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Bug
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Resolution: Fixed
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P2: Important
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6.4.2
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Linux/X11
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7c84550f3 (dev), 708a48a0b (6.5), 802dfb187 (6.4), 4d3daea33 (tqtc/lts-6.2), bea15cdfa (dev), cc473646e (6.5)
For very long input strings, but still with limited length, it will scan the whole input for 0x9c. However it looks like it would use qMin() to limit it to the length anyway:
https://code.qt.io/cgit/qt/qtbase.git/tree/src/gui/text/qfontmetrics.cpp#n496
This scanning results in a performance issue in laying out some text which has very long lines, like some logs.
- relates to
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QTBUG-109717 Q(Any)StringView support for QFontMetrics
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- Reported
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| For Gerrit Dashboard: QTBUG-109838 | ||||||
|---|---|---|---|---|---|---|
| # | Subject | Branch | Project | Status | CR | V |
| 452299,6 | Avoid unneccessarily long text scans | dev | qt/qtbase | Status: MERGED | +2 | 0 |
| 452738,3 | Remove variant length string support | dev | qt/qtbase | Status: ABANDONED | 0 | 0 |
| 453981,1 | Avoid layouting whole string for small length analysis | dev | qt/qtbase | Status: ABANDONED | -1 | 0 |
| 457386,2 | Avoid unneccessarily long text scans | 6.5 | qt/qtbase | Status: MERGED | +2 | 0 |
| 457387,2 | Avoid unneccessarily long text scans | 6.4 | qt/qtbase | Status: MERGED | +2 | 0 |
| 457393,3 | Avoid unneccessarily long text scans | tqtc/lts-6.2 | qt/tqtc-qtbase | Status: MERGED | +2 | 0 |
| 460296,3 | Warn that computational time follows length of text input | dev | qt/qtbase | Status: MERGED | +2 | 0 |
| 460336,2 | Warn that computational time follows length of text input | 6.5 | qt/qtbase | Status: MERGED | +2 | 0 |