Home

DXF File Overview

Introduction

The purpose of this project is to provide a library for reading and (in the future) writing both ASCII and Binary DXF files. A Dxf file is a standardized file that was created by AutoDesk to enable data interoperability. It was originally introduced in 1982 and has had multiple new versions since.

File Structure

The HEADER section provides general file properties and other information

The CLASSES Section holds information for application-defined classes whose instances appear in the BLOCKS, ENTITIES and OBJECTS sections of the database. It generally does not provide sufficient information to allow interoperability with other programs

The TABLES Section contains definitions of named items

The BLOCKS Section contains Block definitions entities describing the entities comprising each block in the drawing

The ENTITIES Section contains the drawing entities (The section that we are most concerned about)

The OBJECTS section contains the data that apply to nongraphical objects, used by other application services

The THUMBNAILIMAGE Section contains the preview image for the DXF File

Tagged Data

The contents within the file are placed into pairs of tagged data, for example below is the entities section from a dxf file:

999
EXAMPLEFILE.DXF

  0
SECTION
  2
ENTITIES
  0
LWPOLYLINE
  5
4D3
330
1F
100
AcDbEntity
  8
PolylineArc
100
AcDbPolyline
 90
        4
 70
     1
 43
0.0
 10
7.5
 20
0.5
 10
10.0
 20
2.5
 42
-0.2
 10
15.0
 20
2.5
 10
17.5
 20
0.5
  0
ENDSEC
  0

As seen above each datapoint is accompanied by and identifier, for exammple the "Group Code" for the layer of this LWPOLYLINE is 8 and the corresponding layer name is PolylineArc