SketcherExample.py

# Example how to use the basic sketcher tools
from Sketcher import *
from Part import *
from FreeCAD import *
import FreeCAD as App

# set some constances for the constraints
StartPoint = 1
EndPoint = 2
MiddlePoint = 3

# create a document and a Sketch object
if(App.activeDocument() is None):App.newDocument()

f = App.activeDocument().addObject("Sketcher::SketchObject","Sketch")

# add geometry to the sketch
f.Geometry = [Line(Vector(0,0,0),Vector(2,20,0)),Line(Vector(0,0,0),Vector(20,2,0))]

# add constraints to the sketch
f.Constraints = [Constraint('Vertical',0),Constraint('Horizontal',1)]

# recompute (solving) the sketch
App.activeDocument().recompute()

# add another constraint to tie the start points together
l = f.Constraints
l.append(Constraint('Coincident',0,StartPoint,1,StartPoint))
f.Constraints = l

# again recompute
App.activeDocument().recompute()

f.Geometry