statistics: render regression item using QSGNode

Render the confidence area and the regression line into a pixmap
and show that using a QSGNode.

It is unclear whether it is preferred to do it this way or to
triangulate the confidence area into triangles to be drawn by
the shader.

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

1 files changed, 2 insertions, 21 deletions

diff --git a/stats/statsview.h b/stats/statsview.h
index f472e1e16..b0a199200 100644
--- a/stats/statsview.h
+++ b/stats/statsview.h
@@ -9,7 +9,6 @@
 #include <QImage>
 #include <QPainter>
 #include <QQuickItem>
-#include <QGraphicsPolygonItem>
 
 struct dive;
 struct StatsBinner;
@@ -17,7 +16,6 @@ struct StatsBin;
 struct StatsState;
 struct StatsVariable;
 
-class QGraphicsLineItem;
 class QGraphicsSimpleTextItem;
 class StatsSeries;
 class CategoryAxis;
@@ -26,6 +24,7 @@ class CountAxis;
 class HistogramAxis;
 class HistogramMarker;
 class QuartileMarker;
+class RegressionItem;
 class StatsAxis;
 class StatsGrid;
 class Legend;
@@ -36,13 +35,6 @@ enum class ChartSubType : int;
 enum class ChartZValue : int;
 enum class StatsOperation : int;
 
-struct regression_data {
-	double a,b;
-	double res2, r2, sx2, xavg;
-	int n;
-};
-
-
 class StatsView : public QQuickItem {
 	Q_OBJECT
 public:
@@ -127,17 +119,6 @@ private:
 	// Helper functions to add feature to the chart
 	void addLineMarker(double pos, double low, double high, const QPen &pen, bool isHorizontal);
 
-	// A regression line
-	struct RegressionLine {
-		std::unique_ptr<QGraphicsPolygonItem> item;
-		std::unique_ptr<QGraphicsPolygonItem> central;
-		StatsAxis *xAxis, *yAxis;
-		const struct regression_data reg;
-		void updatePosition();
-		RegressionLine(const struct regression_data reg, QBrush brush, QGraphicsScene *scene, StatsAxis *xAxis, StatsAxis *yAxis);
-	};
-
-	void addLinearRegression(const struct regression_data reg, StatsAxis *xAxis, StatsAxis *yAxis);
 	void addHistogramMarker(double pos, QColor color, bool isHorizontal, StatsAxis *xAxis, StatsAxis *yAxis);
 
 	StatsState state;
@@ -147,9 +128,9 @@ private:
 	std::vector<std::unique_ptr<StatsSeries>> series;
 	std::unique_ptr<Legend> legend;
 	std::vector<std::unique_ptr<QuartileMarker>> quartileMarkers;
-	std::vector<RegressionLine> regressionLines;
 	std::vector<std::unique_ptr<HistogramMarker>> histogramMarkers;
 	std::unique_ptr<QGraphicsSimpleTextItem> title;
+	std::unique_ptr<RegressionItem> regressionItem;
 	StatsSeries *highlightedSeries;
 	StatsAxis *xAxis, *yAxis;
 	Legend *draggedItem;