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