private _init()

in packages/layers/label/src/LabelLayer.ts [177:277]
83 lines of code
12 McCabe index (conditional complexity)

	private _init(projection, timeline, polaris) {
		const p = polaris as PolarisGSI

		let viewChangedFrames = 0
		let visNeedsCheck = true
		let lastZoom = -1

		// Canvas init
		this.listenProps(['zIndex'], () => {
			this._createCanvas(p)
		})

		this.listenProps(
			[
				'data',
				'baseAlt',
				'inverseByBgColor',
				'getBgColor',
				'text_family',
				'text_weight',
				'text_size',
				'text_color',
				'text_background',
				'text_marginLeft',
				'text_marginTop',
				'text_translate_x',
				'text_translate_y',
				'text_shadow_px',
				'text_shadow_color',
				'customTextStyle',
			],
			() => {
				this._createLocators()
				viewChangedFrames = 0
				visNeedsCheck = true
				this._currInvisibles = []
				this._currVisibles = []
			}
		)

		this.listenProps(['markerComparator', 'markerCompareEnlargePx'], () => {
			const comparator = this.getProps('markerComparator')
			if (!comparator) return
			this.markers.sort((a, b) => {
				return comparator(a ? a.feature : undefined, b ? b.feature : undefined)
			})
			viewChangedFrames = 0
			visNeedsCheck = true
			this._currInvisibles = []
			this._currVisibles = []
		})

		this.onViewChange = (cam, p) => {
			const polaris = p as PolarisGSI

			// viewChange固定几帧之后再进行label抽样测试
			viewChangedFrames = 0

			// 只有zoom改变时才测试
			if (cam.zoom !== lastZoom) {
				visNeedsCheck = true
			}

			// update width/height
			if (this.canvas) {
				if (
					this.canvas.clientWidth !== polaris.width ||
					this.canvas.clientHeight !== polaris.height
				) {
					this.canvas.style.width = polaris.width + 'px'
					this.canvas.style.height = polaris.height + 'px'
					this.canvas.width = polaris.width * this.ratio
					this.canvas.height = polaris.height * this.ratio
				}
			}
		}

		const framesBeforeStable = 3
		this.onBeforeRender = () => {
			const cam = p.cameraProxy
			if (viewChangedFrames < framesBeforeStable) {
				this._calcMarkersBBox()
			}

			// only when static frames > N && view changed, do marker visibility tests
			// const frames = Math.round(1000 / this.getProps('showHideDuration'))
			if (++viewChangedFrames > framesBeforeStable && visNeedsCheck) {
				this._setMarkersVisibility(timeline)
				visNeedsCheck = false
				if (cam.zoom !== lastZoom) {
					lastZoom = cam.zoom
				}
			}
		}

		// Draw labels
		this.onAfterRender = () => {
			this._clearCanvas()
			this._drawLabels()
		}
	}