statistics: make selection keyboard modifiers more general

Up to now, we passed a "shiftPressed" flag to the individual
selection functions. To be more general replace by a struct
with "shift" and "ctrl" flags.

While doing this:
1) Move the struct into a new statsselection file for better
   encapsulation.
2) Change shift to control in the scatter series, since individual
   selection of items is usually done with control, not shift.
   Shift usually means "select range".

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

1 files changed, 15 insertions, 0 deletions

diff --git a/stats/statsselection.h b/stats/statsselection.h
new file mode 100644
index 000000000..e3f590466
--- /dev/null
+++ b/stats/statsselection.h
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+// Functions and data structures handling dive selections.
+
+#ifndef STATS_SELECTION_H
+#define STATS_SELECTION_H
+
+struct SelectionModifier {
+	unsigned int ctrl : 1;
+	unsigned int shift : 1;
+	// Note: default member initializers for bit-fields becomes available with C++20.
+	// Therefore, for now an inline constructor.
+	SelectionModifier() : ctrl(0), shift(0) {}
+};
+
+#endif