Optimize QRCodeData.SaveRawData and QRCodeData.GetRawData

QRCoder/QRCodeData.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics;
 using System.IO.Compression;
 
 namespace QRCoder;
@@ -119,6 +120,8 @@ public QRCodeData(byte[] rawData, Compression compressMode)
                 ModuleMatrix[y][x] = modules.Dequeue();
             }
         }
+
+        Debug.Assert(modules.Count < 8);
     }
 
     /// <summary>
@@ -129,11 +132,30 @@ public QRCodeData(byte[] rawData, Compression compressMode)
     public byte[] GetRawData(Compression compressMode)
     {
         using var output = new MemoryStream();
+
+        WriteRawData(output, compressMode);
+
+        return output.ToArray();
+    }
+
+    /// <summary>
+    /// Saves the raw data of the QR code to a specified file with the specified compression mode.
+    /// </summary>
+    /// <param name="filePath">The path to the file where the raw data will be saved.</param>
+    /// <param name="compressMode">The compression mode used for the raw data.</param>
+    public void SaveRawData(string filePath, Compression compressMode)
+    {
+        using var output = new FileStream(filePath, FileMode.Create, FileAccess.Write, FileShare.Read);
+        WriteRawData(output, compressMode);
+    }
+
+    private void WriteRawData(Stream output, Compression compressMode)
+    {
         Stream targetStream = output;
         DeflateStream? deflateStream = null;
         GZipStream? gzipStream = null;
 
-        //Set up compression stream if needed
+        // Set up compression stream if needed
         if (compressMode == Compression.Deflate)
         {
             deflateStream = new DeflateStream(output, CompressionMode.Compress, true);
@@ -147,61 +169,60 @@ public byte[] GetRawData(Compression compressMode)
 
         try
         {
-            //Add header - signature ("QRR")
+            // Add header - signature ("QRR")
 #if HAS_SPAN
             targetStream.Write([0x51, 0x52, 0x52, 0x00]);
 #else
-            targetStream.Write(new byte[] { 0x51, 0x52, 0x52, 0x00 }, 0, 4);
+            targetStream.Write([0x51, 0x52, 0x52, 0x00], 0, 4);
 #endif
 
-            //Add header - rowsize
+            // Add header - rowsize
             targetStream.WriteByte((byte)ModuleMatrix.Count);
 
-            //Build data queue
-            var capacity = ModuleMatrix.Count * ModuleMatrix.Count + 7; // Total modules + max padding for byte alignment
-            var dataQueue = new Queue<int>(capacity);
+            // Write data one byte at a time
+            int data = 0;
+            int bits = 0;
+
             foreach (var row in ModuleMatrix)
             {
                 for (int i = 0; i < row.Length; i++)
                 {
-                    dataQueue.Enqueue(row[i] ? 1 : 0);
+                    data <<= 1;
+
+                    if (row[i])
+                    {
+                        data += 1;
+                    }
+
+                    bits++;
+
+                    if (bits == 8)
+                    {
+                        targetStream.WriteByte((byte)data);
+                        data = 0;
+                        bits = 0;
+                    }
                 }
             }
-            int mod = (int)(((uint)ModuleMatrix.Count * (uint)ModuleMatrix.Count) % 8);
-            for (int i = 0; i < 8 - mod; i++)
-            {
-                dataQueue.Enqueue(0);
-            }
 
-            //Process queue
-            while (dataQueue.Count > 0)
+            if (bits > 0)
             {
-                byte b = 0;
-                for (int i = 7; i >= 0; i--)
-                {
-                    b += (byte)(dataQueue.Dequeue() << i);
-                }
-                targetStream.WriteByte(b);
+                Debug.Assert(bits < 8);
+
+                data <<= 8 - bits;
+
+                targetStream.WriteByte((byte)data);
             }
         }
         finally
         {
-            //Close compression streams to flush data
+            // Close compression streams to flush data
             deflateStream?.Dispose();
             gzipStream?.Dispose();
         }
 
-        return output.ToArray();
     }
 
-    /// <summary>
-    /// Saves the raw data of the QR code to a specified file with the specified compression mode.
-    /// </summary>
-    /// <param name="filePath">The path to the file where the raw data will be saved.</param>
-    /// <param name="compressMode">The compression mode used for the raw data.</param>
-    public void SaveRawData(string filePath, Compression compressMode)
-        => File.WriteAllBytes(filePath, GetRawData(compressMode));
-
     /// <summary>
     /// Gets the version of the QR code.
     /// </summary>

QRCoderTests/QRGeneratorTests.cs

@@ -737,6 +737,30 @@ public void can_save_and_load_qrcode_data(QRCodeData.Compression compressionMode
         reloadedMatrix.ShouldBe(originalMatrix);
     }
 
+    [Theory]
+    [InlineData(QRCodeData.Compression.Uncompressed)]
+    [InlineData(QRCodeData.Compression.Deflate)]
+    [InlineData(QRCodeData.Compression.GZip)]
+    public void can_save_and_load_qrcode_data_to_file(QRCodeData.Compression compressionMode)
+    {
+        // Arrange - Create a QR code
+        var originalQrData = QRCodeGenerator.GenerateQrCode("https://github.com/Shane32/QRCoder", ECCLevel.H);
+        var originalMatrix = string.Join("", originalQrData.ModuleMatrix.Select(x => x.ToBitString()).ToArray());
+        var filePath = System.IO.Path.GetTempFileName();
+
+        // Act - Save raw data and reload it
+        originalQrData.SaveRawData(filePath, compressionMode);
+        var reloadedQrData = new QRCodeData(filePath, compressionMode);
+        var reloadedMatrix = string.Join("", reloadedQrData.ModuleMatrix.Select(x => x.ToBitString()).ToArray());
+
+        // Assert - Verify the data matches
+        reloadedQrData.Version.ShouldBe(originalQrData.Version);
+        reloadedQrData.ModuleMatrix.Count.ShouldBe(originalQrData.ModuleMatrix.Count);
+        reloadedMatrix.ShouldBe(originalMatrix);
+
+        System.IO.File.Delete(filePath);
+    }
+
     [Theory]
     [InlineData(QRCodeData.Compression.Uncompressed)]
     [InlineData(QRCodeData.Compression.Deflate)]
@@ -887,14 +911,13 @@ public static class ExtensionMethods
 {
     public static string ToBitString(this BitArray bits)
     {
-        var sb = new StringBuilder();
         int bitLength = bits.Length;
+        char[] sb = new char[bitLength];
         for (int i = 0; i < bitLength; i++)
         {
-            char c = bits[i] ? '1' : '0';
-            sb.Append(c);
+            sb[i] = bits[i] ? '1' : '0';
         }
 
-        return sb.ToString();
+        return new string(sb);
     }
 }