+++ /dev/null
-/*
- * 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.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.google.zxing.oned;
-
-import com.google.zxing.BinaryBitmap;
-import com.google.zxing.DecodeHintType;
-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;
-
-/**
- * <p>Encapsulates functionality and implementation that is common to all families
- * of one-dimensional barcodes.</p>
- *
- * @author dswitkin@google.com (Daniel Switkin)
- * @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(BinaryBitmap image) throws ReaderException {
- return decode(image, null);
- }
-
- // 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);
- } catch (ReaderException re) {
- boolean tryHarder = hints != null && hints.containsKey(DecodeHintType.TRY_HARDER);
- if (tryHarder && image.isRotateSupported()) {
- 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;
- }
- result.putMetadata(ResultMetadataType.ORIENTATION, new Integer(orientation));
- return result;
- } else {
- throw re;
- }
- }
- }
-
- /**
- * 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);
-
- 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, not just the center
- } else {
- maxLines = 9; // Nine rows spaced 1/16 apart is roughly the middle half of the image
- }
-
- for (int x = 0; x < maxLines; x++) {
-
- // Scanning from the middle out. Determine which row we're looking at next:
- int rowStepsAboveOrBelow = (x + 1) >> 1;
- boolean isAbove = (x & 0x01) == 0; // i.e. is x even?
- int rowNumber = middle + rowStep * (isAbove ? rowStepsAboveOrBelow : -rowStepsAboveOrBelow);
- if (rowNumber < 0 || rowNumber >= height) {
- // Oops, if we run off the top or bottom, stop
- break;
- }
-
- // Estimate black point for this row and load it:
- try {
- row = image.getBlackRow(rowNumber, row);
- } catch (ReaderException re) {
- continue;
- }
-
- // 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
- Result result = decodeRow(rowNumber, row, hints);
- // 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 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++) {
- counters[i] = 0;
- }
- int end = row.getSize();
- if (start >= end) {
- 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) { // that is, exactly one is true
- counters[counterPosition]++;
- } else {
- counterPosition++;
- if (counterPosition == numCounters) {
- break;
- } else {
- counters[counterPosition] = 1;
- isWhite = !isWhite;
- }
- }
- i++;
- }
- // 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 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.
- *
- * @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, 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];
- }
- 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;
-
- int totalVariance = 0;
- for (int x = 0; x < numCounters; x++) {
- 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 / 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;
-
-}
projects / zxing.git / blobdiff