/*
- * Copyright 2008 Google Inc.
+ * Copyright 2008 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
package com.google.zxing.oned;
-import com.google.zxing.BlackPointEstimationMethod;
+import com.google.zxing.BinaryBitmap;
import com.google.zxing.DecodeHintType;
-import com.google.zxing.MonochromeBitmapSource;
import com.google.zxing.ReaderException;
import com.google.zxing.Result;
import com.google.zxing.ResultMetadataType;
+import com.google.zxing.ResultPoint;
import com.google.zxing.common.BitArray;
import java.util.Hashtable;
* of one-dimensional barcodes.</p>
*
* @author dswitkin@google.com (Daniel Switkin)
- * @author srowen@google.com (Sean Owen)
+ * @author Sean Owen
*/
public abstract class AbstractOneDReader implements OneDReader {
private static final int INTEGER_MATH_SHIFT = 8;
+ static final int PATTERN_MATCH_RESULT_SCALE_FACTOR = 1 << INTEGER_MATH_SHIFT;
- public final Result decode(MonochromeBitmapSource image) throws ReaderException {
+ public final Result decode(BinaryBitmap image) throws ReaderException {
return decode(image, null);
}
- public final Result decode(MonochromeBitmapSource image, Hashtable hints) throws ReaderException {
- boolean tryHarder = hints != null && hints.containsKey(DecodeHintType.TRY_HARDER);
+ // Note that we don't try rotation without the try harder flag, even if rotation was supported.
+ public final Result decode(BinaryBitmap image, Hashtable hints) throws ReaderException {
try {
- return doDecode(image, hints, tryHarder);
+ return doDecode(image, hints);
} catch (ReaderException re) {
+ boolean tryHarder = hints != null && hints.containsKey(DecodeHintType.TRY_HARDER);
if (tryHarder && image.isRotateSupported()) {
- MonochromeBitmapSource rotatedImage = image.rotateCounterClockwise();
- Result result = doDecode(rotatedImage, hints, tryHarder);
+ BinaryBitmap rotatedImage = image.rotateCounterClockwise();
+ Result result = doDecode(rotatedImage, hints);
// Record that we found it rotated 90 degrees CCW / 270 degrees CW
Hashtable metadata = result.getResultMetadata();
int orientation = 270;
if (metadata != null && metadata.containsKey(ResultMetadataType.ORIENTATION)) {
// But if we found it reversed in doDecode(), add in that result here:
- orientation = (orientation + ((Integer) metadata.get(ResultMetadataType.ORIENTATION)).intValue()) % 360;
+ orientation = (orientation +
+ ((Integer) metadata.get(ResultMetadataType.ORIENTATION)).intValue()) % 360;
}
result.putMetadata(ResultMetadataType.ORIENTATION, new Integer(orientation));
return result;
}
}
- private Result doDecode(MonochromeBitmapSource image, Hashtable hints, boolean tryHarder) throws ReaderException {
-
+ /**
+ * We're going to examine rows from the middle outward, searching alternately above and below the
+ * middle, and farther out each time. rowStep is the number of rows between each successive
+ * attempt above and below the middle. So we'd scan row middle, then middle - rowStep, then
+ * middle + rowStep, then middle - (2 * rowStep), etc.
+ * rowStep is bigger as the image is taller, but is always at least 1. We've somewhat arbitrarily
+ * decided that moving up and down by about 1/16 of the image is pretty good; we try more of the
+ * image if "trying harder".
+ *
+ * @param image The image to decode
+ * @param hints Any hints that were requested
+ * @return The contents of the decoded barcode
+ * @throws ReaderException Any spontaneous errors which occur
+ */
+ private Result doDecode(BinaryBitmap image, Hashtable hints) throws ReaderException {
int width = image.getWidth();
int height = image.getHeight();
-
BitArray row = new BitArray(width);
- // We're going to examine rows from the middle outward, searching alternately above and below the middle,
- // and farther out each time. rowStep is the number of rows between each successive attempt above and below
- // the middle. So we'd scan row middle, then middle - rowStep, then middle + rowStep,
- // then middle - 2*rowStep, etc.
- // rowStep is bigger as the image is taller, but is always at least 1. We've somewhat arbitrarily decided
- // that moving up and down by about 1/16 of the image is pretty good; we try more of the image if
- // "trying harder"
int middle = height >> 1;
+ boolean tryHarder = hints != null && hints.containsKey(DecodeHintType.TRY_HARDER);
int rowStep = Math.max(1, height >> (tryHarder ? 7 : 4));
int maxLines;
if (tryHarder) {
- maxLines = height; // Look at the whole image; looking for more than one barcode
+ maxLines = height; // Look at the whole image, not just the center
} else {
- maxLines = 7;
+ maxLines = 9; // Nine rows spaced 1/16 apart is roughly the middle half of the image
}
for (int x = 0; x < maxLines; x++) {
// Estimate black point for this row and load it:
try {
- image.estimateBlackPoint(BlackPointEstimationMethod.ROW_SAMPLING, rowNumber);
+ row = image.getBlackRow(rowNumber, row);
} catch (ReaderException re) {
continue;
}
- image.getBlackRow(rowNumber, row, 0, width);
// While we have the image data in a BitArray, it's fairly cheap to reverse it in place to
// handle decoding upside down barcodes.
for (int attempt = 0; attempt < 2; attempt++) {
if (attempt == 1) { // trying again?
row.reverse(); // reverse the row and continue
+ // This means we will only ever draw result points *once* in the life of this method
+ // since we want to avoid drawing the wrong points after flipping the row, and,
+ // don't want to clutter with noise from every single row scan -- just the scans
+ // that start on the center line.
+ if (hints != null && hints.containsKey(DecodeHintType.NEED_RESULT_POINT_CALLBACK)) {
+ hints = (Hashtable) hints.clone();
+ hints.remove(DecodeHintType.NEED_RESULT_POINT_CALLBACK);
+ }
}
try {
// Look for a barcode
if (attempt == 1) {
// But it was upside down, so note that
result.putMetadata(ResultMetadataType.ORIENTATION, new Integer(180));
+ // And remember to flip the result points horizontally.
+ ResultPoint[] points = result.getResultPoints();
+ points[0] = new ResultPoint(width - points[0].getX() - 1, points[0].getY());
+ points[1] = new ResultPoint(width - points[1].getX() - 1, points[1].getY());
}
return result;
} catch (ReaderException re) {
}
}
- throw new ReaderException("No barcode found");
+ throw ReaderException.getInstance();
}
/**
* @param row row to count from
* @param start offset into row to start at
* @param counters array into which to record counts
- * @throws ReaderException if counters cannot be filled entirely from row before running out of pixels
+ * @throws ReaderException if counters cannot be filled entirely from row before running out
+ * of pixels
*/
static void recordPattern(BitArray row, int start, int[] counters) throws ReaderException {
int numCounters = counters.length;
}
int end = row.getSize();
if (start >= end) {
- throw new ReaderException("Couldn't fully read a pattern");
+ throw ReaderException.getInstance();
}
boolean isWhite = !row.get(start);
int counterPosition = 0;
int i = start;
while (i < end) {
boolean pixel = row.get(i);
- if ((!pixel && isWhite) || (pixel && !isWhite)) {
+ if (pixel ^ isWhite) { // that is, exactly one is true
counters[counterPosition]++;
} else {
counterPosition++;
// If we read fully the last section of pixels and filled up our counters -- or filled
// the last counter but ran off the side of the image, OK. Otherwise, a problem.
if (!(counterPosition == numCounters || (counterPosition == numCounters - 1 && i == end))) {
- throw new ReaderException("Couldn't fully read a pattern");
+ throw ReaderException.getInstance();
}
}
/**
* Determines how closely a set of observed counts of runs of black/white values matches a given
- * target pattern. This is reported as the ratio of the total variance from the expected pattern proportions
- * across all pattern elements, to the length of the pattern.
+ * target pattern. This is reported as the ratio of the total variance from the expected pattern
+ * proportions across all pattern elements, to the length of the pattern.
*
* @param counters observed counters
* @param pattern expected pattern
+ * @param maxIndividualVariance The most any counter can differ before we give up
* @return ratio of total variance between counters and pattern compared to total pattern size,
* where the ratio has been multiplied by 256. So, 0 means no variance (perfect match); 256 means
* the total variance between counters and patterns equals the pattern length, higher values mean
* even more variance
*/
- static int patternMatchVariance(int[] counters, int[] pattern) {
+ static int patternMatchVariance(int[] counters, int[] pattern, int maxIndividualVariance) {
int numCounters = counters.length;
int total = 0;
int patternLength = 0;
// We're going to fake floating-point math in integers. We just need to use more bits.
// Scale up patternLength so that intermediate values below like scaledCounter will have
// more "significant digits"
- patternLength <<= INTEGER_MATH_SHIFT;
- int patternRatio = patternLength / total;
+ int unitBarWidth = (total << INTEGER_MATH_SHIFT) / patternLength;
+ maxIndividualVariance = (maxIndividualVariance * unitBarWidth) >> INTEGER_MATH_SHIFT;
int totalVariance = 0;
for (int x = 0; x < numCounters; x++) {
- int scaledCounter = counters[x] * patternRatio;
- int width = pattern[x] << INTEGER_MATH_SHIFT;
- totalVariance += scaledCounter > width ? scaledCounter - width : width - scaledCounter;
+ int counter = counters[x] << INTEGER_MATH_SHIFT;
+ int scaledPattern = pattern[x] * unitBarWidth;
+ int variance = counter > scaledPattern ? counter - scaledPattern : scaledPattern - counter;
+ if (variance > maxIndividualVariance) {
+ return Integer.MAX_VALUE;
+ }
+ totalVariance += variance;
}
- return (totalVariance << 8) / patternLength;
+ return totalVariance / total;
}
// This declaration should not be necessary, since this class is
// method of an interface it implements, but it is causing NoSuchMethodError
// issues on some Nokia JVMs. So we add this superfluous declaration:
- public abstract Result decodeRow(int rowNumber, BitArray row, Hashtable hints) throws ReaderException;
+ public abstract Result decodeRow(int rowNumber, BitArray row, Hashtable hints)
+ throws ReaderException;
}
projects / zxing.git / blobdiff