/**
* <p>Detects a QR Code in an image, simply.</p>
*
* @param hints optional hints to detector
* @return {@link DetectorResult} encapsulating results of detecting a QR Code
* @throws ReaderException if no QR Code can be found
*/
public DetectorResult detect(System.Collections.Hashtable hints)
{
MonochromeBitmapSource image = this.image;
if (!BlackPointEstimationMethod.TWO_D_SAMPLING.Equals(image.getLastEstimationMethod()))
{
image.estimateBlackPoint(BlackPointEstimationMethod.TWO_D_SAMPLING, 0);
}
FinderPatternFinder finder = new FinderPatternFinder(image);
FinderPatternInfo info = finder.find(hints);
FinderPattern topLeft = info.getTopLeft();
FinderPattern topRight = info.getTopRight();
FinderPattern bottomLeft = info.getBottomLeft();
float moduleSize = calculateModuleSize(topLeft, topRight, bottomLeft);
if (moduleSize < 1.0f)
{
throw new ReaderException();
}
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 / (float)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,
(float)i);
break;
} catch (ReaderException re) {
// try next round
}
}
if (alignmentPattern == null)
{
throw new ReaderException();
}
}
BitMatrix bits = sampleGrid(image, topLeft, topRight, bottomLeft, alignmentPattern, 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));
}
/**
* 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".
*
* @param image The image to decode
* @param hints Any hints that were requested
* @return The contents of the decoded barcode
* @throws ReaderException Any spontaneous errors which occur
*/
private Result doDecode(MonochromeBitmapSource image, System.Collections.Hashtable hints)
{
int width = image.getWidth();
int height = image.getHeight();
BitArray row = new BitArray(width);
int middle = height >> 1;
bool tryHarder = hints != null && hints.ContainsKey(DecodeHintType.TRY_HARDER);
int rowStep = Math.Max(1, height >> (tryHarder ? 7 : 4));
int MaxLines;
if (tryHarder)
{
MaxLines = height; // Look at the whole image, not just the center
}
else
{
MaxLines = 9; // Nine rows spaced 1/16 apart is roughly the middle half of the image
}
for (int x = 0; x < MaxLines; x++)
{
// Scanning from the middle out. Determine which row we're looking at next:
int rowStepsAboveOrBelow = (x + 1) >> 1;
bool isAbove = (x & 0x01) == 0; // i.e. is x even?
int rowNumber = middle + rowStep * (isAbove ? rowStepsAboveOrBelow : -rowStepsAboveOrBelow);
if (rowNumber < 0 || rowNumber >= height)
{
// Oops, if we run off the top or bottom, stop
break;
}
// Estimate black point for this row and load it:
try {
image.estimateBlackPoint(BlackPointEstimationMethod.ROW_SAMPLING, rowNumber);
} catch (ReaderException re) {
continue;
}
image.getBlackRow(rowNumber, row, 0, width);
// While we have the image data in a BitArray, it's fairly cheap to reverse it in place to
// handle decoding upside down barcodes.
for (int attempt = 0; attempt < 2; attempt++)
{
if (attempt == 1) // trying again?
{
row.reverse(); // reverse the row and continue
}
try {
// Look for a barcode
Result result = decodeRow(rowNumber, row, hints);
// We found our barcode
if (attempt == 1)
{
// But it was upside down, so note that
result.putMetadata(ResultMetadataType.ORIENTATION, 180);
// And remember to flip the result points horizontally.
ResultPoint[] points = result.getResultPoints();
points[0] = (ResultPoint) new GenericResultPoint(width - points[0].getX() - 1, points[0].getY());
points[1] = (ResultPoint) new GenericResultPoint(width - points[1].getX() - 1, points[1].getY());
}
return(result);
} catch (ReaderException re) {
// continue -- just couldn't decode this row
}
}
}
throw new ReaderException();
}
/**
* 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".
*
* @param image The image to decode
* @param hints Any hints that were requested
* @return The contents of the decoded barcode
* @throws ReaderException Any spontaneous errors which occur
*/
private Result doDecode(MonochromeBitmapSource image, System.Collections.Hashtable hints)
{
int width = image.getWidth();
int height = image.getHeight();
BitArray row = new BitArray(width);
int middle = height >> 1;
bool tryHarder = hints != null && hints.ContainsKey(DecodeHintType.TRY_HARDER);
int rowStep = Math.Max(1, height >> (tryHarder ? 7 : 4));
int MaxLines;
if (tryHarder) {
MaxLines = height; // Look at the whole image, not just the center
} else {
MaxLines = 9; // Nine rows spaced 1/16 apart is roughly the middle half of the image
}
for (int x = 0; x < MaxLines; x++) {
// Scanning from the middle out. Determine which row we're looking at next:
int rowStepsAboveOrBelow = (x + 1) >> 1;
bool isAbove = (x & 0x01) == 0; // i.e. is x even?
int rowNumber = middle + rowStep * (isAbove ? rowStepsAboveOrBelow : -rowStepsAboveOrBelow);
if (rowNumber < 0 || rowNumber >= height) {
// Oops, if we run off the top or bottom, stop
break;
}
// Estimate black point for this row and load it:
try {
image.estimateBlackPoint(BlackPointEstimationMethod.ROW_SAMPLING, rowNumber);
} catch (ReaderException re) {
continue;
}
image.getBlackRow(rowNumber, row,0, width);
// While we have the image data in a BitArray, it's fairly cheap to reverse it in place to
// handle decoding upside down barcodes.
for (int attempt = 0; attempt < 2; attempt++) {
if (attempt == 1) { // trying again?
row.reverse(); // reverse the row and continue
}
try {
// Look for a barcode
Result result = decodeRow(rowNumber, row, hints);
// We found our barcode
if (attempt == 1) {
// But it was upside down, so note that
result.putMetadata(ResultMetadataType.ORIENTATION, 180);
// And remember to flip the result points horizontally.
ResultPoint[] points = result.getResultPoints();
points[0] = (ResultPoint) new GenericResultPoint(width - points[0].getX() - 1, points[0].getY());
points[1] = (ResultPoint)new GenericResultPoint(width - points[1].getX() - 1, points[1].getY());
}
return result;
} catch (ReaderException re) {
// continue -- just couldn't decode this row
}
}
}
throw new ReaderException();
}
