DnD State Manager

Overview

The DndStateManager is a small internal helper that keeps track of drag state for a single drag interaction context. Each drag context (such as a BaseDropZone or DragListComponent) owns its own instance of the state manager, allowing them to operate independently.

It provides observable streams for the current drop state, instruction feedback, and closest edge, and exposes simple update methods used internally by drag and drop zones.

import { DndStateManager } from 'ngx-builder-dnd';

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API Reference

Properties

Name	Description
dropTarget: DragState	Returns the current drop state value.
instruction: Instruction | null	Returns the current instruction.
closestEdge: Edge | null	Returns the current closest edge.

Observables

Name	Description
dropTarget$: Observable<DragState>	Emits the current drag state for the drop target.
instruction$: Observable<Instruction | null>	Emits the current drag Instruction, or null when no instruction exists.
closestEdge$: Observable<Edge | null>	Emits the closest edge during dragging, or null otherwise.

Methods

DropZone overrides some of the default behaviors defined in BaseDropZone. These changes tailor the class for drop-only tree items:

Method	Description
updateInstruction(instruction: Instruction | null): void	Updates the current instruction emitted during a drag interaction.
updateDropTarget(state: DragState): void	Updates the drop target state.
updateClosestEdge(Edge | null): void	Updates the closest hovered edge.
destroy(): void	Completes all internal subjects and cleans up resources.

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See Also

• Base Drop Zone - Provides shared logic for drop-zone implementations.
• Drag List Component - Renders a draggable list container.