JFToolkit.Dxf

Zero-dependency .NET library for reading and writing DXF files — focused on block extraction and insertion. Open a template, extract blocks, paste them into plot frames at specific positions.

The problem

You have a DXF symbol library with 100+ P&ID blocks (pumps, valves, tanks). You have plot frames (A3, A4 with title blocks). You need to assemble drawing sheets by pasting the right symbols at the right coordinates.

Doing this in AutoCAD by hand: open template, copy block, switch to drawing, paste, position... for every sheet. A P&ID might have 30 sheets.

This library makes it one operation per block.

Install

dotnet add package JFToolkit.Dxf

Zero dependencies. No AutoCAD SDK. Pure C# string I/O.

Usage

Your workflow: extract blocks, insert at coordinates

using JFToolkit.Dxf;

// Open your symbol library and plot frame
var template = DxfDocument.Load("pandid_symbols.dxf");
var drawing  = DxfDocument.Load("a3_landscape.dxf");

// Pull out the blocks you need
drawing.ImportBlock(template.Blocks["PUMP_CENTRIFUGAL"]);
drawing.ImportBlock(template.Blocks["VALVE_GATE_50"]);
drawing.ImportBlock(template.Blocks["TANK_VERTICAL"]);

// Paste at position
drawing.Entities.Add(new DxfInsert
{
    BlockName = "PUMP_CENTRIFUGAL",
    X = 120, Y = 340
});
drawing.Entities.Add(new DxfInsert
{
    BlockName = "TANK_VERTICAL",
    X = 100, Y = 150,
    ScaleX = 2.0, ScaleY = 2.0  // double size
});

drawing.Save("sheet_03.dxf");

Inspect what's in a file

var doc = DxfDocument.Load("mystery.dxf");

Console.WriteLine($"Blocks: {doc.Blocks.Count}");
foreach (var (name, block) in doc.Blocks)
    Console.WriteLine($"  {name}: {block.Entities.Count} entities");

Console.WriteLine($"Inserts: {doc.Entities.OfType<DxfInsert>().Count()}");

Supported entities (v0.1)

Entity	Read	Write	Notes
INSERT	✅	✅	Block reference at position with scale/rotation
LINE	✅	✅
CIRCLE	✅	✅
ARC	✅	✅
TEXT	✅	✅	Single-line text
MTEXT	✅	—	Read-only (converted to plain text)
LWPOLYLINE	✅	✅	Lightweight polyline (2D vertex array)
BLOCK	✅	✅	Block definitions (import/export)

What it does NOT do (by design)

• No DIMENSION, HATCH, SPLINE, or 3D entities
• No binary DXF (text format only)
• No block creation from scratch (blocks come from templates)
• No header variable editing (pass-through only)
• No pre-R2000 DXF versions

Requirements

• .NET 8 or .NET 9
• Any OS (pure text I/O, no Windows-specific dependencies)

License

MIT — use it anywhere, commercial or personal.