class ZoomHistory { lastZoom: number; lastFloorZoom: number; lastIntegerZoom: number; lastIntegerZoomTime: number; first: boolean; constructor() { this.first = true; } update(z: number, now: number) { const floorZ = Math.floor(z); if (this.first) { this.first = false; this.lastIntegerZoom = floorZ; this.lastIntegerZoomTime = 0; this.lastZoom = z; this.lastFloorZoom = floorZ; return true; } if (this.lastFloorZoom > floorZ) { this.lastIntegerZoom = floorZ + 1; this.lastIntegerZoomTime = now; } else if (this.lastFloorZoom < floorZ) { this.lastIntegerZoom = floorZ; this.lastIntegerZoomTime = now; } if (z !== this.lastZoom) { this.lastZoom = z; this.lastFloorZoom = floorZ; return true; } return false; } } export default ZoomHistory;