As it stood, QTableView would sometimes show drawing
artifacts when sections (rows or columns) where
rearranged, in combination with spans.
The reason is that the current code would go through the
currently visible cells in the viewport to check if any of
them where affected by a span. But the stored spans (in
QSpanCollection) is kept in sync with the column layout in
the model, and doesn't know anything about the rearranged
columns in the view. But a column with spans that is moved
to the left of the viewport can affect the painting of
the viewport as well, and needs to be taken into consideration.
For that reason, the current solution that uses
QSpanCollection::spanAt(x, y), will in that case fail.
Since it seems sensible that QSpanCollection is kept in sync with
the model (it makes model changes that affect spans easier to
handle), this patch will not change QSpanCollection. Instead, it
will iterate through all the spans (which is assumed to normally be
a limited size), convert them to the column layout of the view
(visual instead of logical), and find the ones that overlap.
Overlapping spans will, like before, be added as clip rects
to the QPainter.
Fixes: QTBUG-91896
Pick-to: 6.4 6.3 6.2
Change-Id: Iabe20df13cbd41a68f1104d3d9e24b89c4b88913
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
20a40035fa