Dive list view: replace signal-magic by flag

In DiveListView, we have a very fundamental problem: When
On the one hand, we get informed of user-selection in the
DiveListView::selectionChanged() slot. This has to set the
correct flags in the C-backend.

On the other hand, sometimes we have to set the selection
programatically, e.g. when selecting a trip. This is done
by calling QItemSelectionModel::select().

But: this will *also* call into the above slot, in which
we can't tell whether it was a user interaction or an
internal call. This can lead to either infinite loops or
very inefficient behavior, because the current dive
is set numerous times.

The current code is aware of that and disconnects the
corresponding signal. This is scary, as these signals are
set internally by the model and view. Replace this
by a global "command executing" flag in DiveListNotifier.
The flag is set using a "marker" class, which resets the flag
once it goes out of scope (cf. RAII pattern).

In DiveListView, only process a selection if the flag is not
set. Otherwise simply call the QTreeView base class, to reflect
the new selection in the UI.

To have a common point for notifications of selection changes,
add such a signal to DiveListNotifier. This signal will be
used by the DiveListView as well as the Command-objects.

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

1 files changed, 13 insertions, 4 deletions

diff --git a/desktop-widgets/command_divelist.cpp b/desktop-widgets/command_divelist.cpp
index 17d5f00e4..a75004bea 100644
--- a/desktop-widgets/command_divelist.cpp
+++ b/desktop-widgets/command_divelist.cpp
@@ -323,6 +323,8 @@ bool AddDive::workToBeDone()
 
 void AddDive::redo()
 {
+	auto marker = diveListNotifier.enterCommand();
+
 	int idx = divesToAdd[0].idx;
 	divesToRemove = addDives(divesToAdd);
 	mark_divelist_changed(true);
@@ -338,6 +340,8 @@ void AddDive::redo()
 
 void AddDive::undo()
 {
+	auto marker = diveListNotifier.enterCommand();
+
 	// Simply remove the dive that was previously added
 	divesToAdd = removeDives(divesToRemove);
 
@@ -358,12 +362,14 @@ bool DeleteDive::workToBeDone()
 
 void DeleteDive::undo()
 {
+	auto marker = diveListNotifier.enterCommand();
 	divesToDelete = addDives(divesToAdd);
 	mark_divelist_changed(true);
 }
 
 void DeleteDive::redo()
 {
+	auto marker = diveListNotifier.enterCommand();
 	divesToAdd = removeDives(divesToDelete);
 	mark_divelist_changed(true);
 }
@@ -377,6 +383,7 @@ ShiftTime::ShiftTime(const QVector<dive *> &changedDives, int amount)
 
 void ShiftTime::redo()
 {
+	auto marker = diveListNotifier.enterCommand();
 	for (dive *d: diveList)
 		d->when -= timeChanged;
 
@@ -420,6 +427,7 @@ RenumberDives::RenumberDives(const QVector<QPair<dive *, int>> &divesToRenumberI
 
 void RenumberDives::undo()
 {
+	auto marker = diveListNotifier.enterCommand();
 	renumberDives(divesToRenumber);
 	mark_divelist_changed(true);
 }
@@ -442,6 +450,7 @@ bool TripBase::workToBeDone()
 
 void TripBase::redo()
 {
+	auto marker = diveListNotifier.enterCommand();
 	moveDivesBetweenTrips(divesToMove);
 
 	mark_divelist_changed(true);
@@ -554,8 +563,7 @@ bool SplitDives::workToBeDone()
 
 void SplitDives::redo()
 {
-	if (!diveToSplit)
-		return;
+	auto marker = diveListNotifier.enterCommand();
 	divesToUnsplit[0] = addDive(splitDives[0]);
 	divesToUnsplit[1] = addDive(splitDives[1]);
 	unsplitDive = removeDive(diveToSplit);
@@ -564,9 +572,8 @@ void SplitDives::redo()
 
 void SplitDives::undo()
 {
-	if (!unsplitDive.dive)
-		return;
 	// Note: reverse order with respect to redo()
+	auto marker = diveListNotifier.enterCommand();
 	diveToSplit = addDive(unsplitDive);
 	splitDives[1] = removeDive(divesToUnsplit[1]);
 	splitDives[0] = removeDive(divesToUnsplit[0]);
@@ -659,6 +666,7 @@ bool MergeDives::workToBeDone()
 
 void MergeDives::redo()
 {
+	auto marker = diveListNotifier.enterCommand();
 	renumberDives(divesToRenumber);
 	diveToUnmerge = addDive(mergedDive);
 	unmergedDives = removeDives(divesToMerge);
@@ -666,6 +674,7 @@ void MergeDives::redo()
 
 void MergeDives::undo()
 {
+	auto marker = diveListNotifier.enterCommand();
 	divesToMerge = addDives(unmergedDives);
 	mergedDive = removeDive(diveToUnmerge);
 	renumberDives(divesToRenumber);