profile: cache pixmaps for dive event items

For better scalability, we might replace the dive event icons
by SVGs. Since rendering SVGs is potentially very slow, cache
the pixmaps when the scene is generated.

Note: this does not yet do any SVG rendering, only the caching
of pixmaps.

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

profile-widget/profilescene.cpp

@@ -3,6 +3,7 @@
 #include "diveeventitem.h"
 #include "divecartesianaxis.h"
 #include "divepercentageitem.h"
+#include "divepixmapcache.h"
 #include "diveprofileitem.h"
 #include "divetextitem.h"
 #include "tankitem.h"
@@ -71,7 +72,8 @@ ProfileScene::ProfileScene(double dpr, bool printMode, bool isGrayscale) :
 	decoModelParameters(new DiveTextItem(dpr, 1.0, Qt::AlignHCenter | Qt::AlignTop, nullptr)),
 	heartBeatItem(createItem<DiveHeartrateItem>(*heartBeatAxis, DivePlotDataModel::HEARTBEAT, 1, dpr)),
 	percentageItem(new DivePercentageItem(*timeAxis, *percentageAxis, dpr)),
-	tankItem(new TankItem(*timeAxis, dpr))
+	tankItem(new TankItem(*timeAxis, dpr)),
+	pixmaps(getDivePixmaps(dpr))
 {
 	init_plot_info(&plotInfo);
 
@@ -499,7 +501,7 @@ void ProfileScene::plotDive(const struct dive *dIn, int dcIn, DivePlannerPointsM
 		// BUT events are wanted.
 #endif
 		DiveEventItem *item = new DiveEventItem(d, event, lastgasmix, dataModel,
-							timeAxis, profileYAxis, animSpeed, dpr);
+							timeAxis, profileYAxis, animSpeed, *pixmaps);
 		item->setZValue(2);
 		addItem(item);
 		eventItems.push_back(item);