Verica 1.1.0

Verica

An all-in-one PDF + barcode toolkit for .NET 8 / 9 / 10.

Verica is a from-scratch, dependency-light managed PDF library: read, write, transform, secure, sign, OCR, redact, watermark, merge, split, fill forms, validate (PDF/A and PDF/UA), add headers/footers and hyperlinks, and convert HTML / Markdown / SVG to PDF. It also ships 25+ barcode formats (Code128, QR, DataMatrix, PDF417, Aztec, GS1, EAN/UPC, Postnet, Intelligent Mail).

No native binaries. No P/Invoke. Pure managed code.

<PackageReference Include="Verica" Version="1.0.0" />

Why Verica?

Feature matrix

Read & extract

• Per-page plain text, layout-aware text (words / lines / blocks / columns), table extraction, image extraction (DCT / JPX / JBIG2 / CCITTFax pass-through), embedded files, bookmarks / outlines, page labels, annotations, AcroForm fields, structure tree (tagged PDF), optional content (layers), fonts, document info / metadata.
• Export to structured JSON (good for AI / RAG ingestion) or Markdown (heading inference from font sizes).

Write & transform

• Merge N PDFs, split by page range, rotate / reorder / delete / insert / resize / crop pages.
• Watermark (text or JPEG image), page numbering ({page}/{total} templates), Bates numbering, N-up imposition.
• Headers and footers with text in 6 regions (top/bottom × left/center/right) plus an optional JPEG logo.
• Hyperlinks — clickable URL annotations and internal page jumps.
• Annotations: add highlight / underline / strikeout / note / stamp; bulk filter / flatten / remove.
• Redaction: black-box overlay or true text removal (rewrites Tj / TJ operators).
• AcroForm: fill, flatten.
• Document info editor (Title / Author / Subject / Keywords).
• CMYK and RGB color in the content stream (SetFillColorCmyk, SetFillColor(int rgb)).
• Image embedding: drop a JPEG onto a page in two lines via page.AddJpeg(doc, bytes, x, y, w, h).

Security & signatures

• RC4-128 encryption (universal — works in every PDF viewer including iOS / Android browsers) and AES-V5 (AES-256) decryption.
• PKCS#7 / CAdES signature validation (PAdES B / T-aware).
• Add a digital signature with PdfSigner (incremental update); strip signatures with SignatureRemover.

Generators / converters

• HTML → PDF (subset: h1-h6, p, ul/ol, strong, em, basic styling).
• Markdown → PDF (CommonMark subset).
• SVG → PDF (paths, transforms, styles).
• Tagged PDF builder (accessibility-tagged from text elements).
• Barcodes — see Verica.Barcodes.BarcodePng for 1-line PNG bytes generation.

Compliance

• PDF/A (ISO 19005) conformance check.
• PDF/UA accessibility check.

OCR

• IOcrEngine interface with a shell-based Tesseract backend (language code is regex-validated to prevent shell injection).
• High-level OcrService orchestrates rasterize → OCR → text reconstitution.

Quick start

1. Build a PDF from scratch

using Verica.Core;
using Verica.Fonts;

var doc = new PdfDocument();
var page = doc.AddPage(595, 842); // A4

var font = new PdfStandardFont("Helvetica");
var fontObj = font.Register(doc);
page.Resources.AddFont("F1", new PdfObjectRef(fontObj.ObjectNumber));

page.Content
    .BeginText()
    .SetFont("F1", 28)
    .MoveTextPosition(72, 740)
    .ShowText("Hello, Verica!")
    .EndText();

File.WriteAllBytes("hello.pdf", doc.Save());

2. Read text from any PDF

using Verica.Parsing;
using Verica.Parsing.ContentStream;

using var reader = new PdfDocumentReader(File.ReadAllBytes("input.pdf"));
foreach (var page in reader.Pages)
{
    var text = TextExtractor.Extract(page).GetPlainText();
    Console.WriteLine(text);
}

3. Merge PDFs

using Verica.Parsing;
using Verica.Parsing.Writing;

using var a = new PdfDocumentReader(File.ReadAllBytes("a.pdf"));
using var b = new PdfDocumentReader(File.ReadAllBytes("b.pdf"));
var merged = PdfMerger.Merge(new[] { a, b });
File.WriteAllBytes("merged.pdf", merged);

4. Watermark

using var src = new PdfDocumentReader(File.ReadAllBytes("input.pdf"));
var bytes = WatermarkService.AddTextWatermark(src, "DRAFT",
    fontSize: 96, grayLevel: 0.85, rotationDegrees: 45);
File.WriteAllBytes("watermarked.pdf", bytes);

5. Encrypt with a password

using Verica.Core;
using Verica.Security;

var doc = new PdfDocument();
// ... build content ...
PdfSecurityHandler.Apply(doc, new PdfSecurityOptions
{
    EnablePassword = true,
    UserPassword = "secret",
    AllowPrinting = true,
    AllowModification = false,
    AllowCopying = false,
});
File.WriteAllBytes("secured.pdf", doc.Save());

6. Page numbering — multi-format

using var src = new PdfDocumentReader(File.ReadAllBytes("doc.pdf"));
var bytes = PageNumberingService.Add(src,
    template: "Page {page} of {total} — {date}",
    position: PagePosition.BottomCenter,
    fontSize: 10,
    grayLevel: 0.3,
    margin: 36,
    pagePredicate: i => i > 0);  // skip page 0 (cover)
File.WriteAllBytes("numbered.pdf", bytes);

Templates support {page}, {total}, and {date} tokens. Position is one of: TopLeft, TopCenter, TopRight, BottomLeft, BottomCenter, BottomRight.

7. Headers and footers (text + logo)

using var src = new PdfDocumentReader(File.ReadAllBytes("report.pdf"));
var stamped = HeaderFooterService.Apply(src, new HeaderFooterOptions
{
    TopLeft = "Acme Corp",                       // text regions
    TopRight = "{date}",
    BottomLeft = "Confidential",
    BottomCenter = "Page {page} of {total}",
    BottomRight = "v1.0",
    LogoJpegBytes = File.ReadAllBytes("logo.jpg"),  // optional logo (JPEG)
    LogoWidth = 80,
    FontSize = 9,
    GrayLevel = 0.4,
    SkipFirstPage = true,                          // cover-page friendly
});
File.WriteAllBytes("with_header_footer.pdf", stamped);

For SVG logos, convert them to a JPEG first via SvgToPdfConverter + a rasterizer, or use the SVG directly with a separate stamping pass. The LogoJpegBytes route is JPEG-only because Verica embeds JPEGs as a DCTDecode passthrough (no decode dependency).

8. Hyperlinks (clickable URL)

using var src = new PdfDocumentReader(File.ReadAllBytes("doc.pdf"));
var withLink = LinkAnnotationService.AddUrlLink(src,
    pageIndex: 0,
    rect: new LinkAnnotationService.AnnotationRect(72, 700, 200, 30),
    url: "https://example.com");
File.WriteAllBytes("clickable.pdf", withLink);

Internal page jumps:

var withJump = LinkAnnotationService.AddInternalLink(src,
    pageIndex: 0,
    rect: new LinkAnnotationService.AnnotationRect(72, 700, 200, 30),
    targetPageIndex: 5);

9. Embed a JPEG image into a page

var doc = new PdfDocument();
var page = doc.AddPage(595, 842);
page.AddJpeg(doc, File.ReadAllBytes("photo.jpg"),
    x: 72, y: 500, width: 200, height: 200);
File.WriteAllBytes("with_image.pdf", doc.Save());

10. Digital signature

using Verica.Parsing.Signatures;

var signer = new PdfSigner();
var signed = signer.Sign(File.ReadAllBytes("contract.pdf"),
    new PdfSigningOptions
    {
        SignerName = "Alice",
        Reason = "Approved",
        Location = "Mumbai",
    });
File.WriteAllBytes("contract.signed.pdf", signed);

11. OCR a scanned PDF (requires Tesseract on the host)

using Verica.Parsing.Ocr;

var ocr = new OcrService(new TesseractShellOcrEngine(language: "eng+hin"));
foreach (var pageText in ocr.ExtractText(File.ReadAllBytes("scanned.pdf")))
    Console.WriteLine(pageText);

12. HTML / Markdown / SVG → PDF

File.WriteAllBytes("invoice.pdf",
    HtmlToPdfConverter.Convert("<h1>Invoice #42</h1><p>Total: <strong>$1,200</strong></p>"));

File.WriteAllBytes("notes.pdf",
    MarkdownToPdfConverter.Convert("# Notes\n\n- one\n- two\n"));

13. Barcodes — 1-line PNG bytes

using Verica.Barcodes;

var qrPng        = BarcodePng.QrToPng("https://verica.example");
var code128Png   = BarcodePng.Code128ToPng("HELLO-128");
var dataMatrixPng = BarcodePng.DataMatrixToPng("DM-DATA");
var aztecPng     = BarcodePng.AztecToPng("AZTEC");
var pdf417Png    = BarcodePng.Pdf417ToPng("PDF417 payload");

For full configuration (margins, colors, human-readable text, DPI), use the typed barcode classes (Code128Barcode, QrCode, DataMatrixBarcode, …) plus BarcodeGenerator.SavePng(barcode, filePath).

14. CMYK color (prepress)

page.Content
    .SetFillColorCmyk(0, 0.7, 0.9, 0.1) // warm orange
    .Rectangle(72, 700, 200, 50)
    .Fill();

15. Validate against PDF/A

using Verica.Parsing.Compliance;

using var src = new PdfDocumentReader(File.ReadAllBytes("doc.pdf"));
var result = PdfAValidator.Validate(src);
foreach (var issue in result.Issues)
    Console.WriteLine($"{issue.Severity}: {issue.Message}");

Supported standards

• PDF 1.4 – 1.7 (ISO 32000-1)
• PDF/A (ISO 19005) — validation
• PDF/UA (ISO 14289) — validation
• PAdES B / T signature profiles
• PKCS#7 / CAdES detached signatures
• Standard security handler /V 2 /R 3 (RC4-128 — write + read) and /V 5 /R 6 (AES-256 — read)

Architecture

Verica/
├── Core/             PdfDocument, PdfPage, PdfContentStream,
│                     PdfDictionary, PdfStream, image extensions
├── Tokens/           Tokenizer primitives for content streams
├── IO/               Byte-stream input abstraction
├── Reader/           Lightweight reader for incremental updates
├── Filters/          Stream codecs: Flate, ASCII85, ASCIIHex, LZW, RunLength,
│                     CCITTFax G3+G4, DCT (passthrough), JPX (passthrough),
│                     JBIG2 (passthrough), Crypt
├── Fonts/            Font registry, TrueType parser/subsetter, ToUnicode CMaps
├── Images/           PNG decoder, JPEG embedder
├── Svg/              SVG path / transform / style → PDF
├── Security/         Password hashing, RC4 engine, permission flags,
│                     PdfSecurityOptions
├── Parsing/
│   ├── PdfDocumentReader   top-level reader
│   ├── ContentStream       text + layout + tables + JSON + Markdown export
│   ├── Forms               AcroForm read / fill / flatten
│   ├── Annotations         read + add (highlight, note, stamp, ...)
│   ├── Bookmarks           outline tree
│   ├── PageLabels
│   ├── EmbeddedFiles
│   ├── StructureTree       tagged-PDF structure
│   ├── OptionalContent     layers
│   ├── Security            /Encrypt parsing + RC4 + AES-V5 decryption
│   ├── Signatures          read + validate + sign + remove
│   ├── Fonts               Type0 / Type1 / TrueType / Type3 / MMType1
│   ├── Images              decode Image XObjects
│   ├── Compliance          PDF/A + PDF/UA validators
│   ├── Ocr                 IOcrEngine + Tesseract shell backend
│   ├── Diff                structural diff (text + form fields)
│   └── Writing             Merger, Splitter, PageOps, Watermark, Redaction,
│                           NupImposer, PageNumbering, BatesNumbering,
│                           HtmlToPdf, MarkdownToPdf, FormFlattener,
│                           DocumentInfoEditor, AnnotationService,
│                           HeaderFooterService, LinkAnnotationService
├── Barcodes/         25+ formats: Code128, QR, DataMatrix, PDF417, Aztec,
│                     GS1, EAN/UPC, Postnet, Intelligent Mail, ...
│                     plus BarcodePng for 1-line byte[] outputs.
└── DependencyInjection/ AddVerica() extension for IServiceCollection

351 public types across 41 namespaces. Multi-targeted: net8.0, net9.0, net10.0.

License

MIT — see LICENSE.

Acknowledgements

The PDF object model and content-stream parser are derived from the public ISO 32000-1 specification. The Reed-Solomon and matrix-placement code in the barcode subsystem is implemented from the relevant ISO/IEC standards (16022 for DataMatrix, 18004 for QR, 24778 for Aztec, 15438 for PDF417). No third-party PDF or barcode libraries are linked.