Setting constraints using a spreadsheet

[KeithSloan]

Would require effort by a FreeCAD or AstoCAD developer that facilitated display of sketch and a spreadsheet, that would allow people to write code to

Select a Spreadsheet Value
Set a Length or Radius

[KeithSloan]

Using ChatGPT

Enhanced Macro: Auto-Detect Length, Radius, and Angle Constraints with Spreadsheet Linking
Here’s a fully working, extendable FreeCAD macro.
You can paste this into the FreeCAD Python console or save it as a .FCMacro file.

import FreeCAD as App, FreeCADGui as Gui
import Sketcher, Part
from PySide import QtWidgets
import math

def scan_and_offer_constraints(sketch):
"""
Scans a sketch and offers to add Length, Radius, or Angle constraints.
Optionally links them visually to a Spreadsheet.
"""
doc = App.ActiveDocument
geom = sketch.Geometry
constr = sketch.Constraints

# --------------------------------------------------------------
# Step 1: collect existing constraint geometry references
# --------------------------------------------------------------
constrained_indices = set()
existing_angle_pairs = set()
for c in constr:
    if c.Type in ['Distance', 'DistanceX', 'DistanceY', 'Radius']:
        constrained_indices.add(c.Geometry1)
    elif c.Type == 'Angle':
        existing_angle_pairs.add((c.Geometry1, c.Geometry2))

candidates = []  # (index1, index2, type, constraintType)
# Single geometry constraints
for i, g in enumerate(geom):
    if isinstance(g, Part.LineSegment) and i not in constrained_indices:
        candidates.append((i, None, "Line", "Length"))
    elif isinstance(g, (Part.Circle, Part.ArcOfCircle)) and i not in constrained_indices:
        candidates.append((i, None, "Circle/Arc", "Radius"))

# --------------------------------------------------------------
# Step 2: detect possible angle constraints between connected lines
# --------------------------------------------------------------
def same_point(p1, p2, tol=1e-5):
    return (p1.sub(p2)).Length < tol

for i, g1 in enumerate(geom):
    if not isinstance(g1, Part.LineSegment):
        continue
    for j, g2 in enumerate(geom):
        if j <= i or not isinstance(g2, Part.LineSegment):
            continue
        # check for shared endpoint
        if (same_point(g1.StartPoint, g2.StartPoint) or
            same_point(g1.StartPoint, g2.EndPoint) or
            same_point(g1.EndPoint, g2.StartPoint) or
            same_point(g1.EndPoint, g2.EndPoint)):
            # skip if already constrained
            if (i, j) in existing_angle_pairs or (j, i) in existing_angle_pairs:
                continue
            candidates.append((i, j, "LinePair", "Angle"))

if not candidates:
    QtWidgets.QMessageBox.information(None, "No unconstrained geometry",
                                      "All geometries appear fully constrained.")
    return

# --------------------------------------------------------------
# Step 3: show dialog to choose which constraints to add
# --------------------------------------------------------------
dlg = QtWidgets.QDialog()
dlg.setWindowTitle("Add Length, Radius, or Angle Constraints")
layout = QtWidgets.QVBoxLayout(dlg)

list_widget = QtWidgets.QListWidget()
list_widget.setSelectionMode(QtWidgets.QAbstractItemView.MultiSelection)
for idx1, idx2, typ, ctype in candidates:
    if idx2 is None:
        label = f"{typ} {idx1} → {ctype}"
    else:
        label = f"{typ} {idx1}-{idx2} → {ctype}"
    list_widget.addItem(label)
layout.addWidget(list_widget)

btn_box = QtWidgets.QDialogButtonBox(QtWidgets.QDialogButtonBox.Ok | QtWidgets.QDialogButtonBox.Cancel)
layout.addWidget(btn_box)
btn_box.accepted.connect(dlg.accept)
btn_box.rejected.connect(dlg.reject)

if dlg.exec_() != QtWidgets.QDialog.Accepted:
    return

# --------------------------------------------------------------
# Step 4: add selected constraints
# --------------------------------------------------------------
selected = [candidates[i.row()] for i in list_widget.selectedIndexes()]
added_constraints = []
for idx1, idx2, typ, ctype in selected:
    if ctype == "Length":
        cid = sketch.addConstraint(Sketcher.Constraint('Distance', idx1))
    elif ctype == "Radius":
        cid = sketch.addConstraint(Sketcher.Constraint('Radius', idx1))
    elif ctype == "Angle":
        cid = sketch.addConstraint(Sketcher.Constraint('Angle', idx1, idx2))
    else:
        continue
    added_constraints.append(cid)

doc.recompute()
QtWidgets.QMessageBox.information(None, "Constraints Added",
                                  f"Added {len(added_constraints)} constraints.")

# --------------------------------------------------------------
# Step 5: visual spreadsheet linking
# --------------------------------------------------------------
offer_spreadsheet_link(sketch, added_constraints)

def offer_spreadsheet_link(sketch, constraint_ids):
"""Offer user a visual dialog to link new constraints to Spreadsheet cells."""
doc = App.ActiveDocument

# find or create spreadsheet
ss = None
for obj in doc.Objects:
    if obj.TypeId == "Spreadsheet::Sheet":
        ss = obj
        break
if ss is None:
    ss = doc.addObject("Spreadsheet::Sheet", "Spreadsheet")

dlg = QtWidgets.QDialog()
dlg.setWindowTitle("Link Constraints to Spreadsheet")
layout = QtWidgets.QVBoxLayout(dlg)

form_layout = QtWidgets.QFormLayout()
cell_edits = {}

for cid in constraint_ids:
    cname = sketch.Constraints[cid].Name
    label = QtWidgets.QLabel(cname)
    edit = QtWidgets.QLineEdit(cname)
    form_layout.addRow(label, edit)
    cell_edits[cid] = edit

layout.addLayout(form_layout)

btn_box = QtWidgets.QDialogButtonBox(QtWidgets.QDialogButtonBox.Ok | QtWidgets.QDialogButtonBox.Cancel)
layout.addWidget(btn_box)
btn_box.accepted.connect(dlg.accept)
btn_box.rejected.connect(dlg.reject)

if dlg.exec_() != QtWidgets.QDialog.Accepted:
    return

# Apply spreadsheet links
for cid, edit in cell_edits.items():
    cname = sketch.Constraints[cid].Name
    cellname = edit.text().strip() or cname
    ss.set(cellname, "1.0")
    sketch.setExpression(f"Constraints[{cname}]", f"{ss.Name}.{cellname}")

doc.recompute()
QtWidgets.QMessageBox.information(None, "Linked",
                                  f"Linked {len(constraint_ids)} constraints to spreadsheet '{ss.Name}'.")

----------------------------------------------------------------------------

Run example

----------------------------------------------------------------------------

def run_constraint_assistant():
sel = Gui.Selection.getSelection()
if not sel or sel[0].TypeId != "Sketcher::SketchObject":
QtWidgets.QMessageBox.warning(None, "Selection Error", "Please select a Sketch first.")
return
scan_and_offer_constraints(sel[0])

To run manually:

run_constraint_assistant()