Re: Dealing with different character map formats when mapping glyph indicies to character codes

[Nikolaus Waxweiler]

Hi Craig,
you should be able to trust the (Unicode) cmap sub-tables you find in a 
font to give you the intended Unicode character to glyph ID mapping. 
You can probably follow the logic in

https://github.com/fonttools/fonttools/blob/77a35fe16d07c16e3bb52863344df35520e9b770/Lib/fontTools/ttLib/ttFont.py#L806-L841

to determine which cmap to look at. I wouldn't try and do any overlap 
analysis in a first pass.