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moved java files for pre-convert

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Henry Schimke
2022-08-20 12:00:19 -05:00
parent 4997291cb8
commit 1901c96559
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59
src/qrcode/detector/AlignmentPattern.java Normal file
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/*
* 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 com.google.zxing.qrcode.detector;
import com.google.zxing.ResultPoint;
/**
* <p>Encapsulates an alignment pattern, which are the smaller square patterns found in
* all but the simplest QR Codes.</p>
*
* @author Sean Owen
*/
public final class AlignmentPattern extends ResultPoint {
private final float estimatedModuleSize;
AlignmentPattern(float posX, float posY, float estimatedModuleSize) {
super(posX, posY);
this.estimatedModuleSize = estimatedModuleSize;
}
/**
* <p>Determines if this alignment pattern "about equals" an alignment pattern at the stated
* position and size -- meaning, it is at nearly the same center with nearly the same size.</p>
*/
boolean aboutEquals(float moduleSize, float i, float j) {
if (Math.abs(i - getY()) <= moduleSize && Math.abs(j - getX()) <= moduleSize) {
float moduleSizeDiff = Math.abs(moduleSize - estimatedModuleSize);
return moduleSizeDiff <= 1.0f || moduleSizeDiff <= estimatedModuleSize;
}
return false;
}
/**
* Combines this object's current estimate of a finder pattern position and module size
* with a new estimate. It returns a new {@code FinderPattern} containing an average of the two.
*/
AlignmentPattern combineEstimate(float i, float j, float newModuleSize) {
float combinedX = (getX() + j) / 2.0f;
float combinedY = (getY() + i) / 2.0f;
float combinedModuleSize = (estimatedModuleSize + newModuleSize) / 2.0f;
return new AlignmentPattern(combinedX, combinedY, combinedModuleSize);
}
}

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src/qrcode/detector/AlignmentPatternFinder.java Normal file
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/*
* 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 com.google.zxing.qrcode.detector;
import com.google.zxing.NotFoundException;
import com.google.zxing.ResultPointCallback;
import com.google.zxing.common.BitMatrix;
import java.util.ArrayList;
import java.util.List;
/**
* <p>This class attempts to find alignment patterns in a QR Code. Alignment patterns look like finder
* patterns but are smaller and appear at regular intervals throughout the image.</p>
*
* <p>At the moment this only looks for the bottom-right alignment pattern.</p>
*
* <p>This is mostly a simplified copy of {@link FinderPatternFinder}. It is copied,
* pasted and stripped down here for maximum performance but does unfortunately duplicate
* some code.</p>
*
* <p>This class is thread-safe but not reentrant. Each thread must allocate its own object.</p>
*
* @author Sean Owen
*/
final class AlignmentPatternFinder {
private final BitMatrix image;
private final List<AlignmentPattern> possibleCenters;
private final int startX;
private final int startY;
private final int width;
private final int height;
private final float moduleSize;
private final int[] crossCheckStateCount;
private final ResultPointCallback resultPointCallback;
/**
* <p>Creates a finder that will look in a portion of the whole image.</p>
*
* @param image image to search
* @param startX left column from which to start searching
* @param startY top row from which to start searching
* @param width width of region to search
* @param height height of region to search
* @param moduleSize estimated module size so far
*/
AlignmentPatternFinder(BitMatrix image,
int startX,
int startY,
int width,
int height,
float moduleSize,
ResultPointCallback resultPointCallback) {
this.image = image;
this.possibleCenters = new ArrayList<>(5);
this.startX = startX;
this.startY = startY;
this.width = width;
this.height = height;
this.moduleSize = moduleSize;
this.crossCheckStateCount = new int[3];
this.resultPointCallback = resultPointCallback;
}
/**
* <p>This method attempts to find the bottom-right alignment pattern in the image. It is a bit messy since
* it's pretty performance-critical and so is written to be fast foremost.</p>
*
* @return {@link AlignmentPattern} if found
* @throws NotFoundException if not found
*/
AlignmentPattern find() throws NotFoundException {
int startX = this.startX;
int height = this.height;
int maxJ = startX + width;
int middleI = startY + (height / 2);
// We are looking for black/white/black modules in 1:1:1 ratio;
// this tracks the number of black/white/black modules seen so far
int[] stateCount = new int[3];
for (int iGen = 0; iGen < height; iGen++) {
// Search from middle outwards
int i = middleI + ((iGen & 0x01) == 0 ? (iGen + 1) / 2 : -((iGen + 1) / 2));
stateCount[0] = 0;
stateCount[1] = 0;
stateCount[2] = 0;
int j = startX;
// Burn off leading white pixels before anything else; if we start in the middle of
// a white run, it doesn't make sense to count its length, since we don't know if the
// white run continued to the left of the start point
while (j < maxJ && !image.get(j, i)) {
j++;
}
int currentState = 0;
while (j < maxJ) {
if (image.get(j, i)) {
// Black pixel
if (currentState == 1) { // Counting black pixels
stateCount[1]++;
} else { // Counting white pixels
if (currentState == 2) { // A winner?
if (foundPatternCross(stateCount)) { // Yes
AlignmentPattern confirmed = handlePossibleCenter(stateCount, i, j);
if (confirmed != null) {
return confirmed;
}
}
stateCount[0] = stateCount[2];
stateCount[1] = 1;
stateCount[2] = 0;
currentState = 1;
} else {
stateCount[++currentState]++;
}
}
} else { // White pixel
if (currentState == 1) { // Counting black pixels
currentState++;
}
stateCount[currentState]++;
}
j++;
}
if (foundPatternCross(stateCount)) {
AlignmentPattern confirmed = handlePossibleCenter(stateCount, i, maxJ);
if (confirmed != null) {
return confirmed;
}
}
}
// Hmm, nothing we saw was observed and confirmed twice. If we had
// any guess at all, return it.
if (!possibleCenters.isEmpty()) {
return possibleCenters.get(0);
}
throw NotFoundException.getNotFoundInstance();
}
/**
* Given a count of black/white/black pixels just seen and an end position,
* figures the location of the center of this black/white/black run.
*/
private static float centerFromEnd(int[] stateCount, int end) {
return (end - stateCount[2]) - stateCount[1] / 2.0f;
}
/**
* @param stateCount count of black/white/black pixels just read
* @return true iff the proportions of the counts is close enough to the 1/1/1 ratios
* used by alignment patterns to be considered a match
*/
private boolean foundPatternCross(int[] stateCount) {
float moduleSize = this.moduleSize;
float maxVariance = moduleSize / 2.0f;
for (int i = 0; i < 3; i++) {
if (Math.abs(moduleSize - stateCount[i]) >= maxVariance) {
return false;
}
}
return true;
}
/**
* <p>After a horizontal scan finds a potential alignment pattern, this method
* "cross-checks" by scanning down vertically through the center of the possible
* alignment pattern to see if the same proportion is detected.</p>
*
* @param startI row where an alignment pattern was detected
* @param centerJ center of the section that appears to cross an alignment pattern
* @param maxCount maximum reasonable number of modules that should be
* observed in any reading state, based on the results of the horizontal scan
* @return vertical center of alignment pattern, or {@link Float#NaN} if not found
*/
private float crossCheckVertical(int startI, int centerJ, int maxCount,
int originalStateCountTotal) {
BitMatrix image = this.image;
int maxI = image.getHeight();
int[] stateCount = crossCheckStateCount;
stateCount[0] = 0;
stateCount[1] = 0;
stateCount[2] = 0;
// Start counting up from center
int i = startI;
while (i >= 0 && image.get(centerJ, i) && stateCount[1] <= maxCount) {
stateCount[1]++;
i--;
}
// If already too many modules in this state or ran off the edge:
if (i < 0 || stateCount[1] > maxCount) {
return Float.NaN;
}
while (i >= 0 && !image.get(centerJ, i) && stateCount[0] <= maxCount) {
stateCount[0]++;
i--;
}
if (stateCount[0] > maxCount) {
return Float.NaN;
}
// Now also count down from center
i = startI + 1;
while (i < maxI && image.get(centerJ, i) && stateCount[1] <= maxCount) {
stateCount[1]++;
i++;
}
if (i == maxI || stateCount[1] > maxCount) {
return Float.NaN;
}
while (i < maxI && !image.get(centerJ, i) && stateCount[2] <= maxCount) {
stateCount[2]++;
i++;
}
if (stateCount[2] > maxCount) {
return Float.NaN;
}
int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= 2 * originalStateCountTotal) {
return Float.NaN;
}
return foundPatternCross(stateCount) ? centerFromEnd(stateCount, i) : Float.NaN;
}
/**
* <p>This is called when a horizontal scan finds a possible alignment pattern. It will
* cross check with a vertical scan, and if successful, will see if this pattern had been
* found on a previous horizontal scan. If so, we consider it confirmed and conclude we have
* found the alignment pattern.</p>
*
* @param stateCount reading state module counts from horizontal scan
* @param i row where alignment pattern may be found
* @param j end of possible alignment pattern in row
* @return {@link AlignmentPattern} if we have found the same pattern twice, or null if not
*/
private AlignmentPattern handlePossibleCenter(int[] stateCount, int i, int j) {
int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
float centerJ = centerFromEnd(stateCount, j);
float centerI = crossCheckVertical(i, (int) centerJ, 2 * stateCount[1], stateCountTotal);
if (!Float.isNaN(centerI)) {
float estimatedModuleSize = (stateCount[0] + stateCount[1] + stateCount[2]) / 3.0f;
for (AlignmentPattern center : possibleCenters) {
// Look for about the same center and module size:
if (center.aboutEquals(estimatedModuleSize, centerI, centerJ)) {
return center.combineEstimate(centerI, centerJ, estimatedModuleSize);
}
}
// Hadn't found this before; save it
AlignmentPattern point = new AlignmentPattern(centerJ, centerI, estimatedModuleSize);
possibleCenters.add(point);
if (resultPointCallback != null) {
resultPointCallback.foundPossibleResultPoint(point);
}
}
return null;
}
}

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src/qrcode/detector/Detector.java Normal file
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/*
* 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 com.google.zxing.qrcode.detector;
import com.google.zxing.DecodeHintType;
import com.google.zxing.FormatException;
import com.google.zxing.NotFoundException;
import com.google.zxing.ResultPoint;
import com.google.zxing.ResultPointCallback;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.DetectorResult;
import com.google.zxing.common.GridSampler;
import com.google.zxing.common.PerspectiveTransform;
import com.google.zxing.common.detector.MathUtils;
import com.google.zxing.qrcode.decoder.Version;
import java.util.Map;
/**
* <p>Encapsulates logic that can detect a QR Code in an image, even if the QR Code
* is rotated or skewed, or partially obscured.</p>
*
* @author Sean Owen
*/
public class Detector {
private final BitMatrix image;
private ResultPointCallback resultPointCallback;
public Detector(BitMatrix image) {
this.image = image;
}
protected final BitMatrix getImage() {
return image;
}
protected final ResultPointCallback getResultPointCallback() {
return resultPointCallback;
}
/**
* <p>Detects a QR Code in an image.</p>
*
* @return {@link DetectorResult} encapsulating results of detecting a QR Code
* @throws NotFoundException if QR Code cannot be found
* @throws FormatException if a QR Code cannot be decoded
*/
public DetectorResult detect() throws NotFoundException, FormatException {
return detect(null);
}
/**
* <p>Detects a QR Code in an image.</p>
*
* @param hints optional hints to detector
* @return {@link DetectorResult} encapsulating results of detecting a QR Code
* @throws NotFoundException if QR Code cannot be found
* @throws FormatException if a QR Code cannot be decoded
*/
public final DetectorResult detect(Map<DecodeHintType,?> hints) throws NotFoundException, FormatException {
resultPointCallback = hints == null ? null :
(ResultPointCallback) hints.get(DecodeHintType.NEED_RESULT_POINT_CALLBACK);
FinderPatternFinder finder = new FinderPatternFinder(image, resultPointCallback);
FinderPatternInfo info = finder.find(hints);
return processFinderPatternInfo(info);
}
protected final DetectorResult processFinderPatternInfo(FinderPatternInfo info)
throws NotFoundException, FormatException {
FinderPattern topLeft = info.getTopLeft();
FinderPattern topRight = info.getTopRight();
FinderPattern bottomLeft = info.getBottomLeft();
float moduleSize = calculateModuleSize(topLeft, topRight, bottomLeft);
if (moduleSize < 1.0f) {
throw NotFoundException.getNotFoundInstance();
}
int dimension = computeDimension(topLeft, topRight, bottomLeft, moduleSize);
Version provisionalVersion = Version.getProvisionalVersionForDimension(dimension);
int modulesBetweenFPCenters = provisionalVersion.getDimensionForVersion() - 7;
AlignmentPattern alignmentPattern = null;
// Anything above version 1 has an alignment pattern
if (provisionalVersion.getAlignmentPatternCenters().length > 0) {
// Guess where a "bottom right" finder pattern would have been
float bottomRightX = topRight.getX() - topLeft.getX() + bottomLeft.getX();
float bottomRightY = topRight.getY() - topLeft.getY() + bottomLeft.getY();
// Estimate that alignment pattern is closer by 3 modules
// from "bottom right" to known top left location
float correctionToTopLeft = 1.0f - 3.0f / modulesBetweenFPCenters;
int estAlignmentX = (int) (topLeft.getX() + correctionToTopLeft * (bottomRightX - topLeft.getX()));
int estAlignmentY = (int) (topLeft.getY() + correctionToTopLeft * (bottomRightY - topLeft.getY()));
// Kind of arbitrary -- expand search radius before giving up
for (int i = 4; i <= 16; i <<= 1) {
try {
alignmentPattern = findAlignmentInRegion(moduleSize,
estAlignmentX,
estAlignmentY,
i);
break;
} catch (NotFoundException re) {
// try next round
}
}
// If we didn't find alignment pattern... well try anyway without it
}
PerspectiveTransform transform =
createTransform(topLeft, topRight, bottomLeft, alignmentPattern, dimension);
BitMatrix bits = sampleGrid(image, transform, dimension);
ResultPoint[] points;
if (alignmentPattern == null) {
points = new ResultPoint[]{bottomLeft, topLeft, topRight};
} else {
points = new ResultPoint[]{bottomLeft, topLeft, topRight, alignmentPattern};
}
return new DetectorResult(bits, points);
}
private static PerspectiveTransform createTransform(ResultPoint topLeft,
ResultPoint topRight,
ResultPoint bottomLeft,
ResultPoint alignmentPattern,
int dimension) {
float dimMinusThree = dimension - 3.5f;
float bottomRightX;
float bottomRightY;
float sourceBottomRightX;
float sourceBottomRightY;
if (alignmentPattern != null) {
bottomRightX = alignmentPattern.getX();
bottomRightY = alignmentPattern.getY();
sourceBottomRightX = dimMinusThree - 3.0f;
sourceBottomRightY = sourceBottomRightX;
} else {
// Don't have an alignment pattern, just make up the bottom-right point
bottomRightX = (topRight.getX() - topLeft.getX()) + bottomLeft.getX();
bottomRightY = (topRight.getY() - topLeft.getY()) + bottomLeft.getY();
sourceBottomRightX = dimMinusThree;
sourceBottomRightY = dimMinusThree;
}
return PerspectiveTransform.quadrilateralToQuadrilateral(
3.5f,
3.5f,
dimMinusThree,
3.5f,
sourceBottomRightX,
sourceBottomRightY,
3.5f,
dimMinusThree,
topLeft.getX(),
topLeft.getY(),
topRight.getX(),
topRight.getY(),
bottomRightX,
bottomRightY,
bottomLeft.getX(),
bottomLeft.getY());
}
private static BitMatrix sampleGrid(BitMatrix image,
PerspectiveTransform transform,
int dimension) throws NotFoundException {
GridSampler sampler = GridSampler.getInstance();
return sampler.sampleGrid(image, dimension, dimension, transform);
}
/**
* <p>Computes the dimension (number of modules on a size) of the QR Code based on the position
* of the finder patterns and estimated module size.</p>
*/
private static int computeDimension(ResultPoint topLeft,
ResultPoint topRight,
ResultPoint bottomLeft,
float moduleSize) throws NotFoundException {
int tltrCentersDimension = MathUtils.round(ResultPoint.distance(topLeft, topRight) / moduleSize);
int tlblCentersDimension = MathUtils.round(ResultPoint.distance(topLeft, bottomLeft) / moduleSize);
int dimension = ((tltrCentersDimension + tlblCentersDimension) / 2) + 7;
switch (dimension & 0x03) { // mod 4
case 0:
dimension++;
break;
// 1? do nothing
case 2:
dimension--;
break;
case 3:
throw NotFoundException.getNotFoundInstance();
}
return dimension;
}
/**
* <p>Computes an average estimated module size based on estimated derived from the positions
* of the three finder patterns.</p>
*
* @param topLeft detected top-left finder pattern center
* @param topRight detected top-right finder pattern center
* @param bottomLeft detected bottom-left finder pattern center
* @return estimated module size
*/
protected final float calculateModuleSize(ResultPoint topLeft,
ResultPoint topRight,
ResultPoint bottomLeft) {
// Take the average
return (calculateModuleSizeOneWay(topLeft, topRight) +
calculateModuleSizeOneWay(topLeft, bottomLeft)) / 2.0f;
}
/**
* <p>Estimates module size based on two finder patterns -- it uses
* {@link #sizeOfBlackWhiteBlackRunBothWays(int, int, int, int)} to figure the
* width of each, measuring along the axis between their centers.</p>
*/
private float calculateModuleSizeOneWay(ResultPoint pattern, ResultPoint otherPattern) {
float moduleSizeEst1 = sizeOfBlackWhiteBlackRunBothWays((int) pattern.getX(),
(int) pattern.getY(),
(int) otherPattern.getX(),
(int) otherPattern.getY());
float moduleSizeEst2 = sizeOfBlackWhiteBlackRunBothWays((int) otherPattern.getX(),
(int) otherPattern.getY(),
(int) pattern.getX(),
(int) pattern.getY());
if (Float.isNaN(moduleSizeEst1)) {
return moduleSizeEst2 / 7.0f;
}
if (Float.isNaN(moduleSizeEst2)) {
return moduleSizeEst1 / 7.0f;
}
// Average them, and divide by 7 since we've counted the width of 3 black modules,
// and 1 white and 1 black module on either side. Ergo, divide sum by 14.
return (moduleSizeEst1 + moduleSizeEst2) / 14.0f;
}
/**
* See {@link #sizeOfBlackWhiteBlackRun(int, int, int, int)}; computes the total width of
* a finder pattern by looking for a black-white-black run from the center in the direction
* of another point (another finder pattern center), and in the opposite direction too.
*/
private float sizeOfBlackWhiteBlackRunBothWays(int fromX, int fromY, int toX, int toY) {
float result = sizeOfBlackWhiteBlackRun(fromX, fromY, toX, toY);
// Now count other way -- don't run off image though of course
float scale = 1.0f;
int otherToX = fromX - (toX - fromX);
if (otherToX < 0) {
scale = fromX / (float) (fromX - otherToX);
otherToX = 0;
} else if (otherToX >= image.getWidth()) {
scale = (image.getWidth() - 1 - fromX) / (float) (otherToX - fromX);
otherToX = image.getWidth() - 1;
}
int otherToY = (int) (fromY - (toY - fromY) * scale);
scale = 1.0f;
if (otherToY < 0) {
scale = fromY / (float) (fromY - otherToY);
otherToY = 0;
} else if (otherToY >= image.getHeight()) {
scale = (image.getHeight() - 1 - fromY) / (float) (otherToY - fromY);
otherToY = image.getHeight() - 1;
}
otherToX = (int) (fromX + (otherToX - fromX) * scale);
result += sizeOfBlackWhiteBlackRun(fromX, fromY, otherToX, otherToY);
// Middle pixel is double-counted this way; subtract 1
return result - 1.0f;
}
/**
* <p>This method traces a line from a point in the image, in the direction towards another point.
* It begins in a black region, and keeps going until it finds white, then black, then white again.
* It reports the distance from the start to this point.</p>
*
* <p>This is used when figuring out how wide a finder pattern is, when the finder pattern
* may be skewed or rotated.</p>
*/
private float sizeOfBlackWhiteBlackRun(int fromX, int fromY, int toX, int toY) {
// Mild variant of Bresenham's algorithm;
// see http://en.wikipedia.org/wiki/Bresenham's_line_algorithm
boolean steep = Math.abs(toY - fromY) > Math.abs(toX - fromX);
if (steep) {
int temp = fromX;
fromX = fromY;
fromY = temp;
temp = toX;
toX = toY;
toY = temp;
}
int dx = Math.abs(toX - fromX);
int dy = Math.abs(toY - fromY);
int error = -dx / 2;
int xstep = fromX < toX ? 1 : -1;
int ystep = fromY < toY ? 1 : -1;
// In black pixels, looking for white, first or second time.
int state = 0;
// Loop up until x == toX, but not beyond
int xLimit = toX + xstep;
for (int x = fromX, y = fromY; x != xLimit; x += xstep) {
int realX = steep ? y : x;
int realY = steep ? x : y;
// Does current pixel mean we have moved white to black or vice versa?
// Scanning black in state 0,2 and white in state 1, so if we find the wrong
// color, advance to next state or end if we are in state 2 already
if ((state == 1) == image.get(realX, realY)) {
if (state == 2) {
return MathUtils.distance(x, y, fromX, fromY);
}
state++;
}
error += dy;
if (error > 0) {
if (y == toY) {
break;
}
y += ystep;
error -= dx;
}
}
// Found black-white-black; give the benefit of the doubt that the next pixel outside the image
// is "white" so this last point at (toX+xStep,toY) is the right ending. This is really a
// small approximation; (toX+xStep,toY+yStep) might be really correct. Ignore this.
if (state == 2) {
return MathUtils.distance(toX + xstep, toY, fromX, fromY);
}
// else we didn't find even black-white-black; no estimate is really possible
return Float.NaN;
}
/**
* <p>Attempts to locate an alignment pattern in a limited region of the image, which is
* guessed to contain it. This method uses {@link AlignmentPattern}.</p>
*
* @param overallEstModuleSize estimated module size so far
* @param estAlignmentX x coordinate of center of area probably containing alignment pattern
* @param estAlignmentY y coordinate of above
* @param allowanceFactor number of pixels in all directions to search from the center
* @return {@link AlignmentPattern} if found, or null otherwise
* @throws NotFoundException if an unexpected error occurs during detection
*/
protected final AlignmentPattern findAlignmentInRegion(float overallEstModuleSize,
int estAlignmentX,
int estAlignmentY,
float allowanceFactor)
throws NotFoundException {
// Look for an alignment pattern (3 modules in size) around where it
// should be
int allowance = (int) (allowanceFactor * overallEstModuleSize);
int alignmentAreaLeftX = Math.max(0, estAlignmentX - allowance);
int alignmentAreaRightX = Math.min(image.getWidth() - 1, estAlignmentX + allowance);
if (alignmentAreaRightX - alignmentAreaLeftX < overallEstModuleSize * 3) {
throw NotFoundException.getNotFoundInstance();
}
int alignmentAreaTopY = Math.max(0, estAlignmentY - allowance);
int alignmentAreaBottomY = Math.min(image.getHeight() - 1, estAlignmentY + allowance);
if (alignmentAreaBottomY - alignmentAreaTopY < overallEstModuleSize * 3) {
throw NotFoundException.getNotFoundInstance();
}
AlignmentPatternFinder alignmentFinder =
new AlignmentPatternFinder(
image,
alignmentAreaLeftX,
alignmentAreaTopY,
alignmentAreaRightX - alignmentAreaLeftX,
alignmentAreaBottomY - alignmentAreaTopY,
overallEstModuleSize,
resultPointCallback);
return alignmentFinder.find();
}
}

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/*
* 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 com.google.zxing.qrcode.detector;
import com.google.zxing.ResultPoint;
/**
* <p>Encapsulates a finder pattern, which are the three square patterns found in
* the corners of QR Codes. It also encapsulates a count of similar finder patterns,
* as a convenience to the finder's bookkeeping.</p>
*
* @author Sean Owen
*/
public final class FinderPattern extends ResultPoint {
private final float estimatedModuleSize;
private final int count;
FinderPattern(float posX, float posY, float estimatedModuleSize) {
this(posX, posY, estimatedModuleSize, 1);
}
private FinderPattern(float posX, float posY, float estimatedModuleSize, int count) {
super(posX, posY);
this.estimatedModuleSize = estimatedModuleSize;
this.count = count;
}
public float getEstimatedModuleSize() {
return estimatedModuleSize;
}
public int getCount() {
return count;
}
/**
* <p>Determines if this finder pattern "about equals" a finder pattern at the stated
* position and size -- meaning, it is at nearly the same center with nearly the same size.</p>
*/
boolean aboutEquals(float moduleSize, float i, float j) {
if (Math.abs(i - getY()) <= moduleSize && Math.abs(j - getX()) <= moduleSize) {
float moduleSizeDiff = Math.abs(moduleSize - estimatedModuleSize);
return moduleSizeDiff <= 1.0f || moduleSizeDiff <= estimatedModuleSize;
}
return false;
}
/**
* Combines this object's current estimate of a finder pattern position and module size
* with a new estimate. It returns a new {@code FinderPattern} containing a weighted average
* based on count.
*/
FinderPattern combineEstimate(float i, float j, float newModuleSize) {
int combinedCount = count + 1;
float combinedX = (count * getX() + j) / combinedCount;
float combinedY = (count * getY() + i) / combinedCount;
float combinedModuleSize = (count * estimatedModuleSize + newModuleSize) / combinedCount;
return new FinderPattern(combinedX, combinedY, combinedModuleSize, combinedCount);
}
}

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/*
* 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 com.google.zxing.qrcode.detector;
import com.google.zxing.DecodeHintType;
import com.google.zxing.NotFoundException;
import com.google.zxing.ResultPoint;
import com.google.zxing.ResultPointCallback;
import com.google.zxing.common.BitMatrix;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
/**
* <p>This class attempts to find finder patterns in a QR Code. Finder patterns are the square
* markers at three corners of a QR Code.</p>
*
* <p>This class is thread-safe but not reentrant. Each thread must allocate its own object.
*
* @author Sean Owen
*/
public class FinderPatternFinder {
private static final int CENTER_QUORUM = 2;
private static final EstimatedModuleComparator moduleComparator = new EstimatedModuleComparator();
protected static final int MIN_SKIP = 3; // 1 pixel/module times 3 modules/center
protected static final int MAX_MODULES = 97; // support up to version 20 for mobile clients
private final BitMatrix image;
private final List<FinderPattern> possibleCenters;
private boolean hasSkipped;
private final int[] crossCheckStateCount;
private final ResultPointCallback resultPointCallback;
/**
* <p>Creates a finder that will search the image for three finder patterns.</p>
*
* @param image image to search
*/
public FinderPatternFinder(BitMatrix image) {
this(image, null);
}
public FinderPatternFinder(BitMatrix image, ResultPointCallback resultPointCallback) {
this.image = image;
this.possibleCenters = new ArrayList<>();
this.crossCheckStateCount = new int[5];
this.resultPointCallback = resultPointCallback;
}
protected final BitMatrix getImage() {
return image;
}
protected final List<FinderPattern> getPossibleCenters() {
return possibleCenters;
}
final FinderPatternInfo find(Map<DecodeHintType,?> hints) throws NotFoundException {
boolean tryHarder = hints != null && hints.containsKey(DecodeHintType.TRY_HARDER);
int maxI = image.getHeight();
int maxJ = image.getWidth();
// We are looking for black/white/black/white/black modules in
// 1:1:3:1:1 ratio; this tracks the number of such modules seen so far
// Let's assume that the maximum version QR Code we support takes up 1/4 the height of the
// image, and then account for the center being 3 modules in size. This gives the smallest
// number of pixels the center could be, so skip this often. When trying harder, look for all
// QR versions regardless of how dense they are.
int iSkip = (3 * maxI) / (4 * MAX_MODULES);
if (iSkip < MIN_SKIP || tryHarder) {
iSkip = MIN_SKIP;
}
boolean done = false;
int[] stateCount = new int[5];
for (int i = iSkip - 1; i < maxI && !done; i += iSkip) {
// Get a row of black/white values
doClearCounts(stateCount);
int currentState = 0;
for (int j = 0; j < maxJ; j++) {
if (image.get(j, i)) {
// Black pixel
if ((currentState & 1) == 1) { // Counting white pixels
currentState++;
}
stateCount[currentState]++;
} else { // White pixel
if ((currentState & 1) == 0) { // Counting black pixels
if (currentState == 4) { // A winner?
if (foundPatternCross(stateCount)) { // Yes
boolean confirmed = handlePossibleCenter(stateCount, i, j);
if (confirmed) {
// Start examining every other line. Checking each line turned out to be too
// expensive and didn't improve performance.
iSkip = 2;
if (hasSkipped) {
done = haveMultiplyConfirmedCenters();
} else {
int rowSkip = findRowSkip();
if (rowSkip > stateCount[2]) {
// Skip rows between row of lower confirmed center
// and top of presumed third confirmed center
// but back up a bit to get a full chance of detecting
// it, entire width of center of finder pattern
// Skip by rowSkip, but back off by stateCount[2] (size of last center
// of pattern we saw) to be conservative, and also back off by iSkip which
// is about to be re-added
i += rowSkip - stateCount[2] - iSkip;
j = maxJ - 1;
}
}
} else {
doShiftCounts2(stateCount);
currentState = 3;
continue;
}
// Clear state to start looking again
currentState = 0;
doClearCounts(stateCount);
} else { // No, shift counts back by two
doShiftCounts2(stateCount);
currentState = 3;
}
} else {
stateCount[++currentState]++;
}
} else { // Counting white pixels
stateCount[currentState]++;
}
}
}
if (foundPatternCross(stateCount)) {
boolean confirmed = handlePossibleCenter(stateCount, i, maxJ);
if (confirmed) {
iSkip = stateCount[0];
if (hasSkipped) {
// Found a third one
done = haveMultiplyConfirmedCenters();
}
}
}
}
FinderPattern[] patternInfo = selectBestPatterns();
ResultPoint.orderBestPatterns(patternInfo);
return new FinderPatternInfo(patternInfo);
}
/**
* Given a count of black/white/black/white/black pixels just seen and an end position,
* figures the location of the center of this run.
*/
private static float centerFromEnd(int[] stateCount, int end) {
return (end - stateCount[4] - stateCount[3]) - stateCount[2] / 2.0f;
}
/**
* @param stateCount count of black/white/black/white/black pixels just read
* @return 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
*/
protected static boolean foundPatternCross(int[] stateCount) {
int totalModuleSize = 0;
for (int i = 0; i < 5; i++) {
int count = stateCount[i];
if (count == 0) {
return false;
}
totalModuleSize += count;
}
if (totalModuleSize < 7) {
return false;
}
float moduleSize = totalModuleSize / 7.0f;
float maxVariance = moduleSize / 2.0f;
// Allow less than 50% variance from 1-1-3-1-1 proportions
return
Math.abs(moduleSize - stateCount[0]) < maxVariance &&
Math.abs(moduleSize - stateCount[1]) < maxVariance &&
Math.abs(3.0f * moduleSize - stateCount[2]) < 3 * maxVariance &&
Math.abs(moduleSize - stateCount[3]) < maxVariance &&
Math.abs(moduleSize - stateCount[4]) < maxVariance;
}
/**
* @param stateCount count of black/white/black/white/black pixels just read
* @return 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
*/
protected static boolean foundPatternDiagonal(int[] stateCount) {
int totalModuleSize = 0;
for (int i = 0; i < 5; i++) {
int count = stateCount[i];
if (count == 0) {
return false;
}
totalModuleSize += count;
}
if (totalModuleSize < 7) {
return false;
}
float moduleSize = totalModuleSize / 7.0f;
float maxVariance = moduleSize / 1.333f;
// Allow less than 75% variance from 1-1-3-1-1 proportions
return
Math.abs(moduleSize - stateCount[0]) < maxVariance &&
Math.abs(moduleSize - stateCount[1]) < maxVariance &&
Math.abs(3.0f * moduleSize - stateCount[2]) < 3 * maxVariance &&
Math.abs(moduleSize - stateCount[3]) < maxVariance &&
Math.abs(moduleSize - stateCount[4]) < maxVariance;
}
private int[] getCrossCheckStateCount() {
doClearCounts(crossCheckStateCount);
return crossCheckStateCount;
}
@Deprecated
protected final void clearCounts(int[] counts) {
doClearCounts(counts);
}
@Deprecated
protected final void shiftCounts2(int[] stateCount) {
doShiftCounts2(stateCount);
}
protected static void doClearCounts(int[] counts) {
Arrays.fill(counts, 0);
}
protected static void doShiftCounts2(int[] stateCount) {
stateCount[0] = stateCount[2];
stateCount[1] = stateCount[3];
stateCount[2] = stateCount[4];
stateCount[3] = 1;
stateCount[4] = 0;
}
/**
* After a vertical and horizontal scan finds a potential finder pattern, this method
* "cross-cross-cross-checks" by scanning down diagonally through the center of the possible
* finder pattern to see if the same proportion is detected.
*
* @param centerI row where a finder pattern was detected
* @param centerJ center of the section that appears to cross a finder pattern
* @return true if proportions are withing expected limits
*/
private boolean crossCheckDiagonal(int centerI, int centerJ) {
int[] stateCount = getCrossCheckStateCount();
// Start counting up, left from center finding black center mass
int i = 0;
while (centerI >= i && centerJ >= i && image.get(centerJ - i, centerI - i)) {
stateCount[2]++;
i++;
}
if (stateCount[2] == 0) {
return false;
}
// Continue up, left finding white space
while (centerI >= i && centerJ >= i && !image.get(centerJ - i, centerI - i)) {
stateCount[1]++;
i++;
}
if (stateCount[1] == 0) {
return false;
}
// Continue up, left finding black border
while (centerI >= i && centerJ >= i && image.get(centerJ - i, centerI - i)) {
stateCount[0]++;
i++;
}
if (stateCount[0] == 0) {
return false;
}
int maxI = image.getHeight();
int maxJ = image.getWidth();
// Now also count down, right from center
i = 1;
while (centerI + i < maxI && centerJ + i < maxJ && image.get(centerJ + i, centerI + i)) {
stateCount[2]++;
i++;
}
while (centerI + i < maxI && centerJ + i < maxJ && !image.get(centerJ + i, centerI + i)) {
stateCount[3]++;
i++;
}
if (stateCount[3] == 0) {
return false;
}
while (centerI + i < maxI && centerJ + i < maxJ && image.get(centerJ + i, centerI + i)) {
stateCount[4]++;
i++;
}
if (stateCount[4] == 0) {
return false;
}
return foundPatternDiagonal(stateCount);
}
/**
* <p>After a horizontal scan finds a potential finder pattern, this method
* "cross-checks" by scanning down vertically through the center of the possible
* finder pattern to see if the same proportion is detected.</p>
*
* @param startI row where a finder pattern was detected
* @param centerJ center of the section that appears to cross a finder pattern
* @param maxCount maximum reasonable number of modules that should be
* observed in any reading state, based on the results of the horizontal scan
* @return vertical center of finder pattern, or {@link Float#NaN} if not found
*/
private float crossCheckVertical(int startI, int centerJ, int maxCount,
int originalStateCountTotal) {
BitMatrix image = this.image;
int maxI = image.getHeight();
int[] stateCount = getCrossCheckStateCount();
// Start counting up from center
int i = startI;
while (i >= 0 && image.get(centerJ, i)) {
stateCount[2]++;
i--;
}
if (i < 0) {
return Float.NaN;
}
while (i >= 0 && !image.get(centerJ, i) && stateCount[1] <= maxCount) {
stateCount[1]++;
i--;
}
// If already too many modules in this state or ran off the edge:
if (i < 0 || stateCount[1] > maxCount) {
return Float.NaN;
}
while (i >= 0 && image.get(centerJ, i) && stateCount[0] <= maxCount) {
stateCount[0]++;
i--;
}
if (stateCount[0] > maxCount) {
return Float.NaN;
}
// Now also count down from center
i = startI + 1;
while (i < maxI && image.get(centerJ, i)) {
stateCount[2]++;
i++;
}
if (i == maxI) {
return Float.NaN;
}
while (i < maxI && !image.get(centerJ, i) && stateCount[3] < maxCount) {
stateCount[3]++;
i++;
}
if (i == maxI || stateCount[3] >= maxCount) {
return Float.NaN;
}
while (i < maxI && image.get(centerJ, i) && stateCount[4] < maxCount) {
stateCount[4]++;
i++;
}
if (stateCount[4] >= maxCount) {
return Float.NaN;
}
// If we found a finder-pattern-like section, but its size is more than 40% different than
// the original, assume it's a false positive
int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
stateCount[4];
if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= 2 * originalStateCountTotal) {
return Float.NaN;
}
return foundPatternCross(stateCount) ? centerFromEnd(stateCount, i) : Float.NaN;
}
/**
* <p>Like {@link #crossCheckVertical(int, int, int, int)}, and in fact is basically identical,
* except it reads horizontally instead of vertically. This is used to cross-cross
* check a vertical cross check and locate the real center of the alignment pattern.</p>
*/
private float crossCheckHorizontal(int startJ, int centerI, int maxCount,
int originalStateCountTotal) {
BitMatrix image = this.image;
int maxJ = image.getWidth();
int[] stateCount = getCrossCheckStateCount();
int j = startJ;
while (j >= 0 && image.get(j, centerI)) {
stateCount[2]++;
j--;
}
if (j < 0) {
return Float.NaN;
}
while (j >= 0 && !image.get(j, centerI) && stateCount[1] <= maxCount) {
stateCount[1]++;
j--;
}
if (j < 0 || stateCount[1] > maxCount) {
return Float.NaN;
}
while (j >= 0 && image.get(j, centerI) && stateCount[0] <= maxCount) {
stateCount[0]++;
j--;
}
if (stateCount[0] > maxCount) {
return Float.NaN;
}
j = startJ + 1;
while (j < maxJ && image.get(j, centerI)) {
stateCount[2]++;
j++;
}
if (j == maxJ) {
return Float.NaN;
}
while (j < maxJ && !image.get(j, centerI) && stateCount[3] < maxCount) {
stateCount[3]++;
j++;
}
if (j == maxJ || stateCount[3] >= maxCount) {
return Float.NaN;
}
while (j < maxJ && image.get(j, centerI) && stateCount[4] < maxCount) {
stateCount[4]++;
j++;
}
if (stateCount[4] >= maxCount) {
return Float.NaN;
}
// If we found a finder-pattern-like section, but its size is significantly different than
// the original, assume it's a false positive
int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
stateCount[4];
if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal) {
return Float.NaN;
}
return foundPatternCross(stateCount) ? centerFromEnd(stateCount, j) : Float.NaN;
}
/**
* @param stateCount reading state module counts from horizontal scan
* @param i row where finder pattern may be found
* @param j end of possible finder pattern in row
* @param pureBarcode ignored
* @return true if a finder pattern candidate was found this time
* @deprecated only exists for backwards compatibility
* @see #handlePossibleCenter(int[], int, int)
*/
@Deprecated
protected final boolean handlePossibleCenter(int[] stateCount, int i, int j, boolean pureBarcode) {
return handlePossibleCenter(stateCount, i, j);
}
/**
* <p>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.</p>
*
* <p>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
*
* @param stateCount reading state module counts from horizontal scan
* @param i row where finder pattern may be found
* @param j end of possible finder pattern in row
* @return true if a finder pattern candidate was found this time
*/
protected final boolean handlePossibleCenter(int[] stateCount, int i, int j) {
int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
stateCount[4];
float centerJ = centerFromEnd(stateCount, j);
float centerI = crossCheckVertical(i, (int) centerJ, stateCount[2], stateCountTotal);
if (!Float.isNaN(centerI)) {
// Re-cross check
centerJ = crossCheckHorizontal((int) centerJ, (int) centerI, stateCount[2], stateCountTotal);
if (!Float.isNaN(centerJ) && crossCheckDiagonal((int) centerI, (int) centerJ)) {
float estimatedModuleSize = stateCountTotal / 7.0f;
boolean found = false;
for (int index = 0; index < possibleCenters.size(); index++) {
FinderPattern center = possibleCenters.get(index);
// Look for about the same center and module size:
if (center.aboutEquals(estimatedModuleSize, centerI, centerJ)) {
possibleCenters.set(index, center.combineEstimate(centerI, centerJ, estimatedModuleSize));
found = true;
break;
}
}
if (!found) {
FinderPattern point = new FinderPattern(centerJ, centerI, estimatedModuleSize);
possibleCenters.add(point);
if (resultPointCallback != null) {
resultPointCallback.foundPossibleResultPoint(point);
}
}
return true;
}
}
return false;
}
/**
* @return number of rows we could safely skip during scanning, based on the first
* two finder patterns that have been located. In some cases their position will
* allow us to infer that the third pattern must lie below a certain point farther
* down in the image.
*/
private int findRowSkip() {
int max = possibleCenters.size();
if (max <= 1) {
return 0;
}
ResultPoint firstConfirmedCenter = null;
for (FinderPattern center : possibleCenters) {
if (center.getCount() >= CENTER_QUORUM) {
if (firstConfirmedCenter == null) {
firstConfirmedCenter = center;
} else {
// We have two confirmed centers
// How far down can we skip before resuming looking for the next
// pattern? In the worst case, only the difference between the
// difference in the x / y coordinates of the two centers.
// This is the case where you find top left last.
hasSkipped = true;
return (int) (Math.abs(firstConfirmedCenter.getX() - center.getX()) -
Math.abs(firstConfirmedCenter.getY() - center.getY())) / 2;
}
}
}
return 0;
}
/**
* @return true iff we have found at least 3 finder patterns that have been detected
* at least {@link #CENTER_QUORUM} times each, and, the estimated module size of the
* candidates is "pretty similar"
*/
private boolean haveMultiplyConfirmedCenters() {
int confirmedCount = 0;
float totalModuleSize = 0.0f;
int max = possibleCenters.size();
for (FinderPattern pattern : possibleCenters) {
if (pattern.getCount() >= CENTER_QUORUM) {
confirmedCount++;
totalModuleSize += pattern.getEstimatedModuleSize();
}
}
if (confirmedCount < 3) {
return false;
}
// OK, we have at least 3 confirmed centers, but, it's possible that one is a "false positive"
// and that we need to keep looking. We detect this by asking if the estimated module sizes
// vary too much. We arbitrarily say that when the total deviation from average exceeds
// 5% of the total module size estimates, it's too much.
float average = totalModuleSize / max;
float totalDeviation = 0.0f;
for (FinderPattern pattern : possibleCenters) {
totalDeviation += Math.abs(pattern.getEstimatedModuleSize() - average);
}
return totalDeviation <= 0.05f * totalModuleSize;
}
/**
* Get square of distance between a and b.
*/
private static double squaredDistance(FinderPattern a, FinderPattern b) {
double x = a.getX() - b.getX();
double y = a.getY() - b.getY();
return x * x + y * y;
}
/**
* @return the 3 best {@link FinderPattern}s from our list of candidates. The "best" are
* those have similar module size and form a shape closer to a isosceles right triangle.
* @throws NotFoundException if 3 such finder patterns do not exist
*/
private FinderPattern[] selectBestPatterns() throws NotFoundException {
int startSize = possibleCenters.size();
if (startSize < 3) {
// Couldn't find enough finder patterns
throw NotFoundException.getNotFoundInstance();
}
possibleCenters.sort(moduleComparator);
double distortion = Double.MAX_VALUE;
FinderPattern[] bestPatterns = new FinderPattern[3];
for (int i = 0; i < possibleCenters.size() - 2; i++) {
FinderPattern fpi = possibleCenters.get(i);
float minModuleSize = fpi.getEstimatedModuleSize();
for (int j = i + 1; j < possibleCenters.size() - 1; j++) {
FinderPattern fpj = possibleCenters.get(j);
double squares0 = squaredDistance(fpi, fpj);
for (int k = j + 1; k < possibleCenters.size(); k++) {
FinderPattern fpk = possibleCenters.get(k);
float maxModuleSize = fpk.getEstimatedModuleSize();
if (maxModuleSize > minModuleSize * 1.4f) {
// module size is not similar
continue;
}
double a = squares0;
double b = squaredDistance(fpj, fpk);
double c = squaredDistance(fpi, fpk);
// sorts ascending - inlined
if (a < b) {
if (b > c) {
if (a < c) {
double temp = b;
b = c;
c = temp;
} else {
double temp = a;
a = c;
c = b;
b = temp;
}
}
} else {
if (b < c) {
if (a < c) {
double temp = a;
a = b;
b = temp;
} else {
double temp = a;
a = b;
b = c;
c = temp;
}
} else {
double temp = a;
a = c;
c = temp;
}
}
// a^2 + b^2 = c^2 (Pythagorean theorem), and a = b (isosceles triangle).
// Since any right triangle satisfies the formula c^2 - b^2 - a^2 = 0,
// we need to check both two equal sides separately.
// The value of |c^2 - 2 * b^2| + |c^2 - 2 * a^2| increases as dissimilarity
// from isosceles right triangle.
double d = Math.abs(c - 2 * b) + Math.abs(c - 2 * a);
if (d < distortion) {
distortion = d;
bestPatterns[0] = fpi;
bestPatterns[1] = fpj;
bestPatterns[2] = fpk;
}
}
}
}
if (distortion == Double.MAX_VALUE) {
throw NotFoundException.getNotFoundInstance();
}
return bestPatterns;
}
/**
* <p>Orders by {@link FinderPattern#getEstimatedModuleSize()}</p>
*/
private static final class EstimatedModuleComparator implements Comparator<FinderPattern>, Serializable {
@Override
public int compare(FinderPattern center1, FinderPattern center2) {
return Float.compare(center1.getEstimatedModuleSize(), center2.getEstimatedModuleSize());
}
}
}

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src/qrcode/detector/FinderPatternInfo.java Normal file
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/*
* 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 com.google.zxing.qrcode.detector;
/**
* <p>Encapsulates information about finder patterns in an image, including the location of
* the three finder patterns, and their estimated module size.</p>
*
* @author Sean Owen
*/
public final class FinderPatternInfo {
private final FinderPattern bottomLeft;
private final FinderPattern topLeft;
private final FinderPattern topRight;
public FinderPatternInfo(FinderPattern[] patternCenters) {
this.bottomLeft = patternCenters[0];
this.topLeft = patternCenters[1];
this.topRight = patternCenters[2];
}
public FinderPattern getBottomLeft() {
return bottomLeft;
}
public FinderPattern getTopLeft() {
return topLeft;
}
public FinderPattern getTopRight() {
return topRight;
}
}