Class ChartGPUWorkerProxy

src/worker/ChartGPUWorkerProxy.ts:245–2119

 * while maintaining local state cache for synchronous operations.
 */
export class ChartGPUWorkerProxy implements ChartGPUInstance {
  private readonly worker: Worker;
  private readonly chartId: string;
  private readonly messageTimeout: number;
  
  // State cache (synchronized with worker)
  private cachedOptions: ChartGPUOptions;
  private isDisposed = false;
  private isInitialized = false;
  private cachedInteractionX: number | null = null;
  private cachedZoomRange: Readonly<{ start: number; end: number }> | null = null;
  /**
   * Best-effort local series point counts used to keep dataset-aware zoom constraints
   * in sync with worker zoom behavior (especially for streaming appendData()).
   */
  private cachedSeriesPointCountsForZoom: number[] = [];
  
  // Performance metrics cache
  private cachedPerformanceMetrics: Readonly<PerformanceMetrics> | null = null;
  private cachedPerformanceCapabilities: Readonly<PerformanceCapabilities> | null = null;
  private performanceUpdateCallbacks = new Set<(metrics: Readonly<PerformanceMetrics>) => void>();
  
  // Message correlation system
  private readonly pendingRequests = new Map<string, PendingRequest>();
  
  // Event system
  private readonly listeners = new Map<ChartGPUEventName, Set<AnyChartGPUEventCallback>>();
  
  // Worker message handler (bound once)
  private readonly boundMessageHandler: (event: MessageEvent) => void;
  
  // DOM overlays
  private tooltip: Tooltip | null = null;
  private legend: Legend | null = null;
  private textOverlay: TextOverlay | null = null;
  private annotationTextOverlay: TextOverlay | null = null;
  private dataZoomSlider: DataZoomSlider | null = null;
  private dataZoomSliderHost: HTMLDivElement | null = null;
  private zoomState: ZoomState | null = null;
  
  // RAF batching for overlay updates
  private pendingOverlayUpdates: PendingOverlayUpdates = {};
  private overlayUpdateRafId: number | null = null;
  
  // Zoom echo suppression flag
  // Set to true when processing zoom changes FROM the worker to prevent sending them back
  private isProcessingWorkerZoomUpdate = false;
  
  // Event forwarding to worker
  private readonly boundEventHandlers: {
    pointerdown: ((e: PointerEvent) => void) | null;
    pointermove: ((e: PointerEvent) => void) | null;
    pointerup: ((e: PointerEvent) => void) | null;
    pointerleave: ((e: PointerEvent) => void) | null;
    wheel: ((e: WheelEvent) => void) | null;
  } = {
    pointerdown: null,
    pointermove: null,