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- /*
- * Copyright 2007 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 ZXing.Common;
-
- namespace ZXing.QrCode.Internal
- {
- /// <author>Sean Owen</author>
- sealed class BitMatrixParser
- {
- private readonly BitMatrix bitMatrix;
- private Version parsedVersion;
- private FormatInformation parsedFormatInfo;
- private bool mirrored;
-
- /// <param name="bitMatrix">{@link BitMatrix} to parse</param>
- /// <throws>ReaderException if dimension is not >= 21 and 1 mod 4</throws>
- internal static BitMatrixParser createBitMatrixParser(BitMatrix bitMatrix)
- {
- int dimension = bitMatrix.Height;
- if (dimension < 21 || (dimension & 0x03) != 1)
- {
- return null;
- }
- return new BitMatrixParser(bitMatrix);
- }
-
- private BitMatrixParser(BitMatrix bitMatrix)
- {
- // Should only be called from createBitMatrixParser with the important checks before
- this.bitMatrix = bitMatrix;
- }
-
- /// <summary> <p>Reads format information from one of its two locations within the QR Code.</p>
- ///
- /// </summary>
- /// <returns> {@link FormatInformation} encapsulating the QR Code's format info
- /// </returns>
- /// <throws> ReaderException if both format information locations cannot be parsed as </throws>
- /// <summary> the valid encoding of format information
- /// </summary>
- internal FormatInformation readFormatInformation()
- {
- if (parsedFormatInfo != null)
- {
- return parsedFormatInfo;
- }
-
- // Read top-left format info bits
- int formatInfoBits1 = 0;
- for (int i = 0; i < 6; i++)
- {
- formatInfoBits1 = copyBit(i, 8, formatInfoBits1);
- }
- // .. and skip a bit in the timing pattern ...
- formatInfoBits1 = copyBit(7, 8, formatInfoBits1);
- formatInfoBits1 = copyBit(8, 8, formatInfoBits1);
- formatInfoBits1 = copyBit(8, 7, formatInfoBits1);
- // .. and skip a bit in the timing pattern ...
- for (int j = 5; j >= 0; j--)
- {
- formatInfoBits1 = copyBit(8, j, formatInfoBits1);
- }
- // Read the top-right/bottom-left pattern too
- int dimension = bitMatrix.Height;
- int formatInfoBits2 = 0;
- int jMin = dimension - 7;
- for (int j = dimension - 1; j >= jMin; j--)
- {
- formatInfoBits2 = copyBit(8, j, formatInfoBits2);
- }
- for (int i = dimension - 8; i < dimension; i++)
- {
- formatInfoBits2 = copyBit(i, 8, formatInfoBits2);
- }
-
- parsedFormatInfo = FormatInformation.decodeFormatInformation(formatInfoBits1, formatInfoBits2);
- if (parsedFormatInfo != null)
- {
- return parsedFormatInfo;
- }
- return null;
- }
-
- /// <summary> <p>Reads version information from one of its two locations within the QR Code.</p>
- ///
- /// </summary>
- /// <returns> {@link Version} encapsulating the QR Code's version
- /// </returns>
- /// <throws> ReaderException if both version information locations cannot be parsed as </throws>
- /// <summary> the valid encoding of version information
- /// </summary>
- internal Version readVersion()
- {
- if (parsedVersion != null)
- {
- return parsedVersion;
- }
-
- int dimension = bitMatrix.Height;
-
- int provisionalVersion = (dimension - 17) >> 2;
- if (provisionalVersion <= 6)
- {
- return Version.getVersionForNumber(provisionalVersion);
- }
-
- // Read top-right version info: 3 wide by 6 tall
- int versionBits = 0;
- int ijMin = dimension - 11;
- for (int j = 5; j >= 0; j--)
- {
- for (int i = dimension - 9; i >= ijMin; i--)
- {
- versionBits = copyBit(i, j, versionBits);
- }
- }
-
- parsedVersion = Version.decodeVersionInformation(versionBits);
- if (parsedVersion != null && parsedVersion.DimensionForVersion == dimension)
- {
- return parsedVersion;
- }
-
- // Hmm, failed. Try bottom left: 6 wide by 3 tall
- versionBits = 0;
- for (int i = 5; i >= 0; i--)
- {
- for (int j = dimension - 9; j >= ijMin; j--)
- {
- versionBits = copyBit(i, j, versionBits);
- }
- }
-
- parsedVersion = Version.decodeVersionInformation(versionBits);
- if (parsedVersion != null && parsedVersion.DimensionForVersion == dimension)
- {
- return parsedVersion;
- }
- return null;
- }
-
- private int copyBit(int i, int j, int versionBits)
- {
- bool bit = mirrored ? bitMatrix[j, i] : bitMatrix[i, j];
- return bit ? (versionBits << 1) | 0x1 : versionBits << 1;
- }
-
- /// <summary> <p>Reads the bits in the {@link BitMatrix} representing the finder pattern in the
- /// correct order in order to reconstruct the codewords bytes contained within the
- /// QR Code.</p>
- ///
- /// </summary>
- /// <returns> bytes encoded within the QR Code
- /// </returns>
- /// <throws> ReaderException if the exact number of bytes expected is not read </throws>
- internal byte[] readCodewords()
- {
- FormatInformation formatInfo = readFormatInformation();
- if (formatInfo == null)
- return null;
- Version version = readVersion();
- if (version == null)
- return null;
-
- // Get the data mask for the format used in this QR Code. This will exclude
- // some bits from reading as we wind through the bit matrix.
- DataMask dataMask = DataMask.forReference(formatInfo.DataMask);
- int dimension = bitMatrix.Height;
- dataMask.unmaskBitMatrix(bitMatrix, dimension);
-
- BitMatrix functionPattern = version.buildFunctionPattern();
-
- bool readingUp = true;
- byte[] result = new byte[version.TotalCodewords];
- int resultOffset = 0;
- int currentByte = 0;
- int bitsRead = 0;
- // Read columns in pairs, from right to left
- for (int j = dimension - 1; j > 0; j -= 2)
- {
- if (j == 6)
- {
- // Skip whole column with vertical alignment pattern;
- // saves time and makes the other code proceed more cleanly
- j--;
- }
- // Read alternatingly from bottom to top then top to bottom
- for (int count = 0; count < dimension; count++)
- {
- int i = readingUp ? dimension - 1 - count : count;
- for (int col = 0; col < 2; col++)
- {
- // Ignore bits covered by the function pattern
- if (!functionPattern[j - col, i])
- {
- // Read a bit
- bitsRead++;
- currentByte <<= 1;
- if (bitMatrix[j - col, i])
- {
- currentByte |= 1;
- }
- // If we've made a whole byte, save it off
- if (bitsRead == 8)
- {
- result[resultOffset++] = (byte)currentByte;
- bitsRead = 0;
- currentByte = 0;
- }
- }
- }
- }
- readingUp ^= true; // readingUp = !readingUp; // switch directions
- }
- if (resultOffset != version.TotalCodewords)
- {
- return null;
- }
- return result;
- }
-
- /**
- * Revert the mask removal done while reading the code words. The bit matrix should revert to its original state.
- */
- internal void remask()
- {
- if (parsedFormatInfo == null)
- {
- return; // We have no format information, and have no data mask
- }
- DataMask dataMask = DataMask.forReference(parsedFormatInfo.DataMask);
- int dimension = bitMatrix.Height;
- dataMask.unmaskBitMatrix(bitMatrix, dimension);
- }
-
- /**
- * Prepare the parser for a mirrored operation.
- * This flag has effect only on the {@link #readFormatInformation()} and the
- * {@link #readVersion()}. Before proceeding with {@link #readCodewords()} the
- * {@link #mirror()} method should be called.
- *
- * @param mirror Whether to read version and format information mirrored.
- */
- internal void setMirror(bool mirror)
- {
- parsedVersion = null;
- parsedFormatInfo = null;
- mirrored = mirror;
- }
-
- /** Mirror the bit matrix in order to attempt a second reading. */
- internal void mirror()
- {
- for (int x = 0; x < bitMatrix.Width; x++)
- {
- for (int y = x + 1; y < bitMatrix.Height; y++)
- {
- if (bitMatrix[x, y] != bitMatrix[y, x])
- {
- bitMatrix.flip(y, x);
- bitMatrix.flip(x, y);
- }
- }
- }
- }
- }
- }
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