// Given a key, returns the appropriate navigation action.
public static void TranslateKeyToKeyNavigationAction(
FlowDirection flowDirection,
VirtualKey key,
out KeyNavigationAction pNavAction,
out bool pIsValidKey)
{
pIsValidKey = true;
pNavAction = KeyNavigationAction.Up;
bool bInvertForRTL = (flowDirection == FlowDirection.RightToLeft);
switch (key)
{
case VirtualKey.PageUp:
pNavAction = KeyNavigationAction.Previous;
break;
case VirtualKey.PageDown:
pNavAction = KeyNavigationAction.Next;
break;
case VirtualKey.Down:
pNavAction = KeyNavigationAction.Down;
break;
case VirtualKey.Up:
pNavAction = KeyNavigationAction.Up;
break;
case VirtualKey.Left:
pNavAction = (bInvertForRTL
? KeyNavigationAction.Right
: KeyNavigationAction.Left);
break;
case VirtualKey.Right:
pNavAction = (bInvertForRTL
? KeyNavigationAction.Left
: KeyNavigationAction.Right);
break;
case VirtualKey.Home:
pNavAction = KeyNavigationAction.First;
break;
case VirtualKey.End:
pNavAction = KeyNavigationAction.Last;
break;
default:
pIsValidKey = false;
break;
}
}
// Based on current element's index/type and action, return the next element index/type.
public void GetTargetIndexFromNavigationAction(
ElementType elementType,
int elementIndex,
KeyNavigationAction action,
Rect windowConstraint,
out ElementType pTargetElementType,
out int pTargetElementIndex)
{
int totalItems;
int totalGroups;
totalItems = GetLayoutDataInfoProviderNoRef.GetTotalItemCount();
totalGroups = GetLayoutDataInfoProviderNoRef.GetTotalGroupCount();
global::System.Diagnostics.Debug.Assert(0 <= elementIndex && elementIndex < totalItems);
global::System.Diagnostics.Debug.Assert(elementType == ElementType.ItemContainer);
pTargetElementType = ElementType.ItemContainer;
if (action != KeyNavigationAction.Left &&
action != KeyNavigationAction.Right &&
action != KeyNavigationAction.Up &&
action != KeyNavigationAction.Down)
{
throw new ArgumentException(nameof(action));
}
int step = (action == KeyNavigationAction.Left || action == KeyNavigationAction.Up) ? -1 : 1;
pTargetElementIndex = elementIndex;
// Easy case: the action is along layout orientation, therefore handle it.
if ((VirtualizationDirection == Orientation.Vertical && (action == KeyNavigationAction.Left || action == KeyNavigationAction.Right)) ||
(VirtualizationDirection == Orientation.Horizontal && (action == KeyNavigationAction.Up || action == KeyNavigationAction.Down)))
{
pTargetElementIndex = Math.Min(Math.Max(elementIndex + step, 0), totalItems - 1);
}
// The action is not in layout direction. We must jump to the next item in the same row/column.
// We are not grouping, easy.
else
{
// TODO: verify startAt
int maxLineLength = DetermineMaxStackingLine();
int nextIndex = elementIndex + step * maxLineLength;
if (0 <= nextIndex && nextIndex < totalItems)
{
pTargetElementIndex = nextIndex;
}
}
global::System.Diagnostics.Debug.Assert(0 <= pTargetElementIndex && pTargetElementIndex < totalItems);
return;
}