README
¶
barcode-cty-func
A Go module providing barcode image generation as a go-cty / HCL2 function. Supports 11 barcode formats and returns PNG images as bytes objects.
Backed by github.com/boombuler/barcode.
Installation
go get github.com/tsarna/barcode-cty-func
Usage
import (
barcodecty "github.com/tsarna/barcode-cty-func"
"github.com/zclconf/go-cty/cty/function"
)
// Register all functions in an HCL eval context
funcs := barcodecty.GetBarcodeFunctions()
// funcs is map[string]function.Function — merge into your eval context
Functions
| Function | Signature | Description |
|---|---|---|
barcode |
barcode(type string, data string[, options object]) bytes |
Generates a barcode image as a PNG bytes object |
barcode(type, data[, options])
Generates a barcode image and returns it as a bytes object with content_type = "image/png".
img = barcode("qr", "https://example.com")
# img.content_type == "image/png"
Barcode Types
type string |
Format | Dimensions | Notes |
|---|---|---|---|
"qr" |
QR Code | 2D | Supports error_correction option |
"datamatrix" |
Data Matrix | 2D | |
"aztec" |
Aztec Code | 2D | |
"pdf417" |
PDF 417 | 2D (stacked) | |
"code128" |
Code 128 | 1D | Most versatile 1D format; encodes full ASCII |
"code93" |
Code 93 | 1D | |
"code39" |
Code 39 | 1D | |
"codabar" |
Codabar | 1D | Numeric + limited symbols |
"ean13" |
EAN-13 | 1D | Exactly 12 digits (check digit appended) |
"ean8" |
EAN-8 | 1D | Exactly 7 digits (check digit appended) |
"2of5" |
Interleaved 2-of-5 | 1D | Numeric only; even number of digits required |
Options
The optional third argument is an object. All fields are optional. scale and width are mutually exclusive (both control horizontal sizing). height can be used alone or combined with either scale or width.
| Field | Type | Default | Applies to | Description |
|---|---|---|---|---|
scale |
number | 4 |
all | Integer pixel multiplier applied to the barcode's natural symbol size |
width |
number | — | all | Output image width in pixels (requires height; mutually exclusive with scale) |
height |
number | see below | all | Output image height in pixels |
error_correction |
string | "M" |
"qr" only |
Error correction level: "L", "M", "Q", or "H" |
Sizing behaviour:
scale: multiplies the barcode's natural width by the given integer. For 2D codes, height is scaled equally. For 1D codes, height is set to a sensible default (see below). Every module/bar maps to exactlyscalepixels wide with no interpolation artefacts.height: sets an explicit pixel height. Can be combined withscale(which controls width) or used alone (with defaultscale = 4for width).width/height: both dimensions set explicitly. Useful when the image must fit a specific pixel budget.- Neither specified: defaults to
scale = 4.
Default 1D barcode height:
1D barcodes have a natural height of only 1 pixel, so the function applies a default height when none is specified:
- Code 128: 20% of the scaled width, producing a proportional barcode regardless of data length.
- All other 1D types:
scale * 24(96px at the default scale of 4).
These defaults can always be overridden with an explicit height option.
Examples
QR code with defaults
img = barcode("qr", "https://example.com")
QR code with high error correction and explicit scale
img = barcode("qr", "https://example.com/p?id=${ctx.payload.id}", {
scale = 8,
error_correction = "H",
})
QR code at a fixed pixel size
img = barcode("qr", "https://example.com", {
width = 400,
height = 400,
})
Code 128 label
label = barcode("code128", ctx.payload.tracking_number, {
scale = 3,
})
1D barcode with explicit height
label = barcode("code39", "ITEM-42", {
height = 80,
})
EAN-13 for retail product
# data must be exactly 12 digits; check digit is computed and appended
ean = barcode("ean13", ctx.payload.gtin12)
License
Documentation
¶
Index ¶
Constants ¶
This section is empty.
Variables ¶
var BarcodeFunc = function.New(&function.Spec{ Description: "Generates a barcode image as a bytes object with content_type image/png", Params: []function.Parameter{ {Name: "type", Type: cty.String}, {Name: "data", Type: cty.String}, }, VarParam: &function.Parameter{ Name: "options", Type: cty.DynamicPseudoType, AllowDynamicType: true, AllowNull: true, }, Type: func(args []cty.Value) (cty.Type, error) { if len(args) > 3 { return cty.NilType, fmt.Errorf("barcode() takes 2 or 3 arguments") } return bytescty.BytesObjectType, nil }, Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) { btype := args[0].AsString() data := args[1].AsString() var optVal cty.Value if len(args) > 2 { optVal = args[2] } opts, err := parseBarcodeOptions(optVal, btype) if err != nil { return cty.NilVal, err } return encodeBarcode(btype, data, opts) }, })
BarcodeFunc generates a barcode image and returns it as a bytes object with content_type "image/png". Called as barcode(type, data) or barcode(type, data, options).
Functions ¶
func GetBarcodeFunctions ¶
GetBarcodeFunctions returns the barcode function set for registration in a cty evaluation context.
Types ¶
This section is empty.
Source Files