Table of Contents

Class FinderPatternFinder

Namespace
ZXing.QrCode.Internal
Assembly
zxing.dll

This class attempts to find finder patterns in a QR Code. Finder patterns are the square markers at three corners of a QR Code.

This class is thread-safe but not reentrant. Each thread must allocate its own object.

public class FinderPatternFinder
Inheritance
FinderPatternFinder
Derived
Inherited Members

Constructors

FinderPatternFinder(BitMatrix)

Creates a finder that will search the image for three finder patterns.

public FinderPatternFinder(BitMatrix image)

Parameters

image BitMatrix

image to search

FinderPatternFinder(BitMatrix, ResultPointCallback)

Initializes a new instance of the FinderPatternFinder class.

public FinderPatternFinder(BitMatrix image, ResultPointCallback resultPointCallback)

Parameters

image BitMatrix

The image.

resultPointCallback ResultPointCallback

The result point callback.

Fields

MAX_MODULES

support up to version 20 for mobile clients

protected const int MAX_MODULES = 97

Field Value

int

MIN_SKIP

1 pixel/module times 3 modules/center

protected const int MIN_SKIP = 3

Field Value

int

Properties

Image

Gets the image.

protected virtual BitMatrix Image { get; }

Property Value

BitMatrix

PossibleCenters

Gets the possible centers.

protected virtual List<FinderPattern> PossibleCenters { get; }

Property Value

List<FinderPattern>

Methods

clearCounts(int[])

sets everything to 0

[Obsolete]
protected void clearCounts(int[] counts)

Parameters

counts int[]

doClearCounts(int[])

sets everything to 0

protected static void doClearCounts(int[] counts)

Parameters

counts int[]

doShiftCounts2(int[])

shifts left by 2 index

protected static void doShiftCounts2(int[] stateCount)

Parameters

stateCount int[]

foundPatternCross(int[]) 

protected static bool foundPatternCross(int[] stateCount)

Parameters

stateCount int[]

count of black/white/black/white/black pixels just read

Returns

bool

true iff the proportions of the counts is close enough to the 1/1/3/1/1 ratios used by finder patterns to be considered a match

foundPatternDiagonal(int[]) 

protected static bool foundPatternDiagonal(int[] stateCount)

Parameters

stateCount int[]

count of black/white/black/white/black pixels just read

Returns

bool

true if the proportions of the counts is close enough to the 1/1/3/1/1 ratios by finder patterns to be considered a match

handlePossibleCenter(int[], int, int)

This is called when a horizontal scan finds a possible alignment pattern. It will cross check with a vertical scan, and if successful, will, ah, cross-cross-check with another horizontal scan. This is needed primarily to locate the real horizontal center of the pattern in cases of extreme skew. And then we cross-cross-cross check with another diagonal scan.

If that succeeds the finder pattern location is added to a list that tracks the number of times each location has been nearly-matched as a finder pattern. Each additional find is more evidence that the location is in fact a finder pattern center 
protected bool handlePossibleCenter(int[] stateCount, int i, int j)

Parameters

stateCount int[]

reading state module counts from horizontal scan

i int

row where finder pattern may be found

j int

end of possible finder pattern in row

Returns

bool

true if a finder pattern candidate was found this time

handlePossibleCenter(int[], int, int, bool)

@see #handlePossibleCenter(int[], int, int)

[Obsolete("only exists for backwards compatibility")]
protected bool handlePossibleCenter(int[] stateCount, int i, int j, bool pureBarcode)

Parameters

stateCount int[]

reading state module counts from horizontal scan

i int

row where finder pattern may be found

j int

end of possible finder pattern in row

pureBarcode bool

ignored

Returns

bool

true if a finder pattern candidate was found this time

shiftCounts2(int[])

shifts left by 2 index

[Obsolete]
protected void shiftCounts2(int[] stateCount)

Parameters

stateCount int[]