hennedo / escpos Goto Github PK

I'm trying to put it in WASM to be used with JS (in browser). But WASM build is failing.
Build cmd GOOS=js GOARCH=wasm go build -o main.wasm main.go

error

# github.com/qiniu/iconv
/home/user/go/pkg/mod/github.com/qiniu/[email protected]/reader.go:11:11: undefined: Iconv
/home/user/go/pkg/mod/github.com/qiniu/[email protected]/reader.go:19:19: undefined: Iconv
/home/user/go/pkg/mod/github.com/qiniu/[email protected]/reader.go:21:13: undefined: DefaultBufSize
/home/user/go/pkg/mod/github.com/qiniu/[email protected]/reader.go:49:14: undefined: EILSEQ
/home/user/go/pkg/mod/github.com/qiniu/[email protected]/writer.go:12:11: undefined: Iconv
/home/user/go/pkg/mod/github.com/qiniu/[email protected]/writer.go:19:19: undefined: Iconv
/home/user/go/pkg/mod/github.com/qiniu/[email protected]/writer.go:21:13: undefined: DefaultBufSize
/home/user/go/pkg/mod/github.com/qiniu/[email protected]/writer.go:70:15: undefined: EILSEQ
/home/user/go/pkg/mod/github.com/qiniu/[email protected]/writer.go:102:15: undefined: EILSEQ

Can i use this library with printer Epson TMU220 ?

Thanks for the nice library.
There is one question.
How to send Russian characters for printing?
If you write a text in Russian, incomprehensible characters come out, apparently a conversion is needed.

When I run it this way, it warns that there is no function here. Could you please check?

Hello,
I have a problem when I print text: at the end of each line it also prints the number 0 (zero)

p.Bold(true).Size(2, 2).Write("Hello World")

Ouput:
Hello World0

Even the WASM build failing, There's a PR which solves that.
By using that PR I'm able to build a WASM binay & successfully load into browser,

But the unfortunate thing is WASM doesn't supports direct TCP communication so net.Dial doesn't work.

tcp 192.168.0.121:9100: Connection refused

(works natively - when running the (documented) code from terminal)

Is there any plan/ way to do that?

The thing I'm trying is to ship a WASM that will handle swift printing from the client site (since the printer in is clients (local) network.

Is it even possible?

I would like to print a line to separate out some section but I don't know how or can't find example

Hello,
Thank you for making this wonderful lib, I'm facing some issues setting config to the printer,

In the code snipet in the documentation p.SetConfig(escpos.ConfigEpsonTMT20II) is missing,
Following is the error

# command-line-arguments
./main.go:16:4: p.SetConfig undefined (type *escpos.Escpos has no field or method SetConfig)
./main.go:16:21: undefined: escpos.ConfigEpsonTMT20II

How to set config to the printer?

I recently added this library in to a project that requires CGO (due to cross compilation needs), and because of that I compiled iconv as a static library (alternatively, I believe providing an install of the dynamic linked iconv library for the target machine would have also worked - however, I chose to compile and include iconv statically), as github.com/qiniu/iconv, required by this library, has the C "iconv" library as a dependency.

I think some mention of this requirement on the "target" system may be useful in the README; Would instructions for linking iconv statically and/or dynamically using CGO, and/or instructions on how to provide the proper iconv DLL on the target machine, also be something that would be useful to have in the README for this project? I am acutely aware that compile options and procedure for go code is hard to come by, so wanted to get your opinion on if adding something about how to do this in the README would be useful (in your opinion); If so, I can put together a PR with what I have found regarding installing iconv on the target system, and bundling it using CGO (I've been working on cross compiling and including iconv for an app I'm working on, so would be more than happy to share my notes for the README, if you think it'll be of use for others).

Also, thank you for providing this great escpos library; It helped me quite a bit recently with a few label formats I needed to print via escpos on a newer golang project.

For everyone who will be faced with printing gibberish on such model of printer.

During debugging the issue we experimentally figured out that it started printing gibberish when we send command GS v 0 with image height multiple of 48 only : i.e. 240, 192, 144, 96 .
We handled this case with spliting whole image into chunks of multiple of 256 and then if smaller chunk is multiple of 48 then increase image height on 8 and just fill that addition with 255 brightness pixels. Finally send chunks of GS v 0 one by one to the printer.

So it seems a bug with printer`s firmware rather than library issue

if someone needs a fix for such printer here one of the possible solutions

const (
	xPrinterBuggyImageDivisor = 48
)

type Image struct {
	Width  int
	Height int
	Pixels [][]pixel
}

func closestNDivisibleBy8(n int) int {
	q := n / 8
	n1 := q * 8
	if n1%xPrinterBuggyImageDivisor == 0 {
		n1 += 8
	}
	return n1
}

func getPixels(reader io.Reader) ([]Image, error) {

	img, _, err := image.Decode(reader)

	if err != nil {
		return []Image{}, err
	}

	bounds := img.Bounds()
	width, height := bounds.Max.X, bounds.Max.Y
	printWidth := closestNDivisibleBy8(width)
	printHeight := closestNDivisibleBy8(height)

	imageDivisor := 256
	imagesCount := printHeight / imageDivisor
	if printHeight%imageDivisor != 0 {
		imagesCount++
	}

	restTailHeight := printHeight - (imagesCount-1)*imageDivisor
	if restTailHeight%xPrinterBuggyImageDivisor == 0 {
		printHeight += 8
	}

	images := make([]Image, imagesCount)

	previous := 0
	for i := imagesCount; i > 0; i-- {
		localHeight := printHeight - (i-1)*imageDivisor - previous
		pixels := make([][]pixel, localHeight)

		for y := 0; y < localHeight; y++ {
			pixels[y] = make([]pixel, printWidth)
			for x := 0; x < printWidth; x++ {
				if x >= width || y+previous >= height {
					pixels[y][x] = pixel{0xff, 0xff, 0xff, 0x01}
				} else {
					pixels[y][x] = rgbaToPixel(img.At(x, y+previous).RGBA())
				}
			}
		}
		previous += localHeight
		images[imagesCount-i] = Image{printWidth, localHeight, pixels}
	}
	return images, nil
}

Using an EPSON TM-T88II printer with this code snippet works (it prints the image) but is extremely slow. The printer prints one "line" of the image and waits for ~2 seconds, then prints the next line and so on. The printer is definitely capable of much faster printing, I'm also trying out the python-escpos library and that one spits out a complete image in under a second without any delay between lines.

Not sure what is happening here. The python library allows selecting between normal and "high density" mode when printing images, maybe that is the difference, but I don't see how to toggle it here.

	p := escpos.New(socket)
	p.SetConfig(escpos.ConfigEpsonTMT88II)

	f, err := os.Open("./logo.gif")
	if err != nil {
		panic(err)
	}
	defer f.Close()
	img, fmtName, err := image.Decode(f)

	if err != nil {
		panic(err)
	}

	p.PrintImage(img)

I tried to print something in Arabic but it got printed as random mixed chars

printer.QRCode(QrUrl, true, 5, escpos.QRCodeErrorCorrectionLevelH)
I want to center the QR code that I created in this way, so I want it to add a space from the left and go a little more to the right, but I could not center it with any method. Is it possible to do this can you help please?

It didn't work even if I used lineSpacing before qr code generation :(

Hello, I'm trying to use the README example and VSCode gives brokenimport error. I tried go mod tidy and go get the package, but still with error. Let me know what I can do to help.

PrintAndCut operation works with POSBANK A10 Thermal Receipt printer, but cutting cannot be performed on this Hugin GP-80250VN printer. Both are ESC/POS printers. I use the exact same code as the code. Can you help on this issue please 🙏

I have a printer with internal IP of 192.168.0.10. And I am running the code below but it is not responding.

package main

import (
	"net"
	"github.com/hennedo/escpos"
)
func main() {
	socket, err := net.Dial("ip4:1", "192.168.0.10")
	if err != nil {
		println(err.Error())
	}
	defer socket.Close()

	p := escpos.New(socket)
	p.Size(2, 2).Write("TEST")
}

I guess it cannot connect. How do we find the part written "ip4:1", can you please help?

(edited by henne to wrap code into a code block)

I'm using this on a USB Epson TM-T88IV and if something isn't right during printing, the printer just ... stops. There's no way to know what is wrong because the only connection to the printer is through a Writer, and not a ReadWriter.

It is probably not trivial to implement, or maybe it is, but checking for an error after each WriteRaw and exposing that would be lovely.