Support odd-length dash patterns in Agg. #17444
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timhoffm
reviewed
May 18, 2020
| return 0; | ||
| } | ||
| Py_ssize_t nentries = PySequence_Size(dashes_seq); | ||
| Py_ssize_t dash_pattern_length = (nentries % 2) ? 2 * nentries : nentries; |
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Can you add a comment what this is doing and why? It's hard to understand if one doesn't know the context.
All vector backends already support passing an odd-length dash pattern,
duplicating the on/off array (so that on the second repetition "on"
becomes "off" and vice-versa). This is also explicitly supported by
the svg spec for `stroke-dasharray` ("If an odd number of values is
provided, then the list of values is repeated to yield an even number of
values. Thus, 5,3,2 is equivalent to 5,3,2,5,3,2.") and less explicitly
by the pdf and ps specs, and by cairo. So the backend needing support
is Agg; iterating twice over the sequence is likely simplest.
timhoffm
approved these changes
May 18, 2020
QuLogic
approved these changes
May 19, 2020
1 task
brunobeltran
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Jun 9, 2020
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PR Summary
All vector backends already support passing an odd-length dash pattern,
duplicating the on/off array (so that on the second repetition "on"
becomes "off" and vice-versa). This is also explicitly supported by
the svg spec for
stroke-dasharray("If an odd number of values isprovided, then the list of values is repeated to yield an even number of
values. Thus, 5,3,2 is equivalent to 5,3,2,5,3,2.") and less explicitly
by the pdf and ps specs, and by cairo. So the backend needing support
is Agg; iterating twice over the sequence is likely simplest.
PR Checklist