Merge pull request #520 from Shane32/bitarray_codeword_blocks

Deduplicate data block buffers

Author: codebude

QRCoder/Extensions/BitArrayExtensions.cs

@@ -0,0 +1,28 @@
+using System.Collections;
+
+namespace QRCoder
+{
+    /// <summary>
+    /// Helper methods for <see cref="BitArray"/>.
+    /// </summary>
+    internal static class BitArrayExtensions
+    {
+        /// <summary>
+        /// Copies a specified number of elements from one <see cref="BitArray"/> to another starting at the specified offsets.
+        /// </summary>
+        /// <param name="source">The source <see cref="BitArray"/> from which elements will be copied.</param>
+        /// <param name="sourceOffset">The zero-based index in the source <see cref="BitArray"/> at which copying begins.</param>
+        /// <param name="destination">The destination <see cref="BitArray"/> to which elements will be copied.</param>
+        /// <param name="destinationOffset">The zero-based index in the destination <see cref="BitArray"/> at which storing begins.</param>
+        /// <param name="count">The number of elements to copy.</param>
+        /// <returns>The index in the destination <see cref="BitArray"/> immediately following the last copied element.</returns>
+        public static int CopyTo(this BitArray source, BitArray destination, int sourceOffset, int destinationOffset, int count)
+        {
+            for (int i = 0; i < count; i++)
+            {
+                destination[destinationOffset + i] = source[sourceOffset + i];
+            }
+            return destinationOffset + count;
+        }
+    }
+}

QRCoder/QRCodeGenerator.CodewordBlock.cs

@@ -1,4 +1,6 @@
-namespace QRCoder
+using System.Collections;
+
+namespace QRCoder
 {
     public partial class QRCodeGenerator
     {
@@ -11,18 +13,25 @@ private struct CodewordBlock
             /// <summary>
             /// Initializes a new instance of the CodewordBlock struct with specified arrays of code words and error correction (ECC) words.
             /// </summary>
-            /// <param name="codeWords">The array of data codewords for this block. Data codewords carry the actual information.</param>
+            /// <param name="codeWordsOffset">The offset of the data codewords within the main BitArray. Data codewords carry the actual information.</param>
+            /// <param name="codeWordsLength">The length in bits of the data codewords within the main BitArray.</param>
             /// <param name="eccWords">The array of error correction codewords for this block. These codewords help recover the data if the QR code is damaged.</param>
-            public CodewordBlock(byte[] codeWords, byte[] eccWords)
+            public CodewordBlock(int codeWordsOffset, int codeWordsLength, byte[] eccWords)
             {
-                this.CodeWords = codeWords;
+                this.CodeWordsOffset = codeWordsOffset;
+                this.CodeWordsLength = codeWordsLength;
                 this.ECCWords = eccWords;
             }
 
             /// <summary>
-            /// Gets the data codewords associated with this block. 
+            /// Gets the offset of the data codewords in the BitArray.
+            /// </summary>
+            public int CodeWordsOffset { get; }
+
+            /// <summary>
+            /// Gets the length of the data codewords in the BitArray.
             /// </summary>
-            public byte[] CodeWords { get; }
+            public int CodeWordsLength { get; }
 
             /// <summary>
             /// Gets the error correction codewords associated with this block.

QRCoder/QRCodeGenerator.cs

@@ -228,17 +228,17 @@ private static QRCodeData GenerateQrCode(BitArray bitArray, ECCLevel eccLevel, i
             {
                 //Calculate error correction words
                 codeWordWithECC = new List<CodewordBlock>(eccInfo.BlocksInGroup1 + eccInfo.BlocksInGroup2);
-                AddCodeWordBlocks(1, eccInfo.BlocksInGroup1, eccInfo.CodewordsInGroup1, bitArray, 0, bitArray.Length, generatorPolynom);
+                AddCodeWordBlocks(1, eccInfo.BlocksInGroup1, eccInfo.CodewordsInGroup1, 0, bitArray.Length, generatorPolynom);
                 int offset = eccInfo.BlocksInGroup1 * eccInfo.CodewordsInGroup1 * 8;
-                AddCodeWordBlocks(2, eccInfo.BlocksInGroup2, eccInfo.CodewordsInGroup2, bitArray, offset, bitArray.Length - offset, generatorPolynom);
+                AddCodeWordBlocks(2, eccInfo.BlocksInGroup2, eccInfo.CodewordsInGroup2, offset, bitArray.Length - offset, generatorPolynom);
             }
 
             //Calculate interleaved code word lengths
             int interleavedLength = 0;
             for (var i = 0; i < Math.Max(eccInfo.CodewordsInGroup1, eccInfo.CodewordsInGroup2); i++)
             {
                 foreach (var codeBlock in codeWordWithECC)
-                    if (codeBlock.CodeWords.Length > i)
+                    if ((uint)codeBlock.CodeWordsLength / 8 > i)
                         interleavedLength += 8;
             }
             for (var i = 0; i < eccInfo.ECCPerBlock; i++)
@@ -255,8 +255,10 @@ private static QRCodeData GenerateQrCode(BitArray bitArray, ECCLevel eccLevel, i
             for (var i = 0; i < Math.Max(eccInfo.CodewordsInGroup1, eccInfo.CodewordsInGroup2); i++)
             {
                 foreach (var codeBlock in codeWordWithECC)
-                    if (codeBlock.CodeWords.Length > i)
-                        pos = DecToBin(codeBlock.CodeWords[i], 8, interleavedData, pos);
+                {
+                    if ((uint)codeBlock.CodeWordsLength / 8 > i)
+                        pos = bitArray.CopyTo(interleavedData, (int)((uint)i * 8) + codeBlock.CodeWordsOffset, pos, 8);
+                }
             }
             for (var i = 0; i < eccInfo.ECCPerBlock; i++)
             {
@@ -289,17 +291,13 @@ private static QRCodeData GenerateQrCode(BitArray bitArray, ECCLevel eccLevel, i
             ModulePlacer.AddQuietZone(qr);
             return qr;
 
-            void AddCodeWordBlocks(int blockNum, int blocksInGroup, int codewordsInGroup, BitArray bitArray2, int offset2, int count, Polynom generatorPolynom)
+            void AddCodeWordBlocks(int blockNum, int blocksInGroup, int codewordsInGroup, int offset2, int count, Polynom generatorPolynom)
             {
                 var groupLength = codewordsInGroup * 8;
                 for (var i = 0; i < blocksInGroup; i++)
                 {
-                    var bitBlockList = BinaryStringToBitBlockByteList(bitArray2, offset2, groupLength);
-                    var eccWordList = CalculateECCWords(bitArray2, offset2, groupLength, eccInfo, generatorPolynom);
-                    codeWordWithECC.Add(new CodewordBlock(
-                                          bitBlockList,
-                                          eccWordList)
-                                    );
+                    var eccWordList = CalculateECCWords(bitArray, offset2, groupLength, eccInfo, generatorPolynom);
+                    codeWordWithECC.Add(new CodewordBlock(offset2, groupLength, eccWordList));
                     offset2 += groupLength;
                 }
             }
@@ -618,37 +616,6 @@ private static Polynom CalculateGeneratorPolynom(int numEccWords)
             return generatorPolynom; // Return the completed generator polynomial
         }
 
-        /// <summary>
-        /// Converts a segment of a BitArray into a list of bytes where each byte represents a consecutive block of 8 bits from the BitArray.
-        /// </summary>
-        private static byte[] BinaryStringToBitBlockByteList(BitArray bitString, int offset, int count)
-        {
-            const int blockSize = 8;
-            if (count % blockSize != 0)
-                ThrowCountMustBeMultipleOf8Exception();
-            var numberOfBlocks = (int)((uint)count / blockSize);
-            var blocklist = new byte[numberOfBlocks];
-
-            int j = 0;
-            count += offset;
-            for (int i = offset; i < count; i += blockSize)
-            {
-                blocklist[j++] = (byte)(
-                    (bitString[i] ? 128 : 0) + 
-                    (bitString[i + 1] ? 64 : 0) + 
-                    (bitString[i + 2] ? 32 : 0) + 
-                    (bitString[i + 3] ? 16 : 0) + 
-                    (bitString[i + 4] ? 8 : 0) + 
-                    (bitString[i + 5] ? 4 : 0) + 
-                    (bitString[i + 6] ? 2 : 0) + 
-                    (bitString[i + 7] ? 1 : 0));
-            }
-
-            return blocklist;
-
-            void ThrowCountMustBeMultipleOf8Exception() => throw new ArgumentOutOfRangeException(nameof(count), "Count must be a multiple of 8.");
-        }
-
         /// <summary>
         /// Converts a segment of a BitArray into its decimal (integer) equivalent.
         /// </summary>