Sfd generation failed: list index out of range (only happens when selected zoom level is not 1)

[abubelinha]

I continued the example in #11 and tried to generate the sfd file from my set of glyphs.
Some of them glyphtracer did not show a matching alternative so I left 5 of its boxes unselected (one of them, the left box of my double quotes, as explained in previous issue).

When I clicked the "Generate SFD file" button I got this error:

Sfd generation failed: 
list index out of range

I thought this might be due to me not having matched all the recognized glyphs one-to-one.

So I tried to overcome the error just making some fake-matches, so all boxes where matched to one of the selectable characters offered by glyphtracer. But as you can see, that didn't solve the problem:

Environment:
Python 3.8.7
Glyphtracer 2.1
Potrace 1.16
Windows 7 64bit

Thanks
@abubelinha

[abubelinha]

OK. An update on this issue.
I tried to use a very limited character set, only with some letters and numbers.
As they were just a few, I could see them easily with the lower zoom level 1.
And then when I clicked "Generate SFD file" button it just worked OK.

That surprised me, so I tried again with a different zoom level ... and it failed!!

So the issue only happens if you click "Generate SFD file" button when the selected zoom level is not 1.
I will update the issue title to reflect this.
Still an issue, but a minor one.

[ekuester]

Same here, with zoom level 1 all went fine. Otherwise the error happens in subroutine potrace_image in file gtlib.py ... If you use a zoom level greater 1 the invokation of potrace results in an empty eps-file (only with header and footer). The search for 'moveto' fails, in consequence the handling of list 'lines' give the error. Maybe the temporary image for tracing is lost ... Very nasting error, if you are looking in greater text files for characters to transform into glyphs.