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author | Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io> | 2021-01-07 08:20:42 +0100 |
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committer | Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io> | 2021-02-03 09:44:44 +0100 |
commit | fccd419dd632306a4bd85928223e0a56a59510ef (patch) | |
tree | bae8521aa57c8dc68a17331934a3d88f287997ec /tests/auto/gui/text | |
parent | 52fcd0b6d7184bafef6b1b550c3cd887a7ab7c27 (diff) |
Remove false Q_UNREACHABLE from shaping code
This was added by 9ff76c27b9031ae7c49c4c9e8b5a3bea1e0e3c78 on
the basis that it signifies a shaping error and would later assert
or crash.
But the line is easily reachable by user code. If Harfbuzz returns
0 glyphs, it just means it is unable to shape the string, for instance
if the input string only contains default ignorables (like a ZWJ)
and does not have any appropriate glyph to use for replacement.
Qt expects there to always be at least one glyph in the output
(num_glyphs == 0 is used to indicate shaping is not yet done), so
to avoid asserts later on, we simply populate the output with a
single 0 token, which is a required entry in the font that is
reserved for representing unrepresentable characters.
This also adds a test and therefore a zero-width joiner to the test
font to reproduce the issue.
[ChangeLog][QtGui][Text] Fixed a possible crash with certain fonts
when shaping strings consisting only of control characters.
Fixes: QTBUG-89155
Pick-to: 5.15
Pick-to: 6.0
Change-Id: Ia0dd6a04844c9be90dcab6c464bebe339a3dab11
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Diffstat (limited to 'tests/auto/gui/text')
-rw-r--r-- | tests/auto/gui/text/qglyphrun/tst_qglyphrun.cpp | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/tests/auto/gui/text/qglyphrun/tst_qglyphrun.cpp b/tests/auto/gui/text/qglyphrun/tst_qglyphrun.cpp index cf03877516..973a615d5e 100644 --- a/tests/auto/gui/text/qglyphrun/tst_qglyphrun.cpp +++ b/tests/auto/gui/text/qglyphrun/tst_qglyphrun.cpp @@ -63,6 +63,7 @@ private slots: void boundingRect(); void mixedScripts(); void multiLineBoundingRect(); + void defaultIgnorables(); private: int m_testFontId; @@ -631,6 +632,21 @@ void tst_QGlyphRun::multiLineBoundingRect() QVERIFY(firstLineGlyphRun.boundingRect().height() < allGlyphRun.boundingRect().height()); } +void tst_QGlyphRun::defaultIgnorables() +{ + QTextLayout layout; + layout.setFont(QFont("QtsSpecialTestFont")); + layout.setText(QChar(0x200D)); + layout.beginLayout(); + layout.createLine(); + layout.endLayout(); + + QList<QGlyphRun> runs = layout.glyphRuns(); + QCOMPARE(runs.size(), 1); + QCOMPARE(runs.at(0).glyphIndexes().size(), 1); + QCOMPARE(runs.at(0).glyphIndexes()[0], 0); +} + #endif // QT_NO_RAWFONT QTEST_MAIN(tst_QGlyphRun) |