escpos

README

go-escpos

This is a Go library to talk to escpos capable devices, mainly the Epson POS printers.

it will allow you to send print jobs in a simple functional interface, this library also supports automatic discovery of USB devices.

This library works with both Go and TinyGo (for microcontrollers).

Documentation can be found on pkg.go.dev

Example

package main

import (
	"fmt"

	"github.com/conejoninja/go-escpos"
)

func main() {
	p, err := escpos.NewUSBPrinterByPath("") // empry string will do a self discovery
	if err != nil {
		fmt.Println(err)
		return
	}

	p.Init() // start
	p.Smooth(true) // use smootth printing
	p.Size(2, 2) // set font size
	p.PrintLn("HELLO GO")

	p.Size(1, 1)
	p.Font(escpos.FontB) // change font
	p.PrintLn("This is a test of MECT go-escpos")
	p.Font(escpos.FontA)

	p.Align(escpos.AlignRight) // change alignment
	p.PrintLn("An all Go\neasy to use\nEpson POS Printer library")
	p.Align(escpos.AlignLeft)

	p.Size(2, 2)
	p.PrintLn("* No magic numbers")
	p.PrintLn("* ISO8859-15 ŠÙþþØrt")
	p.Underline(true)
	p.PrintLn("* Extended layout")
	p.Underline(false)
	p.PrintLn("* All in Go!")

	p.Align(escpos.AlignCenter)
	p.Barcode("MECT", escpos.BarcodeTypeCODE39) // print barcode
	p.Align(escpos.AlignLeft)

	p.FeedN(2) // feed 2
	p.Cut() // cut
	p.End() // stop
}

(The TinyGo example can be found in demo-tinygo)

Limitations

• The USB discovery only works on Linux due to the use of udev

(PRs to fix these welcome!)

Known to work with

• Epson TM-20III

Documentation

Index

• Variables
• type Alignment
• type BarcodeType
• type ErrorStatus
• type Font
• type Printer
  • func NewPrinterByRW(rwc io.ReadWriteCloser) (*Printer, error)
  • func NewUSBPrinterByPath(devpath string) (*Printer, error)
  • func NewWindowsPrinterByPath(printerPath string) (*Printer, error)
  • func (p *Printer) Align(align Alignment) error
  • func (p *Printer) Barcode(barcode string, format BarcodeType) error
  • func (p *Printer) Close() error
  • func (p *Printer) Cut() error
  • func (p *Printer) End() error
  • func (p *Printer) Feed(n int) error
  • func (p *Printer) Font(font Font) error
  • func (p *Printer) GetErrorStatus() (ErrorStatus, error)
  • func (p *Printer) Init() error
  • func (p *Printer) Print(data string) error
  • func (p *Printer) PrintAreaWidth(width int) error
  • func (p *Printer) PrintLn(data string) error
  • func (p *Printer) QR(code string, size uint8) error
  • func (p *Printer) Size(width, height uint8) error
  • func (p *Printer) Smooth(enabled bool) error
  • func (p *Printer) Underline(enabled bool) error
• type WindowsPrinter
  • func (wprinter WindowsPrinter) Close() error
  • func (wprinter WindowsPrinter) Read(p []byte) (n int, err error)
  • func (wprinter WindowsPrinter) Write(p []byte) (n int, err error)

Variables

var ErrorNoDevicesFound = errors.New("No devices found")

Types

type Alignment

type Alignment uint8

Alignment defines the text blignment

const (
	AlignLeft   Alignment = 0
	AlignCenter Alignment = 1
	AlignRight  Alignment = 2
)

type BarcodeType

type BarcodeType string

BarcodeType defines the type of barcode

const (
	// function type A
	BarcodeTypeUPCA    BarcodeType = "\x00"
	BarcodeTypeUPCE    BarcodeType = "\x01"
	BarcodeTypeEAN13   BarcodeType = "\x02"
	BarcodeTypeEAN8    BarcodeType = "\x03"
	BarcodeTypeCODE39  BarcodeType = "\x04"
	BarcodeTypeITF     BarcodeType = "\x05"
	BarcodeTypeCODABAR BarcodeType = "\x06"

	// function type B
	BarcodeTypeCODE128 BarcodeType = "\x49"
)

type ErrorStatus

type ErrorStatus byte

const (
	ErrorNone      ErrorStatus = 0x00
	ErrorCoverOpen ErrorStatus = 0x04
	ErrorPaperOut  ErrorStatus = 0x20
	ErrorGeneric   ErrorStatus = 0x40
)

type Font

type Font uint8

Font defined the font type

const (
	FontA Font = 0
	FontB Font = 1
	FontC Font = 2
)

type Printer

type Printer struct {
	// contains filtered or unexported fields
}

func NewPrinterByRW

func NewPrinterByRW(rwc io.ReadWriteCloser) (*Printer, error)

func NewUSBPrinterByPath

func NewUSBPrinterByPath(devpath string) (*Printer, error)

NewUSBPrinter returns a new printer with a USB Vendor and Product ID if both are 0 it will return the first found Epson POS printer

func NewWindowsPrinterByPath

func NewWindowsPrinterByPath(printerPath string) (*Printer, error)

func (*Printer) Align

func (p *Printer) Align(align Alignment) error

Align will change the text alignment

func (*Printer) Barcode

func (p *Printer) Barcode(barcode string, format BarcodeType) error

Barcode will print a barcode of a specified type as well as the text value

func (*Printer) Close

func (p *Printer) Close() error

Close closes the connection to the printer, all commands will not work after this

func (*Printer) Cut

func (p *Printer) Cut() error

Cut sends the command to cut the paper

func (*Printer) End

func (p *Printer) End() error

End sends an end signal to finalize the print job

func (*Printer) Feed

func (p *Printer) Feed(n int) error

Feed sends a paper feed command for a specified length

func (*Printer) Font

func (p *Printer) Font(font Font) error

Font changest the font face

func (*Printer) GetErrorStatus

func (p *Printer) GetErrorStatus() (ErrorStatus, error)

func (*Printer) Init

func (p *Printer) Init() error

Init sends an init signal

func (*Printer) Print

func (p *Printer) Print(data string) error

Print prints a string the data is re-encoded from Go's UTF-8 to ISO8859-15

func (*Printer) PrintAreaWidth

func (p *Printer) PrintAreaWidth(width int) error

PrintAreaWidth will set the print area width, by default it is the maximum. Eg. 380 is handy for less wide receipts used by card terminals

func (*Printer) PrintLn

func (p *Printer) PrintLn(data string) error

PrintLn does a Print with a newline attached

func (*Printer) QR

func (p *Printer) QR(code string, size uint8) error

Barcode will print a barcode of a specified type as well as the text value

func (*Printer) Size

func (p *Printer) Size(width, height uint8) error

Size changes the font size

func (*Printer) Smooth

func (p *Printer) Smooth(enabled bool) error

Smooth will enable or disable smooth text printing

func (*Printer) Underline

func (p *Printer) Underline(enabled bool) error

Underline will enable or disable underlined text

type WindowsPrinter

type WindowsPrinter struct {
	// contains filtered or unexported fields
}

func (WindowsPrinter) Close

func (wprinter WindowsPrinter) Close() error

func (WindowsPrinter) Read

func (wprinter WindowsPrinter) Read(p []byte) (n int, err error)

func (WindowsPrinter) Write

func (wprinter WindowsPrinter) Write(p []byte) (n int, err error)