1、问题现象
使用leaflet显示矢量瓦片会出现图片挤压的问题和图片裁剪显示不全的问题
2、解决办法和思路
1)数据抽稀
方法一:在createTile方法通过控制feature在单张瓦片里面显示的数量,在小层级的时候进行筛选过滤,对点数据类型,代码如下:
//判断当期瓦片里面的features,然后对数据进行抽稀,显示的数量不超过5个//小于14层的瓦片,抽稀,显示的数量不超过5个,大于14级全部显示if ((coords.z <= 14 && layer.features.length > 5 && feat.id % Math.ceil(layer.features.length / 5) == 0) ||layer.features.length <= 5 ||coords.z > 14 ||feat.type != 1) {var featureLayer = this._createLayer(feat, pxPerExtent)for (var j = 0; j < styleOptions.length; j++) {var style = L.extend({}, L.Path.prototype.options, styleOptions[j])featureLayer.render(renderer, style)renderer._addPath(featureLayer)}if (this.options.interactive) {featureLayer.makeInteractive()}if (storeFeatures) {renderer._features[id] = {layerName: layerName,feature: featureLayer}}}
方法二:通过设置矢量瓦片vectorTileLayerStyles的样式,可以获取到当前的层级和数据信息,设置一个空的占位图标解决抽稀问题:
vectorTileLayerStyles[layerStyle.layername] = function (properties: any, zoom: number) {if (options && options.length > 0) {let style = {} //返回的数据格式options.forEach((item: any) => {//如何当前的层级落在option的zoom数组范围内if (zoom >= item.zoom[0] && zoom <= item.zoom[1]) {let icon = L.icon({iconUrl: `/static/images/Iconpoint/${item.iconName}.svg`,iconSize: item.iconSize})//点的数据抽稀设置if (item.sliceCount && item.fieldname) {let data = properties[item.fieldname]//测试用// data = data.split('.')[1]//取余数if (data && Number(data) % Number(item.sliceCount) == 0) {style = {icon: icon}} else {style = {icon: defaultIcon}}}}})return style
options配置如下:
options: [{zoom: [1, 10], //不同层级下的显示最小值和最大值sliceCount: 70, //抽稀的数量iconSize: [23, 30],iconName: 'monitorvideo',fieldname: 'gbindexcode'//抽稀属性字段},{zoom: [11, 12], //不同层级下的显示sliceCount: 20, //抽稀的数量iconSize: [23, 30],iconName: 'monitorvideo',fieldname: 'gbindexcode'},{zoom: [13, 15], //不同层级下的显示sliceCount: 10, //抽稀的数量iconSize: [23, 30],iconName: 'monitorvideo',fieldname: 'gbindexcode'},{zoom: [16, 20], //不同层级下的显示sliceCount: 1, //抽稀的数量iconSize: [23, 30],iconName: 'monitorvideo',fieldname: 'gbindexcode'}]
2)图片边缘裁切的问题处理
在gridlayer绘制的时候判断当前的数据是否会超出绘制边界,超出绘制边界后不予显示(可能会存在数据丢失的问题),也可以移动绘制的位置让其显示完全
_updateIcon: function (layer) {if (!this._drawing) {return}var icon = layer.options.icon,options = icon.options,size = L.point(options.iconSize),anchor = options.iconAnchor || (size && size.divideBy(2, true)),p = layer._point.subtract(anchor),ctx = this._ctx,img = layer._getImage()if (img.complete) {if (p.x + size.x > 256 || p.x < 0 || p.y + size.y > 256 || p.y < 0) {console.log('图像超出画板边界!')} else {ctx.drawImage(img, p.x, p.y, size.x, size.y)}} else {L.DomEvent.on(img, 'load', function () {if (p.x + size.x > 256 || p.x < 0 || p.y + size.y > 256 || p.y < 0) {console.log('图像超出画板边界!')} else {ctx.drawImage(img, p.x, p.y, size.x, size.y)}})}this._drawnLayers[layer._leaflet_id] = layer}
})
3、解决结果
4、参考资料
Leaflet.VectorGrid API reference
https://gis.stackexchange.com/questions/448812/leaflet-vectorgrid-circle-markers-cut-off-at-border-in-custom-implementation
Rendering errors (symbol clipping) at vector tile edges · Issue #149 · Leaflet/Leaflet.VectorGrid · GitHub
canvas 绘制图片 - ctx.drawImage()-CSDN博客
leaflet瓦片图层缩放级别外不隐藏_leafeft marker按照zomm显示隐藏-CSDN博客