DetectorTest.java
/*
* Copyright 2013 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.aztec.detector;
import com.google.zxing.NotFoundException;
import com.google.zxing.aztec.AztecDetectorResult;
import com.google.zxing.aztec.decoder.Decoder;
import com.google.zxing.aztec.detector.Detector.Point;
import com.google.zxing.aztec.encoder.AztecCode;
import com.google.zxing.aztec.encoder.Encoder;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.DecoderResult;
import org.junit.Assert;
import org.junit.Test;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Random;
import java.util.TreeSet;
/**
* Tests for the Detector
*
* @author Frank Yellin
*/
public final class DetectorTest extends Assert {
@Test
public void testErrorInParameterLocatorZeroZero() throws Exception {
// Layers=1, CodeWords=1. So the parameter info and its Reed-Solomon info
// will be completely zero!
testErrorInParameterLocator("X");
}
@Test
public void testErrorInParameterLocatorCompact() throws Exception {
testErrorInParameterLocator("This is an example Aztec symbol for Wikipedia.");
}
@Test
public void testErrorInParameterLocatorNotCompact() throws Exception {
String alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYabcdefghijklmnopqrstuvwxyz";
testErrorInParameterLocator(alphabet + alphabet + alphabet);
}
// Test that we can tolerate errors in the parameter locator bits
private static void testErrorInParameterLocator(String data) throws Exception {
AztecCode aztec = Encoder.encode(data, 25, Encoder.DEFAULT_AZTEC_LAYERS);
Random random = new Random(aztec.getMatrix().hashCode()); // pseudo-random, but deterministic
int layers = aztec.getLayers();
boolean compact = aztec.isCompact();
List<Point> orientationPoints = getOrientationPoints(aztec);
for (boolean isMirror : new boolean[] { false, true }) {
for (BitMatrix matrix : getRotations(aztec.getMatrix())) {
// Systematically try every possible 1- and 2-bit error.
for (int error1 = 0; error1 < orientationPoints.size(); error1++) {
for (int error2 = error1; error2 < orientationPoints.size(); error2++) {
BitMatrix copy = isMirror ? transpose(matrix) : clone(matrix);
copy.flip(orientationPoints.get(error1).getX(), orientationPoints.get(error1).getY());
if (error2 > error1) {
// if error2 == error1, we only test a single error
copy.flip(orientationPoints.get(error2).getX(), orientationPoints.get(error2).getY());
}
// The detector doesn't seem to work when matrix bits are only 1x1. So magnify.
AztecDetectorResult r = new Detector(makeLarger(copy, 3)).detect(isMirror);
assertNotNull(r);
assertEquals(r.getNbLayers(), layers);
assertEquals(r.isCompact(), compact);
DecoderResult res = new Decoder().decode(r);
assertEquals(data, res.getText());
}
}
// Try a few random three-bit errors;
for (int i = 0; i < 5; i++) {
BitMatrix copy = clone(matrix);
Collection<Integer> errors = new TreeSet<>();
while (errors.size() < 3) {
// Quick and dirty way of getting three distinct integers between 1 and n.
errors.add(random.nextInt(orientationPoints.size()));
}
for (int error : errors) {
copy.flip(orientationPoints.get(error).getX(), orientationPoints.get(error).getY());
}
try {
new Detector(makeLarger(copy, 3)).detect(false);
fail("Should not reach here");
} catch (NotFoundException expected) {
// continue
}
}
}
}
}
// Zooms a bit matrix so that each bit is factor x factor
private static BitMatrix makeLarger(BitMatrix input, int factor) {
int width = input.getWidth();
BitMatrix output = new BitMatrix(width * factor);
for (int inputY = 0; inputY < width; inputY++) {
for (int inputX = 0; inputX < width; inputX++) {
if (input.get(inputX, inputY)) {
output.setRegion(inputX * factor, inputY * factor, factor, factor);
}
}
}
return output;
}
// Returns a list of the four rotations of the BitMatrix.
private static Iterable<BitMatrix> getRotations(BitMatrix matrix0) {
BitMatrix matrix90 = rotateRight(matrix0);
BitMatrix matrix180 = rotateRight(matrix90);
BitMatrix matrix270 = rotateRight(matrix180);
return Arrays.asList(matrix0, matrix90, matrix180, matrix270);
}
// Rotates a square BitMatrix to the right by 90 degrees
private static BitMatrix rotateRight(BitMatrix input) {
int width = input.getWidth();
BitMatrix result = new BitMatrix(width);
for (int x = 0; x < width; x++) {
for (int y = 0; y < width; y++) {
if (input.get(x,y)) {
result.set(y, width - x - 1);
}
}
}
return result;
}
// Returns the transpose of a bit matrix, which is equivalent to rotating the
// matrix to the right, and then flipping it left-to-right
private static BitMatrix transpose(BitMatrix input) {
int width = input.getWidth();
BitMatrix result = new BitMatrix(width);
for (int x = 0; x < width; x++) {
for (int y = 0; y < width; y++) {
if (input.get(x, y)) {
result.set(y, x);
}
}
}
return result;
}
private static BitMatrix clone(BitMatrix input) {
int width = input.getWidth();
BitMatrix result = new BitMatrix(width);
for (int x = 0; x < width; x++) {
for (int y = 0; y < width; y++) {
if (input.get(x,y)) {
result.set(x,y);
}
}
}
return result;
}
private static List<Point> getOrientationPoints(AztecCode code) {
int center = code.getMatrix().getWidth() / 2;
int offset = code.isCompact() ? 5 : 7;
List<Point> result = new ArrayList<>();
for (int xSign = -1; xSign <= 1; xSign += 2) {
for (int ySign = -1; ySign <= 1; ySign += 2) {
result.add(new Point(center + xSign * offset, center + ySign * offset));
result.add(new Point(center + xSign * (offset - 1), center + ySign * offset));
result.add(new Point(center + xSign * offset, center + ySign * (offset - 1)));
}
}
return result;
}
}