历史轨迹回放是GIS很常见的一个功能,本文结合turf.js
实现轨迹的展示与播放动画。
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class AnimationRoute {
constructor(map, json, play = true) {
this._map = map
this._json = json
this._play = play
this.init()
}
init() {
const that = this
that._index = 0
that._count = 1500
that._step = turf.length(that._json) / that._count
that._flag = 0
that._playId = 'play-' + Date.now()
// 添加路径图层
that._map.addSource(that._playId, {
type: 'geojson',
data: that._json
})
that._map.addLayer({
id: that._playId,
type: 'line',
source: that._playId,
'layout': {
'line-cap': 'round',
'line-join': 'round'
},
'paint': {
'line-color': '#aaaaaa',
'line-width': 10
}
})
// 添加已播放路径
that._map.addSource(that._playId + '-played', {
type: 'geojson',
data: that._json
})
that._map.addLayer({
id: that._playId + '-played',
type: 'line',
source: that._playId + '-played',
'layout': {
'line-cap': 'round',
'line-join': 'round'
},
'paint': {
'line-color': '#09801a',
'line-width': 10
}
})
// 添加路径上的箭头
that._map.loadImage(arrow, function(error, image) {
if (error) throw error
that._map.addImage(that._playId + '-arrow', image)
that._map.addLayer({
'id': that._playId + '-arrow',
'source': that._playId,
'type': 'symbol',
'layout': {
'symbol-placement': 'line',
'symbol-spacing': 50,
'icon-image': that._playId + '-arrow',
'icon-size': 0.6,
'icon-allow-overlap': true
}
})
})
// 添加动态图标
that._map.loadImage(icon, function(error, image) {
if (error) throw error
that._map.addImage(that._playId + '-icon', image)
that._map.addSource(that._playId + '-point', {
'type': 'geojson',
'data': that._getDataByCoords()
})
that._map.addLayer({
'id': that._playId + '-point',
'source': that._playId + '-point',
'type': 'symbol',
'layout': {
'icon-image': that._playId + '-icon',
'icon-size': 0.75,
'icon-allow-overlap': true,
'icon-rotation-alignment': 'map',
'icon-pitch-alignment': 'map',
'icon-rotate': 50
}
})
that._animatePath()
})
}
_animatePath() {
if(this._index > this._count) {
window.cancelAnimationFrame(this._flag)
} else {
const coords = turf.along(this._json, this._step * this._index).geometry.coordinates
// 已播放的线
const start = turf.along(this._json, 0).geometry.coordinates
this._map.getSource(this._playId + '-played').setData(turf.lineSlice(start, coords, this._json))
// 车的图标位置
this._map.getSource(this._playId + '-point').setData(this._getDataByCoords(coords))
// 计算旋转角度
const nextIndex = this._index === this._count ? this._count - 1 : this._index + 1
const coordsNext = turf.along(this._json, this._step * nextIndex).geometry.coordinates
let angle = turf.bearing(
turf.point(coords),
turf.point(coordsNext)
) - 90
if(this._index === this._count) angle += 180
this._map.setLayoutProperty(this._playId + '-point', 'icon-rotate', angle)
this._index++
if(this._play) this._flag = requestAnimationFrame(() => {
this._animatePath()
})
}
}
_getDataByCoords(coords) {
if(!coords || coords.length !== 2) return null
return turf.point(coords, {
'label': this._formatDistance(this._step * this._index)
})
}
_formatDistance(dis) {
if(dis < 1) {
dis = dis * 1000
return dis.toFixed(0) + '米'
} else {
return dis.toFixed(2) + '千米'
}
}
destory() {
window.cancelAnimationFrame(this._flag)
if(this._map.getSource(this._playId + '-point')) {
this._map.removeLayer(this._playId + '-point')
// this._map.removeLayer(this._playId + '-label')
this._map.removeSource(this._playId + '-point')
}
if(this._map.getSource(this._playId)) {
this._map.removeLayer(this._playId)
this._map.removeSource(this._playId)
}
}
}
测试调用代码:
const route1 = {'type':'Feature','properties':{},'geometry':{'type':'LineString','coordinates':[[106.669,22.5785],[106.6374,22.5974],[106.6206,22.608],[106.6037,22.5553],[106.5784,22.4858],[106.5595,22.4373],[106.5637,22.3804],[106.5827,22.3298],[106.6543,22.313],[106.6859,22.2561],[106.7006,22.195],[106.688,22.1613],[106.6943,22.0897],[106.6964,22.018],[106.6838,21.9717],[106.7386,21.9864],[106.7554,22.0138],[106.8334,21.9759],[106.9008,21.9738],[106.9261,21.9422],[106.9767,21.9316],[107.0209,21.9485],[107.0609,21.919],[107.0125,21.8705],[107.0104,21.8305],[107.0609,21.8031],[107.1031,21.7862],[107.1473,21.7483],[107.2063,21.7125],[107.2611,21.6935],[107.2927,21.7251]]}}
new AnimationRoute(map, route1)
说明:如果为多个轨迹同时展示,多次调用new AnimationRoute
即可。