Undo: select dives after add, remove, merge, split dive commands

Select the proper dives after the add, remove, split and merge
dives commands on undo *and* redo. Generally, select the added
dives. For undo of add, remember the pre-addition selection.
For redo of remove, select the closest dive to the first removed
dive.

The biggest part of the commit is the signal-interface between
the dive commands and the dive-list model and dive-list view.
This is done in two steps:
1) To the DiveTripModel in batches of trips. The dive trip model
   transforms the dives into indices.
2) To the DiveListView. The DiveListView has to translate the
   DiveTripModel indexes to actual indexes via its QSortFilterProxy-
   model.

For code-reuse, derive all divelist-changing commands from a new base-class,
which has a flag that describes whether the divelist changed. The helper
functions which add and remove dives are made members of the base class and
set the flag is a selected dive is added or removed.

To properly detect when the current dive was deleted it
became necessary to turn the current dive from an index
to a pointer, because indices are not stable.

Unfortunately, in some cases an index was expected and these
places now have to transform the dive into an index. These
should be converted in due course.

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

1 files changed, 32 insertions, 17 deletions

diff --git a/desktop-widgets/divelistview.cpp b/desktop-widgets/divelistview.cpp
index 2a0d7028c..8ed07b4db 100644
--- a/desktop-widgets/divelistview.cpp
+++ b/desktop-widgets/divelistview.cpp
@@ -44,6 +44,7 @@ DiveListView::DiveListView(QWidget *parent) : QTreeView(parent), mouseClickSelec
 	setContextMenuPolicy(Qt::DefaultContextMenu);
 	setSelectionMode(ExtendedSelection);
 	header()->setContextMenuPolicy(Qt::ActionsContextMenu);
+	connect(DiveTripModel::instance(), &DiveTripModel::selectionChanged, this, &DiveListView::diveSelectionChanged);
 
 	header()->setStretchLastSection(true);
 
@@ -176,23 +177,37 @@ void DiveListView::reset()
 	}
 }
 
+// If items were selected, inform the selection model
+void DiveListView::diveSelectionChanged(const QVector<QModelIndex> &indexes, bool select)
+{
+	MultiFilterSortModel *m = MultiFilterSortModel::instance();
+	QItemSelectionModel *s = selectionModel();
+	auto flags = select ?
+		QItemSelectionModel::Rows | QItemSelectionModel::Select :
+		QItemSelectionModel::Rows | QItemSelectionModel::Deselect;
+	for (const QModelIndex &index: indexes) {
+		// We have to transform the indices into local indices, since
+		// there might be sorting or filtering in effect.
+		QModelIndex localIndex = m->mapFromSource(index);
+
+		// It might be possible that the item is not shown (filter is
+		// in effect). Then we get an invalid index and should ignore
+		// this selection.
+		if (!localIndex.isValid())
+			continue;
+
+		s->select(localIndex, flags);
+	}
+}
+
 // If rows are added, check which of these rows is a trip and expand the first column
 void DiveListView::rowsInserted(const QModelIndex &parent, int start, int end)
 {
 	// First, let the QTreeView do its thing.
 	QTreeView::rowsInserted(parent, start, end);
 
+	// Check for each inserted row whether this is a trip and expand the first column
 	QAbstractItemModel *m = model();
-	QItemSelectionModel *s = selectionModel();
-
-	// Check whether any of the items is selected
-	for (int i = start; i <= end; ++i) {
-		QModelIndex index = m->index(i, 0, parent);
-		if (m->data(index, DiveTripModel::SELECTED_ROLE).toBool())
-			s->select(index, QItemSelectionModel::Select | QItemSelectionModel::Rows);
-	}
-
-	// Now check for each inserted row whether this is a trip and expand the first column
 	if (parent.isValid()) // Trips don't have a parent
 		return;
 	for (int i = start; i <= end; ++i) {
@@ -284,7 +299,7 @@ void DiveListView::clearTripSelection()
 void DiveListView::unselectDives()
 {
 	// make sure we don't try to redraw the dives during the selection change
-	selected_dive = -1;
+	current_dive = nullptr;
 	amount_selected = 0;
 	// clear the Qt selection
 	selectionModel()->clearSelection();
@@ -353,7 +368,7 @@ void DiveListView::selectDives(const QList<int> &newDiveSelection)
 	while (!sortedSelection.isEmpty())
 		selectDive(sortedSelection.takeLast());
 
-	while (selected_dive == -1) {
+	while (!current_dive) {
 		// that can happen if we restored a selection after edit
 		// and the only selected dive is no longer visible because of a filter
 		newSelection--;
@@ -365,7 +380,7 @@ void DiveListView::selectDives(const QList<int> &newDiveSelection)
 			selectDive(newSelection);
 	}
 	QSortFilterProxyModel *m = qobject_cast<QSortFilterProxyModel *>(model());
-	QModelIndexList idxList = m->match(m->index(0, 0), DiveTripModel::DIVE_IDX, selected_dive, 2, Qt::MatchRecursive);
+	QModelIndexList idxList = m->match(m->index(0, 0), DiveTripModel::DIVE_IDX, get_divenr(current_dive), 2, Qt::MatchRecursive);
 	if (!idxList.isEmpty()) {
 		QModelIndex idx = idxList.first();
 		if (idx.parent().isValid())
@@ -441,7 +456,7 @@ void DiveListView::reload(DiveTripModel::Layout layout, bool forceSort)
 	QSortFilterProxyModel *m = qobject_cast<QSortFilterProxyModel *>(model());
 	sortByColumn(sortColumn, currentOrder);
 	if (amount_selected && current_dive != NULL) {
-		selectDive(selected_dive, true);
+		selectDive(get_divenr(current_dive), true);
 	} else {
 		QModelIndex firstDiveOrTrip = m->index(0, 0);
 		if (firstDiveOrTrip.isValid()) {
@@ -567,7 +582,7 @@ void DiveListView::selectionChanged(const QItemSelection &selected, const QItemS
 		if (!dive) // it's a trip!
 			deselect_dives_in_trip((dive_trip_t *)model->data(index, DiveTripModel::TRIP_ROLE).value<void *>());
 		else
-			deselect_dive(get_divenr(dive));
+			deselect_dive(dive);
 	}
 	Q_FOREACH (const QModelIndex &index, newSelected.indexes()) {
 		if (index.column() != 0)
@@ -586,7 +601,7 @@ void DiveListView::selectionChanged(const QItemSelection &selected, const QItemS
 					expand(index);
 			}
 		} else {
-			select_dive(get_divenr(dive));
+			select_dive(dive);
 		}
 	}
 	if (!dontEmitDiveChangedSignal)
@@ -889,7 +904,7 @@ void DiveListView::contextMenuEvent(QContextMenuEvent *event)
 	QAction *actionTaken = popup.exec(event->globalPos());
 	if (actionTaken == collapseAction && collapseAction) {
 		this->setAnimated(false);
-		selectDive(selected_dive, true);
+		selectDive(get_divenr(current_dive), true);
 		scrollTo(selectedIndexes().first());
 		this->setAnimated(true);
 	}