Golang : Generate Codabar

In this tutorial, we will learn how to generate Codabar with Golang. We will use couple of third party packages to achieve our objectives as some of the images packages lack certain functions and clear documentation at the time of writing.

This code example below will :

1. Generate the coda barcode from the code := "A80186B"
2. Scale to larger size.
3. Write the string code "A80186B" to another image.
4. Paste both barcode and string into a new image.
5. Save the image to png file.

Here you go:

 package main

 import (
 "fmt"
 "github.com/boombuler/barcode"
 "github.com/boombuler/barcode/codabar"
 "github.com/disintegration/imaging"
 "github.com/llgcode/draw2d"
 "image"
 "image/color"
 "image/draw"
 "os"
 )

 func main() {

 code := "A80186B"

 fmt.Println("Generating Codabar for : ", code)

 bcode, err := codabar.Encode(code)

 if err != nil {
 fmt.Printf("String %s cannot be encoded", code)
 os.Exit(1)
 }

 // scale to 250x20
 bcode, err = barcode.Scale(bcode, 250, 20)

 if err != nil {
 fmt.Println("Codabar scaling error!")
 os.Exit(1)
 }

 // now we want to append the code at the bottom
 // of the Codabar

 // Create an new image with text data
 // From https://github.com/llgcode/draw2d.samples/tree/master/helloworld
 // Set the global folder for searching fonts
 draw2d.SetFontFolder(".")

 // Initialize the graphic context on an RGBA image
 img := image.NewRGBA(image.Rect(0, 0, 250, 50))

 // set background to white
 white := color.RGBA{255, 255, 255, 255}
 draw.Draw(img, img.Bounds(), &image.Uniform{white}, image.ZP, draw.Src)

 gc := draw2d.NewGraphicContext(img)

 gc.FillStroke()

 // Set the font Montereymbi.ttf
 gc.SetFontData(draw2d.FontData{"Monterey", draw2d.FontFamilyMono, draw2d.FontStyleBold | draw2d.FontStyleItalic})
 // Set the fill text color to black
 gc.SetFillColor(image.Black)

 gc.SetFontSize(14)
 gc.FillStringAt(code, 50, 20)

 // create a new blank image with white background
 newImg := imaging.New(300, 300, color.NRGBA{255, 255, 255, 255})

 //paste the codabar to new blank image
 newImg = imaging.Paste(newImg, bcode, image.Pt(50, 50))

 //paste the text to the new blank image
 newImg = imaging.Paste(newImg, img, image.Pt(90, 90))

 err = draw2d.SaveToPngFile("./codabar.png", newImg)

 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 // everything ok
 fmt.Println("CodaBar code generated and saved to codabar.png")

 }

Sample output :

NOTE : For some odd reason, the luximbi.ttf font from https://github.com/llgcode/draw2d.samples/tree/master/helloworld cannot be used. Therefore, I've replaced it with the Monterey font.

You can get the Monterey font from http://www.1001freefonts.com/monterey.font , unzip the zip file and rename the MontereyFLF.ttf to Montereymbi.ttf with this command and execute the code above in the same directory as the 'Montereymbi.ttf' file.

cp MontereyFLF.ttf Montereymbi.ttf

References :

http://en.wikipedia.org/wiki/Codabar

https://github.com/boombuler/barcode