/*
* Copyright 2008 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.
*/
using System;
using BinaryBitmap = com.google.zxing.BinaryBitmap;
using DecodeHintType = com.google.zxing.DecodeHintType;
using Reader = com.google.zxing.Reader;
using ReaderException = com.google.zxing.ReaderException;
using Result = com.google.zxing.Result;
using ResultMetadataType = com.google.zxing.ResultMetadataType;
using ResultPoint = com.google.zxing.ResultPoint;
using BitArray = com.google.zxing.common.BitArray;
namespace com.google.zxing.oned
{
/// <summary> Encapsulates functionality and implementation that is common to all families
/// of one-dimensional barcodes.
///
/// </summary>
/// <author> dswitkin@google.com (Daniel Switkin)
/// </author>
/// <author> Sean Owen
/// </author>
/// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source
/// </author>
public abstract class OneDReader : Reader
{
private const int INTEGER_MATH_SHIFT = 8;
//UPGRADE_NOTE: Final was removed from the declaration of 'PATTERN_MATCH_RESULT_SCALE_FACTOR '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
internal static readonly int PATTERN_MATCH_RESULT_SCALE_FACTOR = 1 << INTEGER_MATH_SHIFT;
public virtual Result decode(BinaryBitmap image)
{
return decode(image, null);
}
// Note that we don't try rotation without the try harder flag, even if rotation was supported.
public virtual Result decode(BinaryBitmap image, System.Collections.Hashtable hints)
{
try
{
return doDecode(image, hints);
}
catch (ReaderException re)
{
bool tryHarder = hints != null && hints.ContainsKey(DecodeHintType.TRY_HARDER);
if (tryHarder && image.RotateSupported)
{
BinaryBitmap rotatedImage = image.rotateCounterClockwise();
Result result = doDecode(rotatedImage, hints);
// Record that we found it rotated 90 degrees CCW / 270 degrees CW
System.Collections.Hashtable metadata = result.ResultMetadata;
int orientation = 270;
if (metadata != null && metadata.ContainsKey(ResultMetadataType.ORIENTATION))
{
// But if we found it reversed in doDecode(), add in that result here:
orientation = (orientation + ((System.Int32) metadata[ResultMetadataType.ORIENTATION])) % 360;
}
result.putMetadata(ResultMetadataType.ORIENTATION, (System.Object) orientation);
// Update result points
ResultPoint[] points = result.ResultPoints;
int height = rotatedImage.Height;
for (int i = 0; i < points.Length; i++)
{
points[i] = new ResultPoint(height - points[i].Y - 1, points[i].X);
}
return result;
}
else
{
throw re;
}
}
}
/// <summary> 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".
///
/// </summary>
/// <param name="image">The image to decode
/// </param>
/// <param name="hints">Any hints that were requested
/// </param>
/// <returns> The contents of the decoded barcode
/// </returns>
/// <throws> ReaderException Any spontaneous errors which occur </throws>
private Result doDecode(BinaryBitmap image, System.Collections.Hashtable hints)
{
int width = image.Width;
int height = image.Height;
BitArray row = new BitArray(width);
int middle = height >> 1;
bool tryHarder = hints != null && hints.ContainsKey(DecodeHintType.TRY_HARDER);
int rowStep = System.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
{
row = image.getBlackRow(rowNumber, row);
}
catch (ReaderException re)
{
continue;
}
// 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
// This means we will only ever draw result points *once* in the life of this method
// since we want to avoid drawing the wrong points after flipping the row, and,
// don't want to clutter with noise from every single row scan -- just the scans
// that start on the center line.
if (hints != null && hints.ContainsKey(DecodeHintType.NEED_RESULT_POINT_CALLBACK))
{
System.Collections.Hashtable newHints = System.Collections.Hashtable.Synchronized(new System.Collections.Hashtable()); // Can't use clone() in J2ME
System.Collections.IEnumerator hintEnum = hints.Keys.GetEnumerator();
//UPGRADE_TODO: Method 'java.util.Enumeration.hasMoreElements' was converted to 'System.Collections.IEnumerator.MoveNext' which has a different behavior. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1073_javautilEnumerationhasMoreElements'"
while (hintEnum.MoveNext())
{
//UPGRADE_TODO: Method 'java.util.Enumeration.nextElement' was converted to 'System.Collections.IEnumerator.Current' which has a different behavior. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1073_javautilEnumerationnextElement'"
System.Object key = hintEnum.Current;
if (!key.Equals(DecodeHintType.NEED_RESULT_POINT_CALLBACK))
{
newHints[key] = hints[key];
}
}
hints = newHints;
}
}
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, (System.Object) 180);
// And remember to flip the result points horizontally.
ResultPoint[] points = result.ResultPoints;
points[0] = new ResultPoint(width - points[0].X - 1, points[0].Y);
points[1] = new ResultPoint(width - points[1].X - 1, points[1].Y);
}
return result;
}
catch (ReaderException re)
{
// continue -- just couldn't decode this row
}
}
}
throw ReaderException.Instance;
}
/// <summary> Records the size of successive runs of white and black pixels in a row, starting at a given point.
/// The values are recorded in the given array, and the number of runs recorded is equal to the size
/// of the array. If the row starts on a white pixel at the given start point, then the first count
/// recorded is the run of white pixels starting from that point; likewise it is the count of a run
/// of black pixels if the row begin on a black pixels at that point.
///
/// </summary>
/// <param name="row">row to count from
/// </param>
/// <param name="start">offset into row to start at
/// </param>
/// <param name="counters">array into which to record counts
/// </param>
/// <throws> ReaderException if counters cannot be filled entirely from row before running out </throws>
/// <summary> of pixels
/// </summary>
internal static void recordPattern(BitArray row, int start, int[] counters)
{
int numCounters = counters.Length;
for (int i = 0; i < numCounters; i++)
{
counters[i] = 0;
}
int end = row.Size;
if (start >= end)
{
throw ReaderException.Instance;
}
bool isWhite = !row.get_Renamed(start);
int counterPosition = 0;
int i2 = start;
while (i2 < end)
{
bool pixel = row.get_Renamed(i2);
if (pixel ^ isWhite)
{
// that is, exactly one is true
counters[counterPosition]++;
}
else
{
counterPosition++;
if (counterPosition == numCounters)
{
break;
}
else
{
counters[counterPosition] = 1;
isWhite ^= true; // isWhite = !isWhite;
}
}
i2++;
}
// If we read fully the last section of pixels and filled up our counters -- or filled
// the last counter but ran off the side of the image, OK. Otherwise, a problem.
if (!(counterPosition == numCounters || (counterPosition == numCounters - 1 && i2 == end)))
{
throw ReaderException.Instance;
}
}
/// <summary> Determines how closely a set of observed counts of runs of black/white values matches a given
/// target pattern. This is reported as the ratio of the total variance from the expected pattern
/// proportions across all pattern elements, to the length of the pattern.
///
/// </summary>
/// <param name="counters">observed counters
/// </param>
/// <param name="pattern">expected pattern
/// </param>
/// <param name="maxIndividualVariance">The most any counter can differ before we give up
/// </param>
/// <returns> ratio of total variance between counters and pattern compared to total pattern size,
/// where the ratio has been multiplied by 256. So, 0 means no variance (perfect match); 256 means
/// the total variance between counters and patterns equals the pattern length, higher values mean
/// even more variance
/// </returns>
internal static int patternMatchVariance(int[] counters, int[] pattern, int maxIndividualVariance)
{
int numCounters = counters.Length;
int total = 0;
int patternLength = 0;
for (int i = 0; i < numCounters; i++)
{
total += counters[i];
patternLength += pattern[i];
}
if (total < patternLength)
{
// If we don't even have one pixel per unit of bar width, assume this is too small
// to reliably match, so fail:
return System.Int32.MaxValue;
}
// We're going to fake floating-point math in integers. We just need to use more bits.
// Scale up patternLength so that intermediate values below like scaledCounter will have
// more "significant digits"
int unitBarWidth = (total << INTEGER_MATH_SHIFT) / patternLength;
maxIndividualVariance = (maxIndividualVariance * unitBarWidth) >> INTEGER_MATH_SHIFT;
int totalVariance = 0;
for (int x = 0; x < numCounters; x++)
{
int counter = counters[x] << INTEGER_MATH_SHIFT;
int scaledPattern = pattern[x] * unitBarWidth;
int variance = counter > scaledPattern?counter - scaledPattern:scaledPattern - counter;
if (variance > maxIndividualVariance)
{
return System.Int32.MaxValue;
}
totalVariance += variance;
}
return totalVariance / total;
}
/// <summary> <p>Attempts to decode a one-dimensional barcode format given a single row of
/// an image.</p>
///
/// </summary>
/// <param name="rowNumber">row number from top of the row
/// </param>
/// <param name="row">the black/white pixel data of the row
/// </param>
/// <param name="hints">decode hints
/// </param>
/// <returns> {@link Result} containing encoded string and start/end of barcode
/// </returns>
/// <throws> ReaderException if an error occurs or barcode cannot be found </throws>
public abstract Result decodeRow(int rowNumber, BitArray row, System.Collections.Hashtable hints);
}
}