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Some formatting changes, and a few tiny optimizations

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git-svn-id: https://zxing.googlecode.com/svn/trunk@767 59b500cc-1b3d-0410-9834-0bbf25fbcc57
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srowen 2008-12-01 21:36:58 +00:00
parent 7f5c93a71d
commit 36e9361184
1 changed files with 263 additions and 291 deletions
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554
core/src/com/google/zxing/oned/ITFReader.java
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@ -26,335 +26,307 @@ import com.google.zxing.common.GenericResultPoint;
import java.util.Hashtable; import java.util.Hashtable;
/** /**
*<p> * <p>Implements decoding of the ITF format.</p>
* Implements decoding of the ITF format. *
* </p> * <p>"ITF" stands for Interleaved Two of Five. This Reader will scan ITF barcode with 6, 10 or 14 digits.
*<p> * The checksum is optional and is not applied by this Reader. The consumer of the decoded value
* "ITF" stands for Interleaved Two of Five. This Reader will scan ITF barcode with 6, 10 or 14 digits. * will have to apply a checksum if required.</p>
* The checksum is optional and is not applied by this Reader. The consumer of the decoded value will have to apply a checksum if *
* required. * <p><a href="http://en.wikipedia.org/wiki/Interleaved_2_of_5">http://en.wikipedia.org/wiki/Interleaved_2_of_5</a>
* </p> * is a great reference for Interleaved 2 of 5 information.</p>
* *
*<p>
* <a
* href="http://en.wikipedia.org/wiki/Interleaved_2_of_5">http://en.wikipedia.
* org/wiki/Interleaved_2_of_5</a> is a great reference for Interleaved 2 of 5
* information.
* </p>
*
* @author kevin.osullivan@sita.aero, SITA Lab. * @author kevin.osullivan@sita.aero, SITA Lab.
*/ */
public class ITFReader extends AbstractOneDReader { public final class ITFReader extends AbstractOneDReader {
private static final int MAX_AVG_VARIANCE = (int) (PATTERN_MATCH_RESULT_SCALE_FACTOR * 0.42f); private static final int MAX_AVG_VARIANCE = (int) (PATTERN_MATCH_RESULT_SCALE_FACTOR * 0.42f);
private static final int MAX_INDIVIDUAL_VARIANCE = (int) (PATTERN_MATCH_RESULT_SCALE_FACTOR * 0.8f); private static final int MAX_INDIVIDUAL_VARIANCE = (int) (PATTERN_MATCH_RESULT_SCALE_FACTOR * 0.8f);
private static final int W = 3; // Pixel width of a wide line private static final int W = 3; // Pixel width of a wide line
private static final int N = 1; // Pixed width of a narrow line private static final int N = 1; // Pixed width of a narrow line
// Stores the actual narrow line width of the image being decoded. // Stores the actual narrow line width of the image being decoded.
private int narrowLineWidth = -1; private int narrowLineWidth = -1;
/** /**
* Start/end guard pattern. * Start/end guard pattern.
* *
* Note: The end pattern is reversed because the row is reversed before * Note: The end pattern is reversed because the row is reversed before
* searching for the END_PATTERN * searching for the END_PATTERN
*/ */
private static final int[] START_PATTERN = { N, N, N, N }; private static final int[] START_PATTERN = {N, N, N, N};
private static final int[] END_PATTERN_REVERSED = { N, N, W }; private static final int[] END_PATTERN_REVERSED = {N, N, W};
/** /**
* Patterns of Wide / Narrow lines to indicate each digit * Patterns of Wide / Narrow lines to indicate each digit
*/ */
static final int[][] PATTERNS = { { N, N, W, W, N }, // 0 static final int[][] PATTERNS = {
{ W, N, N, N, W }, // 1 {N, N, W, W, N}, // 0
{ N, W, N, N, W }, // 2 {W, N, N, N, W}, // 1
{ W, W, N, N, N }, // 3 {N, W, N, N, W}, // 2
{ N, N, W, N, W }, // 4 {W, W, N, N, N}, // 3
{ W, N, W, N, N }, // 5 {N, N, W, N, W}, // 4
{ N, W, W, N, N }, // 6 {W, N, W, N, N}, // 5
{ N, N, N, W, W }, // 7 {N, W, W, N, N}, // 6
{ W, N, N, W, N }, // 8 {N, N, N, W, W}, // 7
{ N, W, N, W, N } // 9 {W, N, N, W, N}, // 8
}; {N, W, N, W, N} // 9
};
public final Result decodeRow(int rowNumber, BitArray row, Hashtable hints) throws ReaderException { public final Result decodeRow(int rowNumber, BitArray row, Hashtable hints) throws ReaderException {
StringBuffer result = new StringBuffer(20); StringBuffer result = new StringBuffer(20);
/** // Find out where the Middle section (payload) starts & ends
* Find out where the Middle section (payload) starts & ends int[] startRange = decodeStart(row);
*/ int[] endRange = decodeEnd(row);
int[] startRange = decodeStart(row);
int[] endRange = decodeEnd(row);
decodeMiddle(row, startRange[1], endRange[0], result); decodeMiddle(row, startRange[1], endRange[0], result);
String resultString = result.toString(); String resultString = result.toString();
/**
* To avoid false positives with 2D barcodes (and other patterns), make
* an assumption that the decoded string must be 6, 10 or 14 digits.
*/
if ((resultString.length() != 6 && resultString.length() != 10 && resultString.length() != 14) ||
resultString.length() % 2 == 1)
throw ReaderException.getInstance();
return new Result(resultString, // To avoid false positives with 2D barcodes (and other patterns), make
null, // no natural byte representation for these barcodes // an assumption that the decoded string must be 6, 10 or 14 digits.
new ResultPoint[] { new GenericResultPoint(startRange[1], (float) rowNumber), new GenericResultPoint(startRange[0], (float) rowNumber) }, int length = resultString.length();
BarcodeFormat.ITF); if (length != 6 && length != 10 && length != 14) {
} throw ReaderException.getInstance();
}
/** return new Result(
* @param row resultString,
* row of black/white values to search null, // no natural byte representation for these barcodes
* @param payloadStart new ResultPoint[] { new GenericResultPoint(startRange[1], (float) rowNumber),
* offset of start pattern new GenericResultPoint(startRange[0], (float) rowNumber)},
* @param resultString BarcodeFormat.ITF);
* {@link StringBuffer} to append decoded chars to }
* @throws ReaderException
* if decoding could not complete successfully
*/
protected void decodeMiddle(BitArray row, int payloadStart, int payloadEnd, StringBuffer resultString) throws ReaderException {
// Digits are interleaved in pairs - 5 black lines for one digit, and the /**
// 5 * @param row row of black/white values to search
// interleaved white lines for the second digit. * @param payloadStart offset of start pattern
// Therefore, need to scan 10 lines and then * @param resultString {@link StringBuffer} to append decoded chars to
// split these into two arrays * @throws ReaderException if decoding could not complete successfully
int[] counterDigitPair = new int[10]; */
int[] counterBlack = new int[5]; protected void decodeMiddle(BitArray row, int payloadStart, int payloadEnd, StringBuffer resultString) throws ReaderException {
int[] counterWhite = new int[5];
for (int x = 0; payloadStart < payloadEnd; x++) { // Digits are interleaved in pairs - 5 black lines for one digit, and the
// 5
// interleaved white lines for the second digit.
// Therefore, need to scan 10 lines and then
// split these into two arrays
int[] counterDigitPair = new int[10];
int[] counterBlack = new int[5];
int[] counterWhite = new int[5];
// Get 10 runs of black/white. while (payloadStart < payloadEnd) {
recordPattern(row, payloadStart, counterDigitPair);
// Split them into each array
for (int k = 0; k < 5; k++) {
counterBlack[k] = counterDigitPair[k * 2];
counterWhite[k] = counterDigitPair[(k * 2) + 1];
}
int bestMatch = decodeDigit(counterBlack); // Get 10 runs of black/white.
resultString.append((char) ('0' + bestMatch % 10)); recordPattern(row, payloadStart, counterDigitPair);
bestMatch = decodeDigit(counterWhite); // Split them into each array
resultString.append((char) ('0' + bestMatch % 10)); for (int k = 0; k < 5; k++) {
int twoK = k << 1;
counterBlack[k] = counterDigitPair[twoK];
counterWhite[k] = counterDigitPair[twoK + 1];
}
for (int i = 0; i < counterDigitPair.length; i++) { int bestMatch = decodeDigit(counterBlack);
payloadStart += counterDigitPair[i]; resultString.append((char) ('0' + bestMatch % 10));
} bestMatch = decodeDigit(counterWhite);
} resultString.append((char) ('0' + bestMatch % 10));
}
/** for (int i = 0; i < counterDigitPair.length; i++) {
* Identify where the start of the middle / payload section starts. payloadStart += counterDigitPair[i];
* }
* @param row }
* row of black/white values to search }
* @return Array, containing index of start of 'start block' and end of
* 'start block'
* @throws ReaderException
*/
int[] decodeStart(BitArray row) throws ReaderException {
int endStart = skipWhiteSpace(row);
int startPattern[] = findGuardPattern(row, endStart, START_PATTERN);
/** /**
* Determine the width of a narrow line in pixels. We can do this by * Identify where the start of the middle / payload section starts.
* getting the width of the start pattern and dividing by 4 because its *
* made up of 4 narrow lines. * @param row row of black/white values to search
*/ * @return Array, containing index of start of 'start block' and end of
this.narrowLineWidth = (startPattern[1] - startPattern[0]) / 4; * 'start block'
* @throws ReaderException
*/
int[] decodeStart(BitArray row) throws ReaderException {
int endStart = skipWhiteSpace(row);
int startPattern[] = findGuardPattern(row, endStart, START_PATTERN);
validateQuietZone(row, startPattern[0]); // Determine the width of a narrow line in pixels. We can do this by
// getting the width of the start pattern and dividing by 4 because its
// made up of 4 narrow lines.
this.narrowLineWidth = (startPattern[1] - startPattern[0]) >> 2;
return startPattern; validateQuietZone(row, startPattern[0]);
}
/** return startPattern;
* }
* The start & end patterns must be pre/post fixed by a quiet zone. This
* zone must be at least 10 times the width of a narrow line. Scan back until
* we either get to the start of the barcode or match the necessary number of
* quiet zone pixels.
*
* Note: Its assumed the row is reversed when using this method to find
* quiet zone after the end pattern.
*
* ref: http://www.barcode-1.net/i25code.html
*
* @param row - The bit array representing the scanned barcode.
* @param startPattern - The index into row of the start or end pattern.
* @throws ReaderException - If the quiet zone cannot be found, a ReaderException is thrown.
*/
private void validateQuietZone(BitArray row, int startPattern) throws ReaderException {
int quietCount=this.narrowLineWidth * 10; // expect to find this many pixels of quiet zone /**
* The start & end patterns must be pre/post fixed by a quiet zone. This
int i=0; * zone must be at least 10 times the width of a narrow line. Scan back until
for (i=startPattern-1; quietCount>0 && i>=0; i--) * we either get to the start of the barcode or match the necessary number of
{ * quiet zone pixels.
if (row.get(i)==true) *
break; * Note: Its assumed the row is reversed when using this method to find
quietCount--; * quiet zone after the end pattern.
} *
if (quietCount!=0) * ref: http://www.barcode-1.net/i25code.html
{ *
// Unable to find the necessary number of quiet zone pixels. * @param row bit array representing the scanned barcode.
throw ReaderException.getInstance(); * @param startPattern index into row of the start or end pattern.
} * @throws ReaderException if the quiet zone cannot be found, a ReaderException is thrown.
} */
private void validateQuietZone(BitArray row, int startPattern) throws ReaderException {
/** int quietCount = this.narrowLineWidth * 10; // expect to find this many pixels of quiet zone
* Skip all whitespace until we get to the first black line.
*
* @param row
* row of black/white values to search
* @return index of the first black line.
* @throws ReaderException
* Throws exception if no black lines are found in the row
*/
private int skipWhiteSpace(BitArray row) throws ReaderException {
int width = row.getSize();
int endStart = 0;
while (endStart < width) {
if (row.get(endStart)) {
break;
}
endStart++;
}
if (endStart == width)
throw ReaderException.getInstance();
return endStart; for (int i = startPattern - 1; quietCount > 0 && i >= 0; i--) {
} if (row.get(i)) {
break;
}
quietCount--;
}
if (quietCount != 0) {
// Unable to find the necessary number of quiet zone pixels.
throw ReaderException.getInstance();
}
}
/** /**
* Identify where the end of the middle / payload section ends. * Skip all whitespace until we get to the first black line.
* *
* @param row * @param row row of black/white values to search
* row of black/white values to search * @return index of the first black line.
* @return Array, containing index of start of 'end block' and end of 'end * @throws ReaderException Throws exception if no black lines are found in the row
* block' */
* @throws ReaderException private int skipWhiteSpace(BitArray row) throws ReaderException {
*/ int width = row.getSize();
int endStart = 0;
while (endStart < width) {
if (row.get(endStart)) {
break;
}
endStart++;
}
if (endStart == width) {
throw ReaderException.getInstance();
}
int[] decodeEnd(BitArray row) throws ReaderException { return endStart;
}
// For convenience, reverse the row and then /**
// search from 'the start' for the end block * Identify where the end of the middle / payload section ends.
row.reverse(); *
* @param row row of black/white values to search
* @return Array, containing index of start of 'end block' and end of 'end
* block'
* @throws ReaderException
*/
int endStart = skipWhiteSpace(row); int[] decodeEnd(BitArray row) throws ReaderException {
int endPattern[] = null;
try {
endPattern = findGuardPattern(row, endStart, END_PATTERN_REVERSED);
} catch (ReaderException e) {
// Put our row of data back the right way before throwing
row.reverse();
throw e;
}
/** // For convenience, reverse the row and then
* The start & end patterns must be pre/post fixed by a quiet zone. This // search from 'the start' for the end block
* zone must be at least 10 times the width of a narrow line. row.reverse();
*
* ref: http://www.barcode-1.net/i25code.html
*/
validateQuietZone(row, endPattern[0]);
// Now recalc the indicies of where the 'endblock' starts & stops to int endStart = skipWhiteSpace(row);
// accomodate int endPattern[];
// the reversed nature of the search try {
int temp = endPattern[0]; endPattern = findGuardPattern(row, endStart, END_PATTERN_REVERSED);
endPattern[0] = row.getSize() - endPattern[1]; } catch (ReaderException e) {
endPattern[1] = row.getSize() - temp; // Put our row of data back the right way before throwing
row.reverse();
throw e;
}
// Put the row back the righ way. // The start & end patterns must be pre/post fixed by a quiet zone. This
row.reverse(); // zone must be at least 10 times the width of a narrow line.
return endPattern; // ref: http://www.barcode-1.net/i25code.html
} validateQuietZone(row, endPattern[0]);
/** // Now recalc the indicies of where the 'endblock' starts & stops to
* @param row // accomodate
* row of black/white values to search // the reversed nature of the search
* @param rowOffset int temp = endPattern[0];
* position to start search endPattern[0] = row.getSize() - endPattern[1];
* @param pattern endPattern[1] = row.getSize() - temp;
* pattern of counts of number of black and white pixels that are
* being searched for as a pattern
* @return start/end horizontal offset of guard pattern, as an array of two
* ints
* @throws ReaderException
* if pattern is not found
*
* TODO: This is very similar to implementation in AbstractUPCEANReader. Consider if they can be merged to
* a single method.
*/
int[] findGuardPattern(BitArray row, int rowOffset, int[] pattern) throws ReaderException {
int patternLength = pattern.length;
int[] counters = new int[patternLength];
int width = row.getSize();
boolean isWhite = false;
int counterPosition = 0; // Put the row back the righ way.
int patternStart = rowOffset; row.reverse();
for (int x = rowOffset; x < width; x++) { return endPattern;
boolean pixel = row.get(x); }
if ((!pixel && isWhite) || (pixel && !isWhite)) {
counters[counterPosition]++;
} else {
if (counterPosition == patternLength - 1) {
if (patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE) < MAX_AVG_VARIANCE) {
return new int[] { patternStart, x };
}
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 ReaderException.getInstance();
}
/** /**
* Attempts to decode a sequence of ITF black/white lines into single * @param row row of black/white values to search
* digit. * @param rowOffset position to start search
* * @param pattern pattern of counts of number of black and white pixels that are
* @param counters * being searched for as a pattern
* the counts of runs of observed black/white/black/... values * @return start/end horizontal offset of guard pattern, as an array of two
* * ints
* @return The decoded digit * @throws ReaderException if pattern is not found
* */
* @throws ReaderException int[] findGuardPattern(BitArray row, int rowOffset, int[] pattern) throws ReaderException {
* if digit cannot be decoded
*/
static int decodeDigit(int[] counters) throws ReaderException {
int bestVariance = MAX_AVG_VARIANCE; // worst variance we'll accept // TODO: This is very similar to implementation in AbstractUPCEANReader. Consider if they can be merged to
int bestMatch = -1; // a single method.
int max = PATTERNS.length;
for (int i = 0; i < max; i++) { int patternLength = pattern.length;
int[] pattern = PATTERNS[i]; int[] counters = new int[patternLength];
int variance = patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE); int width = row.getSize();
if (variance < bestVariance) { boolean isWhite = false;
bestVariance = variance;
bestMatch = i; int counterPosition = 0;
} int patternStart = rowOffset;
} for (int x = rowOffset; x < width; x++) {
if (bestMatch >= 0) { boolean pixel = row.get(x);
return bestMatch; if ((!pixel && isWhite) || (pixel && !isWhite)) {
counters[counterPosition]++;
} else {
if (counterPosition == patternLength - 1) {
if (patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE) < MAX_AVG_VARIANCE) {
return new int[]{patternStart, x};
}
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 ReaderException.getInstance();
}
/**
* Attempts to decode a sequence of ITF black/white lines into single
* digit.
*
* @param counters the counts of runs of observed black/white/black/... values
* @return The decoded digit
* @throws ReaderException if digit cannot be decoded
*/
static int decodeDigit(int[] counters) throws ReaderException {
int bestVariance = MAX_AVG_VARIANCE; // worst variance we'll accept
int bestMatch = -1;
int max = PATTERNS.length;
for (int i = 0; i < max; i++) {
int[] pattern = PATTERNS[i];
int variance = patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE);
if (variance < bestVariance) {
bestVariance = variance;
bestMatch = i;
}
}
if (bestMatch >= 0) {
return bestMatch;
} else { } else {
throw ReaderException.getInstance(); throw ReaderException.getInstance();
} }