[gnome-sudoku] Add "wrap around" keyboard navigation

[Michael Catanzaro <mcatanzaro src gnome org>]

commit e5726fc17a0b1aef898a8d959eb7a3c565646d94
Author: Abbe98 <albin post gmail com>
Date:   Thu Sep 29 17:17:35 2022 +0200

     Add "wrap around" keyboard navigation
    
    This enables "wrap around" keyboard navigation. Meaning that if one
    tries to navigate past the last row or column one will get back to the
    first.
    
    Part of #57.

 src/sudoku-view.vala | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
---
diff --git a/src/sudoku-view.vala b/src/sudoku-view.vala
index b773bdc..9e9bdcb 100644
--- a/src/sudoku-view.vala
+++ b/src/sudoku-view.vala
@@ -604,6 +604,8 @@ public class SudokuView : AspectFrame
     private DrawingArea drawing;
     private Grid grid;
 
+    private EventControllerKey key_controller;
+
     private int selected_row = -1;
     private int selected_col = -1;
     private void set_selected (int cell_row, int cell_col)
@@ -621,6 +623,35 @@ public class SudokuView : AspectFrame
         }
     }
 
+    private bool on_key_pressed (EventControllerKey _key_controller, uint keyval, uint keycode, ModifierType 
state)
+    {
+        if ((keyval == Gdk.Key.Left || keyval == Gdk.Key.KP_Left) && selected_col == 0)
+        {
+            cells[selected_row, 8].grab_focus ();
+            return true;
+        }
+
+        if ((keyval == Gdk.Key.Right || keyval == Gdk.Key.KP_Right) && selected_col == 8)
+        {
+            cells[selected_row, 0].grab_focus ();
+            return true;
+        }
+
+        if ((keyval == Gdk.Key.Up || keyval == Gdk.Key.KP_Up) && selected_row == 0)
+        {
+            cells[8, selected_col].grab_focus ();
+            return true;
+        }
+
+        if ((keyval == Gdk.Key.Down || keyval == Gdk.Key.KP_Down) && selected_row == 8)
+        {
+            cells[0, selected_col].grab_focus ();
+            return true;
+        }
+
+        return false;
+    }
+
     public SudokuView (SudokuGame game)
     {
         shadow_type = ShadowType.NONE;
@@ -730,6 +761,9 @@ public class SudokuView : AspectFrame
         grid.show_all ();
         overlay.show ();
         drawing.hide ();
+
+        key_controller = new EventControllerKey (this);
+        key_controller.key_pressed.connect (on_key_pressed);
     }
 
     private void update_highlights ()