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// Package pdf417 can create PDF-417 barcodes
package pdf417
import (
"fmt"
"github.com/boombuler/barcode"
"github.com/boombuler/barcode/utils"
)
const (
padding_codeword = 900
)
// Encodes the given data as PDF417 barcode.
// securityLevel should be between 0 and 8. The higher the number, the more
// additional error-correction codes are added.
func Encode(data string, securityLevel byte) (barcode.Barcode, error) {
if securityLevel >= 9 {
return nil, fmt.Errorf("Invalid security level %d", securityLevel)
}
sl := securitylevel(securityLevel)
dataWords, err := highlevelEncode(data)
if err != nil {
return nil, err
}
columns, rows := calcDimensions(len(dataWords), sl.ErrorCorrectionWordCount())
if columns < minCols || columns > maxCols || rows < minRows || rows > maxRows {
return nil, fmt.Errorf("Unable to fit data in barcode")
}
barcode := new(pdfBarcode)
barcode.data = data
codeWords, err := encodeData(dataWords, columns, sl)
if err != nil {
return nil, err
}
grid := [][]int{}
for i := 0; i < len(codeWords); i += columns {
grid = append(grid, codeWords[i:min(i+columns, len(codeWords))])
}
codes := [][]int{}
for rowNum, row := range grid {
table := rowNum % 3
rowCodes := make([]int, 0, columns+4)
rowCodes = append(rowCodes, start_word)
rowCodes = append(rowCodes, getCodeword(table, getLeftCodeWord(rowNum, rows, columns, securityLevel)))
for _, word := range row {
rowCodes = append(rowCodes, getCodeword(table, word))
}
rowCodes = append(rowCodes, getCodeword(table, getRightCodeWord(rowNum, rows, columns, securityLevel)))
rowCodes = append(rowCodes, stop_word)
codes = append(codes, rowCodes)
}
barcode.code = renderBarcode(codes)
barcode.width = (columns+4)*17 + 1
return barcode, nil
}
func encodeData(dataWords []int, columns int, sl securitylevel) ([]int, error) {
dataCount := len(dataWords)
ecCount := sl.ErrorCorrectionWordCount()
padWords := getPadding(dataCount, ecCount, columns)
dataWords = append(dataWords, padWords...)
length := len(dataWords) + 1
dataWords = append([]int{length}, dataWords...)
ecWords := sl.Compute(dataWords)
return append(dataWords, ecWords...), nil
}
func getLeftCodeWord(rowNum int, rows int, columns int, securityLevel byte) int {
tableId := rowNum % 3
var x int
switch tableId {
case 0:
x = (rows - 3) / 3
case 1:
x = int(securityLevel) * 3
x += (rows - 1) % 3
case 2:
x = columns - 1
}
return 30*(rowNum/3) + x
}
func getRightCodeWord(rowNum int, rows int, columns int, securityLevel byte) int {
tableId := rowNum % 3
var x int
switch tableId {
case 0:
x = columns - 1
case 1:
x = (rows - 1) / 3
case 2:
x = int(securityLevel) * 3
x += (rows - 1) % 3
}
return 30*(rowNum/3) + x
}
func min(a, b int) int {
if a <= b {
return a
}
return b
}
func getPadding(dataCount int, ecCount int, columns int) []int {
totalCount := dataCount + ecCount + 1
mod := totalCount % columns
padding := []int{}
if mod > 0 {
padCount := columns - mod
padding = make([]int, padCount)
for i := 0; i < padCount; i++ {
padding[i] = padding_codeword
}
}
return padding
}
func renderBarcode(codes [][]int) *utils.BitList {
bl := new(utils.BitList)
for _, row := range codes {
lastIdx := len(row) - 1
for i, col := range row {
if i == lastIdx {
bl.AddBits(col, 18)
} else {
bl.AddBits(col, 17)
}
}
}
return bl
}
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