Upgrade to .net9

Infra/Encoders/PngPipeEncoder.cs

@@ -0,0 +1,135 @@
+using System.Buffers;
+using System.Buffers.Binary;
+using System.IO.Compression;
+using System.IO.Pipelines;
+using StitchATon2.Infra.Buffers;
+
+namespace StitchATon2.Infra.Encoders;
+
+public class PngPipeEncoder : IDisposable
+{
+    private const int BufferSize = 8 * 1024;
+    private const int FlushThreshold = 1024;
+    
+    private readonly PipeWriter _outputPipe;
+    private readonly MemoryStream _memoryStream;
+    private readonly int _width;
+    private readonly int _height;
+
+    private readonly ZLibStream _zlibStream;
+    private bool _disposed;
+    private bool _shouldFlush;
+    
+    public PngPipeEncoder(PipeWriter outputPipe, int width, int height)
+    {
+        _outputPipe = outputPipe;
+        _width = width;
+        _height = height;
+        _memoryStream = new MemoryStream(BufferSize * 2);
+        _zlibStream = new ZLibStream(_memoryStream, CompressionLevel.Optimal, leaveOpen: true);
+        _memoryStream.SetLength(8);
+        _memoryStream.Position = 8;
+    }
+
+    ~PngPipeEncoder() => Dispose();
+
+    public void WriteHeader()
+    {
+        Span<byte> headerBytes = [
+            0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, // PNG Signature
+            0x00, 0x00, 0x00, 0x0D, // Length
+            
+            // IHDR chunk
+            0x49, 0x48, 0x44, 0x52, // IHDR
+            0x00, 0x00, 0x00, 0x00, // Reserve to write Width
+            0x00, 0x00, 0x00, 0x00, // Reserve to write Height
+            0x08, // Bit depth
+            0x02, // Color type
+            0x00, // Compression method
+            0x00, // Filter method
+            0x00, // Interlace method
+            0x00, 0x00, 0x00, 0x00, // Reserve to write CRC-32
+        ];
+        
+        BinaryPrimitives.WriteInt32BigEndian(headerBytes[16..], _width);
+        BinaryPrimitives.WriteInt32BigEndian(headerBytes[20..], _height);
+        var crc = Crc32.Compute(headerBytes.Slice(12, 17));
+        
+        BinaryPrimitives.WriteUInt32BigEndian(headerBytes[29..], crc);
+        
+        _outputPipe.Write(headerBytes);
+    }
+
+    public void WriteData(IBuffer<byte> buffer, bool disposeBuffer = true, CancellationToken cancellationToken = default)
+    {
+        _zlibStream.Write([0]);
+        
+        var dataSlice = buffer.Span;
+        while (dataSlice.Length > FlushThreshold)
+        {
+            _zlibStream.Write(dataSlice[..FlushThreshold]);
+            _zlibStream.Flush();
+            dataSlice = dataSlice[FlushThreshold..];
+            if(_memoryStream.Length >= BufferSize)
+                Flush(cancellationToken);
+        }
+        
+        if (dataSlice.Length > 0)
+        {
+            _zlibStream.Write(dataSlice);
+            _zlibStream.Flush();
+            _shouldFlush = true;
+        }
+        
+        if(disposeBuffer) buffer.Dispose();
+    }
+
+    private void Flush(CancellationToken cancellationToken)
+    {
+        _zlibStream.Flush();
+        var dataSize = (int)(_memoryStream.Length - 8);
+
+        _memoryStream.Write("\0\0\0\0"u8);
+
+        _memoryStream.Position = 4;
+        _memoryStream.Write("IDAT"u8);
+
+        var buffer = _memoryStream.GetBuffer();
+        BinaryPrimitives.WriteInt32BigEndian(buffer, dataSize);
+
+        // write Crc
+        var crc = Crc32.Compute(buffer.AsSpan(4, dataSize + 4));
+        BinaryPrimitives.WriteUInt32BigEndian(buffer.AsSpan(dataSize + 8), crc);
+            
+        _outputPipe.Write(buffer.AsSpan(0, dataSize + 12));
+        _memoryStream.SetLength(8);
+        _memoryStream.Position = 8;
+        _shouldFlush = false;
+    }
+
+    public void WriteEndOfFile(CancellationToken cancellationToken = default)
+    {
+        if(_shouldFlush)
+            Flush(cancellationToken);
+        
+        Span<byte> endChunk = [
+            0x00, 0x00, 0x00, 0x00, // Length
+            0x49, 0x45, 0x4E, 0x44, // IEND
+            0xAE, 0x42, 0x60, 0x82, // Crc
+        ];
+        
+        _outputPipe.Write(endChunk);
+        Dispose();
+    }
+
+    public void Dispose()
+    {
+        if (!_disposed)
+        {
+            _zlibStream.Dispose();
+            _memoryStream.Dispose();
+            _disposed = true;
+            GC.SuppressFinalize(this);
+        }
+    }
+}