File Format FCStd

From FreeCAD Documentation
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Overview

The FreeCAD Standard file format (.FCStd) is FreeCAD's main file format. It is a compound format, supports compression and embedding of different kinds of data.

Internals of .FCStd files

FCStd is a standard zip file containing one or more files in a specific structure. As such, it is possible to unpack a .FCStd file using a regular zip decompression tool, but care needs to be taken while packing the contents of a .FCStd file. FreeCAD contains a "Project Utility" to re-pack .FCStd files, it's use is described in Change the source of the file .FCStd below.

Document.xml

This is the main .xml file describing all the objects inside a FreeCAD document, that is, only the geometric and parametric definition of the objects, not their visual representation. If FreeCAD is ran in console mode (without the GUI), only this Document.xml will be used.

Example Document.xml

<?xml version='1.0' encoding='utf-8'?>
 <Document SchemaVersion="4">
    <Properties Count="9">
       <Property name="Comment" type="App::PropertyString">
          <String value=""/>
       </Property>
       <Property name="Company" type="App::PropertyString">
          <String value=""/>
       </Property>
       <Property name="CreatedBy" type="App::PropertyString">
          <String value=""/>
       </Property>
       <Property name="CreationDate" type="App::PropertyString">
          <String value="Fri Jan 29 15:14:38 2010 "/>
       </Property>
       <Property name="FileName" type="App::PropertyString">
          <String value="/tmp/test.FCStd"/>
       </Property>
       <Property name="Id" type="App::PropertyString">
          <String value="201b746f-a1ed-4297-bf3d-65d5ec11abe0"/>
       </Property>
       <Property name="Label" type="App::PropertyString">
          <String value="names"/>
       </Property>
       <Property name="LastModifiedBy" type="App::PropertyString">
          <String value=""/>
       </Property>
       <Property name="LastModifiedDate" type="App::PropertyString">
          <String value="Fri Jan 29 15:15:21 2010 "/>
       </Property>
    </Properties>
    <Objects Count="2">
       <Object type="Mesh::Cube" name="Cube" />
       <Object type="Part::Box" name="Box" />
    </Objects>
    <ObjectData Count="2">
       <Object name="Cube">
          <Properties Count="7">
             <Property name="Height" type="App::PropertyFloatConstraint">
                <Float value="10"/>
             </Property>
             <Property name="Label" type="App::PropertyString">
                <String value="Cube"/>
             </Property>
             <Property name="Length" type="App::PropertyFloatConstraint">
                <Float value="10"/>
             </Property>
             <Property name="Mesh" type="Mesh::PropertyMeshKernel">
                <Mesh file="MeshKernel.bms"/>
             </Property>
             <Property name="Placement" type="App::PropertyPlacement">
                <PropertyPlacement Px="0" Py="0" Pz="0" Q0="0" Q1="0" Q2="0" Q3="1"/>
             </Property>
             <Property name="Pos" type="App::PropertyPlacementLink">
                <Link value=""/>
             </Property>
             <Property name="Width" type="App::PropertyFloatConstraint">
                <Float value="10"/>
             </Property>
          </Properties>
       </Object>
       <Object name="Box">
          <Properties Count="7">
             <Property name="Height" type="App::PropertyLength">
                <Float value="10"/>
             </Property>
             <Property name="Label" type="App::PropertyString">
                <String value="Box2"/>
             </Property>
             <Property name="Length" type="App::PropertyLength">
                <Float value="10"/>
             </Property>
             <Property name="Placement" type="App::PropertyPlacement">
                <PropertyPlacement Px="0" Py="0" Pz="0" Q0="0" Q1="0" Q2="0" Q3="1"/>
             </Property>
             <Property name="Pos" type="App::PropertyPlacementLink">
                <Link value=""/>
             </Property>
             <Property name="Shape" type="Part::PropertyPartShape">
                <Part file="PartShape.brp2"/>
             </Property>
             <Property name="Width" type="App::PropertyLength">
                <Float value="10"/>
             </Property>
          </Properties>
       </Object>
    </ObjectData>
 </Document>

GuiDocument.xml

This is the GUI counterpart of the Document.xml file. For each object described in the Document.xml, there is one corresponding object in GuiDocument.xml, describing the visual representation of that object (color, linewidth, etc).

Thumbnails/thumbnail.png

This is a 128x128 pixels thumbnail image of the document, which is a screenshot of the 3D view at save time. Thumbnails are generated only if the corresponding option is enabled in the FreeCAD preferences.

*.brep

These are the B-rep shapes of all objects that have a Part shape in the Document.xml. Each object, even if it is parametric, has its shape stored as an individual .brep file, so it can be accessed by components without the need to recalculate the shape.

*.svg

These are the template svg files used in TechDraw pages.

Typical structure

Structure of a typical .FCStd file. The extension can be changed to .zip to explore it like a normal directory. The Document.xml and GuiDocument.xml are at the root of the archive, together with any number of .brp (BREP) files. One subdirectory may hold the thumbnail, and another the SVG templates used by TechDraw.

File.FCStd (File.zip)
  |
  |--thumbnails/
  |  |
  |  :--Thumbnail.png
  |
  :--Document.xml
  :--GuiDocument.xml
  :--Shape1.brp
  :--Shape2.brp
  :--MyPage.svg
  :--etc.

Embedding other files

In order to embed other file types inside a FCStd file, you must first create a scripted object from the Python console, and give it an App::PropertyFileIncluded property.

Then in the property editor you can go to the added property and choose a file in the computer. Once the FCStd file is saved, the file assigned to the DataPropertyFileIncluded property will be packed inside the .FCStd. When the document is restored, the same file will be restored with the DataPropertyFileIncluded property.

custom_obj = App.ActiveDocument.addObject("App::FeaturePython", "CustomObject")
custom_obj.addProperty("App::PropertyFileIncluded", "AttachedFile")

See the forum thread, PDF inside the project.

Change the source of the file .FCStd

Other