statistics: add series interface class

Add a interface class for the chart series used by the statistics
module. Abstract virtual functions are declared for replotting
and selecting items.

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

stats/CMakeLists.txt

@@ -11,6 +11,8 @@ set(SUBSURFACE_STATS_SRCS
 	statsaxis.cpp
 	statscolors.h
 	statscolors.cpp
+	statsseries.h
+	statsseries.cpp
 	statsvariables.h
 	statsvariables.cpp
 	zvalues.h

stats/statsseries.cpp

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "statsseries.h"
+#include "statsaxis.h"
+
+#include <QChart>
+
+StatsSeries::StatsSeries(QtCharts::QChart *chart, StatsAxis *xAxis, StatsAxis *yAxis)
+{
+	chart->addSeries(this);
+	if (xAxis && yAxis) {
+		attachAxis(xAxis->qaxis());
+		attachAxis(yAxis->qaxis());
+	}
+}
+
+StatsSeries::~StatsSeries()
+{
+}

stats/statsseries.h

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+// Base class for all series. Defines a small virtual interface
+// concerning highlighting of series items.
+#ifndef STATS_SERIES_H
+#define STATS_SERIES_H
+
+#include <QScatterSeries>
+
+namespace QtCharts {
+	class QChart;
+}
+class StatsAxis;
+
+// We derive from a proper scatter series to get access to the map-to
+// and map-from coordinates calls. But we don't use any of its functionality.
+// This should be removed in due course.
+
+class StatsSeries : public QtCharts::QScatterSeries {
+public:
+	StatsSeries(QtCharts::QChart *chart, StatsAxis *xAxis, StatsAxis *yAxis);
+	virtual ~StatsSeries();
+	virtual void updatePositions() = 0;	// Called if chart geometry changes.
+	virtual bool hover(QPointF pos) = 0;	// Called on mouse movement. Return true if an item of this series is highlighted.
+	virtual void unhighlight() = 0;		// Unhighlight any highlighted item.
+};
+
+#endif