split big chunk of data to write to printer

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) {