A property value that is entirely whitespace -- reported in #973 as a
workaround (setting a title-block custom variable to a single space, the
only way to give it a value other than blank before that bug was fixed in
#989) -- did not survive a save/reload cycle. Two independent causes, both
needed for the round trip to actually work:
1. DiagramContext::toXml() called .trimmed() on every stored value before
writing it, unconditionally. For ordinary content this only strips
accidental leading/trailing whitespace, but for a value that IS
whitespace it collapses the entire thing to "", indistinguishable from
a value that was never set.
2. QDomDocument::setContent(), used to parse the project file, discards a
text node that is entirely whitespace by default. Confirmed in
isolation, outside any QET code: parsing "<a> </a>" with the default
ParseOptions gives QDomElement::text() == ""; adding
ParseOption::PreserveSpacingOnlyNodes gives " ". So even once (1) stops
destroying the value on save, the very next load throws it away again.
Fix (1) only trims when the trimmed result isn't empty, i.e. leaves an
all-whitespace value untouched. Fix (2) adds PreserveSpacingOnlyNodes to
the one setContent() call that parses a project file
(QETProject::readProjectXml()) -- not the other ~19 call sites in the
codebase (clipboard paste, element/macro loading, translations, autonum
context), which read different, narrower documents and are not implicated
in this report.
Blast radius of (2): every place that walks a QDomNode's children already
filters on isElement() (see QET::findInDomElement()), so the extra
whitespace-only text-node siblings this keeps around are inert wherever
current code already expected only elements. The one place it isn't inert
is exactly the bug -- calling .text() on an element whose entire content
is whitespace.
Verified end-to-end, not just at one stage: a single-space title-block
variable now survives two successive --resave cycles unchanged (confirmed
byte-for-byte in the saved XML), and renders as blank space rather than
literal placeholder text or a vanished value. Re-saved all 24 shipped
examples with and without this change and diffed: 23 byte-identical, the
one that differs (schema_indus.qet) differs only in element uuids -- and
resaving it twice with the SAME unpatched binary produces that same kind
of diff, confirming it is pre-existing non-determinism in files that
predate persisted uuids, unrelated to this change. Qt 6.10.2, ctest 11/11.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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