76 lines
1.5 KiB
Go
76 lines
1.5 KiB
Go
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// Package datamatrix can create Datamatrix barcodes
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package datamatrix
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import (
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"errors"
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"github.com/boombuler/barcode"
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)
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// Encode returns a Datamatrix barcode for the given content
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func Encode(content string) (barcode.Barcode, error) {
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data := encodeText(content)
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var size *dmCodeSize
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for _, s := range codeSizes {
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if s.DataCodewords() >= len(data) {
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size = s
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break
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}
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}
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if size == nil {
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return nil, errors.New("to much data to encode")
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}
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data = addPadding(data, size.DataCodewords())
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data = ec.calcECC(data, size)
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code := render(data, size)
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if code != nil {
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code.content = content
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return code, nil
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}
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return nil, errors.New("unable to render barcode")
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}
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func render(data []byte, size *dmCodeSize) *datamatrixCode {
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cl := newCodeLayout(size)
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cl.SetValues(data)
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return cl.Merge()
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}
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func encodeText(content string) []byte {
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var result []byte
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input := []byte(content)
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for i := 0; i < len(input); {
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c := input[i]
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i++
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if c >= '0' && c <= '9' && i < len(input) && input[i] >= '0' && input[i] <= '9' {
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// two numbers...
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c2 := input[i]
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i++
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cw := byte(((c-'0')*10 + (c2 - '0')) + 130)
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result = append(result, cw)
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} else if c > 127 {
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// not correct... needs to be redone later...
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result = append(result, 235, c-127)
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} else {
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result = append(result, c+1)
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}
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}
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return result
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}
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func addPadding(data []byte, toCount int) []byte {
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if len(data) < toCount {
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data = append(data, 129)
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}
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for len(data) < toCount {
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R := ((149 * (len(data) + 1)) % 253) + 1
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data = append(data, byte((129+R)%254))
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}
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return data
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}
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