I have borrowed heavily from the Slanter extension for this, though I’ve added a bit of logic, e.g. to avoid adding extreme points (which break compatibility).

However, even though I got this working pretty well earlier today, over time I started getting the following error. It became worse once I started adding in some handling for copying groups & kerning, but there was seemingly no single moment that it started crashing. Does this seem like an upstream issue, or could it be something to do with my computer’s RAM, or have I made some mistake in how I’m approaching this?

Thanks so much for any insight! I’m happy to share my script as GitHub Gist or something, once I get this working well.

Traceback (most recent call last):
  File "/Applications/RoboFont.app/Contents/Resources/lib/python3.7/fs/osfs.py", line 646, in open
FileNotFoundError: [Errno 2] No such file or directory: b'/var/folders/x0/q5zt3sx15ssdz5mjcm9rgvh40000gn/T/tmp7ncr5598/temp.ufo/glyphs/E_.glif'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Applications/RoboFont.app/Contents/Resources/lib/python3.7/fontTools/ufoLib/glifLib.py", line 291, in getGLIF
  File "/Applications/RoboFont.app/Contents/Resources/lib/python3.7/fs/wrapfs.py", line 342, in readbytes
  File "/Applications/RoboFont.app/Contents/Resources/lib/python3.7/fs/base.py", line 603, in readbytes
  File "/Applications/RoboFont.app/Contents/Resources/lib/python3.7/fs/osfs.py", line 646, in open
  File "/Applications/RoboFont.app/Contents/Resources/lib/python3.7/fs/error_tools.py", line 90, in __exit__
  File "six.pyc", line 702, in reraise
  File "/Applications/RoboFont.app/Contents/Resources/lib/python3.7/fs/osfs.py", line 646, in open
fs.errors.ResourceNotFound: resource 'E_.glif' not found

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "prep-faux-italics.py", line 187, in <module>
  File "lib/fontObjects/fontPartsWrappers.pyc", line 1516, in save
  File "/Applications/RoboFont.app/Contents/Resources/lib/python3.7/fontParts/base/font.py", line 208, in save
  File "lib/fontObjects/fontPartsWrappers.pyc", line 1521, in _save
  File "lib/fontObjects/doodleFont.pyc", line 249, in save
  File "/Applications/RoboFont.app/Contents/Resources/lib/python3.7/defcon/objects/layer.py", line 581, in _stampGlyphDataState
  File "/Applications/RoboFont.app/Contents/Resources/lib/python3.7/fontTools/ufoLib/glifLib.py", line 295, in getGLIF
fontTools.ufoLib.errors.GlifLibError: The file 'E_.glif' associated with glyph 'E' in contents.plist does not exist on <osfs '/var/folders/x0/q5zt3sx15ssdz5mjcm9rgvh40000gn/T/tmp7ncr5598/temp.ufo'>/glyphs

Here’s my script so far:

"""
    A script to take the sources of Name Sans and output slanted versions of these, 
    for the purposes of A) prototyping & B) jumpstarting the italic drawings.

    Based largely on the Slanter extension:
    https://github.com/roboDocs/slanterRoboFontExtension/blob/57d7ac8ad9c91b0dce480cccb5a5dc2d4d4c51c4/Slanter.roboFontExt/lib/slanter.py

    GOALS:

    Copy all sources as italic sources, then:

    1. Start from the slanter extension and slant to 10.24 degrees, but:
    2. Slant round glyphs by less – maybe 7 degrees? # TODO
    3. don’t add extreme points (or any points)
    
    (Then, outside of script) make a designspace that will build these into Italic statics and an ital axis.
"""

from vanilla.dialogs import *
from math import radians
from fontTools.misc.transform import Transform
from mojo.roboFont import CurrentGlyph, CurrentFont, RGlyph, RPoint
import os

# ------------------------------
# set preferences below

openNewFonts = False
saveNewFonts = True
addExtremesToNewFonts = False

outputFolder = "faux-italics"

# glyphs that get double-slanted by slanter code
# glyphsToDecompose = "b q u IJ arrowleft arrowright greater".split()
setSkew = 10.24
setRotation = 0
rounds = "O o e c".split()
roundSkew = 10.24 # TODO: set this to 7?
# TODO: if you skew rounds differently, you must move them to match the movement of everything else

dialogMessage = "Select UFOs to copy into faux-italics"

# ------------------------------

# Function mostly copied from the Slanter extension
def getGlyph(glyph, skew, rotation, addComponents=False, skipComponents=False, addExtremes=False):
    skew = radians(skew)
    rotation = radians(-rotation)

    dest = glyph.copy()

    if not addComponents:
        for component in dest.components:
            pointPen = DecomposePointPen(glyph.layer, dest.getPointPen(), component.transformation)
            component.drawPoints(pointPen)
            dest.removeComponent(component)

    for contour in list(dest):
        if contour.open:
            dest.removeContour(contour)

    if skew == 0 and rotation == 0:
        return dest

    for contour in dest:
        for bPoint in contour.bPoints:
            bcpIn = bPoint.bcpIn
            bcpOut = bPoint.bcpOut
            if bcpIn == (0, 0):
                continue
            if bcpOut == (0, 0):
                continue
            if bcpIn[0] == bcpOut[0] and bcpIn[1] != bcpOut[1]:
                bPoint.anchorLabels = ["extremePoint"]
            if rotation and bcpIn[0] != bcpOut[0] and bcpIn[1] == bcpOut[1]:
                bPoint.anchorLabels = ["extremePoint"]

    cx, cy = 0, 0
    box = glyph.bounds
    if box:
        cx = box[0] + (box[2] - box[0]) * .5
        cy = box[1] + (box[3] - box[1]) * .5

    t = Transform()
    t = t.skew(skew)
    t = t.translate(cx, cy).rotate(rotation).translate(-cx, -cy)

    if not skipComponents:
        dest.transformBy(tuple(t))
    else:
        for contour in dest.contours:
            contour.transformBy(tuple(t))

        # this seems to work !!!
        for component in dest.components:
            # get component center
            _box = glyph.layer[component.baseGlyph].bounds
            if not _box:
                continue
            _cx = _box[0] + (_box[2] - _box[0]) * .5
            _cy = _box[1] + (_box[3] - _box[1]) * .5
            # calculate origin in relation to base glyph
            dx = cx - _cx
            dy = cy - _cy
            # create transformation matrix
            tt = Transform()
            tt = tt.skew(skew)
            tt = tt.translate(dx, dy).rotate(rotation).translate(-dx, -dy)
            # apply transformation matrix to component offset
            P = RPoint()
            P.position = component.offset
            P.transformBy(tuple(tt))
            # set component offset position
            component.offset = P.position

    # check if "add extremes" is set to True
    if addExtremes:
        dest.extremePoints(round=0)
        for contour in dest:
            for point in contour.points:
                if "extremePoint" in point.labels:
                    point.selected = True
                    point.smooth = True
                else:
                    point.selected = False

    dest.removeSelection()
    dest.round()
    return dest

# Function adapted from the Slanter extension
def generateFont(fontToCopy):

    outFont = RFont(showInterface=False)
    outFont.info.update(fontToCopy.info.asDict())
    outFont.features.text = fontToCopy.features.text

    for glyph in fontToCopy:
        outFont.newGlyph(glyph.name)
        outGlyph = outFont[glyph.name]
        outGlyph.width = glyph.width
        outGlyph.unicodes = glyph.unicodes

        if glyph.name not in rounds:
            resultGlyph = getGlyph(glyph, setSkew, setRotation, addComponents=True, skipComponents=True, addExtremes=addExtremesToNewFonts)
        else:
            resultGlyph = getGlyph(glyph, roundSkew, setRotation, addComponents=True, skipComponents=True, addExtremes=addExtremesToNewFonts)

        outGlyph.appendGlyph(resultGlyph)

    # copy glyph order
    outFont.templateGlyphOrder = fontToCopy.templateGlyphOrder

    # copy groups & kerning
    outFont.groups.update(fontToCopy.groups.asDict())
    outFont.kerning.update(fontToCopy.kerning.asDict())


    # quick/lazy update to relative feature link
    outFont.features.text = "include(../../features/features.fea);"

    outFont.info.styleName = outFont.info.styleName + " Italic"

    return outFont


# Get input font paths
inputFonts = getFile(dialogMessage, allowsMultipleSelection=True, fileTypes=["ufo"])

# Go through input paths & use to generate slanted fonts
for fontPath in inputFonts:
    font = OpenFont(fontPath, showInterface=False)

    slantedFont = generateFont(font)

    fontDir, fontFile = os.path.split(fontPath)
    italicDir = fontDir + "/" + outputFolder

    if not os.path.exists(italicDir):
        os.makedirs(italicDir)

    slantedFontPath = italicDir + "/" + f"{fontFile.replace('.ufo','_Italic.ufo')}"

    if saveNewFonts:
        slantedFont.save(slantedFontPath)

    if openNewFonts:
        slantedFont.openInterface()
    else:
        slantedFont.close()
    
    font.close()

The font seems to save just fine, and the E is there, slanted.

In previous runs, it was flagging other glyphs, like G.RECT, which were also saving.

The main problem with this error is that it prevents me from running through all my sources in one go.

For now, I’ve made the lazy fix of just adding a try/except:

    try:
        if saveNewFonts:
            slantedFont.save(slantedFontPath)
    except:
        print("file not found error")

...but, I’m worried that this might introduce an error I’m missing. So, any recommendations about how I might want to proceed would be amazing. Thanks again!

are you overwriting ufos?
are you using ufozzzz?

Does this traceback occur every time?
are you overwriting ufos?

Ahh this seems like it might be where the issue is.

Regardless of the UFO (based on a few tests), I don’t get the error when writing to a brand-new italic UFO, but I always get this error if I am generating a faux-italic UFO for the second time, i.e. overwriting an existing one.

That would explain why I didn’t get this right away, but started to after I had already generated UFOs.

So, I think probably the solution will be checking if the UFO already exists, and deleting it before making a new one.

are you using ufozzzz?

Nope!

I will probably evolve this a bit further, but here is the code now:

https://gist.github.com/arrowtype/a3c4445cd6b9a6174f885eccff38e1c9

(Caveat: Not sure whether it would work for UFOZ)