Graphite — PDF, precisely.

A native Windows desktop app for viewing, editing, annotating and converting PDF documents. Built with WPF on .NET 8, styled with an original "liquid glass" design language — floating translucent toolbars and pill controls over the Windows 11 Mica backdrop.

Features

Viewing — PDFium-based rendering (fast and high-fidelity), smooth eased scrolling, smooth zoom (buttons, Ctrl+wheel, fit-width), continuous, single-page and two-page spread modes, page thumbnails, bookmarks/outline navigation, full-text search with per-page highlights, and multi-tab support for several open files (each tab remembers its scroll position).

Reading — fullscreen reading mode (F11, Esc to leave), inverted page colors for comfortable dark reading (toggle in the floating page bar), and reading history: jump around via bookmarks, search or go-to-page, then walk back and forward with Alt+Left / Alt+Right.

Command palette — Ctrl+K opens a searchable palette with every command in the app; type a few letters, Enter runs it.

Printing — Ctrl+P prints through the system dialog; pages are rasterized at 300 dpi with annotations included and fitted to the printable area.

Page editing — add (blank or from another PDF), delete, reorder, rotate and extract pages; merge multiple PDFs into one; split a PDF into single-page files. Right-click any thumbnail for per-page operations. Annotations travel with their pages through every operation.

Content editing — an Edit Text tool (drag over a region, type replacement text and pick the text size — or let Graphite match the original; the region is covered and re-typeset, which is how most PDF editors work under the hood since PDF has no reflowable text model) and a Place Image tool for inserting images onto a page.

Annotation & markup — highlight, underline and strikethrough that snap to words, freehand ink, rectangles, ellipses, arrows, free text (click and start typing right on the page; double-click the text later for font, size and color), sticky notes, and a signature tool: draw your signature once and stamp it onto any page (it's saved between sessions). Images can be placed from a file or pasted straight from the clipboard (Ctrl+V). Every annotation supports a comment and threaded replies. The Markup panel lists everything in the document for review; click a card to jump to it. Annotations are written as standard PDF annotations, so they open in any other viewer. Undo/redo (Ctrl+Z / Ctrl+Y) covers annotations and page operations alike.

Security & info — password-protected PDFs open with a password prompt (and stay protected when you save), and any document can be saved as an encrypted copy (AES-256, from the ⋯ menu). A properties dialog shows title, author, dates, producer, PDF version, page size and file size.

Conversion — export to Word (.docx, reconstructed paragraphs), Excel (.xlsx, one sheet per page with inferred columns), PowerPoint (.pptx, one slide per page) and PNG/JPEG/WebP images. Opening a Word/Excel/PowerPoint file converts it to PDF automatically (uses the installed Microsoft Office via COM; requires Office).

OCR — Tesseract-based recognition for scanned pages. Recognized pages become searchable and selectable immediately, and an invisible text layer is baked into the PDF so it stays searchable after saving, in any viewer.

Platform — dark/light themes (persisted), Windows 11 Mica backdrop with glass panels, system accent color, per-monitor DPI awareness, drag-and-drop, recent files, a OneDrive quick-open button (uses your local OneDrive sync folder), and a script to register the .pdf file association.

Building

Requirements: Windows 10/11, Visual Studio 2022 (or the .NET 8 SDK) with the ".NET desktop development" workload.

dotnet build Graphite.sln -c Release
dotnet run --project src/Graphite.App

Or open Graphite.sln in Visual Studio and press F5. NuGet restores everything (PDFtoImage/PDFium, PdfSharp, PdfPig, DocumentFormat.OpenXml, ClosedXML, Tesseract, CommunityToolkit.Mvvm).

Tests

dotnet test src/Graphite.Tests

Unit tests cover the Core engine: page-range parsing, text layout reconstruction, annotation codec round-trips (through real PDFs), color/geometry helpers, search word mapping, and encryption round-trips. CI runs build + tests on every push and PR.

Optional setup

• OCR data — powershell -File tools\get-tessdata.ps1 downloads eng.traineddata into src/Graphite.App/tessdata (copied next to the exe on build). Pass -Languages eng,deu,... for more languages.
• File association — after building: powershell -File tools\register-file-association.ps1 -ExePath <path>\Graphite.exe, then choose Graphite for .pdf in Settings → Default apps (Windows requires that final choice to be made by the user).

Architecture

Graphite.sln
├─ src/Graphite.Core     ── UI-independent engine (net8.0)
│   ├─ Rendering/        PDFium rasterizer (PDFtoImage), thread-safe
│   ├─ Text/             PdfPig text index: word geometry, search, outline, selection
│   ├─ Pdf/              PdfSharp page surgery: merge, split, extract, rotate, reorder
│   ├─ Annotations/      model + codec that reads/writes real PDF annotations
│   ├─ Editing/          cover-and-replace text edits, image placement
│   ├─ Ocr/              Tesseract engine + invisible-text-layer writer
│   └─ Export/           docx / xlsx / pptx / image exporters, Office→PDF via COM
└─ src/Graphite.App      ── WPF shell (net8.0-windows)
    ├─ Themes/           light/dark palettes, styles, original icon geometry
    ├─ ViewModels/       Main / Document / Page / Annotation (CommunityToolkit.Mvvm)
    ├─ Controls/         AnnotationLayer — per-page interactive overlay
    ├─ Services/         theme/settings, signature store, printing
    ├─ Views/            MainWindow + dialogs (input, edit-text, password, signature, properties)
    └─ Interop/          Mica backdrop + dark title bar (DWM)

src/Graphite.Tests       ── xUnit tests for the Core engine

Design decisions worth knowing:

• Operations are pure (bytes in → bytes out). Before any structural operation the current annotations are baked into the PDF, and re-read afterwards — so they stay glued to their pages through deletes, moves and merges.
• Rendering is decoupled from layout. Pages lay out at size × zoom immediately; bitmaps re-render ~1.5× oversampled in the background (debounced on zoom), so zooming feels instant.
• The viewer virtualizes. Pages render lazily as they scroll into view; thumbnails likewise.

Design language

Graphite pairs its warm-gray monochrome identity with a liquid-glass treatment that sits naturally on Windows 11: a floating glass command bar and a pill-shaped page-control bar hover over the document, side panels are translucent gradient glass with a luminous top edge and soft 16px radii, tabs are pills, and everything floats over the Mica backdrop with soft shadows. Buttons animate on hover and compress slightly on press. The Windows accent color appears sparingly — checked tools, focus rings, the unsaved-changes dot — while functional color stays reserved for the document itself: highlights, ink and shapes. Icons remain original 1.3px hairline stroke geometry (no icon font).

Known limitations

• Text editing is cover-and-replace (see above) — original fonts are not re-embedded.
• Word/Excel export reconstructs layout heuristically from text geometry; complex layouts and tables degrade gracefully but imperfectly.
• Creating PDFs from Office files requires Microsoft Office to be installed.
• Annotations on pages rotated via /Rotate metadata (rather than upright content) can be offset; upright documents — the overwhelming majority — behave correctly.
• Graphite writes annotations without appearance streams; virtually all viewers (Acrobat, browsers, SumatraPDF) regenerate them automatically.