/*
* Copyright 2009 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.pdf417;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.BinaryBitmap;
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.ResultPoint;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.DecoderResult;
import com.google.zxing.common.DetectorResult;
import com.google.zxing.pdf417.decoder.Decoder;
import com.google.zxing.pdf417.detector.Detector;
import java.util.Hashtable;
/**
* This implementation can detect and decode PDF417 codes in an image.
*
* @author SITA Lab (kevin.osullivan@sita.aero)
*/
public final class PDF417Reader implements Reader {
private static final ResultPoint[] NO_POINTS = new ResultPoint[0];
private final Decoder decoder = new Decoder();
/**
* Locates and decodes a PDF417 code in an image.
*
* @return a String representing the content encoded by the PDF417 code
* @throws NotFoundException if a PDF417 code cannot be found,
* @throws FormatException if a PDF417 cannot be decoded
*/
public Result decode(BinaryBitmap image) throws NotFoundException, FormatException {
return decode(image, null);
}
public Result decode(BinaryBitmap image, Hashtable hints) throws NotFoundException, FormatException {
DecoderResult decoderResult;
ResultPoint[] points;
if (hints != null && hints.containsKey(DecodeHintType.PURE_BARCODE)) {
BitMatrix bits = extractPureBits(image.getBlackMatrix());
decoderResult = decoder.decode(bits);
points = NO_POINTS;
} else {
DetectorResult detectorResult = new Detector(image).detect();
decoderResult = decoder.decode(detectorResult.getBits());
points = detectorResult.getPoints();
}
return new Result(decoderResult.getText(), decoderResult.getRawBytes(), points,
BarcodeFormat.PDF417);
}
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.qrcode.QRCodeReader#extractPureBits(BitMatrix)
* @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();
}
int moduleSize = moduleSize(leftTopBlack, image);
int top = leftTopBlack[1];
int bottom = rightBottomBlack[1];
int left = findPatternStart(leftTopBlack[0], top, image);
int right = findPatternEnd(leftTopBlack[0], top, image);
int matrixWidth = (right - left + 1) / moduleSize;
int matrixHeight = (bottom - top + 1) / moduleSize;
if (matrixWidth == 0 || matrixHeight == 0) {
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 x = leftTopBlack[0];
int y = leftTopBlack[1];
int width = image.getWidth();
while (x < width && image.get(x, y)) {
x++;
}
if (x == width) {
throw NotFoundException.getNotFoundInstance();
}
int moduleSize = (x - leftTopBlack[0]) >>> 3; // We've crossed left first bar, which is 8x
if (moduleSize == 0) {
throw NotFoundException.getNotFoundInstance();
}
return moduleSize;
}
private static int findPatternStart(int x, int y, BitMatrix image) throws NotFoundException {
int width = image.getWidth();
int start = x;
// start should be on black
int transitions = 0;
boolean black = true;
while (start < width - 1 && transitions < 8) {
start++;
boolean newBlack = image.get(start, y);
if (black != newBlack) {
transitions++;
}
black = newBlack;
}
if (start == width - 1) {
throw NotFoundException.getNotFoundInstance();
}
return start;
}
private static int findPatternEnd(int x, int y, BitMatrix image) throws NotFoundException {
int width = image.getWidth();
int end = width - 1;
// end should be on black
while (end > x && !image.get(end, y)) {
end--;
}
int transitions = 0;
boolean black = true;
while (end > x && transitions < 9) {
end--;
boolean newBlack = image.get(end, y);
if (black != newBlack) {
transitions++;
}
black = newBlack;
}
if (end == x) {
throw NotFoundException.getNotFoundInstance();
}
return end;
}
}