/*
* Copyright 2007 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.qrcode;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.ChecksumException;
import com.google.zxing.DecodeHintType;
import com.google.zxing.FormatException;
import com.google.zxing.NotFoundException;
import com.google.zxing.Reader;
import com.google.zxing.Result;
import com.google.zxing.ResultMetadataType;
import com.google.zxing.ResultPoint;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.DecoderResult;
import com.google.zxing.common.DetectorResult;
import com.google.zxing.qrcode.decoder.Decoder;
import com.google.zxing.qrcode.decoder.QRCodeDecoderMetaData;
import com.google.zxing.qrcode.detector.Detector;
import java.util.List;
import java.util.Map;
/**
* This implementation can detect and decode QR Codes in an image.
*
* @author Sean Owen
*/
public class QRCodeReader implements Reader {
private static final ResultPoint[] NO_POINTS = new ResultPoint[0];
private final Decoder decoder = new Decoder();
protected final Decoder getDecoder() {
return decoder;
}
/**
* Locates and decodes a QR code in an image.
*
* @return a String representing the content encoded by the QR code
* @throws NotFoundException
* if a QR code cannot be found
* @throws FormatException
* if a QR code cannot be decoded
* @throws ChecksumException
* if error correction fails
*/
@Override
public Result decode(BinaryBitmap image) throws NotFoundException,
ChecksumException, FormatException {
return decode(image, null);
}
@Override
public final Result decode(BinaryBitmap image, Map<DecodeHintType, ?> hints)
throws NotFoundException, ChecksumException, FormatException {
DecoderResult decoderResult;
ResultPoint[] points;
if (hints != null && hints.containsKey(DecodeHintType.PURE_BARCODE)) {
BitMatrix bits = extractPureBits(image.getBlackMatrix());
decoderResult = decoder.decode(bits, hints);
points = NO_POINTS;
} else {
DetectorResult detectorResult = new Detector(image.getBlackMatrix())
.detect(hints);
decoderResult = decoder.decode(detectorResult.getBits(), hints);
points = detectorResult.getPoints();
}
// If the code was mirrored: swap the bottom-left and the top-right
// points.
if (decoderResult.getOther() instanceof QRCodeDecoderMetaData) {
((QRCodeDecoderMetaData) decoderResult.getOther())
.applyMirroredCorrection(points);
}
Result result = new Result(decoderResult.getText(),
decoderResult.getRawBytes(), points, BarcodeFormat.QR_CODE);
List<byte[]> byteSegments = decoderResult.getByteSegments();
if (byteSegments != null) {
result.putMetadata(ResultMetadataType.BYTE_SEGMENTS, byteSegments);
}
String ecLevel = decoderResult.getECLevel();
if (ecLevel != null) {
result.putMetadata(ResultMetadataType.ERROR_CORRECTION_LEVEL,
ecLevel);
}
if (decoderResult.hasStructuredAppend()) {
result.putMetadata(ResultMetadataType.STRUCTURED_APPEND_SEQUENCE,
decoderResult.getStructuredAppendSequenceNumber());
result.putMetadata(ResultMetadataType.STRUCTURED_APPEND_PARITY,
decoderResult.getStructuredAppendParity());
}
return result;
}
@Override
public void reset() {
// do nothing
}
/**
* This method detects a code in a "pure" image -- that is, pure monochrome
* image which contains only an unrotated, unskewed, image of a code, with
* some white border around it. This is a specialized method that works
* exceptionally fast in this special case.
*
* @see com.google.zxing.datamatrix.DataMatrixReader#extractPureBits(BitMatrix)
*/
private static BitMatrix extractPureBits(BitMatrix image)
throws NotFoundException {
int[] leftTopBlack = image.getTopLeftOnBit();
int[] rightBottomBlack = image.getBottomRightOnBit();
if (leftTopBlack == null || rightBottomBlack == null) {
throw NotFoundException.getNotFoundInstance();
}
float moduleSize = moduleSize(leftTopBlack, image);
int top = leftTopBlack[1];
int bottom = rightBottomBlack[1];
int left = leftTopBlack[0];
int right = rightBottomBlack[0];
// Sanity check!
if (left >= right || top >= bottom) {
throw NotFoundException.getNotFoundInstance();
}
if (bottom - top != right - left) {
// Special case, where bottom-right module wasn't black so we found
// something else in the last row
// Assume it's a square, so use height as the width
right = left + (bottom - top);
}
int matrixWidth = Math.round((right - left + 1) / moduleSize);
int matrixHeight = Math.round((bottom - top + 1) / moduleSize);
if (matrixWidth <= 0 || matrixHeight <= 0) {
throw NotFoundException.getNotFoundInstance();
}
if (matrixHeight != matrixWidth) {
// Only possibly decode square regions
throw NotFoundException.getNotFoundInstance();
}
// Push in the "border" by half the module width so that we start
// sampling in the middle of the module. Just in case the image is a
// little off, this will help recover.
int nudge = (int) (moduleSize / 2.0f);
top += nudge;
left += nudge;
// But careful that this does not sample off the edge
int nudgedTooFarRight = left + (int) ((matrixWidth - 1) * moduleSize)
- (right - 1);
if (nudgedTooFarRight > 0) {
if (nudgedTooFarRight > nudge) {
// Neither way fits; abort
throw NotFoundException.getNotFoundInstance();
}
left -= nudgedTooFarRight;
}
int nudgedTooFarDown = top + (int) ((matrixHeight - 1) * moduleSize)
- (bottom - 1);
if (nudgedTooFarDown > 0) {
if (nudgedTooFarDown > nudge) {
// Neither way fits; abort
throw NotFoundException.getNotFoundInstance();
}
top -= nudgedTooFarDown;
}
// Now just read off the bits
BitMatrix bits = new BitMatrix(matrixWidth, matrixHeight);
for (int y = 0; y < matrixHeight; y++) {
int iOffset = top + (int) (y * moduleSize);
for (int x = 0; x < matrixWidth; x++) {
if (image.get(left + (int) (x * moduleSize), iOffset)) {
bits.set(x, y);
}
}
}
return bits;
}
private static float moduleSize(int[] leftTopBlack, BitMatrix image)
throws NotFoundException {
int height = image.getHeight();
int width = image.getWidth();
int x = leftTopBlack[0];
int y = leftTopBlack[1];
boolean inBlack = true;
int transitions = 0;
while (x < width && y < height) {
if (inBlack != image.get(x, y)) {
if (++transitions == 5) {
break;
}
inBlack = !inBlack;
}
x++;
y++;
}
if (x == width || y == height) {
throw NotFoundException.getNotFoundInstance();
}
return (x - leftTopBlack[0]) / 7.0f;
}
}