Imprimir Imagen en impresora Bluetooth desde Android

En mi post anterior os deje como imprimir texto en una impresora bluetooth desde Android.
Hoy agregamos el codigo para imprimir una imagen.
La imagen se debe imprimir en bytes y en blanco y negro.

1. Debemos crear una clase con los comandos para enviar a nuestro dispositivo.

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, 255, 3};
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};
}

Ahora que tenemos nuestra clase, creamos los metodos.
convertBitmap para convertir la imagen a blanco y negro.

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());
    }
}

Finalmente el metodo desde donde se imprime:

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

        int offset = 0;
        while (offset < bmp.getHeight()) {
            mService.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));
                    }
                    mService.write(slice);
                }
            }
            offset += 24;
            mService.write(PrinterCommands.FEED_LINE);
            mService.write(PrinterCommands.FEED_LINE);          
            mService.write(PrinterCommands.FEED_LINE);
            mService.write(PrinterCommands.FEED_LINE);
            mService.write(PrinterCommands.FEED_LINE);
            mService.write(PrinterCommands.FEED_LINE);
        }
        mService.write(PrinterCommands.SET_LINE_SPACING_30);


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

Basado en Este post de Stackoverflow

Mas info:

Github link: https://github.com/imrankst1221/Thermal-Printer-in-Android

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