Draft DXF

Opening
This function opens a DXF file (any version from 12 to 2007) in a new drawing. The following DXF object types are currently supported: Other DXF entities are currently not imported because there is no corresponding FreeCAD object. As new functionality gets implemented, it will be possible to import more entity types.
 * lines
 * polylines and lwpolylines
 * circles
 * arcs
 * layers (layers containing objects are conveted to FreeCAD Groups)
 * texts and mtexts
 * dimensions
 * blocks (only geometry. texts, dims and attributes inside blocks will be skipped)

Importing
This works the same way as opening, but it will add the contents of the dxf file in the active documento instead of creating a new document.

Exporting
The exported DXF is compatible with Autocad version 12 and up, so it should open in about any application that supports dxf format. Currently the following FreeCAD objects get exported:
 * lines and wires (polylines)
 * arcs and circles
 * texts
 * colors are mapped from objects RGB colors to autocad color index (ACI). Black will always be "by layer"
 * layers are mapped from group names. When groups are nested, the deepest group gives the layer name.
 * dimensions, which are exported with "Standard" dimstyle

Preferences
The following parameters can be specified in the Draft Preferences tab (menu Edit -> Preferences -> Draft):
 * Import style: This lets you choose the way objects from the dxf file will be drawn in FreeCAD. You can choose between:
 * None: this is the faster way, there is no conversion, all objects will be black with 2px width (FreeCAD default)
 * Use default color and linewidth: All imported dxf objects will take current linewidth/color from the draft command bar
 * Original color and linewidth: Objects will keep the color and linewidth (if specified) they have in the dxf file
 * Colors mapped to linewidth: If this option is selected, the mapping file option below is used.
 * Color mapping file: This allows you to specify a mapping file to be used for translating dxf colors to color and linewidth, the same way as a plot style works in Autocad. The mapping file must be a tab-separated text file. There is a nice free utility called Plot style viewer that can convert Autocad CTB or STB (plot styles) files to tab-separated mapping files ready to use in FreeCAD. Alternatively, we have a couple of home-made mapping files availables here.
 * Import texts: This allows you to specify if you want to import dxf texts and dimensions or not. Many texts might make your work in FreeCAD very heavy, so you might want to use this option some time.
 * Import layout objects: Turn this on if you want to import paper space object. They will be merged in the same document than model space objects.