moveOrEscape function

KeyEventResult moveOrEscape({ required bool atEdge, required void move(), })

Signature for a key-event handler on a Focus or FocusNode. The keyboard convention for a widget that navigates with arrow keys.

Move within the widget on an interior arrow, but bubble — return KeyEventResult.ignored — at the widget's edge, so the arrow reaches the enclosing directional focus traversal and focus can leave the widget. The same arrow keys you navigate with also get you out, at a boundary. (Tab / Shift+Tab always move between widgets; this extends that to arrows.)

Returns ignored when atEdge; otherwise runs move and returns handled. Arrow-capturing widgets should route each directional key through this so a clamp at the edge becomes an escape rather than a dead key.

Implementation

/// The keyboard convention for a widget that navigates with arrow keys.
///
/// Move within the widget on an interior arrow, but **bubble** — return
/// [KeyEventResult.ignored] — at the widget's edge, so the arrow reaches the
/// enclosing directional focus traversal and focus can *leave* the widget. The
/// same arrow keys you navigate with also get you out, at a boundary. (Tab /
/// Shift+Tab always move between widgets; this extends that to arrows.)
///
/// Returns ignored when [atEdge]; otherwise runs [move] and returns handled.
/// Arrow-capturing widgets should route each directional key through this so a
/// clamp at the edge becomes an escape rather than a dead key.
KeyEventResult moveOrEscape({
  required bool atEdge,
  required void Function() move,
}) {
  if (atEdge) return KeyEventResult.ignored;
  move();
  return KeyEventResult.handled;
}