如何在安卓的蓝牙打印机上打印图像？
2022-08-31 17:20:06
我必须在热敏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。我想我需要获取图像数据。我尝试以这种方式获取图像的数据：byte[]
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，打印机打印了很多奇怪的字符（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并发送，但我不知道该怎么做。byte[]
谢谢
更新：
经过这么多时间，我正在这样做：我有一个名为print_image（String file）的方法，它获取了我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();
}
}
我根据这篇文章做了
这是类 PrinterCommands：
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};
}
正如在print_image方法中看到的那样，我正在调用一个名为convertBitmap的方法，并且im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/行
这就是我喜欢做的事情（我用同一台打印机做了，但是从Play商店下载了一个应用程序）
这就是我现在得到的
近：
关闭时间2：
可以看到图像的一小部分，所以我认为我更接近可以打印图像...
我使用的图像是这样的（576x95）：
这是转换后的图像（我用上面的代码转换它）：
所以，答案是：我做错了什么？，我认为错误在这个命令中：
public static byte[] SELECT_BIT_IMAGE_MODE = {0x1B, 0x2A, 33, -128, 0};
但是，我如何计算图像的正确值？，谢谢
