Printing using Bluetooth printers in Android

Printing using Bluetooth printers is usually not desired for android developers, every printer has it’s own SDK, And if you use a large verity of printers you need to include many lib’s and thus deal with them, this will affect the apk size and might cause issues.

Photo by Matthew Kwong on Unsplash

How printers work?

Android devices talk with printers via Bluetooth socket by sending a set of commands, these commands are defined in the printer’s command manual, and each command has a specific job.

command sample: 0x1B, 0x33 (to initialize printer)

The commands are usually similar in most printers, And every printer provides you with an Android SDK interface for using these commands and to deliver them to the printer.

Command manual sample

Well, We can deal with all printers without using their SDK’s by sending the set of commands via Bluetooth directly.

Printooth

Printooth is an android library, provides us a simple interface to deal with all kinds and types of Bluetooth printers. one library for all printers.

You can make a simple demo by following a few steps :

Add the JitPack repository to your build file

allprojects {
	repositories {
		...
		maven { url 'https://jitpack.io' }
	}
}

Add dependency

dependencies {
	implementation 'com.github.mazenrashed:Printooth:${LAST_VERSION}'
}

Add permissions to manifest

<uses-permission android:name="android.permission.BLUETOOTH" />  
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

Initialize Printooth

Should be initialized once in Application.onCreate():

Printooth.init(context);

Scan and pair printer

Printooth provides a scanning activity to make pairing process easy. Just start ScanningActivity and you will skip the process of pairing and saving the printer.

startActivityForResult(Intent(this, ScanningActivity::class.java), ScanningActivity.SCANNING_FOR_PRINTER)

When the printer is ready:

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {  
    super.onActivityResult(requestCode, resultCode, data)  
    if (requestCode == ScanningActivity.SCANNING_FOR_PRINTER && resultCode == Activity.RESULT_OK)  
        //Printer is ready now 
}

If you want to create your own user interface, you can pass your paired printer to Printooth like this:

Printooth.setPrinter(printerName, printerAddress)

Printing

Printooth provide a simple builder to design your paper. To print Hello World simply write this code:

var printables = ArrayList<Printable>()
var printable = Printable.PrintableBuilder()  
        .setText("Hello World")
printables.add(printable)
BluetoothPrinter.printer().print(printables)

Use all builder functionalities:

var printables = ArrayList<Printable>()
var printable = Printable.PrintableBuilder()  
        .setText("Hello World") //The text you want to print
        .setAlignment(DefaultPrinter.ALLIGMENT_CENTER)
        .setEmphasizedMode(DefaultPrinter.EMPHASISED_MODE_BOLD) //Bold or normal  
        .setFontSize(DefaultPrinter.FONT_SIZE_NORMAL)
        .setUnderlined(DefaultPrinter.UNDELINED_MODE_ON) // Underline on/off
        .setCharacterCode(DefaultPrinter.CHARACTER_CODE_USA_CP437) // Character code to support languages
        .setLineSpacing(DefaultPrinter.LINE_SPACING_60)
        .setNewLinesAfter(1) // To provide n lines after sentence
        .build()
printables.add(printable)
BluetoothPrinter.printer().print(printables)

Finally

Printooth provides many solutions to a large verity of cases and options to ease up the process of dealing and tweaking the printers you want.

mazenrashed/Printooth

That was everything for today, If you have any questions please reach out on Linkedin or leave a comment.

Mazen Rashed - Android Engineer - ArabiaWeather Inc. | LinkedIn