/*
* 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 ntu.com.google.zxing.qrcode;
import java.util.Hashtable;
import ntu.com.google.zxing.BarcodeFormat;
import ntu.com.google.zxing.BinaryBitmap;
import ntu.com.google.zxing.ChecksumException;
import ntu.com.google.zxing.DecodeHintType;
import ntu.com.google.zxing.FormatException;
import ntu.com.google.zxing.NotFoundException;
import ntu.com.google.zxing.Reader;
import ntu.com.google.zxing.Result;
import ntu.com.google.zxing.ResultMetadataType;
import ntu.com.google.zxing.ResultPoint;
import ntu.com.google.zxing.common.BitMatrix;
import ntu.com.google.zxing.common.DecoderResult;
import ntu.com.google.zxing.common.DetectorResult;
import ntu.com.google.zxing.qrcode.decoder.Decoder;
import ntu.com.google.zxing.qrcode.detector.Detector;
/**
* 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 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
*/
public Result decode(BinaryBitmap image) throws NotFoundException, ChecksumException, FormatException {
return decode(image, null);
}
public Result decode(BinaryBitmap image, Hashtable 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();
}
Result result = new Result(decoderResult.getText(), decoderResult.getRawBytes(), points, BarcodeFormat.QR_CODE);
if (decoderResult.getByteSegments() != null) {
result.putMetadata(ResultMetadataType.BYTE_SEGMENTS, decoderResult.getByteSegments());
}
if (decoderResult.getECLevel() != null) {
result.putMetadata(ResultMetadataType.ERROR_CORRECTION_LEVEL, decoderResult.getECLevel().toString());
}
return result;
}
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 ntu.com.google.zxing.pdf417.PDF417Reader#extractPureBits(BitMatrix)
* @see ntu.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();
}
int moduleSize = moduleSize(leftTopBlack, image);
int top = leftTopBlack[1];
int bottom = rightBottomBlack[1];
int left = leftTopBlack[0];
int right = rightBottomBlack[0];
int matrixWidth = (right - left + 1) / moduleSize;
int matrixHeight = (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 = moduleSize >> 1;
top += nudge;
left += nudge;
// Now just read off the bits
BitMatrix bits = new BitMatrix(matrixWidth, matrixHeight);
for (int y = 0; y < matrixHeight; y++) {
int iOffset = top + y * moduleSize;
for (int x = 0; x < matrixWidth; x++) {
if (image.get(left + x * moduleSize, iOffset)) {
bits.set(x, y);
}
}
}
return bits;
}
private static int moduleSize(int[] leftTopBlack, BitMatrix image) throws NotFoundException {
int height = image.getHeight();
int width = image.getWidth();
int x = leftTopBlack[0];
int y = leftTopBlack[1];
while (x < width && y < height && image.get(x, y)) {
x++;
y++;
}
if (x == width || y == height) {
throw NotFoundException.getNotFoundInstance();
}
int moduleSize = x - leftTopBlack[0];
if (moduleSize == 0) {
throw NotFoundException.getNotFoundInstance();
}
return moduleSize;
}
}