/*
* Copyright 2009 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.Collections.Generic;
using ZXing.Common;
using ZXing.PDF417.Internal;
namespace ZXing.PDF417
{
/// <summary>
/// This implementation can detect and decode PDF417 codes in an image.
///
/// <author>SITA Lab ([email protected])</author>
/// </summary>
public sealed class PDF417Reader : Reader
{
private static readonly ResultPoint[] NO_POINTS = new ResultPoint[0];
private readonly Decoder decoder = new Decoder();
/// <summary>
/// Locates and decodes a PDF417 code in an image.
///
/// <returns>a String representing the content encoded by the PDF417 code</returns>
/// <exception cref="FormatException">if a PDF417 cannot be decoded</exception>
/// </summary>
public Result decode(BinaryBitmap image)
{
return decode(image, null);
}
/// <summary>
/// Locates and decodes a barcode in some format within an image. This method also accepts
/// hints, each possibly associated to some data, which may help the implementation decode.
/// </summary>
/// <param name="image">image of barcode to decode</param>
/// <param name="hints">passed as a <see cref="IDictionary{TKey, TValue}"/> from
/// to arbitrary data. The
/// meaning of the data depends upon the hint type. The implementation may or may not do
/// anything with these hints.</param>
/// <returns>
/// String which the barcode encodes
/// </returns>
public Result decode(BinaryBitmap image,
IDictionary<DecodeHintType, object> hints)
{
DecoderResult decoderResult;
ResultPoint[] points;
if (hints != null && hints.ContainsKey(DecodeHintType.PURE_BARCODE))
{
BitMatrix bits = extractPureBits(image.BlackMatrix);
if (bits == null)
return null;
decoderResult = decoder.decode(bits);
points = NO_POINTS;
}
else
{
DetectorResult detectorResult = new Detector(image).detect(hints);
if (detectorResult == null || detectorResult.Bits == null)
return null;
decoderResult = decoder.decode(detectorResult.Bits);
points = detectorResult.Points;
}
if (decoderResult == null)
return null;
return new Result(decoderResult.Text, decoderResult.RawBytes, points,
BarcodeFormat.PDF_417);
}
/// <summary>
/// Resets any internal state the implementation has after a decode, to prepare it
/// for reuse.
/// </summary>
public void reset()
{
// do nothing
}
/// <summary>
/// This method detects a code in a "pure" image -- that is, pure monochrome image
/// which contains only an unrotated, unskewed, image of a code, with some white border
/// around it. This is a specialized method that works exceptionally fast in this special
/// case.
///
/// <see cref="QrCode.QRCodeReader.extractPureBits(BitMatrix)" />
/// <see cref="Datamatrix.DataMatrixReader.extractPureBits(BitMatrix)" />
/// </summary>
private static BitMatrix extractPureBits(BitMatrix image)
{
int[] leftTopBlack = image.getTopLeftOnBit();
int[] rightBottomBlack = image.getBottomRightOnBit();
if (leftTopBlack == null || rightBottomBlack == null)
{
return null;
}
int moduleSize;
if (!PDF417Reader.moduleSize(leftTopBlack, image, out moduleSize))
return null;
int top = leftTopBlack[1];
int bottom = rightBottomBlack[1];
int left;
if (!findPatternStart(leftTopBlack[0], top, image, out left))
return null;
int right;
if (!findPatternEnd(leftTopBlack[0], top, image, out right))
return null;
int matrixWidth = (right - left + 1) / moduleSize;
int matrixHeight = (bottom - top + 1) / moduleSize;
if (matrixWidth <= 0 || matrixHeight <= 0)
{
return null;
}
// Push in the "border" by half the module width so that we start
// sampling in the middle of the module. Just in case the image is a
// little off, this will help recover.
int nudge = moduleSize >> 1;
top += nudge;
left += nudge;
// Now just read off the bits
var bits = new BitMatrix(matrixWidth, matrixHeight);
for (int y = 0; y < matrixHeight; y++)
{
int iOffset = top + y * moduleSize;
for (int x = 0; x < matrixWidth; x++)
{
if (image[left + x * moduleSize, iOffset])
{
bits[x, y] = true;
}
}
}
return bits;
}
private static bool moduleSize(int[] leftTopBlack, BitMatrix image, out int msize)
{
int x = leftTopBlack[0];
int y = leftTopBlack[1];
int width = image.Width;
while (x < width && image[x, y])
{
x++;
}
if (x == width)
{
msize = 0;
return false;
}
msize = (int)((uint)(x - leftTopBlack[0]) >> 3); // (x - leftTopBlack[0]) >>> 3// We've crossed left first bar, which is 8x
if (msize == 0)
{
return false;
}
return true;
}
private static bool findPatternStart(int x, int y, BitMatrix image, out int start)
{
int width = image.Width;
start = x;
// start should be on black
int transitions = 0;
bool black = true;
while (start < width - 1 && transitions < 8)
{
start++;
bool newBlack = image[start, y];
if (black != newBlack)
{
transitions++;
}
black = newBlack;
}
if (start == width - 1)
{
return false;
}
return true;
}
private static bool findPatternEnd(int x, int y, BitMatrix image, out int end)
{
int width = image.Width;
end = width - 1;
// end should be on black
while (end > x && !image[end, y])
{
end--;
}
int transitions = 0;
bool black = true;
while (end > x && transitions < 9)
{
end--;
bool newBlack = image[end, y];
if (black != newBlack)
{
transitions++;
}
black = newBlack;
}
if (end == x)
{
return false;
}
return true;
}
}
}
