I'm using zxing to generate an EAN13 barcode. Everything works fine when I use this code:

```
new EAN13Writer().encode(eanValue, BarcodeFormat.EAN_13, requestedWidth, requestedHeight);
```

Result:

Now, the customer wants to have a *lead*, *separater* and a *trailer* like this one:

(Image source)

As far as I understand the code of zxing (see here) I'm using above can't make those lines longer than others. ~~But I've found out that there are two ~~*encode*-methods in the EAN13Writer and it seems like, the second encode-function does exactly what I want to do. But the problem is that this function doesn't return a bitmatrix but a boolean array. (Edit: Nope the function does not achieve what I want to do)

Can anybody tell me how I can achieve the second barcode style?

# Best How To :

As I couldn't find a solution in the zxing code I wrote my own EAN13Writer. I had to copy paste some methods and constants as they were package-private in the zxing package.

Basically it just stores the position of the lines which shall be longer in a member variable. When the BitMatrix is rendered every line which should not be longer will be shortened by 5%. If anybody has the same problem this code might help a little bit.

```
/**
* This is a custom implementation as the customer wants a modified barcode with longer and shorter lines for start, middle and end.
* Most code is based on Code from the OneDimensionalCodeWriter, EAN13Writer and UPCEANReader but
* had to be copied as the methods were package private
*
*/
public class CustomEAN13Writer extends OneDimensionalCodeWriter {
// For an EAN-13 barcode, the first digit is represented by the parities used
// to encode the next six digits, according to the table below. For example,
// if the barcode is 5 123456 789012 then the value of the first digit is
// signified by using odd for '1', even for '2', even for '3', odd for '4',
// odd for '5', and even for '6'. See http://en.wikipedia.org/wiki/EAN-13
//
// Parity of next 6 digits
// Digit 0 1 2 3 4 5
// 0 Odd Odd Odd Odd Odd Odd
// 1 Odd Odd Even Odd Even Even
// 2 Odd Odd Even Even Odd Even
// 3 Odd Odd Even Even Even Odd
// 4 Odd Even Odd Odd Even Even
// 5 Odd Even Even Odd Odd Even
// 6 Odd Even Even Even Odd Odd
// 7 Odd Even Odd Even Odd Even
// 8 Odd Even Odd Even Even Odd
// 9 Odd Even Even Odd Even Odd
//
// Note that the encoding for '0' uses the same parity as a UPC barcode. Hence
// a UPC barcode can be converted to an EAN-13 barcode by prepending a 0.
//
// The encoding is represented by the following array, which is a bit pattern
// using Odd = 0 and Even = 1. For example, 5 is represented by:
//
// Odd Even Even Odd Odd Even
// in binary:
// 0 1 1 0 0 1 == 0x19
//
static final int[] FIRST_DIGIT_ENCODINGS = {
0x00, 0x0B, 0x0D, 0xE, 0x13, 0x19, 0x1C, 0x15, 0x16, 0x1A
};
/**
* Start/end guard pattern.
*/
static final int[] START_END_PATTERN = {1, 1, 1,};
/**
* As above but also including the "even", or "G" patterns used to encode UPC/EAN digits.
*/
static final int[][] L_AND_G_PATTERNS;
/**
* "Odd", or "L" patterns used to encode UPC/EAN digits.
*/
static final int[][] L_PATTERNS = {
{3, 2, 1, 1}, // 0
{2, 2, 2, 1}, // 1
{2, 1, 2, 2}, // 2
{1, 4, 1, 1}, // 3
{1, 1, 3, 2}, // 4
{1, 2, 3, 1}, // 5
{1, 1, 1, 4}, // 6
{1, 3, 1, 2}, // 7
{1, 2, 1, 3}, // 8
{3, 1, 1, 2} // 9
};
/**
* Pattern marking the middle of a UPC/EAN pattern, separating the two halves.
*/
static final int[] MIDDLE_PATTERN = {1, 1, 1, 1, 1};
static {
L_AND_G_PATTERNS = new int[20][];
System.arraycopy(L_PATTERNS, 0, L_AND_G_PATTERNS, 0, 10);
for (int i = 10; i < 20; i++) {
int[] widths = L_PATTERNS[i - 10];
int[] reversedWidths = new int[widths.length];
for (int j = 0; j < widths.length; j++) {
reversedWidths[j] = widths[widths.length - j - 1];
}
L_AND_G_PATTERNS[i] = reversedWidths;
}
}
private static final int CODE_WIDTH = 3 + // start guard
(7 * 6) + // left bars
5 + // middle guard
(7 * 6) + // right bars
3; // end guard
private static final int DEFAULT_MARGIN = 10;
//This list should contain all positions of lines which should be longer than the other lines
private List<Integer> mLongLinePositions;
public CustomEAN13Writer() {
mLongLinePositions = new ArrayList<>();
}
/**
* @param target encode black/white pattern into this array
* @param pos position to start encoding at in {@code target}
* @param pattern lengths of black/white runs to encode
* @param startColor starting color - false for white, true for black
* @return the number of elements added to target.
*/
public int appendPatternAndConsiderLongLinePosition(boolean[] target, int pos, int[] pattern,
boolean startColor) {
boolean color = startColor;
int numAdded = 0;
for (int len : pattern) {
for (int j = 0; j < len; j++) {
//If the pattern is the start-, middle- or end-pattern save the position for rendering later
if (pattern.equals(START_END_PATTERN) || pattern.equals(MIDDLE_PATTERN) || pattern
.equals(START_END_PATTERN)) {
mLongLinePositions.add(pos);
}
target[pos++] = color;
}
numAdded += len;
color = !color; // flip color after each segment
}
return numAdded;
}
@Override
public boolean[] encode(final String contents) {
if (contents.length() != 13) {
throw new IllegalArgumentException(
"Requested contents should be 13 digits long, but got " + contents.length());
}
try {
if (!checkStandardUPCEANChecksum(contents)) {
throw new IllegalArgumentException("Contents do not pass checksum");
}
} catch (FormatException ignored) {
throw new IllegalArgumentException("Illegal contents");
}
int firstDigit = Integer.parseInt(contents.substring(0, 1));
int parities = FIRST_DIGIT_ENCODINGS[firstDigit];
boolean[] result = new boolean[CODE_WIDTH];
int pos = 0;
pos += appendPatternAndConsiderLongLinePosition(result, pos, START_END_PATTERN, true);
// See {@link #EAN13Reader} for a description of how the first digit & left bars are encoded
for (int i = 1; i <= 6; i++) {
int digit = Integer.parseInt(contents.substring(i, i + 1));
if ((parities >> (6 - i) & 1) == 1) {
digit += 10;
}
pos += appendPatternAndConsiderLongLinePosition(result, pos, L_AND_G_PATTERNS[digit],
false);
}
pos += appendPatternAndConsiderLongLinePosition(result, pos, MIDDLE_PATTERN, false);
for (int i = 7; i <= 12; i++) {
int digit = Integer.parseInt(contents.substring(i, i + 1));
pos += appendPatternAndConsiderLongLinePosition(result, pos, L_PATTERNS[digit], true);
}
appendPatternAndConsiderLongLinePosition(result, pos, START_END_PATTERN, true);
return result;
}
public BitMatrix encodeAndRender(String contents, int width, int height) {
boolean[] code = encode(contents);
int inputWidth = code.length;
// Add quiet zone on both sides.
int fullWidth = inputWidth + DEFAULT_MARGIN;
int outputWidth = Math.max(width, fullWidth);
int outputHeight = Math.max(1, height);
int multiple = outputWidth / fullWidth;
int leftPadding = (outputWidth - (inputWidth * multiple)) / 2;
BitMatrix output = new BitMatrix(outputWidth, outputHeight);
for (int inputX = 0, outputX = leftPadding; inputX < inputWidth;
inputX++, outputX += multiple) {
if (code[inputX]) {
int barcodeHeight = outputHeight;
//if the position isn't in the list for long lines we have to shorten the line by 5%
if (!mLongLinePositions.contains(inputX)) {
barcodeHeight = (int) ((float) outputHeight * 0.95f);
}
output.setRegion(outputX, 0, multiple, barcodeHeight);
}
}
return output;
}
/**
* Computes the UPC/EAN checksum on a string of digits, and reports whether the checksum is
* correct or not.
*
* @param s string of digits to check
* @return true iff string of digits passes the UPC/EAN checksum algorithm
* @throws FormatException if the string does not contain only digits
*/
static boolean checkStandardUPCEANChecksum(CharSequence s) throws FormatException {
int length = s.length();
if (length == 0) {
return false;
}
int sum = 0;
for (int i = length - 2; i >= 0; i -= 2) {
int digit = (int) s.charAt(i) - (int) '0';
if (digit < 0 || digit > 9) {
throw FormatException.getFormatInstance();
}
sum += digit;
}
sum *= 3;
for (int i = length - 1; i >= 0; i -= 2) {
int digit = (int) s.charAt(i) - (int) '0';
if (digit < 0 || digit > 9) {
throw FormatException.getFormatInstance();
}
sum += digit;
}
return sum % 10 == 0;
}
}
```