X-Git-Url: http://git.rot13.org/?a=blobdiff_plain;f=core%2Fsrc%2Fcom%2Fgoogle%2Fzxing%2Foned%2FAbstractOneDReader.java;h=508e05c2cb82c85cc1494efdc206b607844e454e;hb=26b7d057252b6fb33e16958e7f90036501db10aa;hp=66eee2b03c2f40fa18e8ae3f879181e7fe40427f;hpb=adfeb7f7bbcea109c07075807f42b98a94e29efe;p=zxing.git diff --git a/core/src/com/google/zxing/oned/AbstractOneDReader.java b/core/src/com/google/zxing/oned/AbstractOneDReader.java index 66eee2b0..508e05c2 100644 --- a/core/src/com/google/zxing/oned/AbstractOneDReader.java +++ b/core/src/com/google/zxing/oned/AbstractOneDReader.java @@ -1,5 +1,5 @@ /* - * 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. @@ -22,6 +22,7 @@ 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; @@ -31,22 +32,25 @@ import java.util.Hashtable; * of one-dimensional barcodes.

* * @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 { return decode(image, null); } public final Result decode(MonochromeBitmapSource image, Hashtable hints) throws ReaderException { - boolean tryHarder = hints != null && hints.containsKey(DecodeHintType.TRY_HARDER); 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); + Result result = doDecode(rotatedImage, hints); // Record that we found it rotated 90 degrees CCW / 270 degrees CW Hashtable metadata = result.getResultMetadata(); int orientation = 270; @@ -62,40 +66,35 @@ public abstract class AbstractOneDReader implements OneDReader { } } - 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(MonochromeBitmapSource image, Hashtable hints) throws ReaderException { int width = image.getWidth(); int height = image.getHeight(); - BitArray row = new BitArray(width); - //int barcodesToSkip = 0; - //if (hints != null) { - // Integer number = (Integer) hints.get(DecodeHintType.SKIP_N_BARCODES); - // if (number != null) { - // barcodesToSkip = number.intValue(); - // } - //} - - // 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 || barcodesToSkip > 0) { 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 } - //Result lastResult = null; - for (int x = 0; x < maxLines; x++) { // Scanning from the middle out. Determine which row we're looking at next: @@ -113,51 +112,48 @@ public abstract class AbstractOneDReader implements OneDReader { } catch (ReaderException re) { continue; } - image.getBlackRow(rowNumber, row, 0, width); + row = image.getBlackRow(rowNumber, row, 0, width); - // We may try twice for each row, if "trying harder": + // 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? - if (tryHarder) { // only if "trying harder" - row.reverse(); // reverse the row and continue - } else { - break; - } + row.reverse(); // reverse the row and continue } - try { - // Look for a barcode Result result = decodeRow(rowNumber, row, hints); - - //if (lastResult != null && lastResult.getText().equals(result.getText())) { - // Just saw the last barcode again, proceed - //continue; - //} - - //if (barcodesToSkip > 0) { // See if we should skip and keep looking - // barcodesToSkip--; - // lastResult = result; // Remember what we just saw - //} else { - // We found our barcode - if (attempt == 1) { - // But it was upside down, so note that - result.putMetadata(ResultMetadataType.ORIENTATION, new Integer(180)); - } - return result; - //} - + // We found our 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) { // continue -- just couldn't decode this row } - } } - throw new ReaderException("No barcode found"); + throw ReaderException.getInstance(); } + /** + * Records the size of successive runs of white and black pixels in a row, starting at a given point. + * The values are recorded in the given array, and the number of runs recorded is equal to the size + * of the array. If the row starts on a white pixel at the given start point, then the first count + * recorded is the run of white pixels starting from that point; likewise it is the count of a run + * of black pixels if the row begin on a black pixels at that point. + * + * @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 + */ static void recordPattern(BitArray row, int start, int[] counters) throws ReaderException { int numCounters = counters.length; for (int i = 0; i < numCounters; i++) { @@ -165,14 +161,14 @@ public abstract class AbstractOneDReader implements OneDReader { } 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++; @@ -180,7 +176,7 @@ public abstract class AbstractOneDReader implements OneDReader { break; } else { counters[counterPosition] = 1; - isWhite = !isWhite; + isWhite ^= true; // isWhite = !isWhite; Is this too clever? shorter byte code, no conditional } } i++; @@ -188,37 +184,60 @@ public abstract class AbstractOneDReader implements OneDReader { // 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 - * @return average variance between counters and 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 float patternMatchVariance(int[] counters, int[] pattern) { - int total = 0; + static int patternMatchVariance(int[] counters, int[] pattern, int maxIndividualVariance) { int numCounters = counters.length; + int total = 0; int patternLength = 0; for (int i = 0; i < numCounters; i++) { total += counters[i]; patternLength += pattern[i]; } - float unitBarWidth = (float) total / (float) patternLength; + if (total < patternLength) { + // If we don't even have one pixel per unit of bar width, assume this is too small + // to reliably match, so fail: + return Integer.MAX_VALUE; + } + // 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" + int unitBarWidth = (total << INTEGER_MATH_SHIFT) / patternLength; + maxIndividualVariance = (maxIndividualVariance * unitBarWidth) >> INTEGER_MATH_SHIFT; - float totalVariance = 0.0f; + int totalVariance = 0; for (int x = 0; x < numCounters; x++) { - float scaledCounter = (float) counters[x] / unitBarWidth; - float width = pattern[x]; - float abs = scaledCounter > width ? scaledCounter - width : width - scaledCounter; - totalVariance += abs; + 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 / (float) patternLength; + return totalVariance / total; } + // This declaration should not be necessary, since this class is + // abstract and so does not have to provide an implementation for every + // 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; + }