如何在Android的蓝牙打印机上打印图像？

Question

我必须在热蓝牙打印机上打印一些数据，我正在这样做：

String message="abcdef any message 12345";
byte[] send;
send = message.getBytes();
mService.write(send);

它适用于文本，但不适用于图像。我想我需要获取byte[]图像数据。我尝试通过这种方式获取图像数据：

Bitmap bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.qrcode);
ByteArrayOutputStream stream=new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 90, stream);
byte[] image=stream.toByteArray();

不幸的是，打印机打印了许多奇怪的字符（大约50厘米的纸张）。我不知道如何打印图像。

我想尝试获取位图的像素，然后将其转换为a byte[]并发送，但是我不知道该怎么做。

谢谢

更新：

经过这么长时间，我正在执行此操作：我有一个名为print_image（String file）的方法，该方法获取要打印的图像的路径：

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();
    }
}

这是PrinterCommands类：

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, -128, 0};
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};
}

如在print_image方法中所见，我正在调用一个名为convertBitmap的方法，并即时发送一个位图，这是代码：

   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());
    }
}

这是我正在使用的打印机，分辨率：8点/毫米，576点/线

这就是我想要做的（我使用同一台打印机，但是使用了从Play商店下载的应用程序） 我要打印的图像

这就是我现在要得到的 我的印刷尝试

可以看到图像的一小部分，所以我认为我可以打印图像了。

这是转换后的图像（我正在使用上层代码对其进行转换）：

倒

因此，答案是：我做错了什么？，我认为该命令中存在错误：

  public static byte[] SELECT_BIT_IMAGE_MODE = {0x1B, 0x2A, 33, -128, 0};

但是，如何计算图像的正确值呢？谢谢

Answer 1

解决了！我在初始化打印机时做错了…核心方法是：

 public static byte[] SELECT_BIT_IMAGE_MODE = {0x1B, 0x2A, 33, 255, 3};

因此，通过这种方式可以完全打印出图像