Adds basic POC for PDFToImage

POC/PdfToImage.sln

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+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.5.2.0
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "PdfToImage", "PdfToImage\PdfToImage.csproj", "{515835BA-A8E0-C3F6-57E3-24410428E129}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{515835BA-A8E0-C3F6-57E3-24410428E129}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{515835BA-A8E0-C3F6-57E3-24410428E129}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{515835BA-A8E0-C3F6-57E3-24410428E129}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{515835BA-A8E0-C3F6-57E3-24410428E129}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {2F6D3A0F-356F-483E-863D-C672AEE8323E}
+	EndGlobalSection
+EndGlobal

POC/PdfToImage/PdfToImage.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net9.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Docnet.Core" Version="2.6.0" />
+  </ItemGroup>
+
+</Project>

POC/PdfToImage/Program.cs

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+using Docnet.Core;
+using Docnet.Core.Models;
+
+Console.WriteLine("=== PDF til Billede Konverter ===");
+Console.WriteLine();
+
+Console.Write("Indtast sti til PDF-fil: ");
+string? pdfPath = Console.ReadLine()?.Trim().Trim('"');
+
+if (string.IsNullOrEmpty(pdfPath))
+{
+    Console.WriteLine("Fejl: Ingen fil angivet.");
+    Console.ReadKey();
+    return;
+}
+
+if (!File.Exists(pdfPath))
+{
+    Console.WriteLine($"Fejl: Filen '{pdfPath}' blev ikke fundet.");
+    Console.ReadKey();
+    return;
+}
+
+Console.Write("Indtast output-mappe (tryk Enter for samme mappe som PDF): ");
+string? outputInput = Console.ReadLine()?.Trim().Trim('"');
+string outputFolder = string.IsNullOrEmpty(outputInput)
+    ? Path.GetDirectoryName(pdfPath) ?? "."
+    : outputInput;
+
+Directory.CreateDirectory(outputFolder);
+
+string fileNameWithoutExt = Path.GetFileNameWithoutExtension(pdfPath);
+
+Console.WriteLine($"Konverterer: {pdfPath}");
+
+using var docReader = DocLib.Instance.GetDocReader(pdfPath, new PageDimensions(1080, 1920));
+
+int pageCount = docReader.GetPageCount();
+Console.WriteLine($"Antal sider: {pageCount}");
+
+for (int i = 0; i < pageCount; i++)
+{
+    using var pageReader = docReader.GetPageReader(i);
+
+    int width = pageReader.GetPageWidth();
+    int height = pageReader.GetPageHeight();
+    byte[] rawBytes = pageReader.GetImage();
+
+    string outputPath = Path.Combine(outputFolder, $"{fileNameWithoutExt}_side_{i + 1}.png");
+
+    SaveAsPng(rawBytes, width, height, outputPath);
+
+    Console.WriteLine($"Gemt: {outputPath}");
+}
+
+Console.WriteLine("Konvertering fuldført!");
+Console.WriteLine();
+Console.WriteLine("Tryk på en tast for at afslutte...");
+Console.ReadKey();
+
+static void SaveAsPng(byte[] bgraData, int width, int height, string outputPath)
+{
+    using var fileStream = File.Create(outputPath);
+    using var bw = new BinaryWriter(fileStream);
+
+    // PNG Signature
+    bw.Write(new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A });
+
+    // IHDR chunk
+    byte[] ihdrData;
+    using (var ms = new MemoryStream())
+    {
+        WriteBigEndianInt(ms, width);
+        WriteBigEndianInt(ms, height);
+        ms.WriteByte(8);  // bit depth
+        ms.WriteByte(6);  // color type (RGBA)
+        ms.WriteByte(0);  // compression
+        ms.WriteByte(0);  // filter
+        ms.WriteByte(0);  // interlace
+        ihdrData = ms.ToArray();
+    }
+    WriteChunk(bw, "IHDR", ihdrData);
+
+    // Byg uncompressed data (filter-byte + RGBA pixels per scanline)
+    int scanlineSize = 1 + width * 4; // 1 filter byte + RGBA
+    byte[] uncompressed = new byte[height * scanlineSize];
+
+    for (int y = 0; y < height; y++)
+    {
+        int rowStart = y * scanlineSize;
+        uncompressed[rowStart] = 0; // filter type: none
+
+        for (int x = 0; x < width; x++)
+        {
+            int srcIdx = (y * width + x) * 4;
+            int dstIdx = rowStart + 1 + x * 4;
+
+            // BGRA til RGBA
+            uncompressed[dstIdx + 0] = bgraData[srcIdx + 2]; // R
+            uncompressed[dstIdx + 1] = bgraData[srcIdx + 1]; // G
+            uncompressed[dstIdx + 2] = bgraData[srcIdx + 0]; // B
+            uncompressed[dstIdx + 3] = bgraData[srcIdx + 3]; // A
+        }
+    }
+
+    // Komprimer med Deflate
+    using var compressedStream = new MemoryStream();
+    using (var deflate = new System.IO.Compression.DeflateStream(compressedStream, System.IO.Compression.CompressionLevel.Fastest, true))
+    {
+        deflate.Write(uncompressed);
+    }
+    byte[] compressed = compressedStream.ToArray();
+
+    // Beregn Adler-32 på uncompressed data
+    uint adler = Adler32(uncompressed);
+
+    // Byg zlib stream: header + compressed + adler32
+    using var zlibStream = new MemoryStream();
+    zlibStream.WriteByte(0x78); // CMF
+    zlibStream.WriteByte(0x01); // FLG
+    zlibStream.Write(compressed);
+    WriteBigEndianUInt(zlibStream, adler);
+
+    WriteChunk(bw, "IDAT", zlibStream.ToArray());
+
+    // IEND chunk
+    WriteChunk(bw, "IEND", Array.Empty<byte>());
+}
+
+static void WriteChunk(BinaryWriter bw, string type, byte[] data)
+{
+    byte[] lengthBytes = BitConverter.GetBytes(data.Length);
+    if (BitConverter.IsLittleEndian) Array.Reverse(lengthBytes);
+    bw.Write(lengthBytes);
+
+    byte[] typeBytes = System.Text.Encoding.ASCII.GetBytes(type);
+    bw.Write(typeBytes);
+    bw.Write(data);
+
+    // CRC32
+    byte[] crcData = new byte[4 + data.Length];
+    Array.Copy(typeBytes, crcData, 4);
+    Array.Copy(data, 0, crcData, 4, data.Length);
+    uint crc = Crc32(crcData);
+    byte[] crcBytes = BitConverter.GetBytes(crc);
+    if (BitConverter.IsLittleEndian) Array.Reverse(crcBytes);
+    bw.Write(crcBytes);
+}
+
+static void WriteBigEndianInt(Stream stream, int value)
+{
+    byte[] bytes = BitConverter.GetBytes(value);
+    if (BitConverter.IsLittleEndian) Array.Reverse(bytes);
+    stream.Write(bytes);
+}
+
+static void WriteBigEndianUInt(Stream stream, uint value)
+{
+    byte[] bytes = BitConverter.GetBytes(value);
+    if (BitConverter.IsLittleEndian) Array.Reverse(bytes);
+    stream.Write(bytes);
+}
+
+static uint Crc32(byte[] data)
+{
+    uint crc = 0xFFFFFFFF;
+    foreach (byte b in data)
+    {
+        crc ^= b;
+        for (int i = 0; i < 8; i++)
+            crc = (crc >> 1) ^ (0xEDB88320 & ~((crc & 1) - 1));
+    }
+    return ~crc;
+}
+
+static uint Adler32(byte[] data)
+{
+    uint a = 1, b = 0;
+    foreach (byte d in data)
+    {
+        a = (a + d) % 65521;
+        b = (b + a) % 65521;
+    }
+    return (b << 16) | a;
+}