alphanumeric.go raw

   1  package qr
   2  
   3  import (
   4  	"errors"
   5  	"fmt"
   6  	"strings"
   7  
   8  	"github.com/boombuler/barcode/utils"
   9  )
  10  
  11  const charSet string = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:"
  12  
  13  func stringToAlphaIdx(content string) <-chan int {
  14  	result := make(chan int)
  15  	go func() {
  16  		for _, r := range content {
  17  			idx := strings.IndexRune(charSet, r)
  18  			result <- idx
  19  			if idx < 0 {
  20  				break
  21  			}
  22  		}
  23  		close(result)
  24  	}()
  25  
  26  	return result
  27  }
  28  
  29  func encodeAlphaNumeric(content string, ecl ErrorCorrectionLevel) (*utils.BitList, *versionInfo, error) {
  30  
  31  	contentLenIsOdd := len(content)%2 == 1
  32  	contentBitCount := (len(content) / 2) * 11
  33  	if contentLenIsOdd {
  34  		contentBitCount += 6
  35  	}
  36  	vi := findSmallestVersionInfo(ecl, alphaNumericMode, contentBitCount)
  37  	if vi == nil {
  38  		return nil, nil, errors.New("To much data to encode")
  39  	}
  40  
  41  	res := new(utils.BitList)
  42  	res.AddBits(int(alphaNumericMode), 4)
  43  	res.AddBits(len(content), vi.charCountBits(alphaNumericMode))
  44  
  45  	encoder := stringToAlphaIdx(content)
  46  
  47  	for idx := 0; idx < len(content)/2; idx++ {
  48  		c1 := <-encoder
  49  		c2 := <-encoder
  50  		if c1 < 0 || c2 < 0 {
  51  			return nil, nil, fmt.Errorf("\"%s\" can not be encoded as %s", content, AlphaNumeric)
  52  		}
  53  		res.AddBits(c1*45+c2, 11)
  54  	}
  55  	if contentLenIsOdd {
  56  		c := <-encoder
  57  		if c < 0 {
  58  			return nil, nil, fmt.Errorf("\"%s\" can not be encoded as %s", content, AlphaNumeric)
  59  		}
  60  		res.AddBits(c, 6)
  61  	}
  62  
  63  	addPaddingAndTerminator(res, vi)
  64  
  65  	return res, vi, nil
  66  }
  67