Two position comparisons handed to std::sort were not strict weak
orderings, which std::sort requires; with the wrong kind of comparator
the sort is undefined behaviour (libstdc++ can read past the range,
MSVC debug builds assert "invalid comparator").
- comparPos(), used when renumbering the elements of a project, ended
with "<=" on x and y, so two elements at the same position (pasted at
the origin, placed by a script, stacked symbols) were each "before"
the other.
- The terminal numbering dialog compared positions with a 1 px
tolerance ("within 1 px counts as aligned, then compare the other
axis"), which is not transitive: terminals at x = 2, 1.1 and 0.2 give
a < b, b < c and c < a.
Move the comparisons into positionorder.h, a header-only helper:
xThenY()/yThenX() with "<", and roundedXThenY()/roundedYThenX(), which
round the positions to whole pixels first so that items a fraction of a
pixel apart still count as aligned, as the tolerance meant to, while
staying transitive. comparPos() keeps its folio and row-letter stages
and calls xThenY() for the last one.
No file-format change. Elements at distinct positions sort exactly as
before; the terminal order changes only for terminals less than a pixel
apart that straddle a half-pixel boundary.
Tests: tst_positionorder checks each order on a grid of awkward
positions by brute force (irreflexive, asymmetric, transitive, with a
transitive equivalence), the three-terminal cycle, twenty items at one
position, and that std::sort leaves the list sorted and intact. The
helper is new, so the test cannot fail on master; the call sites are
the two replacements in the diff.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Signed-off-by: Beat Hangartner <beat@hangartners.ch>
Beat Hangartner
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