add printer

printer.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"C"
+	_ "image/png"
+	"os"
+	"strings"
+
+	"bufio"
+	"log"
+	"net"
+
+	"time"
+
+	"github.com/kenshaw/escpos"
+)
+
+//export PrintImg
+func PrintImg(printer *C.char, imagePath *C.char) *C.char {
+	goPrinter := C.GoString(printer)
+	goImagePath := C.GoString(imagePath)
+
+	// printer := "tcp:192.168.100.151:9100"
+	// printer := "usb:/dev/usb/lp1"
+	var w *bufio.ReadWriter
+	if strings.HasPrefix(goPrinter, "tcp:") {
+		location := strings.TrimLeft(goPrinter, "tcp:")
+		conn, err := net.Dial("tcp", location)
+		if err != nil {
+			log.Println("error dialing:", err.Error())
+			return NewErr(err)
+		}
+		defer conn.Close()
+		w = bufio.NewReadWriter(bufio.NewReader(conn), bufio.NewWriter(conn))
+	} else if strings.HasPrefix(goPrinter, "usb:") {
+		location := strings.TrimLeft(goPrinter, "usb:")
+		f, err := os.OpenFile(location, os.O_RDWR, os.ModeDevice)
+		if err != nil {
+			log.Println("error OpenFile usb:", err.Error())
+			return NewErr(err)
+		}
+		defer f.Close()
+		w = bufio.NewReadWriter(bufio.NewReader(f), bufio.NewWriter(f))
+	}
+	prt := escpos.New(w)
+
+	prt.Init()
+	prt.SetSmooth(1)
+	err := printImg(prt, goImagePath)
+	if err != nil {
+		return NewErr(err)
+	}
+	prt.Cut()
+	prt.End()
+	w.Flush()
+	time.Sleep(100 * time.Millisecond)
+	return NewOk(nil)
+}