ESC / POS热敏打印机，如何在Android中居中位图图像？

Question

我正在Android中编写一个简单的应用程序，通过ESC / POS热敏打印机进行打印。 我只是一个问题。 该应用程序生成QR码（使用zxing库），将其转换为位图并将其发送到打印机。 打印机打印它，但我无法将它居中。 而不是文字我没有定位问题。

这是打印文本和QR的代码。

byte[] INIT = {27, 64};
byte[] FEED_LINE = {10};

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

byte[] FONT_B = {0x1B, 0x4D, 0x01};
byte[] ALLINEA_SX = {0x1B, 0x61, 0x00};
byte[] ALLINEA_CT = {0x1B, 0x61, 0x01};
byte[] ALLINEA_DX = {0x1B, 0x61, 0x02};
byte[] GRASSETTO_ON = {0x1B, 0x47, 0x11};
byte[] GRASSETTO_OFF = {0x1B, 0x47, 0x00};
byte[] SET_6 = {0x1B, 0x52, 0x06};
byte[] CODICI = {0x1B, 0x74, 0x13};
byte[] EURO = {(byte) 0xD5};
byte[] PALLINO = {(byte) 0x5B};
byte[] FONT_3X = {0x1D, 0x21, 0x21};
byte[] FONT_2X = {0x1D, 0x21, 0x11};
byte[] FONT_1X = {0x1D, 0x21, 0x00};

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

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

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

byte[] SELECT_BIT_IMAGE_MODE = {0x1B, 0x2A, 33, 127, 3};
byte[] SET_LINE_SPACING_24 = {0x1B, 0x33, 24};
byte[] SET_LINE_SPACING_30 = {0x1B, 0x33, 30};

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

mService.write(INIT);
mService.write(ALLINEA_CT); //text to center
mService.write(SELECT_FONT_A);
mService.write(FONT_2X);
mService.write("Hello stackoverflow!!\n".getBytes());
mService.write(FONT_1X);
mService.write(ALLINEA_SX); //text to left
mService.write("Thanks for help!\n".getBytes());


int QRCODE_IMAGE_HEIGHT = 255;
int QRCODE_IMAGE_WIDTH = 255;

QRCodeWriter qrWriter = new QRCodeWriter();
try {
    Hashtable<EncodeHintType, ErrorCorrectionLevel> hints = new Hashtable<EncodeHintType, ErrorCorrectionLevel>();
    hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);
BitMatrix bitMatrix = qrWriter.encode("https://stackoverflow.com",
        BarcodeFormat.QR_CODE,
        QRCODE_IMAGE_WIDTH,
        QRCODE_IMAGE_HEIGHT, hints);

    int bitMatrixWidth = bitMatrix.getWidth();

    int bitMatrixHeight = bitMatrix.getHeight();

    int[] pixels = new int[bitMatrixWidth * bitMatrixHeight];

    for (int y = 0; y < bitMatrixHeight; y++) {
        int offset = y * bitMatrixWidth;

        for (int x = 0; x < bitMatrixWidth; x++) {

            pixels[offset + x] = bitMatrix.get(x, y) ?
                    getResources().getColor(R.color.QRCodeBlackColor):getResources().getColor(R.color.QRCodeWhiteColor);
        }
    }
    Bitmap bitmap = Bitmap.createBitmap(bitMatrixWidth, bitMatrixHeight, Bitmap.Config.ARGB_4444);

    bitmap.setPixels(pixels, 0, 255, 0, 0, bitMatrixWidth, bitMatrixHeight);

    Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.k_city5);

    Bitmap bmOverlay = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());
    Canvas canvas = new Canvas(bmOverlay);
    canvas.drawBitmap(bitmap, new Matrix(), null);
    canvas.drawBitmap(bmp, 94, 94, null); //34x34
    //canvas.drawBitmap(bmp, 86, 86, null); //42x42

    if(bmOverlay!=null) {
        byte[] command = Utils.decodeBitmap(bmOverlay);
        mService.write(ALLINEA_CT); //This command should center my QR, but it's not working
        mService.write(command);
        mService.write(FEED_LINE);
        mService.write(FEED_LINE);
    }

这是印刷的结果：

Answer 1

将图像填充在左侧，直到它看起来正确。 请参阅Android：padding留下白色的位图 。

您可以通过反复试验来完成此操作，或者以点的形式获取打印机的宽度（可在数据表中找到）并进行数学计算：

padding = (page width - image width) / 2

ESC / POS中有命令将文本居中，而在某些打印机上，这将使图像居中。 还有其他方法可以在给定位置（页面模式）打印图像，或者以更像文本（列格式）的方式对齐，但填充图像对您的示例进行更简单的修改 。

Answer 2

可能对其他人有用：我在QR码命令之前添加了这个命令：

[0x1b, 0x61, 0x01] // align to center [0x1b, 0x3d, 0x01] //select 。

从CITIZEN S310II打印机命令参考手册中得到它。 基本上如果不起作用，您只需要找到打印机型号的居中命令。 希望这有助于某人:)