statistics: refactor QSG memory management

The code was wrong, because it deleted the ChartItems in the
main UI thread, not the render thread. This would delete the
QSG nodes in the UI thread and then crash on mobile.

Therefore refactor this part of the code by adding the
items to be deleted to a list that will be deleted by the
render thread.

As a drop in replacement of std::unique_ptr, implement
a silly ChartItemPtr class, which auto-initializes to null.

This turns the deterministic and easily controlled memory
management into a steaming pile of insanity. Obviously,
this can be made much more elegant, but this has to do for now.

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

1 files changed, 4 insertions, 3 deletions

diff --git a/stats/barseries.h b/stats/barseries.h
index 5f030ad76..50ef1e72d 100644
--- a/stats/barseries.h
+++ b/stats/barseries.h
@@ -5,6 +5,7 @@
 #ifndef BAR_SERIES_H
 #define BAR_SERIES_H
 
+#include "statshelper.h"
 #include "statsseries.h"
 #include "statsvariables.h"
 
@@ -81,7 +82,7 @@ private:
 
 	// A label that is composed of multiple lines
 	struct BarLabel {
-		std::unique_ptr<ChartTextItem> item;
+		ChartItemPtr<ChartTextItem> item;
 		bool isOutside; // Is shown outside of bar
 		BarLabel(StatsView &view, const std::vector<QString> &labels, int bin_nr, int binCount);
 		void setVisible(bool visible);
@@ -90,7 +91,7 @@ private:
 	};
 
 	struct SubItem {
-		std::unique_ptr<ChartBarItem> item;
+		ChartItemPtr<ChartBarItem> item;
 		std::unique_ptr<BarLabel> label;
 		double value_from;
 		double value_to;
@@ -116,7 +117,7 @@ private:
 		int getSubItemUnderMouse(const QPointF &f, bool horizontal, bool stacked) const;
 	};
 
-	std::unique_ptr<InformationBox> information;
+	ChartItemPtr<InformationBox> information;
 	std::vector<Item> items;
 	bool horizontal;
 	bool stacked;