selection: create global single_selected_trip() function

The DiveListView had a singleSelectedTrip function that
returns the selected trip if exactly one trip is selected.
This could be very slow if numerous non-trip items were
selected, because all the selection indices were back-
translated by the proxy model.

This could make selection changes very slow, because the
MainTab used said function to determine whether it should
show trip or dive data.. Indeed, with a 3500 dive test log,
when selecting all dives in tree mode, the updating of the
TabWidgets is sped up from 130 ms to 5 ms this commit.

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

1 files changed, 2 insertions, 2 deletions

diff --git a/desktop-widgets/tab-widgets/maintab.cpp b/desktop-widgets/tab-widgets/maintab.cpp
index 00f9d6ad4..7204cd7b0 100644
--- a/desktop-widgets/tab-widgets/maintab.cpp
+++ b/desktop-widgets/tab-widgets/maintab.cpp
@@ -365,7 +365,8 @@ void MainTab::updateDiveInfo()
 		// 2) the filter is reset, potentially erasing the current trip under our feet.
 		// TODO: Don't hard code tab location!
 		bool onDiveSiteTab = ui.tabWidget->currentIndex() == 6;
-		if ((currentTrip = MainWindow::instance()->diveList->singleSelectedTrip()) != nullptr) {
+		currentTrip = single_selected_trip();
+		if (currentTrip) {
 			// Remember the tab selected for last dive but only if we're not on the dive site tab
 			if (lastSelectedDive && !onDiveSiteTab)
 				lastTabSelectedDive = ui.tabWidget->currentIndex();
@@ -412,7 +413,6 @@ void MainTab::updateDiveInfo()
 			if (!lastSelectedDive && !onDiveSiteTab)
 				ui.tabWidget->setCurrentIndex(lastTabSelectedDive);
 			lastSelectedDive = true;
-			currentTrip = NULL;
 			// make all the fields visible writeable
 			ui.diveTripLocation->hide();
 			ui.location->show();