Printing POS/ESC Apex3 image S.O.S

Question

I have an Apex3 and I have been able to follow most of the documentation without problem, but when it comes to images things turns very weird (lack of examples + lack of consistency in how to do it).

First I try the naive approach of trying to pass a Bitmap byte[] array compress with JPEG and 0 quality since I did not mind, using the command:

ESC V n1 n2 data

That did not work out well.

Then I discover there is an android library for apex3 that accept a bitmap and supose to print it but it does not work just print weird symbols like this:

I try to decode the jar source using JD gui and they seem to do some work with the bitmap bytes this is their code (piece of advice code like addToDoc(m_Document, ESC + "B"); just put the code in a ByteArrayOutputStream the data), (decompiled source from here):

public void writeImage(Bitmap imageObject, int printHeadWidth)
    throws IllegalArgumentException
  {
    if (imageObject == null) {
      throw new IllegalArgumentException("Parameter 'imageObject' was null.");
    }
    if (printHeadWidth < 1) {
      throw new IllegalArgumentException("Parameter 'printHeadWidth' must be greater than 0.");
    }
    int height = imageObject.getHeight();
    int width = imageObject.getWidth();
    

    byte blanklineCount = 0;
    byte[] dataline = new byte[printHeadWidth + 7 >> 3];
    int[] imageData = new int[height * width];
    
    imageObject.getPixels(imageData, 0, width, 0, 0, width, height);
    

    addToDoc(m_Document, ESC + "B");
    for (int row = 0; row < height; row++)
    {
      boolean blankLine = true;
      for (int index = 0; index < width; index += 8)
      {
        byte currentByte = 0;
        int offset = row * width + index;
        if (index >= printHeadWidth) {
          break;
        }
        int value = index + 0 < width ? imageData[(offset + 0)] & 0xFFFFFF : 16777215;
        boolean set = (value >> 0 & 0xFF) + (value >> 8 & 0xFF) + (value >> 16 & 0xFF) < 384;
        currentByte = (byte)(currentByte | (set ? -128 : 0));
        
        value = index + 1 < width ? imageData[(offset + 1)] & 0xFFFFFF : 16777215;
        set = (value >> 0 & 0xFF) + (value >> 8 & 0xFF) + (value >> 16 & 0xFF) < 384;
        currentByte = (byte)(currentByte | (set ? 64 : 0));
        
        value = index + 2 < width ? imageData[(offset + 2)] & 0xFFFFFF : 16777215;
        set = (value >> 0 & 0xFF) + (value >> 8 & 0xFF) + (value >> 16 & 0xFF) < 384;
        currentByte = (byte)(currentByte | (set ? 32 : 0));
        
        value = index + 3 < width ? imageData[(offset + 3)] & 0xFFFFFF : 16777215;
        set = (value >> 0 & 0xFF) + (value >> 8 & 0xFF) + (value >> 16 & 0xFF) < 384;
        currentByte = (byte)(currentByte | (set ? 16 : 0));
        
        value = index + 4 < width ? imageData[(offset + 4)] & 0xFFFFFF : 16777215;
        set = (value >> 0 & 0xFF) + (value >> 8 & 0xFF) + (value >> 16 & 0xFF) < 384;
        currentByte = (byte)(currentByte | (set ? 8 : 0));
        
        value = index + 5 < width ? imageData[(offset + 5)] & 0xFFFFFF : 16777215;
        set = (value >> 0 & 0xFF) + (value >> 8 & 0xFF) + (value >> 16 & 0xFF) < 384;
        currentByte = (byte)(currentByte | (set ? 4 : 0));
        
        value = index + 6 < width ? imageData[(offset + 6)] & 0xFFFFFF : 16777215;
        set = (value >> 0 & 0xFF) + (value >> 8 & 0xFF) + (value >> 16 & 0xFF) < 384;
        currentByte = (byte)(currentByte | (set ? 2 : 0));
        
        value = index + 7 < width ? imageData[(offset + 7)] & 0xFFFFFF : 16777215;
        set = (value >> 0 & 0xFF) + (value >> 8 & 0xFF) + (value >> 16 & 0xFF) < 384;
        currentByte = (byte)(currentByte | (set ? 1 : 0));
        

        dataline[(index >> 3)] = currentByte;
        blankLine &= currentByte == 0;
      }
      if (!blankLine)
      {
        if (blanklineCount > 0)
        {
          addToDoc(m_Document, "A");
          addToDoc(m_Document, blanklineCount);
          blanklineCount = 0;
        }
        addToDoc(m_Document, compressGraphicLine(dataline));
      }
      else
      {
        blanklineCount = (byte)(blanklineCount + 1);
        if (blanklineCount == 255)
        {
          addToDoc(m_Document, "A");
          addToDoc(m_Document, blanklineCount);
          blanklineCount = 0;
        }
      }
    }
    if (blanklineCount > 0)
    {
      addToDoc(m_Document, "A");
      addToDoc(m_Document, blanklineCount);
      blanklineCount = 0;
    }
    addToDoc(m_Document, ESC + "E");
  }
  
  private byte[] compressGraphicLine(byte[] dataline)
  {
    byte count = 0;
    byte currentByte = 0;
    ByteArrayOutputStream rleString = new ByteArrayOutputStream(128);
    

    addToDoc(rleString, "G");
    for (int index = 0; index < dataline.length; index++) {
      if (count == 0)
      {
        currentByte = dataline[index];
        addToDoc(rleString, currentByte);
        count = (byte)(count + 1);
      }
      else if ((count < 255) && (currentByte == dataline[index]))
      {
        count = (byte)(count + 1);
      }
      else
      {
        addToDoc(rleString, count);
        count = 0;
        

        currentByte = dataline[index];
        addToDoc(rleString, currentByte);
        count = (byte)(count + 1);
      }
    }
    if (count > 0) {
      addToDoc(rleString, count);
    }
    if (rleString.size() > dataline.length + 1)
    {
      rleString.reset();
      addToDoc(rleString, "U");
      for (int item = 0; item < dataline.length; item++) {
        addToDoc(rleString, dataline[item]);
      }
    }
    return rleString.toByteArray();
  }

But I don't get why it is not working.

Finally I try to use How can I print an image on a Bluetooth printer in Android? with the same algorithm as a guide but still printing random weird symbols.

Answer 1

instead of wasting time with decompiling some apk, why not having a look in the offical SDK? On the manufacturer webpage Downloads & Drivers there is a link to the Java SDK which includes a source Sample.java. In the source an BufferedImage is created so I guess (I don't own such a printer) this will give you an entry point for your problem. And most probably they provide on the same page the source for the Android demo Printer Demo Source code for Android

edit Ok. Let's summarize: You have an image and want to print it. In the example Sample.java this case is covered

  BufferedImage newImage = new BufferedImage(1024, 512, BufferedImage.TYPE_4BYTE_ABGR);
  // some lines and rectangles are drawn in the image
  ...
  // the image is printed, following the SDK javadoc for DocumentLP.writeImage
  // "This will cause the image specified to be printed. Images will be expanded to occupy
  // the entire width of the printer, so the correct current width of the printer must be
  // specified. Images that are too wide will be cropped, and images that are too narrow 
  // will be padded on the right."
  testDoc.writeImage(newImage, m_PrinterWidth);

For me the only things you have to do:

• create an BufferedImage object
• draw your image from the file into the buffered image
• call the writeImage method of your DocumentLP object

edit 2 pseudo code snippet

// taken from SDK javadoc
DocumentLP docLP;
docLP = new DocumentLP("$");

// own code
BufferedInputStream bis = new BufferedInputStream(--from your image--);
BufferedImage bufImage = ImageIO.read(bis);

// have a look into Sample.java for the expected value of m_PrinterWidth
testDoc.writeImage(bufImage, m_PrinterWidth);

edit 3 code snippet for Android (taken from the DO_AndroidSDKDemo_MainActivity.java provided with the datamax o´neil Android SDK

File file = new File(selectedPath);
byte[] readBuffer = new byte[(int)file.length()];
InputStream inputStream= new BufferedInputStream(new FileInputStream(file));
inputStream.read(readBuffer);
inputStream.close();
fileData = readBuffer;

Bitmap m_imageObject = BitmapFactory.decodeByteArray(fileData, 0, fileData.length);
documentLP.clear();
ocumentLP.writeImage(m_imageObject, m_printHeadWidth);