/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
namespace com.google.zxing.oned
{
using System;
using System.Text;
using com.google.zxing.common;
public sealed class Code39Reader : AbstractOneDReader
{
private static String ALPHABET_STRING = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. *$/+%";
private static char[] ALPHABET = ALPHABET_STRING.ToCharArray();
/**
* These represent the encodings of characters, as patterns of wide and narrow bars.
* The 9 least-significant bits of each int correspond to the pattern of wide and narrow,
* with 1s representing "wide" and 0s representing narrow.
*/
private static int[] CHARACTER_ENCODINGS = {
0x034, 0x121, 0x061, 0x160, 0x031, 0x130, 0x070, 0x025, 0x124, 0x064, // 0-9
0x109, 0x049, 0x148, 0x019, 0x118, 0x058, 0x00D, 0x10C, 0x04C, 0x01C, // A-J
0x103, 0x043, 0x142, 0x013, 0x112, 0x052, 0x007, 0x106, 0x046, 0x016, // K-T
0x181, 0x0C1, 0x1C0, 0x091, 0x190, 0x0D0, 0x085, 0x184, 0x0C4, 0x094, // U-*
0x0A8, 0x0A2, 0x08A, 0x02A // $-%
};
private static int ASTERISK_ENCODING = CHARACTER_ENCODINGS[39];
private bool usingCheckDigit;
private bool extendedMode;
/**
* Creates a reader that assumes all encoded data is data, and does not treat the
* character as a check digit. It will not decoded "extended Code 39" sequences.
*/
public Code39Reader() {
usingCheckDigit = false;
extendedMode = false;
}
/**
* Creates a reader that can be configured to check the last character as a check digit.
* It will not decoded "extended Code 39" sequences.
*
* @param usingCheckDigit if true, treat the last data character as a check digit, not
* data, and verify that the checksum passes.
*/
public Code39Reader(bool usingCheckDigit) {
this.usingCheckDigit = usingCheckDigit;
this.extendedMode = false;
}
/**
* Creates a reader that can be configured to check the last character as a check digit,
* or optionally attempt to decode "extended Code 39" sequences that are used to encode
* the full ASCII character set.
*
* @param usingCheckDigit if true, treat the last data character as a check digit, not
* data, and verify that the checksum passes.
* @param extendedMode if true, will attempt to decode extended Code 39 sequences in the
* text.
*/
public Code39Reader(bool usingCheckDigit, bool extendedMode) {
this.usingCheckDigit = usingCheckDigit;
this.extendedMode = extendedMode;
}
public override Result decodeRow(int rowNumber, BitArray row, System.Collections.Hashtable hints) {
int[] start = findAsteriskPattern(row);
int nextStart = start[1];
int end = row.getSize();
// Read off white space
while (nextStart < end && !row.get(nextStart)) {
nextStart++;
}
StringBuilder result = new StringBuilder();
int[] counters = new int[9];
char decodedChar;
int lastStart;
do {
recordPattern(row, nextStart, counters);
int pattern = toNarrowWidePattern(counters);
decodedChar = patternToChar(pattern);
result.Append(decodedChar);
lastStart = nextStart;
for (int i = 0; i < counters.Length; i++) {
nextStart += counters[i];
}
// Read off white space
while (nextStart < end && !row.get(nextStart)) {
nextStart++;
}
} while (decodedChar != '*');
result.Remove(result.Length - 1, 1); // remove asterisk
// Look for whitespace after pattern:
int lastPatternSize = 0;
for (int i = 0; i < counters.Length; i++) {
lastPatternSize += counters[i];
}
int whiteSpaceAfterEnd = nextStart - lastStart - lastPatternSize;
// If 50% of last pattern size, following last pattern, is not whitespace, fail
// (but if it's whitespace to the very end of the image, that's OK)
if (nextStart != end && whiteSpaceAfterEnd / 2 < lastPatternSize) {
throw new ReaderException();
}
if (usingCheckDigit) {
int max = result.Length - 1;
int total = 0;
for (int i = 0; i < max; i++) {
total += ALPHABET_STRING.IndexOf(result[i]);
}
if (total % 43 != ALPHABET_STRING.IndexOf(result[max]))
{
throw new ReaderException();
}
result.Remove(max,1);
}
String resultString = result.ToString();
if (extendedMode) {
resultString = decodeExtended(resultString);
}
if (resultString.Length == 0) {
// Almost surely a false positive
throw new ReaderException();
}
float left = (float) (start[1] + start[0]) / 2.0f;
float right = (float) (nextStart + lastStart) / 2.0f;
return new Result(
resultString,
null,
new ResultPoint[]{
new GenericResultPoint(left, (float) rowNumber),
new GenericResultPoint(right, (float) rowNumber)},
BarcodeFormat.CODE_39);
}
private static int[] findAsteriskPattern(BitArray row) {
int width = row.getSize();
int rowOffset = 0;
while (rowOffset < width) {
if (row.get(rowOffset)) {
break;
}
rowOffset++;
}
int counterPosition = 0;
int[] counters = new int[9];
int patternStart = rowOffset;
bool isWhite = false;
int patternLength = counters.Length;
for (int i = rowOffset; i < width; i++) {
bool pixel = row.get(i);
if ((!pixel && isWhite) || (pixel && !isWhite)) {
counters[counterPosition]++;
} else {
if (counterPosition == patternLength - 1) {
try {
if (toNarrowWidePattern(counters) == ASTERISK_ENCODING) {
// Look for whitespace before start pattern, >= 50% of width of start pattern
if (row.isRange(Math.Max(0, patternStart - (i - patternStart) / 2), patternStart, false)) {
return new int[]{patternStart, i};
}
}
} catch (ReaderException re) {
// no match, continue
}
patternStart += counters[0] + counters[1];
for (int y = 2; y < patternLength; y++) {
counters[y - 2] = counters[y];
}
counters[patternLength - 2] = 0;
counters[patternLength - 1] = 0;
counterPosition--;
} else {
counterPosition++;
}
counters[counterPosition] = 1;
isWhite = !isWhite;
}
}
throw new ReaderException();
}
private static int toNarrowWidePattern(int[] counters) {
int numCounters = counters.Length;
int maxNarrowCounter = 0;
int wideCounters;
do {
int minCounter = int.MaxValue;
for (int i = 0; i < numCounters; i++) {
int counter = counters[i];
if (counter < minCounter && counter > maxNarrowCounter) {
minCounter = counter;
}
}
maxNarrowCounter = minCounter;
wideCounters = 0;
int totalWideCountersWidth = 0;
int pattern = 0;
for (int i = 0; i < numCounters; i++) {
int counter = counters[i];
if (counters[i] > maxNarrowCounter) {
pattern |= 1 << (numCounters - 1 - i);
wideCounters++;
totalWideCountersWidth += counter;
}
}
if (wideCounters == 3) {
// Found 3 wide counters, but are they close enough in width?
// We can perform a cheap, conservative check to see if any individual
// counter is more than 1.5 times the average:
for (int i = 0; i < numCounters && wideCounters > 0; i++) {
int counter = counters[i];
if (counters[i] > maxNarrowCounter) {
wideCounters--;
// totalWideCountersWidth = 3 * average, so this checks if counter >= 3/2 * average
if ((counter << 1) >= totalWideCountersWidth) {
throw new ReaderException();
}
}
}
return pattern;
}
} while (wideCounters > 3);
throw new ReaderException();
}
private static char patternToChar(int pattern) {
for (int i = 0; i < CHARACTER_ENCODINGS.Length; i++) {
if (CHARACTER_ENCODINGS[i] == pattern) {
return ALPHABET[i];
}
}
throw new ReaderException();
}
private static String decodeExtended(String encoded) {
int Length = encoded.Length;
StringBuilder decoded = new StringBuilder(Length);
for (int i = 0; i < Length; i++) {
char c = encoded[i];
if (c == '+' || c == '$' || c == '%' || c == '/') {
char next = encoded[i + 1];
char decodedChar = '\0';
switch (c) {
case '+':
// +A to +Z map to a to z
if (next >= 'A' && next <= 'Z') {
decodedChar = (char) (next + 32);
} else {
throw new ReaderException();
}
break;
case '$':
// $A to $Z map to control codes SH to SB
if (next >= 'A' && next <= 'Z') {
decodedChar = (char) (next - 64);
} else {
throw new ReaderException();
}
break;
case '%':
// %A to %E map to control codes ESC to US
if (next >= 'A' && next <= 'E') {
decodedChar = (char) (next - 38);
} else if (next >= 'F' && next <= 'W') {
decodedChar = (char) (next - 11);
} else {
throw new ReaderException();
}
break;
case '/':
// /A to /O map to ! to , and /Z maps to :
if (next >= 'A' && next <= 'O') {
decodedChar = (char) (next - 32);
} else if (next == 'Z') {
decodedChar = ':';
} else {
throw new ReaderException();
}
break;
}
decoded.Append(decodedChar);
// bump up i again since we read two characters
i++;
} else {
decoded.Append(c);
}
}
return decoded.ToString();
}
}
}