JAVA ESC Pos upload NV graphic to printer

Question

Using Esc/Pos, I want to upload a bitmap image to the NV graphics memory on a printer.

I'm using GS ( L / GS 8 L <Function 67> of the Esc/Pos manual.

I'm able to use <Function 65> and <Function 66> to delete all or one of the graphics.

I know I'm missing something when adding the Bitmap to the function.

Heres is my command string including the Bitmap. The bitmapString has the file header and info header of the Bitmap removed (first 62 bytes)(DataOffset).:

String bitmapString = new String(bitmapBytes, Charsets.US_ASCII);
bitmapString = bitmapString.substring(DataOffset, bitmapStringSize);
String commandString = "";

int commandLength = (bitmapStringSize.length) + 11;
    pL = commandLength % 256;
    if (commandLength < 256) {
        pH = 0;
    } else {
        pH = (commandLength - pL) / 256;
    }

    xL = bitmapWidth % 256;
    if (bitmapWidth < 256) {
        xH = 0;
    } else {
        xH = (bitmapWidth - (bitmapWidth % 256)) / 256;
    }

    yL = bitmapHeight % 256;
    if (bitmapHeight < 256) {
        yH = 0;
    } else {
        yH = (bitmapHeight - (bitmapHeight % 256)) / 256;
    }

    commandString
            += Utils.H("1B")// 27
            + Utils.H("40") // 64
            + Utils.H("1B") // 27
            + Utils.H("3D") // 61
            + Utils.H("01") // 1

            + Utils.H("1D") // GS = 29
            + Utils.H("28") // ( = 40
            + Utils.H("4C") // L = 76

            + Utils.D(pL)   // pL
            + Utils.D(pH)   // pH

            + Utils.H("30") // m = 48
            + Utils.H("43") // fn = 67
            + Utils.H("30") // a = 48

            + Utils.H(KC1)  // kc1
            + Utils.H(KC2)  // kc2

            + Utils.H("01") // b = 1

            + Utils.D(xL)   // xL
            + Utils.D(xH)   // xH
            + Utils.D(yL)   // yL
            + Utils.D(yH)   // yH

            + Utils.H("31");// c = 49

    commandString += bitmapString;

I'm using ePOS-Print.jar to open and write to the printer:

EpsonIo epsonio = new EpsonIo();
byte[] commandBytes = commandString.getBytes(Charsets.US_ASCII);

        epsonio.open(DevType.BLUETOOTH, MAC, null, ESCPosService.this);

        while (n > 0) {

            epsonio.write(commandBytes, i, n > bufferSize ? bufferSize : n, SEND_TIMEOUT);

            Thread.sleep(450);

            i += bufferSize;
            n -= bufferSize;
        }

But when I print the graphic it is distorted:

Cheese Bread Cheese Bread · Accepted Answer · 2016-05-18T14:00:12

I've solved the issue.

The bitmap bytes being sent over had to be decoded using the method below. The method converts the bitmap pixels into monochrome bytes. 1's or 0's.

Hope this help's someone if the future!

public static byte[] decodeBitmap(byte[] bitmapBytes) {

    Bitmap bmp = BitmapFactory.decodeByteArray(bitmapBytes, 0, bitmapBytes.length);

    int zeroCount = bmp.getWidth() % 8;
    String zeroStr = "";
    if (zeroCount > 0) {
        for (int i = 0; i < (8 - zeroCount); i++) {
            zeroStr = zeroStr + "0";
        }
    }

    List<String> list = new ArrayList<>();
    for (int i = 0; i < bmp.getHeight(); i++) {
        StringBuilder sb = new StringBuilder();
        for (int j = 0; j < bmp.getWidth(); j++) {
            int color = bmp.getPixel(j, i);

            int r = (color >> 16) & 0xff;
            int g = (color >> 8) & 0xff;
            int b = color & 0xff;

            // if color close to white，bit='0', else bit='1'
            if (r > 160 && g > 160 && b > 160)
                sb.append("0");
            else
                sb.append("1");
        }
        if (zeroCount > 0) {
            sb.append(zeroStr);
        }

        list.add(sb.toString());
    }

    List<String> bmpHexList = binaryListToHexStringList(list);
    List<String> commandList = new ArrayList<>();
    commandList.addAll(bmpHexList);

    return hexListToBytes(commandList);
}

JAVA ESC Pos upload NV graphic to printer

1 Answers