2 * Copyright 2007 ZXing authors
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 package com.google.zxing.datamatrix;
19 import com.google.zxing.BarcodeFormat;
20 import com.google.zxing.DecodeHintType;
21 import com.google.zxing.BinaryBitmap;
22 import com.google.zxing.Reader;
23 import com.google.zxing.ReaderException;
24 import com.google.zxing.Result;
25 import com.google.zxing.ResultPoint;
26 import com.google.zxing.ResultMetadataType;
27 import com.google.zxing.common.BitMatrix;
28 import com.google.zxing.common.DecoderResult;
29 import com.google.zxing.common.DetectorResult;
30 import com.google.zxing.datamatrix.decoder.Decoder;
31 import com.google.zxing.datamatrix.detector.Detector;
33 import java.util.Hashtable;
36 * This implementation can detect and decode Data Matrix codes in an image.
38 * @author bbrown@google.com (Brian Brown)
40 public final class DataMatrixReader implements Reader {
42 private static final ResultPoint[] NO_POINTS = new ResultPoint[0];
44 private final Decoder decoder = new Decoder();
47 * Locates and decodes a Data Matrix code in an image.
49 * @return a String representing the content encoded by the Data Matrix code
50 * @throws ReaderException if a Data Matrix code cannot be found, or cannot be decoded
52 public Result decode(BinaryBitmap image) throws ReaderException {
53 return decode(image, null);
56 public Result decode(BinaryBitmap image, Hashtable hints)
57 throws ReaderException {
58 DecoderResult decoderResult;
60 if (hints != null && hints.containsKey(DecodeHintType.PURE_BARCODE)) {
61 BitMatrix bits = extractPureBits(image.getBlackMatrix());
62 decoderResult = decoder.decode(bits);
65 DetectorResult detectorResult = new Detector(image.getBlackMatrix()).detect();
66 decoderResult = decoder.decode(detectorResult.getBits());
67 points = detectorResult.getPoints();
69 Result result = new Result(decoderResult.getText(), decoderResult.getRawBytes(), points, BarcodeFormat.DATAMATRIX);
70 if (decoderResult.getByteSegments() != null) {
71 result.putMetadata(ResultMetadataType.BYTE_SEGMENTS, decoderResult.getByteSegments());
73 if (decoderResult.getECLevel() != null) {
74 result.putMetadata(ResultMetadataType.ERROR_CORRECTION_LEVEL, decoderResult.getECLevel().toString());
80 * This method detects a Data Matrix code in a "pure" image -- that is, pure monochrome image
81 * which contains only an unrotated, unskewed, image of a Data Matrix code, with some white border
82 * around it. This is a specialized method that works exceptionally fast in this special
85 private static BitMatrix extractPureBits(BitMatrix image) throws ReaderException {
86 // Now need to determine module size in pixels
88 int height = image.getHeight();
89 int width = image.getWidth();
90 int minDimension = Math.min(height, width);
92 // First, skip white border by tracking diagonally from the top left down and to the right:
94 while (borderWidth < minDimension && !image.get(borderWidth, borderWidth)) {
97 if (borderWidth == minDimension) {
98 throw ReaderException.getInstance();
101 // And then keep tracking across the top-left black module to determine module size
102 int moduleEnd = borderWidth + 1;
103 while (moduleEnd < width && image.get(moduleEnd, borderWidth)) {
106 if (moduleEnd == width) {
107 throw ReaderException.getInstance();
110 int moduleSize = moduleEnd - borderWidth;
112 // And now find where the bottommost black module on the first column ends
113 int columnEndOfSymbol = height - 1;
114 while (columnEndOfSymbol >= 0 && !image.get(borderWidth, columnEndOfSymbol)) {
117 if (columnEndOfSymbol < 0) {
118 throw ReaderException.getInstance();
122 // Make sure width of barcode is a multiple of module size
123 if ((columnEndOfSymbol - borderWidth) % moduleSize != 0) {
124 throw ReaderException.getInstance();
126 int dimension = (columnEndOfSymbol - borderWidth) / moduleSize;
128 // Push in the "border" by half the module width so that we start
129 // sampling in the middle of the module. Just in case the image is a
130 // little off, this will help recover.
131 borderWidth += moduleSize >> 1;
133 int sampleDimension = borderWidth + (dimension - 1) * moduleSize;
134 if (sampleDimension >= width || sampleDimension >= height) {
135 throw ReaderException.getInstance();
138 // Now just read off the bits
139 BitMatrix bits = new BitMatrix(dimension);
140 for (int i = 0; i < dimension; i++) {
141 int iOffset = borderWidth + i * moduleSize;
142 for (int j = 0; j < dimension; j++) {
143 if (image.get(borderWidth + j * moduleSize, iOffset)) {