Table of Contents

Class OneDReader

Namespace
ZXing.OneD
Assembly
zxing.dll

Encapsulates functionality and implementation that is common to all families of one-dimensional barcodes. dswitkin@google.com (Daniel Switkin) Sean Owen

public abstract class OneDReader : Reader
Inheritance
OneDReader
Implements
Derived
Inherited Members

Constructors

OneDReader() 

protected OneDReader()

Fields

INTEGER_MATH_SHIFT 

protected static int INTEGER_MATH_SHIFT

Field Value

int

PATTERN_MATCH_RESULT_SCALE_FACTOR 

protected static int PATTERN_MATCH_RESULT_SCALE_FACTOR

Field Value

int

Methods

decode(BinaryBitmap)

Locates and decodes a barcode in some format within an image.

public Result decode(BinaryBitmap image)

Parameters

image BinaryBitmap

image of barcode to decode

Returns

Result

String which the barcode encodes

decode(BinaryBitmap, IDictionary<DecodeHintType, object>)

Locates and decodes a barcode in some format within an image. This method also accepts hints, each possibly associated to some data, which may help the implementation decode. Note that we don't try rotation without the try harder flag, even if rotation was supported.

public virtual Result decode(BinaryBitmap image, IDictionary<DecodeHintType, object> hints)

Parameters

image BinaryBitmap

image of barcode to decode

hints IDictionary<DecodeHintType, object>

passed as a IDictionary<TKey, TValue> from DecodeHintType to arbitrary data. The meaning of the data depends upon the hint type. The implementation may or may not do anything with these hints.

Returns

Result

String which the barcode encodes

decodeRow(int, BitArray, IDictionary<DecodeHintType, object>)

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

public abstract Result decodeRow(int rowNumber, BitArray row, IDictionary<DecodeHintType, object> hints)

Parameters

rowNumber int

row number from top of the row

row BitArray

the black/white pixel data of the row

hints IDictionary<DecodeHintType, object>

decode hints

Returns

Result

Resultcontaining encoded string and start/end of barcode

doDecode(BinaryBitmap, IDictionary<DecodeHintType, object>)

We're going to examine rows from the middle outward, searching alternately above and below the middle, and farther out each time. rowStep is the number of rows between each successive attempt above and below the middle. So we'd scan row middle, then middle - rowStep, then middle + rowStep, then middle - (2 * rowStep), etc. rowStep is bigger as the image is taller, but is always at least 1. We've somewhat arbitrarily decided that moving up and down by about 1/16 of the image is pretty good; we try more of the image if "trying harder".

protected virtual Result doDecode(BinaryBitmap image, IDictionary<DecodeHintType, object> hints)

Parameters

image BinaryBitmap

The image to decode

hints IDictionary<DecodeHintType, object>

Any hints that were requested

Returns

Result

The contents of the decoded barcode

patternMatchVariance(int[], int[], int)

Determines how closely a set of observed counts of runs of black/white values matches a given target pattern. This is reported as the ratio of the total variance from the expected pattern proportions across all pattern elements, to the length of the pattern.

protected static int patternMatchVariance(int[] counters, int[] pattern, int maxIndividualVariance)

Parameters

counters int[]

observed counters

pattern int[]

expected pattern

maxIndividualVariance int

The most any counter can differ before we give up

Returns

int

ratio of total variance between counters and pattern compared to total pattern size, where the ratio has been multiplied by 256. So, 0 means no variance (perfect match); 256 means the total variance between counters and patterns equals the pattern length, higher values mean even more variance

recordPattern(BitArray, int, int[])

Records the size of successive runs of white and black pixels in a row, starting at a given point. The values are recorded in the given array, and the number of runs recorded is equal to the size of the array. If the row starts on a white pixel at the given start point, then the first count recorded is the run of white pixels starting from that point; likewise it is the count of a run of black pixels if the row begin on a black pixels at that point.

protected static bool recordPattern(BitArray row, int start, int[] counters)

Parameters

row BitArray

row to count from

start int

offset into row to start at

counters int[]

array into which to record counts

Returns

bool

recordPattern(BitArray, int, int[], int)

Records the size of successive runs of white and black pixels in a row, starting at a given point. The values are recorded in the given array, and the number of runs recorded is equal to the size of the array. If the row starts on a white pixel at the given start point, then the first count recorded is the run of white pixels starting from that point; likewise it is the count of a run of black pixels if the row begin on a black pixels at that point.

protected static bool recordPattern(BitArray row, int start, int[] counters, int numCounters)

Parameters

row BitArray

row to count from

start int

offset into row to start at

counters int[]

array into which to record counts

numCounters int

Returns

bool

recordPatternInReverse(BitArray, int, int[])

Records the pattern in reverse.

protected static bool recordPatternInReverse(BitArray row, int start, int[] counters)

Parameters

row BitArray

The row.

start int

The start.

counters int[]

The counters.

Returns

bool

reset()

Resets any internal state the implementation has after a decode, to prepare it for reuse.

public virtual void reset()