statistics: implement a box-and-whisker series

Implements a simple box-and-whisker series to display
quartile based data. When hovering over a box-and-whiskers
item the precise data of the quartiles is shown.

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

1 files changed, 61 insertions, 0 deletions

diff --git a/stats/boxseries.h b/stats/boxseries.h
new file mode 100644
index 000000000..964e3aec1
--- /dev/null
+++ b/stats/boxseries.h
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+// A small custom box plot series, which displays quartiles.
+// The QtCharts bar series were  too inflexible with respect
+// to placement of the bars.
+#ifndef BOX_SERIES_H
+#define BOX_SERIES_H
+
+#include "statsseries.h"
+#include "statsvariables.h" // for StatsQuartiles
+
+#include <memory>
+#include <vector>
+#include <QGraphicsLineItem>
+#include <QGraphicsRectItem>
+
+class InformationBox;
+
+class BoxSeries : public StatsSeries {
+public:
+	BoxSeries(QtCharts::QChart *chart, StatsAxis *xAxis, StatsAxis *yAxis,
+		  const QString &variable, const QString &unit, int decimals);
+	~BoxSeries();
+
+	void updatePositions() override;
+	bool hover(QPointF pos) override;
+	void unhighlight() override;
+
+	// Note: this expects that all items are added with increasing pos
+	// and that no bar is inside another bar, i.e. lowerBound and upperBound
+	// are ordered identically.
+	void append(double lowerBound, double upperBound, const StatsQuartiles &q, const QString &binName);
+
+private:
+	// Get item under mouse pointer, or -1 if none
+	int getItemUnderMouse(const QPointF &f);
+
+	struct Item {
+		QGraphicsRectItem box;
+		QGraphicsLineItem topWhisker, bottomWhisker;
+		QGraphicsLineItem topBar, bottomBar;
+		QGraphicsLineItem center;
+		QRectF bounding; // bounding box in screen coordinates
+		~Item();
+		double lowerBound, upperBound;
+		StatsQuartiles q;
+		QString binName;
+		Item(QtCharts::QChart *chart, BoxSeries *series, double lowerBound, double upperBound, const StatsQuartiles &q, const QString &binName);
+		void updatePosition(QtCharts::QChart *chart, BoxSeries *series);
+		void highlight(bool highlight);
+	};
+
+	QString variable, unit;
+	int decimals;
+
+	std::vector<QString> formatInformation(const Item &item) const;
+	std::unique_ptr<InformationBox> information;
+	std::vector<std::unique_ptr<Item>> items;
+	int highlighted; // -1: no item highlighted
+};
+
+#endif