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Changed validation method in order to prevent false positives on other 1D barcodes

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git-svn-id: https://zxing.googlecode.com/svn/trunk@1407 59b500cc-1b3d-0410-9834-0bbf25fbcc57
This commit is contained in:
bas5winkel 2010-06-01 14:39:24 +00:00
parent 97060619fe
commit d818288177
1 changed files with 50 additions and 26 deletions
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76
core/src/com/google/zxing/oned/CodaBarReader.java
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@ -45,11 +45,20 @@ public final class CodaBarReader extends OneDReader {
0x01A, 0x029 //TN
};
// minimal number of characters that should be present (inclusing start and stop characters)
// this check has been added to reduce the number of false positive on other formats
// until the cause for this behaviour has been determined
// under normal circumstances this should be set to 3
private static final int minCharacterLength = 6;
// multiple start/end patterns
// official start and end patterns
private static final char[] STARTEND_ENCODING = {'E', '*', 'A', 'B', 'C', 'D', 'T', 'N'};
// some codabar generator allow the codabar string to be closed by every character
private static final char[] STARTEND_ENCODING = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '$', ':', '/', '.', '+', 'A', 'B', 'C', 'D', 'T', 'N'};
//private static final char[] STARTEND_ENCODING = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '$', ':', '/', '.', '+', 'A', 'B', 'C', 'D', 'T', 'N'};
// some industries use a checksum standard but this is not part of the original codabar standard
// for more information see : http://www.mecsw.com/specs/codabar.html
public Result decodeRow(int rowNumber, BitArray row, Hashtable hints) throws NotFoundException {
int[] start = findAsteriskPattern(row);
@ -87,29 +96,12 @@ public final class CodaBarReader extends OneDReader {
}
} while (nextStart < end); // no fixed end pattern so keep on reading while data is available
// find last character in STARTEND_ENCODING
for (int k = result.length() - 1; k >= 0; k--) {
if (arrayContains(STARTEND_ENCODING, result.charAt(k))) {
// valid character -> remove and break out of loop
result.deleteCharAt(k);
k = -1;// break out of loop
} else {
// not a valid character -> remove anyway
result.deleteCharAt(k);
}
}
// remove first character
if (result.length() > 0) {
result.deleteCharAt(0);
}
// 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)
@ -117,17 +109,49 @@ public final class CodaBarReader extends OneDReader {
throw NotFoundException.getNotFoundInstance();
}
String resultString = result.toString();
if (resultString.length() == 0) {
// Almost surely a false positive
throw NotFoundException.getNotFoundInstance();
// valid result?
if (result.length() < 2)
{
throw NotFoundException.getNotFoundInstance();
}
char startchar = result.charAt(0);
if (!arrayContains(STARTEND_ENCODING, startchar))
{
//invalid start character
throw NotFoundException.getNotFoundInstance();
}
// find stop character
for (int k = 1;k < result.length() ;k++)
{
if (result.charAt(k) == startchar)
{
// found stop character -> discard rest of the string
if ((k+1) != result.length())
{
result.delete(k+1,result.length()-1);
k = result.length();// break out of loop
}
}
}
// remove stop/start characters character and check if a string longer than 5 characters is contained
if (result.length() > minCharacterLength)
{
result.deleteCharAt(result.length()-1);
result.deleteCharAt(0);
}
else
{
// Almost surely a false positive ( start + stop + at least 1 character)
throw NotFoundException.getNotFoundInstance();
}
float left = (float) (start[1] + start[0]) / 2.0f;
float right = (float) (nextStart + lastStart) / 2.0f;
return new Result(
resultString,
result.toString(),
null,
new ResultPoint[]{
new ResultPoint(left, (float) rowNumber),