Code SnippetAutomation2026-03-04

Parse DXF Files in C#

Read and extract geometry entities (lines, arcs, circles) from AutoCAD DXF files using C#. Essential for nesting, laser cutting, and CNC manufacturing workflows.

csharp

// Using the netDxf library (NuGet: netDxf)
using netDxf;
using netDxf.Entities;

public List<EntityInfo> ParseDxfFile(string filePath)
{
    var doc = DxfDocument.Load(filePath);
    var results = new List<EntityInfo>();

    foreach (var line in doc.Entities.Lines)
    {
        results.Add(new EntityInfo
        {
            Type = "Line",
            Layer = line.Layer.Name,
            StartX = line.StartPoint.X, StartY = line.StartPoint.Y,
            EndX = line.EndPoint.X, EndY = line.EndPoint.Y
        });
    }

    foreach (var arc in doc.Entities.Arcs)
    {
        results.Add(new EntityInfo
        {
            Type = "Arc",
            Layer = arc.Layer.Name,
            CenterX = arc.Center.X, CenterY = arc.Center.Y,
            Radius = arc.Radius
        });
    }

    foreach (var circle in doc.Entities.Circles)
    {
        results.Add(new EntityInfo
        {
            Type = "Circle",
            Layer = circle.Layer.Name,
            CenterX = circle.Center.X, CenterY = circle.Center.Y,
            Radius = circle.Radius
        });
    }

    return results;
}

How It Works

DXF (Drawing Exchange Format) is the universal interchange format for 2D CAD data. This snippet uses the netDxf NuGet package to parse a DXF file into typed entity objects:

Load the document — netDxf handles both ASCII and binary DXF formats
Iterate entity collections — Lines, Arcs, Circles, LwPolylines, etc. are accessed separately
Extract geometry data — coordinates, radii, layer names, and other properties

DXF Format Structure

A DXF file is organized into sections:

HEADER: Drawing settings (units, limits, variables)
TABLES: Layer definitions, line types, text styles
BLOCKS: Reusable block definitions (like symbols or standard parts)
ENTITIES: The actual geometry — lines, arcs, polylines, text, dimensions

Each entity is encoded as group code/value pairs. For example, a LINE has group code 10/20 for start point X/Y and 11/21 for end point X/Y.

Common Use Cases

Nesting software: Read DXF profiles to arrange parts on sheet metal
Laser/plasma cutting: Extract contours for toolpath generation
Quality inspection: Compare DXF design geometry against measured dimensions
File conversion: Transform DXF geometry into other formats (SVG, G-code, custom XML)

Tips

Install via NuGet: dotnet add package netDxf
Always check the Layer property — manufacturing DXFs often separate cut lines, bend lines, and text on different layers
LwPolyline (lightweight polyline) is the most common entity in manufactured part DXFs — it represents a continuous chain of line/arc segments
For simple parsing without a library, DXF is plain text — you can parse group codes directly with a state machine

DXFC#CADFile ParsingCNC