Add and use clip_index and wrap_index helpers.

diff --git a/src/gui/gui.py b/src/gui/gui.py
index 94ade0689c9a09b1a4a212d9f38a61660a579c4b..a981b61111d5c44bd7daadbe7360cb9154294729 100644 (file)
--- a/src/gui/gui.py
+++ b/src/gui/gui.py
@@ -217,7 +217,7 @@ class ListView(View):
         we'll have to adjust the index with the direction of the
         keypress (-1 for up, +1 for down).
         """
-        self.current_index = (self.selected_index() + dir) % len(self.items())
+        self.current_index = self.wrap_index(self.selected_index() + dir)
         self.index_changed()
         self.current_index = None
 
@@ -258,6 +258,24 @@ class ListView(View):
         else:
             return self.view.current()
 
+    def clip_index(self, index):
+        """
+        Make sure the given index fits within the bounds of this
+        list. If it doesn't, clip it off at the ends of the list (e.g,
+        -1 becomes 0).
+        """
+        max_index = len(self.items_cache) - 1
+        return max (0, min(max_index, index))
+
+    def wrap_index(self, index):
+        """
+        Make sure the given index fits within the bounds of this
+        list. If it doesn't, wrap it around (e.g., -1 becomes 5 in a
+        6-element list).
+        """
+        count = len(self.items_cache)
+        return index % count
+    
 class WidgetBasedListView(ListView):
     def __init__(self):
         self.binding_map = {}