com.google.zxing.oned

Class UPCEANReader

java.lang.Object

com.google.zxing.oned.OneDReader

com.google.zxing.oned.UPCEANReader

All Implemented Interfaces:

Reader

Direct Known Subclasses:

EAN13Reader, EAN8Reader, UPCAReader, UPCEReader

public abstract class UPCEANReader
extends OneDReader

Encapsulates functionality and implementation that is common to UPC and EAN families of one-dimensional barcodes.

Author:

dswitkin@google.com (Daniel Switkin), Sean Owen, alasdair@google.com (Alasdair Mackintosh)

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	UPCEANReader()

Method Summary

Modifier and Type	Method and Description
protected abstract int	decodeMiddle(BitArray row, int[] startRange, StringBuilder resultString) Subclasses override this to decode the portion of a barcode between the start and end guard patterns.
Result	decodeRow(int rowNumber, BitArray row, int[] startGuardRange, Map<DecodeHintType,?> hints) Like decodeRow(int, BitArray, Map), but allows caller to inform method about where the UPC/EAN start pattern is found.
Result	decodeRow(int rowNumber, BitArray row, Map<DecodeHintType,?> hints) Attempts to decode a one-dimensional barcode format given a single row of an image.

Methods inherited from class com.google.zxing.oned.OneDReader

decode, decode, patternMatchVariance, recordPattern, recordPatternInReverse, reset

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

UPCEANReader

protected UPCEANReader()

Method Detail

decodeRow

public Result decodeRow(int rowNumber,
                        BitArray row,
                        Map<DecodeHintType,?> hints)
                 throws NotFoundException,
                        ChecksumException,
                        FormatException

Description copied from class: OneDReader

Attempts to decode a one-dimensional barcode format given a single row of an image.

Specified by:

decodeRow in class OneDReader

Parameters:

rowNumber - row number from top of the row

row - the black/white pixel data of the row

hints - decode hints

Returns:

Result containing encoded string and start/end of barcode

Throws:

NotFoundException - if no potential barcode is found

ChecksumException - if a potential barcode is found but does not pass its checksum

FormatException - if a potential barcode is found but format is invalid

decodeRow

public Result decodeRow(int rowNumber,
                        BitArray row,
                        int[] startGuardRange,
                        Map<DecodeHintType,?> hints)
                 throws NotFoundException,
                        ChecksumException,
                        FormatException

Like decodeRow(int, BitArray, Map), but allows caller to inform method about where the UPC/EAN start pattern is found. This allows this to be computed once and reused across many implementations.

Parameters:

rowNumber - row index into the image

row - encoding of the row of the barcode image

startGuardRange - start/end column where the opening start pattern was found

hints - optional hints that influence decoding

Returns:

Result encapsulating the result of decoding a barcode in the row

Throws:

NotFoundException - if no potential barcode is found

ChecksumException - if a potential barcode is found but does not pass its checksum

FormatException - if a potential barcode is found but format is invalid

decodeMiddle

protected abstract int decodeMiddle(BitArray row,
                                    int[] startRange,
                                    StringBuilder resultString)
                             throws NotFoundException

Subclasses override this to decode the portion of a barcode between the start and end guard patterns.

Parameters:

row - row of black/white values to search

startRange - start/end offset of start guard pattern

resultString - StringBuilder to append decoded chars to

Returns:

horizontal offset of first pixel after the "middle" that was decoded

Throws:

NotFoundException - if decoding could not complete successfully