How to append colored glyphs from a font to another?

[thomasponsmicroej]

Hello,

First thanks for the great job with fonttools!

I am using fonttools 4.33.3 and I am trying to append come colored emojis from a font (i.e., SegoeUI Emoji) to another font (say NotoSans-Regular). I see two options with foottools: pyftmerge and ttx -m.

• When using pyftmerge with the following command pyftmerge NotoSans-Regular.ttf seguiemj.ttf I get this traceback:

WARNING: Dropped cmap subtable from font '1':   format 14, platformID  0, platEncID  5
Traceback (most recent call last):
  File "C:\Users\xxx\AppData\Local\Programs\Python\Python38\lib\runpy.py", line 192, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Users\xxx\AppData\Local\Programs\Python\Python38\lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "C:\Users\xxx\AppData\Local\Programs\Python\Python38\Scripts\pyftmerge.exe\__main__.py", line 7, in <module>
  File "C:\Users\xxx\AppData\Local\Programs\Python\Python38\lib\site-packages\fontTools\misc\loggingTools.py", line 372, in wrapper
    return func(*args, **kwds)
  File "C:\Users\xxx\AppData\Local\Programs\Python\Python38\lib\site-packages\fontTools\merge\__init__.py", line 199, in main
    font = merger.merge(fontfiles)
  File "C:\Users\xxx\AppData\Local\Programs\Python\Python38\lib\site-packages\fontTools\merge\__init__.py", line 98, in merge
    self._preMerge(font)
  File "C:\Users\xxx\AppData\Local\Programs\Python\Python38\lib\site-packages\fontTools\merge\__init__.py", line 153, in _preMerge
    layoutPreMerge(font)
  File "C:\Users\xxx\AppData\Local\Programs\Python\Python38\lib\site-packages\fontTools\merge\layout.py", line 400, in layoutPreMerge
    markFilteringSetMap = {i:v for i,v in enumerate(GDEF.table.MarkGlyphSetsDef.Coverage)}
AttributeError: 'NoneType' object has no attribute 'Coverage'

• When using ttx with the following command ttx -d ttx seguiemj.ttf I get a TTX file that I can later merge with a TTF like: ttx -m NotoSans-Regular.ttf ttx/seguiemj.ttx. In that case, the result is a font that has all attributes of the SegoeUI Emoji but none of the Noto. It kinds of "override" Noto's attribute rather than merge the ttx into the ttf. Maybe I got wrong the purpose of the ttx tool.

So, would you see how I could effectively "merge" a range of colored emojis into a specified font? What am I missing with the above?
PS: seguiemj.ttf comes from my Windows 10 fonts folder and NotoSans-Regular.ttf from google fonts.

Thank you :)

Thomas

[anthrotype]

pytftmerge doesn't support COLR table yet #2501.
ttx -m does not merge two fonts in the same sense that pyftmerge does, but simply takes the tables defined in the .ttx file and replaces the ones with the same sfnt tag in the destination .ttf.
merging fonts is not trivial, and doing that by only manipulating XML files is a bit tricky.