FreeCAD macro to wrap text on a cylinder

TextOnCylinder

# Macro to put text on a cylinder. Select a cylinder and one or more
# ShapeStrings to place on the cylinder. You can edit the vertical
# and angular offset of the text in the TextOnCylinder properties.
#
# Michael Ang <http://github.com/mangtronix>
# http://michaelang.com
#
# TODO:
#  - Split up the string and actually wrap it around the cylinder
#  - Make into a proper module. Currently if you save and then reopen
#    the TextOnCylinder objects are no longer editable.
#  - More placement options
#  - Work on any surface

import FreeCAD
import Draft, Units

from FreeCAD import Base
from Units import Quantity

v = FreeCAD.Vector
_debug = False

# General idea
# - find text width
# - extrude text
# - center (optional)
# - place extruded text
#   - rotate so text face normal is pointing out
#   - place at radius
#   - rotate around circle (optional)
#   - translate to cylinder surface

class TextOnCylinder:
    def __init__(self, obj,
            Thickness = Quantity("1 mm"),
            BaseLineOffset = Quantity("2 mm"),
            AngleOffset = Quantity("0 deg"),
        ):
        
        if _debug:
            FreeCAD.Console.PrintMessage("__init__\n")
        
        obj.addProperty("App::PropertyDistance","Thickness","Text","Distance into/out of surface").Thickness = Thickness
        obj.addProperty("App::PropertyDistance","BaseLineOffset","Text","Baseline offset from bottom of cylinder").BaseLineOffset = BaseLineOffset
        obj.addProperty("App::PropertyAngle","AngleOffset","Text","Rotation around cylinder").AngleOffset = AngleOffset
        
        obj.addProperty("App::PropertyLink","Cylinder","Links","Link to Cylinder")
        obj.addProperty("App::PropertyLink","ShapeString","Links","Link to ShapeString")
        # $$$ rotation degrees, vertical offset
        obj.Proxy = self

    def execute(self, feature):
        if _debug:
            FreeCAD.Console.PrintMessage("execute\n")
        
        if feature.ShapeString:
            # We reset the placement of the text before extruding
            shape_copy = feature.ShapeString.Shape.copy()
            shape_copy.Placement = Base.Placement()
            extruded = shape_copy.extrude(v(0,0,feature.Thickness*2))
            feature.Shape = extruded
        else:
            return # No text linked
            
        # Figure out placement
        if feature.Cylinder:
        
            # Start by placing text as if on a default upright cylinder
            
            # Rotate around z-axis
            text_placement = Base.Placement(v(0,0,0), Base.Rotation(v(0,0,1), feature.AngleOffset))
        
            # Place text upright and at front outside of cylinder
            # Rotate from default text rotation (x-y plane) to cylinder default upright
            # then rotate by the cylinder rotation
            text_placement = text_placement.multiply(Base.Placement(v(0,-feature.Cylinder.Radius,0), Base.Rotation(v(0,1,0), v(0,0,1))))
            
            # Center text
            center_offset = v(-extruded.BoundBox.XLength/2,0,-extruded.BoundBox.ZLength/2)
            text_placement = text_placement.multiply(Base.Placement(center_offset, Base.Rotation()))
            
            # Apply baseline offset
            text_placement = text_placement.multiply(Base.Placement(v(0,feature.BaseLineOffset,0), Base.Rotation()))
            
            # Now multiply by the cylinder's actual placement, to get into the cylinder's
            # coordinate space
            feature.Placement = feature.Cylinder.Placement.multiply(text_placement)
            
    def onChanged(self, feature, property):
        if _debug:
            FreeCAD.Console.PrintMessage("onChanged: %s\n" % property)
        pass

def TextOnCylinderCmd():
    max_label_length = 30

    selection = FreeCADGui.Selection.getSelection()
    strings = findShapeStrings(selection)
    cylinders = findByDerivedTypeId(selection, 'Part::Cylinder')
    
    if cylinders and strings:
        cylinder = cylinders[0]
        for string in strings:
            label = "TextOnCyl_%s" % string.Label
            label = label[:max_label_length]
            tocf = FreeCAD.ActiveDocument.addObject("Part::FeaturePython",label)
            TextOnCylinder(tocf)
            tocf.ShapeString = string
            tocf.Cylinder = cylinder
            tocf.ViewObject.Proxy=0
        FreeCAD.ActiveDocument.recompute()
    else:
        if cylinders or strings:
            # Might be trying to select a valid combo
            FreeCAD.Console.PrintWarning("Please select a cylinder and at least one ShapeString\n")
        else:
            FreeCAD.Console.PrintWarning("Running demo since no cylinder or shape strings selected\n")
            demo()


# Utility

def findShapeStrings(selection):
    shape_strings = []
    for thing in selection:
        if 'String' in thing.PropertiesList: # $$$ more reliable way to detect?
            shape_strings.append(thing)
    return shape_strings
    
def findByDerivedTypeId(selection, typeId):
    things = []
    for thing in selection:
        if thing.isDerivedFrom(typeId):
            things.append(thing)
    return things


# Demo        
def demo():
    import FreeCADGui
    
    # Make a new document if none active
    if not FreeCAD.ActiveDocument:
        doc = FreeCAD.newDocument("Text on cylinder")

    # Full path to a font
    font = u'/Users/mangtronix/Dropbox/Work/Changemakrs-mang/changemakrs-ios-module-insanity/Changemakrs/Changemakrs/Assets/Argumentum-Medium.otf'

    # Create Cylinder
    cf = FreeCAD.ActiveDocument.addObject("Part::Cylinder","Cylinder")
    cf.Radius = Quantity("5 mm")
    cf.Height = Quantity("30 mm")
    cf.Placement = Base.Placement(v(0,20,10), Base.Rotation(v(0,1,0),15))

    # Create ShapeString feature
    text = u"Hi"
    ssf = Draft.makeShapeString(String=text,FontFile=font,Size=1.0,Tracking=0)
    ssf.Label = text
    
    # The ShapeString.Placement doesn't affect the placement on the cylinder
    # Just rotating to see it easier in the UI.
    upright_rotation = Base.Rotation(v(1,0,0), 90)
    ssf.Placement.Base = v(0,2,0)
    ssf.Placement.Rotation = upright_rotation
    
    # Put it on the cylinder
    tocf=FreeCAD.ActiveDocument.addObject("Part::FeaturePython","HiOnCylinder")
    TextOnCylinder(tocf)
    tocf.ShapeString = ssf
    tocf.Cylinder = cf
    tocf.ViewObject.Proxy=0

    
    # More text
    text = u"23"
    ssf2 = Draft.makeShapeString(String=text,FontFile=font,Size=1.0,Tracking=0)
    
    # Store text height so we can put the new text above the existing text
    text_height = ssf2.Shape.BoundBox.YLength # Approximately
    
    # Make sure the text height is a Quantity with correct Unit
    text_height = Quantity(text_height)
    if text_height.Unit != Units.Length:
        text_height.Unit = Units.Length
    
    ssf2.Label = text
    ssf2.Placement.Base = v(10,2,0)
    ssf2.Placement.Rotation = upright_rotation
    
    tocf2 = FreeCAD.ActiveDocument.addObject("Part::FeaturePython","NumberOnCylinder")
    TextOnCylinder(tocf2)
    tocf2.ShapeString = ssf2
    tocf2.Cylinder = cf
    tocf2.ViewObject.Proxy=0
    
    # Offset the text above the previous text
    if _debug:
        FreeCAD.Console.PrintMessage("text height %s" % text_height)
    tocf2.BaseLineOffset += text_height * 1.2 # 20% line spacing
    
    
    # Text 90 degrees around
    text = u"90"
    ssf3 = Draft.makeShapeString(String=text,FontFile=font,Size=1.0,Tracking=0)
    ssf3.Label = text
    ssf3.Placement.Base = v(20,2,0)
    ssf3.Placement.Rotation = upright_rotation
    
    
    tocf3 = FreeCAD.ActiveDocument.addObject("Part::FeaturePython","RotatedOnCylinder")
    TextOnCylinder(tocf3)
    tocf3.ShapeString = ssf3
    tocf3.Cylinder = cf
    tocf3.AngleOffset = Quantity('90 deg')
    tocf3.ViewObject.Proxy=0
    
    
    # So everything shows up
    FreeCAD.ActiveDocument.recompute()
    
    FreeCADGui.ActiveDocument.ActiveView.viewFront()
    FreeCADGui.SendMsgToActiveView("ViewFit")


if __name__ == "__main__":
    TextOnCylinderCmd()