Decompose in Robofont

Ondrej Jób

Hello typefolks!

I'm writing a script for FL and RF and I need to translate a glyph to SVG. I'm trying to find the best way to do this with a glyph with components and I have a problem with this sollutions:


if len(g.components): # if glyph has components

g = g.copy() # create a copy of it

g.decompose() # decompose it without affecting the original glyph

# do stuff with the decomposed glyph

This method works great in FL, in RF however, it doesn't create a copy, but decomposes the glyph directly in the font. I tried to implement prepareUndo and performUndo methods, but they didn't seem to work. Do you have any tips on how I could make this work in RF?

Ondrej Jób

Update: RF doesn't decompose the glyph, as @typemytype pointed out on Twitter, the copy cannot be decomposed because it doesn't have a parent font.

Alexander Lubovenko

it seems you need create a copy of font, then you can decompose any glyphs

Ondrej Jób

Yes, this is how I do it eventually: I add the copy as a new glyph to my font, decompose, do my stuff and then get rid of it. I was affraid this will make the script slower, but it didn't affect the performance at all.

Kent Lew

Seems like you could also use layers for this.

g.copyToLayer('copyLayer')
gCopy = g.getLayer('copyLayer')
gCopy.decompose()
# do stuff with gCopy
# and then when you're all done
f.removeLayer('copyLayer')

If, for some reason, it worked better to do stuff in the foreground (so you could easily generate on-the-fly, for instance), you could decompose and do stuff to the glyph in the foreground, then at the end run a loop to swap your originals back into place.

for g in f:
    g.flipLayers('foreground', 'copyLayer')

I don’t know if there’s any real performance advantage to using layers over making new dummy glyphs. Just seems more self-contained.

Georg Seifert

Wouldn't it be easier to write a svg pen. Then you don't need to decompose anything.

Kent Lew

I’ve never used this, so I can’t vouch for the functionality, but Tal has a ufo2svg tool/library here:

https://github.com/typesupply/ufo2svg

(including a SVGPathPen)