mini-prog/miniprogram/engine/map/mapEngine.ts

import { getTileSizePx, screenToWorld, worldToScreen, type CameraState } from '../camera/camera'
import { CompassHeadingController } from '../sensor/compassHeadingController'
import { WebGLMapRenderer } from '../renderer/webglMapRenderer'
import { type MapRendererStats } from '../renderer/mapRenderer'
import { worldTileToLonLat, type LonLatPoint } from '../../utils/projection'
import { type RemoteMapConfig, type TileZoomBounds } from '../../utils/remoteMapConfig'

const RENDER_MODE = 'Single WebGL Pipeline'
const PROJECTION_MODE = 'WGS84 -> WorldTile -> Camera -> Screen'
const MAP_NORTH_OFFSET_DEG = 0
let MAGNETIC_DECLINATION_DEG = -6.91
let MAGNETIC_DECLINATION_TEXT = '6.91° W'
const MIN_ZOOM = 15
const MAX_ZOOM = 20
const DEFAULT_ZOOM = 17
const DESIRED_VISIBLE_COLUMNS = 3
const OVERDRAW = 1
const DEFAULT_TOP_LEFT_TILE_X = 108132
const DEFAULT_TOP_LEFT_TILE_Y = 51199
const DEFAULT_CENTER_TILE_X = DEFAULT_TOP_LEFT_TILE_X + 1
const DEFAULT_CENTER_TILE_Y = DEFAULT_TOP_LEFT_TILE_Y + 1
const TILE_SOURCE = 'https://oss-mbh5.colormaprun.com/wxMap/lcx/{z}/{x}/{y}.png'
const MIN_PREVIEW_SCALE = 0.55
const MAX_PREVIEW_SCALE = 1.85
const INERTIA_FRAME_MS = 16
const INERTIA_DECAY = 0.92
const INERTIA_MIN_SPEED = 0.02
const PREVIEW_RESET_DURATION_MS = 140
const UI_SYNC_INTERVAL_MS = 80
const ROTATE_STEP_DEG = 15
const AUTO_ROTATE_FRAME_MS = 8
const AUTO_ROTATE_EASE = 0.34
const AUTO_ROTATE_SNAP_DEG = 0.1
const AUTO_ROTATE_DEADZONE_DEG = 4
const AUTO_ROTATE_MAX_STEP_DEG = 0.75
const AUTO_ROTATE_HEADING_SMOOTHING = 0.32
const COMPASS_NEEDLE_SMOOTHING = 0.12

const SAMPLE_TRACK_WGS84: LonLatPoint[] = [
  worldTileToLonLat({ x: DEFAULT_CENTER_TILE_X - 0.72, y: DEFAULT_CENTER_TILE_Y + 0.44 }, DEFAULT_ZOOM),
  worldTileToLonLat({ x: DEFAULT_CENTER_TILE_X - 0.18, y: DEFAULT_CENTER_TILE_Y + 0.08 }, DEFAULT_ZOOM),
  worldTileToLonLat({ x: DEFAULT_CENTER_TILE_X + 0.22, y: DEFAULT_CENTER_TILE_Y - 0.16 }, DEFAULT_ZOOM),
  worldTileToLonLat({ x: DEFAULT_CENTER_TILE_X + 0.64, y: DEFAULT_CENTER_TILE_Y - 0.52 }, DEFAULT_ZOOM),
]
const SAMPLE_GPS_WGS84: LonLatPoint = worldTileToLonLat(
  { x: DEFAULT_CENTER_TILE_X + 0.12, y: DEFAULT_CENTER_TILE_Y - 0.06 },
  DEFAULT_ZOOM,
)

type TouchPoint = WechatMiniprogram.TouchDetail

type GestureMode = 'idle' | 'pan' | 'pinch'
type RotationMode = 'manual' | 'auto'
type OrientationMode = 'manual' | 'north-up' | 'heading-up'
type AutoRotateSourceMode = 'sensor' | 'course' | 'fusion'
type NorthReferenceMode = 'magnetic' | 'true'

const DEFAULT_NORTH_REFERENCE_MODE: NorthReferenceMode = 'magnetic'

export interface MapEngineStageRect {
  width: number
  height: number
  left: number
  top: number
}

export interface MapEngineViewState {
  buildVersion: string
  renderMode: string
  projectionMode: string
  mapReady: boolean
  mapReadyText: string
  mapName: string
  configStatusText: string
  zoom: number
  rotationDeg: number
  rotationText: string
  rotationMode: RotationMode
  rotationModeText: string
  rotationToggleText: string
  orientationMode: OrientationMode
  orientationModeText: string
  sensorHeadingText: string
  compassDeclinationText: string
  northReferenceButtonText: string
  autoRotateSourceText: string
  autoRotateCalibrationText: string
  northReferenceText: string
  compassNeedleDeg: number
  centerTileX: number
  centerTileY: number
  centerText: string
  tileSource: string
  visibleColumnCount: number
  visibleTileCount: number
  readyTileCount: number
  memoryTileCount: number
  diskTileCount: number
  memoryHitCount: number
  diskHitCount: number
  networkFetchCount: number
  cacheHitRateText: string
  tileTranslateX: number
  tileTranslateY: number
  tileSizePx: number
  stageWidth: number
  stageHeight: number
  stageLeft: number
  stageTop: number
  statusText: string
}

export interface MapEngineCallbacks {
  onData: (patch: Partial<MapEngineViewState>) => void
}

const VIEW_SYNC_KEYS: Array<keyof MapEngineViewState> = [
  'buildVersion',
  'renderMode',
  'projectionMode',
  'mapReady',
  'mapReadyText',
  'mapName',
  'configStatusText',
  'zoom',
  'rotationDeg',
  'rotationText',
  'rotationMode',
  'rotationModeText',
  'rotationToggleText',
  'orientationMode',
  'orientationModeText',
  'sensorHeadingText',
  'compassDeclinationText',
  'northReferenceButtonText',
  'autoRotateSourceText',
  'autoRotateCalibrationText',
  'northReferenceText',
  'compassNeedleDeg',
  'centerText',
  'tileSource',
  'visibleTileCount',
  'readyTileCount',
  'memoryTileCount',
  'diskTileCount',
  'memoryHitCount',
  'diskHitCount',
  'networkFetchCount',
  'cacheHitRateText',
  'tileSizePx',
  'statusText',
]

function buildCenterText(zoom: number, x: number, y: number): string {
  return `z${zoom} / x${x} / y${y}`
}

function clamp(value: number, min: number, max: number): number {
  return Math.max(min, Math.min(max, value))
}

function normalizeRotationDeg(rotationDeg: number): number {
  const normalized = rotationDeg % 360
  return normalized < 0 ? normalized + 360 : normalized
}

function normalizeAngleDeltaRad(angleDeltaRad: number): number {
  let normalized = angleDeltaRad

  while (normalized > Math.PI) {
    normalized -= Math.PI * 2
  }

  while (normalized < -Math.PI) {
    normalized += Math.PI * 2
  }

  return normalized
}

function normalizeAngleDeltaDeg(angleDeltaDeg: number): number {
  let normalized = angleDeltaDeg

  while (normalized > 180) {
    normalized -= 360
  }

  while (normalized < -180) {
    normalized += 360
  }

  return normalized
}

function interpolateAngleDeg(currentDeg: number, targetDeg: number, factor: number): number {
  return normalizeRotationDeg(currentDeg + normalizeAngleDeltaDeg(targetDeg - currentDeg) * factor)
}

function formatRotationText(rotationDeg: number): string {
  return `${Math.round(normalizeRotationDeg(rotationDeg))}deg`
}

function formatHeadingText(headingDeg: number | null): string {
  if (headingDeg === null) {
    return '--'
  }

  return `${Math.round(normalizeRotationDeg(headingDeg))}deg`
}

function formatOrientationModeText(mode: OrientationMode): string {
  if (mode === 'north-up') {
    return 'North Up'
  }

  if (mode === 'heading-up') {
    return 'Heading Up'
  }

  return 'Manual Gesture'
}

function formatRotationModeText(mode: OrientationMode): string {
  return formatOrientationModeText(mode)
}

function formatRotationToggleText(mode: OrientationMode): string {
  if (mode === 'manual') {
    return '切到北朝上'
  }

  if (mode === 'north-up') {
    return '切到朝向朝上'
  }

  return '切到手动旋转'
}

function formatAutoRotateSourceText(mode: AutoRotateSourceMode, hasCourseHeading: boolean): string {
  if (mode === 'sensor') {
    return 'Sensor Only'
  }

  if (mode === 'course') {
    return hasCourseHeading ? 'Course Only' : 'Course Pending'
  }

  return hasCourseHeading ? 'Sensor + Course' : 'Sensor Only'
}

function formatAutoRotateCalibrationText(pending: boolean, offsetDeg: number | null): string {
  if (pending) {
    return 'Pending'
  }

  if (offsetDeg === null) {
    return '--'
  }

  return `Offset ${Math.round(normalizeRotationDeg(offsetDeg))}deg`
}

function getTrueHeadingDeg(magneticHeadingDeg: number): number {
  return normalizeRotationDeg(magneticHeadingDeg + MAGNETIC_DECLINATION_DEG)
}

function getMagneticHeadingDeg(trueHeadingDeg: number): number {
  return normalizeRotationDeg(trueHeadingDeg - MAGNETIC_DECLINATION_DEG)
}

function getMapNorthOffsetDeg(_mode: NorthReferenceMode): number {
  return MAP_NORTH_OFFSET_DEG
}

function getCompassReferenceHeadingDeg(mode: NorthReferenceMode, magneticHeadingDeg: number): number {
  if (mode === 'true') {
    return getTrueHeadingDeg(magneticHeadingDeg)
  }

  return normalizeRotationDeg(magneticHeadingDeg)
}

function getMapReferenceHeadingDegFromSensor(mode: NorthReferenceMode, magneticHeadingDeg: number): number {
  if (mode === 'magnetic') {
    return normalizeRotationDeg(magneticHeadingDeg)
  }

  return getTrueHeadingDeg(magneticHeadingDeg)
}

function getMapReferenceHeadingDegFromCourse(mode: NorthReferenceMode, trueHeadingDeg: number): number {
  if (mode === 'magnetic') {
    return getMagneticHeadingDeg(trueHeadingDeg)
  }

  return normalizeRotationDeg(trueHeadingDeg)
}

function formatNorthReferenceText(mode: NorthReferenceMode): string {
  if (mode === 'magnetic') {
    return `Compass Magnetic / Heading-Up Magnetic (${MAGNETIC_DECLINATION_TEXT})`
  }

  return `Compass True / Heading-Up True (${MAGNETIC_DECLINATION_TEXT})`
}

function formatCompassDeclinationText(mode: NorthReferenceMode): string {
  if (mode === 'true') {
    return MAGNETIC_DECLINATION_TEXT
  }

  return ''
}

function formatNorthReferenceButtonText(mode: NorthReferenceMode): string {
  return mode === 'magnetic' ? '北参考：磁北' : '北参考：真北'
}

function formatNorthReferenceStatusText(mode: NorthReferenceMode): string {
  if (mode === 'magnetic') {
    return '已切到磁北模式'
  }

  return '已切到真北模式'
}

function getNextNorthReferenceMode(mode: NorthReferenceMode): NorthReferenceMode {
  return mode === 'magnetic' ? 'true' : 'magnetic'
}

function formatCompassNeedleDegForMode(mode: NorthReferenceMode, magneticHeadingDeg: number | null): number {
  if (magneticHeadingDeg === null) {
    return 0
  }

  const referenceHeadingDeg = mode === 'true'
    ? getTrueHeadingDeg(magneticHeadingDeg)
    : normalizeRotationDeg(magneticHeadingDeg)

  return normalizeRotationDeg(360 - referenceHeadingDeg)
}

function formatCacheHitRate(memoryHitCount: number, diskHitCount: number, networkFetchCount: number): string {
  const total = memoryHitCount + diskHitCount + networkFetchCount
  if (!total) {
    return '--'
  }

  const hitRate = ((memoryHitCount + diskHitCount) / total) * 100
  return `${Math.round(hitRate)}%`
}
export class MapEngine {
  buildVersion: string
  renderer: WebGLMapRenderer
  compassController: CompassHeadingController
  onData: (patch: Partial<MapEngineViewState>) => void
  state: MapEngineViewState
  previewScale: number
  previewOriginX: number
  previewOriginY: number
  panLastX: number
  panLastY: number
  panLastTimestamp: number
  panVelocityX: number
  panVelocityY: number
  pinchStartDistance: number
  pinchStartScale: number
  pinchStartAngle: number
  pinchStartRotationDeg: number
  pinchAnchorWorldX: number
  pinchAnchorWorldY: number
  gestureMode: GestureMode
  inertiaTimer: number
  previewResetTimer: number
  viewSyncTimer: number
  autoRotateTimer: number
  pendingViewPatch: Partial<MapEngineViewState>
  mounted: boolean
  northReferenceMode: NorthReferenceMode
  sensorHeadingDeg: number | null
  smoothedSensorHeadingDeg: number | null
  compassDisplayHeadingDeg: number | null
  autoRotateHeadingDeg: number | null
  courseHeadingDeg: number | null
  targetAutoRotationDeg: number | null
  autoRotateSourceMode: AutoRotateSourceMode
  autoRotateCalibrationOffsetDeg: number | null
  autoRotateCalibrationPending: boolean
  minZoom: number
  maxZoom: number
  defaultZoom: number
  defaultCenterTileX: number
  defaultCenterTileY: number
  tileBoundsByZoom: Record<number, TileZoomBounds> | null

  constructor(buildVersion: string, callbacks: MapEngineCallbacks) {
    this.buildVersion = buildVersion
    this.onData = callbacks.onData
    this.renderer = new WebGLMapRenderer(
      (stats) => {
        this.applyStats(stats)
      },
      (message) => {
        this.setState({
          statusText: `${message} (${this.buildVersion})`,
        })
      },
    )
    this.compassController = new CompassHeadingController({
      onHeading: (headingDeg) => {
        this.handleCompassHeading(headingDeg)
      },
      onError: (message) => {
        this.handleCompassError(message)
      },
    })
    this.minZoom = MIN_ZOOM
    this.maxZoom = MAX_ZOOM
    this.defaultZoom = DEFAULT_ZOOM
    this.defaultCenterTileX = DEFAULT_CENTER_TILE_X
    this.defaultCenterTileY = DEFAULT_CENTER_TILE_Y
    this.tileBoundsByZoom = null
    this.state = {
      buildVersion: this.buildVersion,
      renderMode: RENDER_MODE,
      projectionMode: PROJECTION_MODE,
      mapReady: false,
      mapReadyText: 'BOOTING',
      mapName: 'LCX 测试地图',
      configStatusText: '远程配置待加载',
      zoom: DEFAULT_ZOOM,
      rotationDeg: 0,
      rotationText: formatRotationText(0),
      rotationMode: 'manual',
      rotationModeText: formatRotationModeText('manual'),
      rotationToggleText: formatRotationToggleText('manual'),
      orientationMode: 'manual',
      orientationModeText: formatOrientationModeText('manual'),
      sensorHeadingText: '--',
      compassDeclinationText: formatCompassDeclinationText(DEFAULT_NORTH_REFERENCE_MODE),
      northReferenceButtonText: formatNorthReferenceButtonText(DEFAULT_NORTH_REFERENCE_MODE),
      autoRotateSourceText: formatAutoRotateSourceText('fusion', false),
      autoRotateCalibrationText: formatAutoRotateCalibrationText(false, getMapNorthOffsetDeg(DEFAULT_NORTH_REFERENCE_MODE)),
      northReferenceText: formatNorthReferenceText(DEFAULT_NORTH_REFERENCE_MODE),
      compassNeedleDeg: 0,
      centerTileX: DEFAULT_CENTER_TILE_X,
      centerTileY: DEFAULT_CENTER_TILE_Y,
      centerText: buildCenterText(DEFAULT_ZOOM, DEFAULT_CENTER_TILE_X, DEFAULT_CENTER_TILE_Y),
      tileSource: TILE_SOURCE,
      visibleColumnCount: DESIRED_VISIBLE_COLUMNS,
      visibleTileCount: 0,
      readyTileCount: 0,
      memoryTileCount: 0,
      diskTileCount: 0,
      memoryHitCount: 0,
      diskHitCount: 0,
      networkFetchCount: 0,
      cacheHitRateText: '--',
      tileTranslateX: 0,
      tileTranslateY: 0,
      tileSizePx: 0,
      stageWidth: 0,
      stageHeight: 0,
      stageLeft: 0,
      stageTop: 0,
      statusText: `单 WebGL 管线已准备接入方向传感器 (${this.buildVersion})`,
    }
    this.previewScale = 1
    this.previewOriginX = 0
    this.previewOriginY = 0
    this.panLastX = 0
    this.panLastY = 0
    this.panLastTimestamp = 0
    this.panVelocityX = 0
    this.panVelocityY = 0
    this.pinchStartDistance = 0
    this.pinchStartScale = 1
    this.pinchStartAngle = 0
    this.pinchStartRotationDeg = 0
    this.pinchAnchorWorldX = 0
    this.pinchAnchorWorldY = 0
    this.gestureMode = 'idle'
    this.inertiaTimer = 0
    this.previewResetTimer = 0
    this.viewSyncTimer = 0
    this.autoRotateTimer = 0
    this.pendingViewPatch = {}
    this.mounted = false
    this.northReferenceMode = DEFAULT_NORTH_REFERENCE_MODE
    this.sensorHeadingDeg = null
    this.smoothedSensorHeadingDeg = null
    this.compassDisplayHeadingDeg = null
    this.autoRotateHeadingDeg = null
    this.courseHeadingDeg = null
    this.targetAutoRotationDeg = null
    this.autoRotateSourceMode = 'fusion'
    this.autoRotateCalibrationOffsetDeg = getMapNorthOffsetDeg(DEFAULT_NORTH_REFERENCE_MODE)
    this.autoRotateCalibrationPending = false
  }

  getInitialData(): MapEngineViewState {
    return { ...this.state }
  }

  destroy(): void {
    this.clearInertiaTimer()
    this.clearPreviewResetTimer()
    this.clearViewSyncTimer()
    this.clearAutoRotateTimer()
    this.compassController.destroy()
    this.renderer.destroy()
    this.mounted = false
  }

  setStage(rect: MapEngineStageRect): void {
    this.previewScale = 1
    this.previewOriginX = rect.width / 2
    this.previewOriginY = rect.height / 2
    this.commitViewport(
      {
        stageWidth: rect.width,
        stageHeight: rect.height,
        stageLeft: rect.left,
        stageTop: rect.top,
      },
      `地图视口与 WebGL 引擎已对齐 (${this.buildVersion})`,
      true,
    )
  }

  attachCanvas(canvasNode: any, width: number, height: number, dpr: number): void {
    this.renderer.attachCanvas(canvasNode, width, height, dpr)
    this.mounted = true
    this.state.mapReady = true
    this.state.mapReadyText = 'READY'
    this.onData({
      mapReady: true,
      mapReadyText: 'READY',
      statusText: `单 WebGL 管线已就绪，可切换手动或自动朝向 (${this.buildVersion})`,
    })
    this.syncRenderer()
    this.compassController.start()
  }

  applyRemoteMapConfig(config: RemoteMapConfig): void {
    MAGNETIC_DECLINATION_DEG = config.magneticDeclinationDeg
    MAGNETIC_DECLINATION_TEXT = config.magneticDeclinationText
    this.minZoom = config.minZoom
    this.maxZoom = config.maxZoom
    this.defaultZoom = config.defaultZoom
    this.defaultCenterTileX = config.initialCenterTileX
    this.defaultCenterTileY = config.initialCenterTileY
    this.tileBoundsByZoom = config.tileBoundsByZoom

    const statePatch: Partial<MapEngineViewState> = {
      configStatusText: '远程配置已载入',
      projectionMode: config.projectionModeText,
      tileSource: config.tileSource,
      sensorHeadingText: formatHeadingText(this.smoothedSensorHeadingDeg === null ? null : getCompassReferenceHeadingDeg(this.northReferenceMode, this.smoothedSensorHeadingDeg)),
      compassDeclinationText: formatCompassDeclinationText(this.northReferenceMode),
      northReferenceButtonText: formatNorthReferenceButtonText(this.northReferenceMode),
      northReferenceText: formatNorthReferenceText(this.northReferenceMode),
      compassNeedleDeg: formatCompassNeedleDegForMode(this.northReferenceMode, this.smoothedSensorHeadingDeg),
    }

    if (!this.state.stageWidth || !this.state.stageHeight) {
      this.setState({
        ...statePatch,
        zoom: this.defaultZoom,
        centerTileX: this.defaultCenterTileX,
        centerTileY: this.defaultCenterTileY,
        centerText: buildCenterText(this.defaultZoom, this.defaultCenterTileX, this.defaultCenterTileY),
        statusText: `远程地图配置已载入 (${this.buildVersion})`,
      }, true)
      return
    }

    this.commitViewport({
      ...statePatch,
      zoom: this.defaultZoom,
      centerTileX: this.defaultCenterTileX,
      centerTileY: this.defaultCenterTileY,
      tileTranslateX: 0,
      tileTranslateY: 0,
    }, `远程地图配置已载入 (${this.buildVersion})`, true, () => {
      this.resetPreviewState()
      this.syncRenderer()
      if (this.state.orientationMode === 'heading-up' && this.refreshAutoRotateTarget()) {
        this.scheduleAutoRotate()
      }
    })
  }

  handleTouchStart(event: WechatMiniprogram.TouchEvent): void {
    this.clearInertiaTimer()
    this.clearPreviewResetTimer()
    this.renderer.setAnimationPaused(true)
    this.panVelocityX = 0
    this.panVelocityY = 0

    if (event.touches.length >= 2) {
      const origin = this.getStagePoint(event.touches)
      this.gestureMode = 'pinch'
      this.pinchStartDistance = this.getTouchDistance(event.touches)
      this.pinchStartScale = this.previewScale || 1
      this.pinchStartAngle = this.getTouchAngle(event.touches)
      this.pinchStartRotationDeg = this.state.rotationDeg
      const anchorWorld = screenToWorld(this.getCameraState(), origin, true)
      this.pinchAnchorWorldX = anchorWorld.x
      this.pinchAnchorWorldY = anchorWorld.y
      this.setPreviewState(this.pinchStartScale, origin.x, origin.y)
      this.syncRenderer()
    this.compassController.start()
      return
    }

    if (event.touches.length === 1) {
      this.gestureMode = 'pan'
      this.panLastX = event.touches[0].pageX
      this.panLastY = event.touches[0].pageY
      this.panLastTimestamp = event.timeStamp || Date.now()
    }
  }

  handleTouchMove(event: WechatMiniprogram.TouchEvent): void {
    if (event.touches.length >= 2) {
      const distance = this.getTouchDistance(event.touches)
      const angle = this.getTouchAngle(event.touches)
      const origin = this.getStagePoint(event.touches)
      if (!this.pinchStartDistance) {
        this.pinchStartDistance = distance
        this.pinchStartScale = this.previewScale || 1
        this.pinchStartAngle = angle
        this.pinchStartRotationDeg = this.state.rotationDeg
        const anchorWorld = screenToWorld(this.getCameraState(), origin, true)
        this.pinchAnchorWorldX = anchorWorld.x
        this.pinchAnchorWorldY = anchorWorld.y
      }

      this.gestureMode = 'pinch'
      const nextRotationDeg = this.state.orientationMode === 'heading-up'
        ? this.state.rotationDeg
        : normalizeRotationDeg(this.pinchStartRotationDeg + normalizeAngleDeltaRad(angle - this.pinchStartAngle) * 180 / Math.PI)
      const anchorOffset = this.getWorldOffsetFromScreen(origin.x, origin.y, nextRotationDeg)
      const resolvedViewport = this.resolveViewportForExactCenter(
        this.pinchAnchorWorldX - anchorOffset.x,
        this.pinchAnchorWorldY - anchorOffset.y,
        nextRotationDeg,
      )
      this.setPreviewState(
        clamp(this.pinchStartScale * (distance / this.pinchStartDistance), MIN_PREVIEW_SCALE, MAX_PREVIEW_SCALE),
        origin.x,
        origin.y,
      )
      this.commitViewport(
        {
          ...resolvedViewport,
          rotationDeg: nextRotationDeg,
          rotationText: formatRotationText(nextRotationDeg),
        },
        this.state.orientationMode === 'heading-up'
          ? `双指缩放中，自动朝向保持开启 (${this.buildVersion})`
          : `双指缩放与旋转中 (${this.buildVersion})`,
      )
      return
    }

    if (this.gestureMode !== 'pan' || event.touches.length !== 1) {
      return
    }
    const touch = event.touches[0]
    const deltaX = touch.pageX - this.panLastX
    const deltaY = touch.pageY - this.panLastY
    const nextTimestamp = event.timeStamp || Date.now()
    const elapsed = Math.max(nextTimestamp - this.panLastTimestamp, 16)
    const instantVelocityX = deltaX / elapsed
    const instantVelocityY = deltaY / elapsed

    this.panVelocityX = this.panVelocityX * 0.72 + instantVelocityX * 0.28
    this.panVelocityY = this.panVelocityY * 0.72 + instantVelocityY * 0.28
    this.panLastX = touch.pageX
    this.panLastY = touch.pageY
    this.panLastTimestamp = nextTimestamp

    this.normalizeTranslate(
      this.state.tileTranslateX + deltaX,
      this.state.tileTranslateY + deltaY,
      `已拖拽单 WebGL 地图引擎 (${this.buildVersion})`,
    )
  }

  handleTouchEnd(event: WechatMiniprogram.TouchEvent): void {
    if (this.gestureMode === 'pinch' && event.touches.length < 2) {
      const gestureScale = this.previewScale || 1
      const zoomDelta = Math.round(Math.log2(gestureScale))
      const originX = this.previewOriginX || this.state.stageWidth / 2
      const originY = this.previewOriginY || this.state.stageHeight / 2

      if (zoomDelta) {
        const residualScale = gestureScale / Math.pow(2, zoomDelta)
        this.zoomAroundPoint(zoomDelta, originX, originY, residualScale)
      } else {
        this.animatePreviewToRest()
      }

      this.resetPinchState()
      this.panVelocityX = 0
      this.panVelocityY = 0

      if (event.touches.length === 1) {
        this.gestureMode = 'pan'
        this.panLastX = event.touches[0].pageX
        this.panLastY = event.touches[0].pageY
        this.panLastTimestamp = event.timeStamp || Date.now()
        return
      }

      this.gestureMode = 'idle'
      this.renderer.setAnimationPaused(false)
      this.scheduleAutoRotate()
      return
    }

    if (event.touches.length === 1) {
      this.gestureMode = 'pan'
      this.panLastX = event.touches[0].pageX
      this.panLastY = event.touches[0].pageY
      this.panLastTimestamp = event.timeStamp || Date.now()
      return
    }

    if (this.gestureMode === 'pan' && (Math.abs(this.panVelocityX) >= INERTIA_MIN_SPEED || Math.abs(this.panVelocityY) >= INERTIA_MIN_SPEED)) {
      this.startInertia()
      this.gestureMode = 'idle'
      this.resetPinchState()
      return
    }

    this.gestureMode = 'idle'
    this.resetPinchState()
    this.renderer.setAnimationPaused(false)
    this.scheduleAutoRotate()
  }

  handleTouchCancel(): void {
    this.gestureMode = 'idle'
    this.resetPinchState()
    this.panVelocityX = 0
    this.panVelocityY = 0
    this.clearInertiaTimer()
    this.animatePreviewToRest()
    this.renderer.setAnimationPaused(false)
    this.scheduleAutoRotate()
  }

  handleRecenter(): void {
    this.clearInertiaTimer()
    this.clearPreviewResetTimer()
    this.panVelocityX = 0
    this.panVelocityY = 0
    this.renderer.setAnimationPaused(false)
    this.commitViewport(
      {
        zoom: this.defaultZoom,
        centerTileX: this.defaultCenterTileX,
        centerTileY: this.defaultCenterTileY,
        tileTranslateX: 0,
        tileTranslateY: 0,
      },
      `已回到单 WebGL 引擎默认首屏 (${this.buildVersion})`,
      true,
      () => {
        this.resetPreviewState()
        this.syncRenderer()
    this.compassController.start()
        this.scheduleAutoRotate()
      },
    )
  }

  handleRotateStep(stepDeg = ROTATE_STEP_DEG): void {
    if (this.state.rotationMode === 'auto') {
      this.setState({
        statusText: `当前不是手动旋转模式，请先切回手动 (${this.buildVersion})`,
      }, true)
      return
    }

    const exactCenter = this.getExactCenterFromTranslate(this.state.tileTranslateX, this.state.tileTranslateY)
    const nextRotationDeg = normalizeRotationDeg(this.state.rotationDeg + stepDeg)
    const resolvedViewport = this.resolveViewportForExactCenter(exactCenter.x, exactCenter.y, nextRotationDeg)

    this.clearInertiaTimer()
    this.clearPreviewResetTimer()
    this.panVelocityX = 0
    this.panVelocityY = 0
    this.renderer.setAnimationPaused(false)
    this.commitViewport(
      {
        ...resolvedViewport,
        rotationDeg: nextRotationDeg,
        rotationText: formatRotationText(nextRotationDeg),
      },
      `旋转角度调整到 ${formatRotationText(nextRotationDeg)} (${this.buildVersion})`,
      true,
      () => {
        this.resetPreviewState()
        this.syncRenderer()
    this.compassController.start()
      },
    )
  }

  handleRotationReset(): void {
    if (this.state.rotationMode === 'auto') {
      this.setState({
        statusText: `当前不是手动旋转模式，请先切回手动 (${this.buildVersion})`,
      }, true)
      return
    }

    const targetRotationDeg = MAP_NORTH_OFFSET_DEG
    if (Math.abs(normalizeAngleDeltaDeg(this.state.rotationDeg - targetRotationDeg)) <= 0.01) {
      return
    }

    const exactCenter = this.getExactCenterFromTranslate(this.state.tileTranslateX, this.state.tileTranslateY)
    const resolvedViewport = this.resolveViewportForExactCenter(exactCenter.x, exactCenter.y, targetRotationDeg)

    this.clearInertiaTimer()
    this.clearPreviewResetTimer()
    this.panVelocityX = 0
    this.panVelocityY = 0
    this.renderer.setAnimationPaused(false)
    this.commitViewport(
      {
        ...resolvedViewport,
        rotationDeg: targetRotationDeg,
        rotationText: formatRotationText(targetRotationDeg),
      },
      `旋转角度已回到真北参考 (${this.buildVersion})`,
      true,
      () => {
        this.resetPreviewState()
        this.syncRenderer()
    this.compassController.start()
      },
    )
  }

  handleToggleRotationMode(): void {
    if (this.state.orientationMode === 'manual') {
      this.setNorthUpMode()
      return
    }

    if (this.state.orientationMode === 'north-up') {
      this.setHeadingUpMode()
      return
    }

    this.setManualMode()
  }

  handleSetManualMode(): void {
    this.setManualMode()
  }

  handleSetNorthUpMode(): void {
    this.setNorthUpMode()
  }

  handleSetHeadingUpMode(): void {
    this.setHeadingUpMode()
  }

  handleCycleNorthReferenceMode(): void {
    this.cycleNorthReferenceMode()
  }

  handleAutoRotateCalibrate(): void {
    if (this.state.orientationMode !== 'heading-up') {
      this.setState({
        statusText: `请先切到朝向朝上模式再校准 (${this.buildVersion})`,
      }, true)
      return
    }

    if (!this.calibrateAutoRotateToCurrentOrientation()) {
      this.setState({
        statusText: `当前还没有传感器方向数据，暂时无法校准 (${this.buildVersion})`,
      }, true)
      return
    }

    this.setState({
      statusText: `已按当前持机方向完成朝向校准 (${this.buildVersion})`,
    }, true)
    this.scheduleAutoRotate()
  }

  setManualMode(): void {
    this.clearAutoRotateTimer()
    this.targetAutoRotationDeg = null
    this.autoRotateCalibrationPending = false
    this.setState({
      rotationMode: 'manual',
      rotationModeText: formatRotationModeText('manual'),
      rotationToggleText: formatRotationToggleText('manual'),
      orientationMode: 'manual',
      orientationModeText: formatOrientationModeText('manual'),
      autoRotateCalibrationText: formatAutoRotateCalibrationText(false, this.autoRotateCalibrationOffsetDeg),
      statusText: `已切回手动地图旋转 (${this.buildVersion})`,
    }, true)
  }

  setNorthUpMode(): void {
    this.clearAutoRotateTimer()
    this.targetAutoRotationDeg = null
    this.autoRotateCalibrationPending = false

    const mapNorthOffsetDeg = MAP_NORTH_OFFSET_DEG
    this.autoRotateCalibrationOffsetDeg = mapNorthOffsetDeg
    const exactCenter = this.getExactCenterFromTranslate(this.state.tileTranslateX, this.state.tileTranslateY)
    const resolvedViewport = this.resolveViewportForExactCenter(exactCenter.x, exactCenter.y, mapNorthOffsetDeg)

    this.commitViewport(
      {
        ...resolvedViewport,
        rotationDeg: mapNorthOffsetDeg,
        rotationText: formatRotationText(mapNorthOffsetDeg),
        rotationMode: 'manual',
        rotationModeText: formatRotationModeText('north-up'),
        rotationToggleText: formatRotationToggleText('north-up'),
        orientationMode: 'north-up',
        orientationModeText: formatOrientationModeText('north-up'),
        autoRotateCalibrationText: formatAutoRotateCalibrationText(false, mapNorthOffsetDeg),
        northReferenceText: formatNorthReferenceText(this.northReferenceMode),
      },
      `地图已固定为真北朝上 (${this.buildVersion})`,
      true,
      () => {
        this.resetPreviewState()
        this.syncRenderer()
      },
    )
  }

  setHeadingUpMode(): void {
    this.autoRotateCalibrationPending = false
    this.autoRotateCalibrationOffsetDeg = getMapNorthOffsetDeg(this.northReferenceMode)
    this.targetAutoRotationDeg = null
    this.setState({
      rotationMode: 'auto',
      rotationModeText: formatRotationModeText('heading-up'),
      rotationToggleText: formatRotationToggleText('heading-up'),
      orientationMode: 'heading-up',
      orientationModeText: formatOrientationModeText('heading-up'),
      autoRotateCalibrationText: formatAutoRotateCalibrationText(false, this.autoRotateCalibrationOffsetDeg),
      northReferenceText: formatNorthReferenceText(this.northReferenceMode),
      statusText: `正在启用朝向朝上模式 (${this.buildVersion})`,
    }, true)
    if (this.refreshAutoRotateTarget()) {
      this.scheduleAutoRotate()
    }
  }

  handleCompassHeading(headingDeg: number): void {
    this.sensorHeadingDeg = normalizeRotationDeg(headingDeg)
    this.smoothedSensorHeadingDeg = this.smoothedSensorHeadingDeg === null
      ? this.sensorHeadingDeg
      : interpolateAngleDeg(this.smoothedSensorHeadingDeg, this.sensorHeadingDeg, AUTO_ROTATE_HEADING_SMOOTHING)

    const compassHeadingDeg = getCompassReferenceHeadingDeg(this.northReferenceMode, this.smoothedSensorHeadingDeg)
    this.compassDisplayHeadingDeg = this.compassDisplayHeadingDeg === null
      ? compassHeadingDeg
      : interpolateAngleDeg(this.compassDisplayHeadingDeg, compassHeadingDeg, COMPASS_NEEDLE_SMOOTHING)

    this.autoRotateHeadingDeg = this.resolveAutoRotateInputHeadingDeg()

    this.setState({
      sensorHeadingText: formatHeadingText(compassHeadingDeg),
      compassDeclinationText: formatCompassDeclinationText(this.northReferenceMode),
      northReferenceButtonText: formatNorthReferenceButtonText(this.northReferenceMode),
      autoRotateSourceText: formatAutoRotateSourceText(this.autoRotateSourceMode, this.courseHeadingDeg !== null),
      compassNeedleDeg: formatCompassNeedleDegForMode(this.northReferenceMode, this.smoothedSensorHeadingDeg),
      northReferenceText: formatNorthReferenceText(this.northReferenceMode),
    })

    if (!this.refreshAutoRotateTarget()) {
      return
    }

    if (this.state.orientationMode === 'heading-up') {
      this.scheduleAutoRotate()
    }
  }

  handleCompassError(message: string): void {
    this.clearAutoRotateTimer()
    this.targetAutoRotationDeg = null
    this.autoRotateCalibrationPending = false
    this.setState({
      autoRotateCalibrationText: formatAutoRotateCalibrationText(false, this.autoRotateCalibrationOffsetDeg),
      statusText: `${message} (${this.buildVersion})`,
    }, true)
  }

  cycleNorthReferenceMode(): void {
    const nextMode = getNextNorthReferenceMode(this.northReferenceMode)
    const nextMapNorthOffsetDeg = getMapNorthOffsetDeg(nextMode)
    const compassHeadingDeg = this.smoothedSensorHeadingDeg === null
      ? null
      : getCompassReferenceHeadingDeg(nextMode, this.smoothedSensorHeadingDeg)

    this.northReferenceMode = nextMode
    this.autoRotateCalibrationOffsetDeg = nextMapNorthOffsetDeg
    this.compassDisplayHeadingDeg = compassHeadingDeg

    if (this.state.orientationMode === 'north-up') {
      const exactCenter = this.getExactCenterFromTranslate(this.state.tileTranslateX, this.state.tileTranslateY)
      const resolvedViewport = this.resolveViewportForExactCenter(exactCenter.x, exactCenter.y, MAP_NORTH_OFFSET_DEG)
      this.commitViewport(
        {
          ...resolvedViewport,
          rotationDeg: MAP_NORTH_OFFSET_DEG,
          rotationText: formatRotationText(MAP_NORTH_OFFSET_DEG),
          northReferenceText: formatNorthReferenceText(nextMode),
          sensorHeadingText: formatHeadingText(compassHeadingDeg),
          compassDeclinationText: formatCompassDeclinationText(nextMode),
          northReferenceButtonText: formatNorthReferenceButtonText(nextMode),
          compassNeedleDeg: formatCompassNeedleDegForMode(nextMode, this.smoothedSensorHeadingDeg),
          autoRotateCalibrationText: formatAutoRotateCalibrationText(false, nextMapNorthOffsetDeg),
        },
        `${formatNorthReferenceStatusText(nextMode)} (${this.buildVersion})`,
        true,
        () => {
          this.resetPreviewState()
          this.syncRenderer()
        },
      )
      return
    }

    this.setState({
      northReferenceText: formatNorthReferenceText(nextMode),
      sensorHeadingText: formatHeadingText(compassHeadingDeg),
      compassDeclinationText: formatCompassDeclinationText(nextMode),
      northReferenceButtonText: formatNorthReferenceButtonText(nextMode),
      compassNeedleDeg: formatCompassNeedleDegForMode(nextMode, this.smoothedSensorHeadingDeg),
      autoRotateCalibrationText: formatAutoRotateCalibrationText(false, nextMapNorthOffsetDeg),
      statusText: `${formatNorthReferenceStatusText(nextMode)} (${this.buildVersion})`,
    }, true)

    if (this.state.orientationMode === 'heading-up' && this.refreshAutoRotateTarget()) {
      this.scheduleAutoRotate()
    }
  }

  setCourseHeading(headingDeg: number | null): void {
    this.courseHeadingDeg = headingDeg === null ? null : normalizeRotationDeg(headingDeg)
    this.setState({
      autoRotateSourceText: formatAutoRotateSourceText(this.autoRotateSourceMode, this.courseHeadingDeg !== null),
    })

    if (this.refreshAutoRotateTarget()) {
      this.scheduleAutoRotate()
    }
  }

  resolveAutoRotateInputHeadingDeg(): number | null {
    const sensorHeadingDeg = this.smoothedSensorHeadingDeg === null
      ? null
      : getMapReferenceHeadingDegFromSensor(this.northReferenceMode, this.smoothedSensorHeadingDeg)
    const courseHeadingDeg = this.courseHeadingDeg === null
      ? null
      : getMapReferenceHeadingDegFromCourse(this.northReferenceMode, this.courseHeadingDeg)

    if (this.autoRotateSourceMode === 'sensor') {
      return sensorHeadingDeg
    }

    if (this.autoRotateSourceMode === 'course') {
      return courseHeadingDeg === null ? sensorHeadingDeg : courseHeadingDeg
    }

    if (sensorHeadingDeg !== null && courseHeadingDeg !== null) {
      return interpolateAngleDeg(sensorHeadingDeg, courseHeadingDeg, 0.35)
    }

    return sensorHeadingDeg === null ? courseHeadingDeg : sensorHeadingDeg
  }

  calibrateAutoRotateToCurrentOrientation(): boolean {
    const inputHeadingDeg = this.resolveAutoRotateInputHeadingDeg()
    if (inputHeadingDeg === null) {
      return false
    }

    this.autoRotateCalibrationOffsetDeg = normalizeRotationDeg(this.state.rotationDeg + inputHeadingDeg)
    this.autoRotateCalibrationPending = false
    this.targetAutoRotationDeg = normalizeRotationDeg(this.autoRotateCalibrationOffsetDeg - inputHeadingDeg)
    this.setState({
      autoRotateCalibrationText: formatAutoRotateCalibrationText(false, this.autoRotateCalibrationOffsetDeg),
    })
    return true
  }

  refreshAutoRotateTarget(): boolean {
    const inputHeadingDeg = this.resolveAutoRotateInputHeadingDeg()
    if (inputHeadingDeg === null) {
      return false
    }

    if (this.autoRotateCalibrationPending || this.autoRotateCalibrationOffsetDeg === null) {
      if (!this.calibrateAutoRotateToCurrentOrientation()) {
        return false
      }
      return true
    }

    this.targetAutoRotationDeg = normalizeRotationDeg(this.autoRotateCalibrationOffsetDeg - inputHeadingDeg)
    this.setState({
      autoRotateCalibrationText: formatAutoRotateCalibrationText(false, this.autoRotateCalibrationOffsetDeg),
    })
    return true
  }

  scheduleAutoRotate(): void {
    if (this.autoRotateTimer || this.state.rotationMode !== 'auto' || this.targetAutoRotationDeg === null) {
      return
    }

    const step = () => {
      this.autoRotateTimer = 0

      if (this.state.rotationMode !== 'auto' || this.targetAutoRotationDeg === null) {
        return
      }

      if (this.gestureMode !== 'idle' || this.inertiaTimer || this.previewResetTimer) {
        this.scheduleAutoRotate()
        return
      }

      const currentRotationDeg = this.state.rotationDeg
      const deltaDeg = normalizeAngleDeltaDeg(this.targetAutoRotationDeg - currentRotationDeg)
      if (Math.abs(deltaDeg) <= AUTO_ROTATE_SNAP_DEG) {
        if (Math.abs(deltaDeg) > 0.01) {
          this.applyAutoRotation(this.targetAutoRotationDeg)
        }
        this.scheduleAutoRotate()
        return
      }

      if (Math.abs(deltaDeg) <= AUTO_ROTATE_DEADZONE_DEG) {
        this.scheduleAutoRotate()
        return
      }

      const easedStepDeg = clamp(deltaDeg * AUTO_ROTATE_EASE, -AUTO_ROTATE_MAX_STEP_DEG, AUTO_ROTATE_MAX_STEP_DEG)
      this.applyAutoRotation(normalizeRotationDeg(currentRotationDeg + easedStepDeg))
      this.scheduleAutoRotate()
    }

    this.autoRotateTimer = setTimeout(step, AUTO_ROTATE_FRAME_MS) as unknown as number
  }

  applyAutoRotation(nextRotationDeg: number): void {
    const exactCenter = this.getExactCenterFromTranslate(this.state.tileTranslateX, this.state.tileTranslateY)
    const resolvedViewport = this.resolveViewportForExactCenter(exactCenter.x, exactCenter.y, nextRotationDeg)

    this.state = {
      ...this.state,
      ...resolvedViewport,
      rotationDeg: nextRotationDeg,
      rotationText: formatRotationText(nextRotationDeg),
      centerText: buildCenterText(this.state.zoom, resolvedViewport.centerTileX, resolvedViewport.centerTileY),
    }
    this.syncRenderer()
  }

  applyStats(stats: MapRendererStats): void {
    this.setState({
      visibleTileCount: stats.visibleTileCount,
      readyTileCount: stats.readyTileCount,
      memoryTileCount: stats.memoryTileCount,
      diskTileCount: stats.diskTileCount,
      memoryHitCount: stats.memoryHitCount,
      diskHitCount: stats.diskHitCount,
      networkFetchCount: stats.networkFetchCount,
      cacheHitRateText: formatCacheHitRate(stats.memoryHitCount, stats.diskHitCount, stats.networkFetchCount),
    })
  }

  setState(patch: Partial<MapEngineViewState>, immediateUi = false): void {
    this.state = {
      ...this.state,
      ...patch,
    }

    const viewPatch = this.pickViewPatch(patch)
    if (!Object.keys(viewPatch).length) {
      return
    }

    this.pendingViewPatch = {
      ...this.pendingViewPatch,
      ...viewPatch,
    }

    if (immediateUi) {
      this.flushViewPatch()
      return
    }

    if (this.viewSyncTimer) {
      return
    }

    this.viewSyncTimer = setTimeout(() => {
      this.viewSyncTimer = 0
      this.flushViewPatch()
    }, UI_SYNC_INTERVAL_MS) as unknown as number
  }
  commitViewport(
    patch: Partial<MapEngineViewState>,
    statusText: string,
    immediateUi = false,
    afterUpdate?: () => void,
  ): void {
    const nextZoom = typeof patch.zoom === 'number' ? patch.zoom : this.state.zoom
    const nextCenterTileX = typeof patch.centerTileX === 'number' ? patch.centerTileX : this.state.centerTileX
    const nextCenterTileY = typeof patch.centerTileY === 'number' ? patch.centerTileY : this.state.centerTileY
    const nextStageWidth = typeof patch.stageWidth === 'number' ? patch.stageWidth : this.state.stageWidth
    const nextStageHeight = typeof patch.stageHeight === 'number' ? patch.stageHeight : this.state.stageHeight
    const tileSizePx = getTileSizePx({
      centerWorldX: nextCenterTileX,
      centerWorldY: nextCenterTileY,
      viewportWidth: nextStageWidth,
      viewportHeight: nextStageHeight,
      visibleColumns: DESIRED_VISIBLE_COLUMNS,
    })

    this.setState({
      ...patch,
      tileSizePx,
      centerText: buildCenterText(nextZoom, nextCenterTileX, nextCenterTileY),
      statusText,
    }, immediateUi)
    this.syncRenderer()
    this.compassController.start()
    if (afterUpdate) {
      afterUpdate()
    }
  }

  buildScene() {
    return {
      tileSource: this.state.tileSource,
      zoom: this.state.zoom,
      centerTileX: this.state.centerTileX,
      centerTileY: this.state.centerTileY,
      tileBoundsByZoom: this.tileBoundsByZoom,
      viewportWidth: this.state.stageWidth,
      viewportHeight: this.state.stageHeight,
      visibleColumns: DESIRED_VISIBLE_COLUMNS,
      overdraw: OVERDRAW,
      translateX: this.state.tileTranslateX,
      translateY: this.state.tileTranslateY,
      rotationRad: this.getRotationRad(this.state.rotationDeg),
      previewScale: this.previewScale || 1,
      previewOriginX: this.previewOriginX || this.state.stageWidth / 2,
      previewOriginY: this.previewOriginY || this.state.stageHeight / 2,
      track: SAMPLE_TRACK_WGS84,
      gpsPoint: SAMPLE_GPS_WGS84,
    }
  }

  syncRenderer(): void {
    if (!this.mounted || !this.state.stageWidth || !this.state.stageHeight) {
      return
    }

    this.renderer.updateScene(this.buildScene())
  }

  getCameraState(rotationDeg = this.state.rotationDeg): CameraState {
    return {
      centerWorldX: this.state.centerTileX,
      centerWorldY: this.state.centerTileY,
      viewportWidth: this.state.stageWidth,
      viewportHeight: this.state.stageHeight,
      visibleColumns: DESIRED_VISIBLE_COLUMNS,
      translateX: this.state.tileTranslateX,
      translateY: this.state.tileTranslateY,
      rotationRad: this.getRotationRad(rotationDeg),
    }
  }

  getRotationRad(rotationDeg = this.state.rotationDeg): number {
    return normalizeRotationDeg(rotationDeg) * Math.PI / 180
  }

  getBaseCamera(centerWorldX = this.state.centerTileX, centerWorldY = this.state.centerTileY, rotationDeg = this.state.rotationDeg): CameraState {
    return {
      centerWorldX,
      centerWorldY,
      viewportWidth: this.state.stageWidth,
      viewportHeight: this.state.stageHeight,
      visibleColumns: DESIRED_VISIBLE_COLUMNS,
      rotationRad: this.getRotationRad(rotationDeg),
    }
  }

  getWorldOffsetFromScreen(stageX: number, stageY: number, rotationDeg = this.state.rotationDeg): { x: number; y: number } {
    const baseCamera = {
      centerWorldX: 0,
      centerWorldY: 0,
      viewportWidth: this.state.stageWidth,
      viewportHeight: this.state.stageHeight,
      visibleColumns: DESIRED_VISIBLE_COLUMNS,
      rotationRad: this.getRotationRad(rotationDeg),
    }

    return screenToWorld(baseCamera, { x: stageX, y: stageY }, false)
  }

  getExactCenterFromTranslate(translateX: number, translateY: number): { x: number; y: number } {
    if (!this.state.stageWidth || !this.state.stageHeight) {
      return {
        x: this.state.centerTileX,
        y: this.state.centerTileY,
      }
    }

    const screenCenterX = this.state.stageWidth / 2
    const screenCenterY = this.state.stageHeight / 2
    return screenToWorld(this.getBaseCamera(), {
      x: screenCenterX - translateX,
      y: screenCenterY - translateY,
    }, false)
  }

  resolveViewportForExactCenter(centerWorldX: number, centerWorldY: number, rotationDeg = this.state.rotationDeg): {
    centerTileX: number
    centerTileY: number
    tileTranslateX: number
    tileTranslateY: number
  } {
    const nextCenterTileX = Math.round(centerWorldX)
    const nextCenterTileY = Math.round(centerWorldY)

    if (!this.state.stageWidth || !this.state.stageHeight) {
      return {
        centerTileX: nextCenterTileX,
        centerTileY: nextCenterTileY,
        tileTranslateX: 0,
        tileTranslateY: 0,
      }
    }

    const roundedCamera = this.getBaseCamera(nextCenterTileX, nextCenterTileY, rotationDeg)
    const projectedCenter = worldToScreen(roundedCamera, { x: centerWorldX, y: centerWorldY }, false)

    return {
      centerTileX: nextCenterTileX,
      centerTileY: nextCenterTileY,
      tileTranslateX: this.state.stageWidth / 2 - projectedCenter.x,
      tileTranslateY: this.state.stageHeight / 2 - projectedCenter.y,
    }
  }

  setPreviewState(scale: number, originX: number, originY: number): void {
    this.previewScale = scale
    this.previewOriginX = originX
    this.previewOriginY = originY
  }

  resetPreviewState(): void {
    this.setPreviewState(1, this.state.stageWidth / 2, this.state.stageHeight / 2)
  }

  resetPinchState(): void {
    this.pinchStartDistance = 0
    this.pinchStartScale = 1
    this.pinchStartAngle = 0
    this.pinchStartRotationDeg = this.state.rotationDeg
    this.pinchAnchorWorldX = 0
    this.pinchAnchorWorldY = 0
  }

  clearPreviewResetTimer(): void {
    if (this.previewResetTimer) {
      clearTimeout(this.previewResetTimer)
      this.previewResetTimer = 0
    }
  }

  clearInertiaTimer(): void {
    if (this.inertiaTimer) {
      clearTimeout(this.inertiaTimer)
      this.inertiaTimer = 0
    }
  }

  clearViewSyncTimer(): void {
    if (this.viewSyncTimer) {
      clearTimeout(this.viewSyncTimer)
      this.viewSyncTimer = 0
    }
  }

  clearAutoRotateTimer(): void {
    if (this.autoRotateTimer) {
      clearTimeout(this.autoRotateTimer)
      this.autoRotateTimer = 0
    }
  }
  pickViewPatch(patch: Partial<MapEngineViewState>): Partial<MapEngineViewState> {
    const viewPatch = {} as Partial<MapEngineViewState>
    for (const key of VIEW_SYNC_KEYS) {
      if (Object.prototype.hasOwnProperty.call(patch, key)) {
        ;(viewPatch as any)[key] = patch[key]
      }
    }
    return viewPatch
  }

  flushViewPatch(): void {
    if (!Object.keys(this.pendingViewPatch).length) {
      return
    }

    const patch = this.pendingViewPatch
    this.pendingViewPatch = {}
    this.onData(patch)
  }

  getTouchDistance(touches: TouchPoint[]): number {
    if (touches.length < 2) {
      return 0
    }

    const first = touches[0]
    const second = touches[1]
    const deltaX = first.pageX - second.pageX
    const deltaY = first.pageY - second.pageY
    return Math.sqrt(deltaX * deltaX + deltaY * deltaY)
  }

  getTouchAngle(touches: TouchPoint[]): number {
    if (touches.length < 2) {
      return 0
    }

    const first = touches[0]
    const second = touches[1]
    return Math.atan2(second.pageY - first.pageY, second.pageX - first.pageX)
  }

  getStagePoint(touches: TouchPoint[]): { x: number; y: number } {
    if (!touches.length) {
      return {
        x: this.state.stageWidth / 2,
        y: this.state.stageHeight / 2,
      }
    }

    let pageX = 0
    let pageY = 0
    for (const touch of touches) {
      pageX += touch.pageX
      pageY += touch.pageY
    }

    return {
      x: pageX / touches.length - this.state.stageLeft,
      y: pageY / touches.length - this.state.stageTop,
    }
  }

  animatePreviewToRest(): void {
    this.clearPreviewResetTimer()

    const startScale = this.previewScale || 1
    const originX = this.previewOriginX || this.state.stageWidth / 2
    const originY = this.previewOriginY || this.state.stageHeight / 2

    if (Math.abs(startScale - 1) < 0.01) {
      this.resetPreviewState()
      this.syncRenderer()
    this.compassController.start()
      this.scheduleAutoRotate()
      return
    }

    const startAt = Date.now()
    const step = () => {
      const progress = Math.min(1, (Date.now() - startAt) / PREVIEW_RESET_DURATION_MS)
      const eased = 1 - Math.pow(1 - progress, 3)
      const nextScale = startScale + (1 - startScale) * eased
      this.setPreviewState(nextScale, originX, originY)
      this.syncRenderer()
    this.compassController.start()

      if (progress >= 1) {
        this.resetPreviewState()
        this.syncRenderer()
    this.compassController.start()
        this.previewResetTimer = 0
        this.scheduleAutoRotate()
        return
      }

      this.previewResetTimer = setTimeout(step, INERTIA_FRAME_MS) as unknown as number
    }

    step()
  }

  normalizeTranslate(translateX: number, translateY: number, statusText: string): void {
    if (!this.state.stageWidth) {
      this.setState({
        tileTranslateX: translateX,
        tileTranslateY: translateY,
      })
      this.syncRenderer()
    this.compassController.start()
      return
    }

    const exactCenter = this.getExactCenterFromTranslate(translateX, translateY)
    const resolvedViewport = this.resolveViewportForExactCenter(exactCenter.x, exactCenter.y)
    const centerChanged = resolvedViewport.centerTileX !== this.state.centerTileX || resolvedViewport.centerTileY !== this.state.centerTileY

    if (centerChanged) {
      this.commitViewport(resolvedViewport, statusText)
      return
    }

    this.setState({
      tileTranslateX: resolvedViewport.tileTranslateX,
      tileTranslateY: resolvedViewport.tileTranslateY,
    })
    this.syncRenderer()
    this.compassController.start()
  }

  zoomAroundPoint(zoomDelta: number, stageX: number, stageY: number, residualScale: number): void {
    const nextZoom = clamp(this.state.zoom + zoomDelta, this.minZoom, this.maxZoom)
    const appliedDelta = nextZoom - this.state.zoom
    if (!appliedDelta) {
      this.animatePreviewToRest()
      return
    }

    if (!this.state.stageWidth || !this.state.stageHeight) {
      this.commitViewport(
        {
          zoom: nextZoom,
          centerTileX: appliedDelta > 0 ? this.state.centerTileX * 2 : Math.floor(this.state.centerTileX / 2),
          centerTileY: appliedDelta > 0 ? this.state.centerTileY * 2 : Math.floor(this.state.centerTileY / 2),
          tileTranslateX: 0,
          tileTranslateY: 0,
        },
        `缩放级别调整到 ${nextZoom}`,
        true,
        () => {
          this.setPreviewState(residualScale, stageX, stageY)
          this.syncRenderer()
    this.compassController.start()
          this.animatePreviewToRest()
        },
      )
      return
    }

    const camera = this.getCameraState()
    const world = screenToWorld(camera, { x: stageX, y: stageY }, true)
    const zoomFactor = Math.pow(2, appliedDelta)
    const nextWorldX = world.x * zoomFactor
    const nextWorldY = world.y * zoomFactor
    const anchorOffset = this.getWorldOffsetFromScreen(stageX, stageY)
    const exactCenterX = nextWorldX - anchorOffset.x
    const exactCenterY = nextWorldY - anchorOffset.y
    const resolvedViewport = this.resolveViewportForExactCenter(exactCenterX, exactCenterY)

    this.commitViewport(
      {
        zoom: nextZoom,
        ...resolvedViewport,
      },
      `缩放级别调整到 ${nextZoom}`,
      true,
      () => {
        this.setPreviewState(residualScale, stageX, stageY)
        this.syncRenderer()
    this.compassController.start()
        this.animatePreviewToRest()
      },
    )
  }

  startInertia(): void {
    this.clearInertiaTimer()

    const step = () => {
      this.panVelocityX *= INERTIA_DECAY
      this.panVelocityY *= INERTIA_DECAY

      if (Math.abs(this.panVelocityX) < INERTIA_MIN_SPEED && Math.abs(this.panVelocityY) < INERTIA_MIN_SPEED) {
        this.setState({
          statusText: `惯性滑动结束 (${this.buildVersion})`,
        })
        this.renderer.setAnimationPaused(false)
        this.inertiaTimer = 0
        this.scheduleAutoRotate()
        return
      }

      this.normalizeTranslate(
        this.state.tileTranslateX + this.panVelocityX * INERTIA_FRAME_MS,
        this.state.tileTranslateY + this.panVelocityY * INERTIA_FRAME_MS,
        `惯性滑动中 (${this.buildVersion})`,
      )

      this.inertiaTimer = setTimeout(step, INERTIA_FRAME_MS) as unknown as number
    }

    this.inertiaTimer = setTimeout(step, INERTIA_FRAME_MS) as unknown as number
  }
}