feat: unpack direction info in keyboard drag strategy

Author: rachel-fenichel

src/keyboard_drag_strategy.ts

@@ -4,14 +4,33 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import {dragging} from 'blockly';
+import {dragging, utils} from 'blockly';
+import {Direction, getDirectionFromXY} from './drag_direction';
 
 export class KeyboardDragStrategy extends dragging.BlockDragStrategy {
+  private currentDragDirection: Direction | null = null;
+
   override startDrag(e?: PointerEvent) {
     super.startDrag(e);
     // Set position of the dragging block, so that it doesn't pop
     // to the top left of the workspace.
     // @ts-expect-error block and startLoc are private.
     this.block.moveDuringDrag(this.startLoc);
   }
+
+  override drag(newLoc: utils.Coordinate, e?: PointerEvent): void {
+    if (!e) return;
+    this.currentDragDirection = getDirectionFromXY({x: e.tiltX, y: e.tiltY});
+    super.drag(newLoc);
+  }
+
+  /**
+   * Get whether the most recent drag event represents a constrained
+   * keyboard drag.
+   *
+   * @returns true if the current movement is constrained, otherwise false.
+   */
+  private isConstrainedMovement(): boolean {
+    return !!this.currentDragDirection;
+  }
 }