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a11y: QComboBox: Reset all model connections when setting model 

When setting the model either directly for the combobox
itself or for the combobox's view, disconnect from the model
signals and connect to them anew. Always set the model for the
view first before connecting the combobox's own slots to the model's
signals. Since slots are activated in the order in which they are
connected [1] and both of them are connected to the
QAbstractItemModel::rowsInserted signal, this ensures that the
QAbstractItemViewPrivate::rowsInserted/QListView::rowsInserted
slot will get activated before the QComboBoxPrivate::rowsInserted one.
(QAbstractItemView::setModel connects its slots to the model's signals.)

Activating these slots the other way around is problematic
as described in more detail in
ecef704624 and QTBUG-120121.
(macOS accessibility bridge depends on
QAbstractItemViewPrivate::rowsInserted to
update its table representation, which may be necessary
before activating other slots; ATs or platform a11y caches
may depend on correct event order.)

In a quick test, this commit fixes the QTBUG-119526 crash reliably
reproducible after 5093e517b9
even without the previous fix ecef704624
in place. However, leave that one in place, too, as
relying on the order in which the connected slots are called
is quite fragile (s. the discussion in the Gerrit change
for ecef704624).

[1] https://doc.qt.io/qt-6/qobject.html#connect

Fixes: QTBUG-120121
Task-number: QTBUG-119526
Pick-to: 6.7 6.6 6.5
Change-Id: If75fef661f7fcfc1e30e90ec851a2555cf25a65d
Reviewed-by: Christian Ehrlicher <ch.ehrlicher@gmx.de>
bb10
Michael Weghorn 2023-12-11 15:42:02 +01:00
parent 87f7d2c6b0
commit 7120859fdb
1 changed files with 8 additions and 2 deletions
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10
src/widgets/widgets/qcombobox.cpp
View File

@ -1064,7 +1064,9 @@ QComboBoxPrivateContainer* QComboBoxPrivate::viewContainer()
Q_Q(QComboBox);
container = new QComboBoxPrivateContainer(new QComboBoxListView(q), q);
disconnectModel();
container->itemView()->setModel(model);
connectModel();
container->itemView()->setTextElideMode(Qt::ElideMiddle);
updateDelegate(true);
updateLayoutDirection();
@ -2055,7 +2057,6 @@ void QComboBox::setModel(QAbstractItemModel *model)
}
d->model = model;
d->connectModel();
if (d->container) {
d->container->itemView()->setModel(model);
@ -2064,6 +2065,8 @@ void QComboBox::setModel(QAbstractItemModel *model)
d, &QComboBoxPrivate::emitHighlighted, Qt::UniqueConnection);
}
d->connectModel();
setRootModelIndex(QModelIndex());
d->trySetValidIndex();
@ -2487,8 +2490,11 @@ void QComboBox::setView(QAbstractItemView *itemView)
return;
}
if (itemView->model() != d->model)
if (itemView->model() != d->model) {
d->disconnectModel();
itemView->setModel(d->model);
d->connectModel();
}
d->viewContainer()->setItemView(itemView);
}