statistics: implement rectangle selection in scatter plot

Allow the user to select regions of the scatter plot using
a rectangular selection. When shift is pressed, do an
incremental selection.

Unfortunately, the list-selection code is so slow that this
becomes unusable for a large number of selected dives.

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

1 files changed, 4 insertions, 0 deletions

diff --git a/stats/statsview.h b/stats/statsview.h
index 87dcdad29..279889104 100644
--- a/stats/statsview.h
+++ b/stats/statsview.h
@@ -19,6 +19,7 @@ struct StatsVariable;
 class StatsSeries;
 class CategoryAxis;
 class ChartItem;
+class ChartRectLineItem;
 class ChartTextItem;
 class CountAxis;
 class HistogramAxis;
@@ -142,7 +143,10 @@ private:
 	ChartItemPtr<Legend> legend;
 	Legend *draggedItem;
 	ChartItemPtr<RegressionItem> regressionItem;
+	ChartItemPtr<ChartRectLineItem> selectionRect;
 	QPointF dragStartMouse, dragStartItem;
+	bool shiftSelection;
+	std::vector<dive *> oldSelection;
 
 	void hoverEnterEvent(QHoverEvent *event) override;
 	void hoverMoveEvent(QHoverEvent *event) override;