The label or other content to which the LEADER is attached is stored as a separate entity, and is not part of the LEADER itself.Īs noted above, LEADER shares its styling infrastructure with DIMENSION. The LEADER entity represents an arrow, made up of one or more vertices (or spline fit points) and an arrowhead. And here is a demo DXF file with all kinds of different LEADER and MULTILEADER objects which you can use to test your implementation. It should not be too difficult to read most of that code even if you're completely unfamiliar with OGR or GDAL. Here is the C++ code of the DXF LEADER and MULTILEADER translator that I developed for GDAL/OGR. I assume a basic level of familiarity with the DXF format. I hope these notes, which are intended to supplement the DXF specification, will help those who need to interact with the DXF format programmatically but have limited AutoCAD knowledge, or possibly even no access to the software. See below for some tips on how to get it implemented in your project. MULTILEADER is one of the worst-documented DXF entities the description in the DXF spec is next to useless. You can conceptualise it as a strange combination of MTEXT, INSERT, ATTRIB and LWPOLYLINE with enough secret sauce poured on top that you're never really quite sure what's going on.

The MULTILEADER entity, perhaps better known to AutoCAD users as MLEADER (the name of the command), was introduced in AutoCAD 2008.

The documentation for LEADER in the DXF specification is reasonably comprehensive see the section below.

The 'classic' LEADER entity has been part of AutoCAD since the early days, and shares a lot in common with the DIMENSION entity, including a common styling infrastructure (DIMSTYLE and the override system).

Demystifying DXF: LEADER and MULTILEADER implementation notesĪs part of my work on the DXF driver in the open-source Geospatial Data Abstraction Library ( GDAL), I was tasked with the job of implementing support for leader elements.įor those unfamiliar with CAD, leaders are essentially arrows emanating from a text label or symbol, serving to point out some important aspect of the drawing.ĪutoCAD offers two different kinds of leader objects:

Autocad lisp create leader dimstyles