split big chunk of data to write to printer

cmd/main.go

@@ -9,6 +9,8 @@ import (
 	_ "image/png"
 )
 import (
+	"encoding/json"
+
 	"gt.mokkon.com/sainw/libgofunc"
 )
 
@@ -99,11 +101,24 @@ func main() {
 စက်သုံးဆီ အရေအတွက် နှင့် အရည်အသွေးစျေးနှုန်းများ အားသံသယရှိပါက ph 09450539099, 09765421033, 09765421029 သို့တိုင်ကြား     နိုင်ပါသည်။</p>
 
 `
+	type Data struct {
+		Status string   `json:"status"`
+		Result []string `json:"result"`
+	}
+
 	result := libgofunc.GenImg(550, "./", payload, temp, "./")
 	fmt.Println("Result:", result)
 	// PrintImg(C.CString("usb:/dev/usb/lp1"), C.CString("build/out.png"))
 	// libgofunc.Print("int:/dev/bus/usb/001/046", "./out.png")
-	// libgofunc.Print("tcp:192.168.100.110:9100", "./out.png")
+
+	data := Data{}
+	json.Unmarshal([]byte(result), &data)
+	fmt.Println("Data:", data)
+
+	for _, imgPath := range data.Result {
+		fmt.Println("Printing image:", imgPath)
+		libgofunc.Print("tcp:192.168.100.151:9100", imgPath)
+	}
 	// libgofunc.Print("usb:/dev/usb/lp1", "./out.png")
 	// printer := "tcp:192.168.100.151:9100"
 	// ListUSB()

img.go

@@ -22,8 +22,6 @@ import (
 	"golang.org/x/net/html"
 
 	"encoding/json"
-
-	"github.com/kenshaw/escpos"
 )
 import (
 	"log"
@@ -377,30 +375,25 @@ func findNode(n *html.Node, tag string) *html.Node {
 	return nil
 }
 
-func printImg(prt *escpos.Escpos, imgPath string) error {
+func imgData(imgPath string) ([]byte, error) {
 	imgFile, err := os.Open(imgPath)
 	if err != nil {
 		fmt.Println(err)
-		return err
+		return nil, err
 	}
 
 	img, _, err := image.Decode(imgFile)
 	defer imgFile.Close()
 	if err != nil {
 		fmt.Println(err)
-		return err
+		return nil, err
 	}
 	data := []byte{0x1D, 0x4C, 0x00, 0x00}
-	_, err = prt.WriteRaw(data)
-	if err != nil {
-		fmt.Println("error 0x1D, 0x4C:", err.Error())
-	}
 
 	gray := toMonochrome(img)
-	data = escposRaster(gray)
-
-	_, err = prt.WriteRaw(data)
-	return err
+	imgData := escposRaster(gray)
+	data = append(data, imgData...)
+	return data, err
 }
 
 func LoadFont(size float64) (*font.Face, error) {

printer.go

@@ -17,7 +17,9 @@ import (
 
 	"github.com/kenshaw/escpos"
 )
-import "errors"
+import (
+	"errors"
+)
 
 //export PrintImg
 func PrintImg(printer *C.char, imagePath *C.char) *C.char {
@@ -87,10 +89,17 @@ func PrintImg(printer *C.char, imagePath *C.char) *C.char {
 	prt.SetSmooth(1)
 	prt.SetAlign("left")
 
-	err := printImg(prt, goImagePath)
+	imgBytes, err := imgData(goImagePath)
 	if err != nil {
 		return NewErr(err)
 	}
+	err = WriteChunk(w, prt, imgBytes)
+	if err != nil {
+		return NewErr(err)
+	}
+	time.Sleep(500 * time.Millisecond)
+	w.Flush()
+
 	prt.WriteRaw([]byte{0x1B, 0x64, 0x03})
 	prt.Cut()
 	prt.End()
@@ -104,3 +113,24 @@ func Print(printer, imagePath string) string {
 	r := C.GoString(result)
 	return r
 }
+
+// WriteChunk breaks the large byte array into smaller chunks
+func WriteChunk(w *bufio.ReadWriter, prt *escpos.Escpos, data []byte) error {
+	chunkSize := 1024 // 1 KB chunks work best for network printers
+	for i := 0; i < len(data); i += chunkSize {
+		end := min(i+chunkSize, len(data))
+
+		_, err := prt.WriteRaw(data[i:end])
+		if err != nil {
+			log.Println("Error writing image chunk:", err)
+			return err
+		}
+		if err := w.Flush(); err != nil {
+			log.Println("Error flushing buffer:", err)
+			return err
+		}
+		// Give the printer's network chip a microsecond to breathe
+		time.Sleep(5 * time.Millisecond)
+	}
+	return nil
+}