design_system/components/key_directions library

Direction-aware keyboard helpers shared by every component that navigates a horizontal axis with the arrow keys (BrowserStyleTabBar, EditableTable, ReadableTable, Tree).

Navigation state is stored as a logical index, but in an RTL layout that index axis is mirrored on screen. A naive handler that always maps arrowRight → index + 1 therefore moves the highlight to the left in Arabic. These helpers keep the visual meaning of the key intact in both directions: the right arrow always moves toward the right of the screen.

Usage — replace a hardcoded ±1 with horizontalStep:

final step = horizontalStep(key, Directionality.of(context));
if (step != 0) controller.moveSelection(0, step);

Functions

arrowGoesInto(LogicalKeyboardKey key, TextDirection dir) → bool

True when a horizontal arrow key points toward deeper nesting for the given text dir — the arrow a Tree should treat as expand / step-in. In LTR that is the right arrow; in RTL the indent mirrors, so it is the left arrow. The opposite arrow collapses / steps out.

horizontalStep(LogicalKeyboardKey key, TextDirection dir) → int

Resolves a horizontal arrow key to a logical index step for the given text dir. Returns +1 (next index) or -1 (previous index) for the right/left arrows, mirrored under RTL, and 0 for any other key.