DeltaValue writer fails to write #3757
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Updating the DeltaFormat write tool which appears to fail on compilation due to a list being inside a list.
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I expect there could be a different / better way to solve this bug than this approach, but I'll leave that to someone who understands the backend of fonttools better than I to sort out :) |
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Ouch. It must have hurt to debug that. I'll check soon. The correct fix might be somewhere else, as we should NOT be getting a list of lists to begin with. Can you attach or email me a full ttx file? Thanks! |
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Sent! |
behdad
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Jan 30, 2025
The "" marker is used when a custom converter expects a list. For DeltaValues, we expect a list as a single value, not a list to be enumerated in XML. So, None is appropriate here. Cryptic, I know... Fixes #3757
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Proper fix in #3758 |
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I have a font with Delta values built into the
GPOStable that I am trying to round-trip through TTX:Here is an example of it:
However, every time I tried to build the font, fonttools errors on the deltavalues above. Stepping through the specific code in otConverters, I found that the problem is due to this line
assert len(DeltaValue) == nItems. In manually counting the items, this assertion appears to be fine, but I discovered that thevaluethat is being passed intoDeltaValueis not[2, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1]as it should be, but[[2, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1]], which is of course returning alenof 1 instead of 13.Adding
[0]to the declaration forDeltaValuesolves this problem.