Don't show a pixmap for heading event

Some dive computers appear to have heading data in every sample. In order
to avoid a completely cluttered dive profile we no longer show a flag for
every heading event but instead show a basically transparent pixmap (which
is invisible to the user) that allows us to report the heading information
in the tooltip but leaves the profile uncluttered.

Fixes #586

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

qt-ui/profile/diveeventitem.cpp

@@ -20,6 +20,12 @@ DiveEventItem::DiveEventItem(QObject *parent) : DivePixmapItem(parent),
 	internalEvent(NULL)
 {
 	setFlag(ItemIgnoresTransformations);
+	// create a narrow but somewhat tall, basically transparent pixmap
+	// that allows tooltips to work when we don't want to show a specific
+	// pixmap for an event, but want to show the event value in the tooltip
+	// (e.g. if there is heading data in every sample)
+	transparentPixmap = new QPixmap(4, 20);
+	transparentPixmap->fill(QColor::fromRgbF(1.0, 1.0, 1.0, 0.01));
 }
 
 
@@ -70,7 +76,10 @@ void DiveEventItem::setupPixmap()
 	} else if (internalEvent->type == SAMPLE_EVENT_BOOKMARK) {
 		setPixmap(EVENT_PIXMAP(":flag"));
 	} else if (strcmp(internalEvent->name, "heading") == 0) {
-		setPixmap(EVENT_PIXMAP(":flag"));
+		// some dive computers have heading in every sample...
+		// set an "almost invisible" pixmap
+		// so we get the tooltip but not the clutter
+		setPixmap(*transparentPixmap);
 	} else if (event_is_gaschange(internalEvent)) {
 		if (internalEvent->gas.mix.he.permille)
 			setPixmap(EVENT_PIXMAP_BIGGER(":gaschangeTrimix"));

qt-ui/profile/diveeventitem.h

@@ -29,6 +29,7 @@ private:
 	DiveCartesianAxis *hAxis;
 	DivePlotDataModel *dataModel;
 	struct event *internalEvent;
+	QPixmap *transparentPixmap;
 };
 
 #endif // DIVEEVENTITEM_H