Dive list: cache shown flag in model (quick-fix for undo-crash)

We have a very fundamental problem with data-duplication in
core and qt-models. In a particular case, this led to an easily
reproducible crash:
1) An undo command moved the last dive of a trip to another.
2) When an undo-command removed the last dive of
   a trip to a different trip, the dive was removed from the
   trip in the core. Then, the model was updated.
3) That lead at first to a rearrangement of the trips, because
   the trip with the added dive is moved before the trip with
   the removed dive.
4) In such a case, the filter-model checks the visibility of
   the trip.
5) Since the trip with the removed dive has no dives in the core,
   visibility was determined as false.
6) From this point on the mappings of the QSortFilterProxyModel
   were messed up. Accesses led to crashes. It is unclear
   whether this is a Qt bug or only a QOI issue.

As a quick-fix, cache the visibility flag of trips directly
in the Qt-models. Don't set the visibility directly in the
core, but go via the Qt-models. Thus, a more clear layering
is achieved.

In the long run, we can hopefully get rid of the data-duplication
in the models.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

1 files changed, 36 insertions, 27 deletions

diff --git a/qt-models/filtermodels.cpp b/qt-models/filtermodels.cpp
index 8e7239e35..9ef910def 100644
--- a/qt-models/filtermodels.cpp
+++ b/qt-models/filtermodels.cpp
@@ -194,25 +194,9 @@ bool MultiFilterSortModel::showDive(const struct dive *d) const
 
 bool MultiFilterSortModel::filterAcceptsRow(int source_row, const QModelIndex &source_parent) const
 {
-	QModelIndex index0 = sourceModel()->index(source_row, 0, source_parent);
-	struct dive *d = sourceModel()->data(index0, DiveTripModelBase::DIVE_ROLE).value<struct dive *>();
-
-	// For dives, simply check the hidden_by_filter flag
-	if (d)
-		return !d->hidden_by_filter;
-
-	// Since this is not a dive, it must be a trip
-	dive_trip *trip = sourceModel()->data(index0, DiveTripModelBase::TRIP_ROLE).value<dive_trip *>();
-
-	if (!trip)
-		return false; // Oops. Neither dive nor trip, something is seriously wrong.
-
-	// Show the trip if any dive is visible
-	for (int i = 0; i < trip->dives.nr; ++i) {
-		if (!trip->dives.dives[i]->hidden_by_filter)
-			return true;
-	}
-	return false;
+	QAbstractItemModel *m = sourceModel();
+	QModelIndex index0 = m->index(source_row, 0, source_parent);
+	return m->data(index0, DiveTripModelBase::SHOWN_ROLE).value<bool>();
 }
 
 void MultiFilterSortModel::filterChanged(const QModelIndex &from, const QModelIndex &to, const QVector<int> &roles)
@@ -225,8 +209,9 @@ void MultiFilterSortModel::filterChanged(const QModelIndex &from, const QModelIn
 
 void MultiFilterSortModel::myInvalidate()
 {
-	int i;
-	struct dive *d;
+	QAbstractItemModel *m = sourceModel();
+	if (!m)
+		return;
 
 	{
 		// This marker prevents the UI from getting notifications on selection changes.
@@ -240,12 +225,36 @@ void MultiFilterSortModel::myInvalidate()
 
 		divesDisplayed = 0;
 
-		// Apply filter for each dive
-		for_each_dive (i, d) {
-			bool show = showDive(d);
-			filter_dive(d, show);
-			if (show)
-				divesDisplayed++;
+		for (int i = 0; i < m->rowCount(QModelIndex()); ++i) {
+			QModelIndex idx = m->index(i, 0, QModelIndex());
+
+			dive_trip *trip = m->data(idx, DiveTripModelBase::TRIP_ROLE).value<dive_trip *>();
+			if (trip) {
+				// This is a trip -> loop over all dives and see if any is selected
+
+				bool showTrip = false;
+				for (int j = 0; j < m->rowCount(idx); ++j) {
+					QModelIndex idx2 = m->index(j, 0, idx);
+					dive *d = m->data(idx2, DiveTripModelBase::DIVE_ROLE).value<dive *>();
+					if (!d) {
+						qWarning("MultiFilterSortModel::myInvalidate(): subitem not a dive!?");
+						continue;
+					}
+					bool show = showDive(d);
+					if (show) {
+						divesDisplayed++;
+						showTrip = true;
+					}
+					m->setData(idx2, show, DiveTripModelBase::SHOWN_ROLE);
+				}
+				m->setData(idx, showTrip, DiveTripModelBase::SHOWN_ROLE);
+			} else {
+				dive *d = m->data(idx, DiveTripModelBase::DIVE_ROLE).value<dive *>();
+				bool show = showDive(d);
+				if (show)
+					divesDisplayed++;
+				m->setData(idx, show, DiveTripModelBase::SHOWN_ROLE);
+			}
 		}
 
 		invalidateFilter();