import com.google.zxing.common.Comparator;
import com.google.zxing.common.DetectorResult;
import com.google.zxing.common.GridSampler;
-import com.google.zxing.common.detector.MonochromeRectangleDetector;
+import com.google.zxing.common.detector.WhiteRectangleDetector;
import java.util.Enumeration;
import java.util.Hashtable;
*/
public final class Detector {
- //private static final int MAX_MODULES = 32;
+ private static final int MIN_GIVEUP_THRESHOLD = 3;
// Trick to avoid creating new Integer objects below -- a sort of crude copy of
// the Integer.valueOf(int) optimization added in Java 5, not in J2ME
// No, can't use valueOf()
private final BitMatrix image;
- private final MonochromeRectangleDetector rectangleDetector;
+ private final WhiteRectangleDetector rectangleDetector;
public Detector(BitMatrix image) {
this.image = image;
- rectangleDetector = new MonochromeRectangleDetector(image);
+ rectangleDetector = new WhiteRectangleDetector(image);
}
/**
* <p>Detects a Data Matrix Code in an image.</p>
*
- * @return {@link DetectorResult} encapsulating results of detecting a QR Code
+ * @return {@link DetectorResult} encapsulating results of detecting a Data Matrix Code
* @throws NotFoundException if no Data Matrix Code can be found
*/
public DetectorResult detect() throws NotFoundException {
ResultPointsAndTransitions lSideOne = (ResultPointsAndTransitions) transitions.elementAt(0);
ResultPointsAndTransitions lSideTwo = (ResultPointsAndTransitions) transitions.elementAt(1);
+ //give up if there is no chance we'll decode something...
+ if (lSideOne.transitions > MIN_GIVEUP_THRESHOLD ||
+ lSideTwo.transitions > MIN_GIVEUP_THRESHOLD) {
+ throw NotFoundException.getNotFoundInstance();
+ }
+
// Figure out which point is their intersection by tallying up the number of times we see the
// endpoints in the four endpoints. One will show up twice.
Hashtable pointCount = new Hashtable();
// The top right point is actually the corner of a module, which is one of the two black modules
// adjacent to the white module at the top right. Tracing to that corner from either the top left
- // or bottom right should work here. The number of transitions could be higher than it should be
- // due to noise. So we try both and take the min.
-
- int dimension = Math.min(transitionsBetween(topLeft, topRight).getTransitions(),
+ // or bottom right should work here.
+ int dimension = Math.max(transitionsBetween(topLeft, topRight).getTransitions(),
transitionsBetween(bottomRight, topRight).getTransitions());
if ((dimension & 0x01) == 1) {
// it can't be odd, so, round... up?
}
dimension += 2;
- BitMatrix bits = sampleGrid(image, topLeft, bottomLeft, bottomRight, dimension);
- return new DetectorResult(bits, new ResultPoint[] {pointA, pointB, pointC, pointD});
+ //correct top right point to match the white module
+ ResultPoint correctedTopRight = correctTopRight(bottomLeft, bottomRight, topLeft, topRight, dimension);
+
+ //We redetermine the dimension using the corrected top right point
+ int dimension2 = Math.min(transitionsBetween(topLeft, correctedTopRight).getTransitions(),
+ transitionsBetween(bottomRight, correctedTopRight).getTransitions());
+ dimension2++;
+ if ((dimension2 & 0x01) == 1) {
+ dimension2++;
+ }
+
+ BitMatrix bits = sampleGrid(image, topLeft, bottomLeft, bottomRight, correctedTopRight, dimension2);
+
+ return new DetectorResult(bits, new ResultPoint[]{topLeft, bottomLeft, bottomRight, correctedTopRight});
+ }
+
+ /**
+ * Calculates the position of the white top right module using the output of the rectangle detector
+ */
+ private ResultPoint correctTopRight(ResultPoint bottomLeft,
+ ResultPoint bottomRight,
+ ResultPoint topLeft,
+ ResultPoint topRight,
+ int dimension) {
+ float corr = distance(bottomLeft, bottomRight) / (float) dimension;
+ float corrx = 0.0f;
+ float corry = 0.0f;
+ int norm = distance(topLeft, topRight);
+ float cos = (topRight.getX() - topLeft.getX()) / norm;
+ float sin = -(topRight.getY() - topLeft.getY()) / norm;
+
+ if (cos > 0.0f && sin > 0.0f) {
+ if (cos > sin) {
+ corrx = corr * cos;
+ corry = -corr * sin;
+ } else {
+ corrx = -corr * sin;
+ corry = -corr * cos;
+ }
+ } else if (cos > 0.0f && sin < 0.0f) {
+ if (cos > -sin) {
+ corrx = -corr * sin;
+ corry = -corr * cos;
+ } else {
+ corrx = corr * cos;
+ corry = -corr * sin;
+ }
+ } else if (cos < 0.0f && sin < 0.0f) {
+ if (-cos > -sin) {
+ corrx = corr * cos;
+ corry = -corr * sin;
+ } else {
+ corrx = -corr * sin;
+ corry = -corr * cos;
+ }
+ } else if (cos < 0.0f && sin > 0.0f) {
+ if (-cos > sin) {
+ corrx = -corr * sin;
+ corry = -corr * cos;
+ } else {
+ corrx = corr * cos;
+ corry = -corr * sin;
+ }
+ }
+
+ return new ResultPoint(topRight.getX() + corrx, topRight.getY() + corry);
+ }
+
+ // L2 distance
+ private static int distance(ResultPoint a, ResultPoint b) {
+ return (int) Math.round(Math.sqrt((a.getX() - b.getX())
+ * (a.getX() - b.getX()) + (a.getY() - b.getY())
+ * (a.getY() - b.getY())));
}
/**
ResultPoint topLeft,
ResultPoint bottomLeft,
ResultPoint bottomRight,
+ ResultPoint topRight,
int dimension) throws NotFoundException {
- // We make up the top right point for now, based on the others.
- // TODO: we actually found a fourth corner above and figured out which of two modules
- // it was the corner of. We could use that here and adjust for perspective distortion.
- float topRightX = (bottomRight.getX() - bottomLeft.getX()) + topLeft.getX();
- float topRightY = (bottomRight.getY() - bottomLeft.getY()) + topLeft.getY();
-
- // Note that unlike in the QR Code sampler, we didn't find the center of modules, but the
- // very corners. So there is no 0.5f here; 0.0f is right.
GridSampler sampler = GridSampler.getInstance();
- return sampler.sampleGrid(
- image,
- dimension,
- 0.0f,
- 0.0f,
- dimension,
- 0.0f,
- dimension,
- dimension,
- 0.0f,
- dimension,
- topLeft.getX(),
- topLeft.getY(),
- topRightX,
- topRightY,
- bottomRight.getX(),
- bottomRight.getY(),
- bottomLeft.getX(),
- bottomLeft.getY());
+
+ return sampler.sampleGrid(image,
+ dimension,
+ 0.5f,
+ 0.5f,
+ dimension - 0.5f,
+ 0.5f,
+ dimension - 0.5f,
+ dimension - 0.5f,
+ 0.5f,
+ dimension - 0.5f,
+ topLeft.getX(),
+ topLeft.getY(),
+ topRight.getX(),
+ topRight.getY(),
+ bottomRight.getX(),
+ bottomRight.getY(),
+ bottomLeft.getX(),
+ bottomLeft.getY());
}
/**
projects / zxing.git / blobdiff