tvSampleQty);
            TextView tv5 = (TextView)row.findViewById(R.id.tvTotalOrderKg);
            TextView tv6 = (TextView)row.findViewById(R.id.tvTotalFreeKg);
           TextView tv7 = (TextView)row.findViewById(R.id.tvTotalSampleKg);

            StringTokenizer tokens = new StringTokenizer(String.valueOf(product_info[current]), "^");
            //System.out.println("tokens.nextToken().trim()"+tokens.nextToken().trim());
            tv1.setText(tokens.nextToken().trim());
            tv2.setText(tokens.nextToken().trim());
            tv3.setText(tokens.nextToken().trim());
            tv4.setText(tokens.nextToken().trim());
            tv5.setText(tokens.nextToken().trim());
            tv6.setText(tokens.nextToken().trim());
            tv7.setText(tokens.nextToken().trim());

            tl2.addView(row);

    }

        try {

            // we have three buttons for specific functions
            Button openButton = (Button) findViewById(R.id.open);
            Button sendButton = (Button) findViewById(R.id.send);
            Button closeButton = (Button) findViewById(R.id.close);

            myLabel = (TextView) findViewById(R.id.label);

            // open bluetooth connection
            openButton.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {

                    devid = devName.getText().toString().trim();

                    try {
                        findBT();
                        openBT();
                    } catch (IOException ex) {
                    }

                }
            });

            // send data typed by the user to be printed
            sendButton.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    try {
                        sendData();
                    } catch (IOException ex) {
                    }
                }
            });

            // close bluetooth connection
            closeButton.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    try {
                        closeBT();
                    } catch (IOException ex) {
                    }
                }
            });

        } catch (NullPointerException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /*
     * This will find a bluetooth printer device
     */
    void findBT() {

        try {
            mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

            if (mBluetoothAdapter == null) {
                myLabel.setText("No bluetooth adapter available");
            }

            if (!mBluetoothAdapter.isEnabled()) {
                Intent enableBluetooth = new Intent(
                        BluetoothAdapter.ACTION_REQUEST_ENABLE);
                startActivityForResult(enableBluetooth, 0);
            }

            Set<BluetoothDevice> pairedDevices = mBluetoothAdapter
                    .getBondedDevices();
            if (pairedDevices.size() > 0) {
                for (BluetoothDevice device : pairedDevices) {

                System.out.println("device.getName(): "+device.getName().toString());

                    if (device.getName().equals("BTprinter0377")) {
                        mmDevice = device;
                        break;
                    }
                }
            }
            myLabel.setText("Bluetooth Device Found");
        } catch (NullPointerException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /*
     * Tries to open a connection to the bluetooth printer device
     */
    void openBT() throws IOException {
        try {
            // Standard SerialPortService ID
            UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb"); 

            mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
            mmSocket.connect();
            mmOutputStream = mmSocket.getOutputStream();
            mmInputStream = mmSocket.getInputStream();

            beginListenForData();

            myLabel.setText("Bluetooth Opened");
        } catch (NullPointerException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /*
     * After opening a connection to bluetooth printer device, 
     * we have to listen and check if a data were sent to be printed.
     */
    void beginListenForData() {
        try {
            final Handler handler = new Handler();

            // This is the ASCII code for a newline character
            final byte delimiter = 10;

            stopWorker = false;
            readBufferPosition = 0;
            readBuffer = new byte[1024];

            workerThread = new Thread(new Runnable() {
                public void run() {
                    while (!Thread.currentThread().isInterrupted()
                            && !stopWorker) {

                        try {

                            int bytesAvailable = mmInputStream.available();
                            if (bytesAvailable > 0) {
                                byte[] packetBytes = new byte[bytesAvailable];
                                mmInputStream.read(packetBytes);
                                for (int i = 0; i < bytesAvailable; i++) {
                                    byte b = packetBytes[i];
                                    if (b == delimiter) {
                                        byte[] encodedBytes = new byte[readBufferPosition];
                                        System.arraycopy(readBuffer, 0,
                                                encodedBytes, 0,
                                                encodedBytes.length);
                                        final String data = new String(
                                                encodedBytes, "US-ASCII");
                                        readBufferPosition = 0;

                                        handler.post(new Runnable() {
                                            public void run() {
                                                myLabel.setText(data);
                                            }
                                        });
                                    } else {
                                        readBuffer[readBufferPosition++] = b;
                                    }
                                }
                            }

                        } catch (IOException ex) {
                            stopWorker = true;
                        }

                    }
                }
            });

            workerThread.start();
        } catch (NullPointerException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /*
     * This will send data to be printed by the bluetooth printer
     */
    void sendData() throws IOException {
        System.out.println("tl2.getChildCount(): "+tl2.getChildCount());
        try {

            print_image("/sdcard/tryimg.png");

            String msg22;
            msg22 = "\n";
            msg22 += "PN     Or Fr Sa TOKg TFKg TSKg";
            msg22 += "\n";

            //mmOutputStream.write(msg22.getBytes());

            // tell the user data were sent
            myLabel.setText("Data Sent");

        } catch (NullPointerException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /*
     * Close the connection to bluetooth printer.
     */
    void closeBT() throws IOException {
        try {
            stopWorker = true;
            mmOutputStream.close();
            mmInputStream.close();
            mmSocket.close();
            myLabel.setText("Bluetooth Closed");
        } catch (NullPointerException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    public String convertBitmap(Bitmap inputBitmap) {

        mWidth = inputBitmap.getWidth();
        mHeight = inputBitmap.getHeight();

        convertArgbToGrayscale(inputBitmap, mWidth, mHeight);
        mStatus = "ok";
        return mStatus;

    }

    private void convertArgbToGrayscale(Bitmap bmpOriginal, int width,
            int height) {
        int pixel;
        int k = 0;
        int B = 0, G = 0, R = 0;
         dots = new BitSet();
        try {

            for (int x = 0; x < height; x++) {
                for (int y = 0; y < width; y++) {
                    // get one pixel color
                    pixel = bmpOriginal.getPixel(y, x);

                    // retrieve color of all channels
                    R = Color.red(pixel);
                    G = Color.green(pixel);
                    B = Color.blue(pixel);
                    // take conversion up to one single value by calculating
                    // pixel intensity.
                    R = G = B = (int) (0.299 * R + 0.587 * G + 0.114 * B);
                    // set bit into bitset, by calculating the pixel's luma
                    if (R < 55) {                       
                        dots.set(k);//this is the bitset that i'm printing
                    }
                    k++;

                }


            }


        } catch (Exception e) {
            // TODO: handle exception
            Log.e(TAG, e.toString());
        }
    }


    private void print_image(String file) throws IOException {
        File fl = new File(file);
        if (fl.exists()) {
            Bitmap bmp = BitmapFactory.decodeFile(file);
            convertBitmap(bmp);
            mmOutputStream.write(PrinterCommands.SET_LINE_SPACING_24);

            int offset = 0;
            while (offset < bmp.getHeight()) {
                mmOutputStream.write(PrinterCommands.SELECT_BIT_IMAGE_MODE);
                for (int x = 0; x < bmp.getWidth(); ++x) {

                    for (int k = 0; k < 3; ++k) {

                        byte slice = 0;
                        for (int b = 0; b < 8; ++b) {
                            int y = (((offset / 8) + k) * 8) + b;
                            int i = (y * bmp.getWidth()) + x;
                            boolean v = false;
                            if (i < dots.length()) {
                                v = dots.get(i);
                            }
                            slice |= (byte) ((v ? 1 : 0) << (7 - b));
                        }
                        mmOutputStream.write(slice);
                    }
                }
                offset += 24;
                mmOutputStream.write(PrinterCommands.FEED_LINE);
                mmOutputStream.write(PrinterCommands.FEED_LINE);          
                mmOutputStream.write(PrinterCommands.FEED_LINE);
                mmOutputStream.write(PrinterCommands.FEED_LINE);
                mmOutputStream.write(PrinterCommands.FEED_LINE);
                mmOutputStream.write(PrinterCommands.FEED_LINE);
            }
            mmOutputStream.write(PrinterCommands.SET_LINE_SPACING_30);


        } else {
            Toast.makeText(this, "file doesn't exists", Toast.LENGTH_SHORT).show();
        }
    }

}

The PrinterCommands Class:

public class PrinterCommands {
public static final byte[] INIT = {27, 64};
public static byte[] FEED_LINE = {10};

public static byte[] SELECT_FONT_A = {27, 33, 0};

public static byte[] SET_BAR_CODE_HEIGHT = {29, 104, 100};
public static byte[] PRINT_BAR_CODE_1 = {29, 107, 2};
public static byte[] SEND_NULL_BYTE = {0x00};

public static byte[] SELECT_PRINT_SHEET = {0x1B, 0x63, 0x30, 0x02};
public static byte[] FEED_PAPER_AND_CUT = {0x1D, 0x56, 66, 0x00};

public static byte[] SELECT_CYRILLIC_CHARACTER_CODE_TABLE = {0x1B, 0x74, 0x11};

public static byte[] SELECT_BIT_IMAGE_MODE = {0x1B, 0x2A, 33, (byte) 255, 3};
//public static byte[] SELECT_BIT_IMAGE_MODE = {0x1B, 0x2A, 0x64, 0x63, 48, (byte) 255};

public static byte[] SET_LINE_SPACING_24 = {0x1B, 0x33, 24};
public static byte[] SET_LINE_SPACING_30 = {0x1B, 0x33, 30};

public static byte[] TRANSMIT_DLE_PRINTER_STATUS = {0x10, 0x04, 0x01};
public static byte[] TRANSMIT_DLE_OFFLINE_PRINTER_STATUS = {0x10, 0x04, 0x02};
public static byte[] TRANSMIT_DLE_ERROR_STATUS = {0x10, 0x04, 0x03};
public static byte[] TRANSMIT_DLE_ROLL_PAPER_SENSOR_STATUS = {0x10, 0x04, 0x04};
}

As mentioned in the dev manual of the printer(pdf):

Bit Map Image Print
1. Select the image either from PC or from mobile's SD card.
2. Convert the image into monochrome bmp.
3. Resize the image to fit into the printer paper area if it is exceeding
4. Now read the processed image through fileinputstream and save it into byte array.
5. Make the packet of image and then send it to printer over outputstream.

The required packet structure:

The packet fields chart:

Alignment table & other info:

Portal

Hi dude, exactly, what are you getting wrong??, can you solved with the explained sended by the mail??... – Skirret

Hi can you write here solution of your problem thx. – Ictinus

@PavolFranek sorry I don't have access to the code now. As you can see it's nearly an year old question. But I will try to post if I get my hands on. AFAIK the solution was API dependent. – Portal

Answer 1

private byte[] printbyte = {(byte)0x1B,(byte)0x2A,(byte)0x6F,(byte)0x63} 

File file = new File(Environment.getExternalStorageDirectory + File.seprator()+"file_name");
FileInputStream fin = new FileInputStream(file);
byte imageContent[] = new byte[(int)file.length()];
fin.read(imageContent);

byte [] width  = hexToBuffer(Integer.toHexString(your_width));
byte [] height = hexToBuffer(Integer.toHexString(your_height));

byte[] imageToPrint = new byte[printbyte.lenght()+imageContent.lenght()+width.lenght()+height.lenght()];

  System.arraycopy(imagetoprint,0,printbyte,0,printbyte.lenght());
  System.arraycopy(imagetoprint,printbyte.lenght(),width ,0,width.lenght());
  System.arraycopy(imagetoprint,width.lenght(),height,0,height.lenght());  
  System.arraycopy(imagetoprint,height.lenght(),imageContent,0,imageContent.lenght()); 

  mmOutputStream.write(imagetoprint);  

Hex to Buffer method -

public static byte[] hexToBuffer(String hexString)
    throws NumberFormatException {
    int length = hexString.length();
    byte[] buffer = new byte[(length + 1) / 2];
    boolean evenByte = true;
    byte nextByte = 0;
    int bufferOffset = 0;

    if ((length % 2) == 1) {
        evenByte = false;
    }

    for (int i = 0; i < length; i++) {
        char c = hexString.charAt(i);
        int nibble; // A "nibble" is 4 bits: a decimal 0..15

        if ((c >= '0') && (c <= '9')) {
            nibble = c - '0';
        } else if ((c >= 'A') && (c <= 'F')) {
            nibble = c - 'A' + 0x0A;
        } else if ((c >= 'a') && (c <= 'f')) {
            nibble = c - 'a' + 0x0A;
        } else {
            throw new NumberFormatException("Invalid hex digit '" + c +
                "'.");
        }

        if (evenByte) {
            nextByte = (byte) (nibble << 4);
        } else {
            nextByte += (byte) nibble;
            buffer[bufferOffset++] = nextByte;
        }

        evenByte = !evenByte;
    }

    return buffer;
}

Kershaw

Hello @mjosh What is the hexString in hexToBuffer method haw can get it – Caftan

Answer 2

I have a thermal printer with bluetooth and Usb connection, if your printer support ESC/POS command search for its commands on internet, for print raster image you should send this:

[Name] Print raster bit image
[Format] ASCII GS v 0 m xL xH yL yH d1...dk
         Hex 1D 76 30 m xL xH yL yH d1...dk
         Decimal 29 118 48 m xL xH yL yH d1...dk
[Range] 0£ m£ 3, 48£ m £ 51
0£ xL£ 255
0£ xH£ 255
0£ yL£ 255
0£ d£ 255
k=(xL+ xH*256)*(yL+yH*256)

Follow your printer guidelines, it is may be different from others.

Bopp