mirror of
https://github.com/protomaps/PMTiles.git
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rename mjs to src.mjs
This commit is contained in:
Brandon Liu
182
js/index.src.mjs
Normal file
182
js/index.src.mjs
Normal file
@@ -0,0 +1,182 @@
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const shift = (number, shift) => {
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return number * Math.pow(2, shift)
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}
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const getUint24 = (dataview, pos) => {
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return shift(dataview.getUint16(pos+1,true),8) + dataview.getUint8(pos,true)
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}
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const getUint48 = (dataview, pos) => {
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return shift(dataview.getUint32(pos+2,true),16) + dataview.getUint16(pos,true)
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}
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const parseHeader = dataview => {
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var magic = dataview.getUint16(0,true)
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if (magic !== 19792) {
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throw new Error('File header does not begin with "PM"')
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}
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var version = dataview.getUint16(2,true)
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var json_size = dataview.getUint32(4,true)
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var root_entries = dataview.getUint16(8,true)
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return {version:version,json_size:json_size,root_entries:root_entries}
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}
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const bytesToMap = dataview => {
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let m = new Map()
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for (var i = 0; i < dataview.byteLength; i+=17) {
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var z_raw = dataview.getUint8(i,true)
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var z = z_raw & 127
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var is_dir = z_raw >> 7
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var x = getUint24(dataview,i+1)
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var y = getUint24(dataview,i+4)
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var offset = getUint48(dataview,i+7)
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var length = dataview.getUint32(i+13,true)
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m.set(z + '_' + x + '_' + y,[offset,length,is_dir])
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}
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return m
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}
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export class PMTiles {
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constructor(url) {
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this.url = url
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const controller = new AbortController()
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const signal = controller.signal
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this.root = fetch(this.url,{signal:signal, headers:{Range:'bytes=0-511999'}}).then(resp => {
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if (resp.headers.get('Content-Length') != 512000) {
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console.error("Content-Length mismatch indicates byte serving not supported; aborting.")
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controller.abort()
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}
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return resp.arrayBuffer()
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}).then(buf => {
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const header = parseHeader(new DataView(buf,0,10))
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var dec = new TextDecoder("utf-8")
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return {
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metadata: JSON.parse(dec.decode(new DataView(buf,10,header.json_size))),
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dir:bytesToMap(new DataView(buf,10+header.json_size,17*header.root_entries))
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}
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})
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this.step = 0
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this.leaves = new Map()
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this.outstanding_requests = new Map()
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}
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metadata = func => {
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return new Promise((resolve,reject) => {
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this.root.then(root => {
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resolve(root.metadata)
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})
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})
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}
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getLeaf = (offset, len) => {
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return new Promise((resolve,reject) => {
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if (this.leaves.has(offset)) {
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this.leaves.get(offset)[0]++
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resolve(this.leaves.get(offset)[1])
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} else if (this.outstanding_requests.has(offset)) {
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this.outstanding_requests.get(offset).push(resolve)
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} else {
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this.outstanding_requests.set(offset,[])
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fetch(this.url, {headers:{Range:'bytes=' + offset + '-' + (offset + len-1)}}).then(resp => {
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return resp.arrayBuffer()
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}).then(buf => {
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var map = bytesToMap(new DataView(buf),len/17)
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if (this.leaves.size > 32) {
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var minStep = Infinity
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var minKey = undefined
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this.leaves.forEach((val,key) => {
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if (val[0] < minStep) {
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minStep = val[0]
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minKey = key
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}
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})
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this.leaves.delete(minKey)
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}
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this.leaves.set(offset,[this.step++,map])
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resolve(map)
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this.outstanding_requests.get(offset).forEach(f => f(map))
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this.outstanding_requests.delete(offset)
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})
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}
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})
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}
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getZxy = (z,x,y) => {
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var strid = z + '_' + x + '_' + y
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return this.root.then(root => {
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if (root.dir.has(strid) && root.dir.get(strid)[2] == 0) {
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return root.dir.get(strid)
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} else {
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if (z >= 7) {
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var z7_tile_diff = (z - 7)
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var z7_tile = [7,Math.trunc(x / (1 << z7_tile_diff)), Math.trunc(y / (1 << z7_tile_diff))]
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var z7_tile_str = z7_tile[0] + "_" + z7_tile[1] + "_" + z7_tile[2]
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if (root.dir.has(z7_tile_str) && root.dir.get(z7_tile_str)[2] == 1) {
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const val = root.dir.get(z7_tile_str)
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return this.getLeaf(val[0],val[1]).then(leafdir => {
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if (leafdir.has(strid)) {
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return leafdir.get(strid)
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}
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return null
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})
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}
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}
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}
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return null
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})
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}
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transformRequest = (u,t,tile,done) => {
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if (u.endsWith('.pmtiles') && done) {
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var tid = tile.tileID.canonical
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var strid = tid.z + '_' + tid.x + '_' + tid.y
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this.getZxy(tid.z,tid.x,tid.y).then(val => {
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if (val) {
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done({url: this.url, headers:{'Range':'bytes=' + val[0] + '-' + (val[0]+val[1]-1)}})
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}
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})
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}
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return {url: u}
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}
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// take URL here
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leafletLayer = options => {
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const self = this
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var cls = L.GridLayer.extend({
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createTile: function(coord, done){
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var tile = document.createElement('img')
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var error
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self.getZxy(coord.z,coord.x,coord.y).then(result => {
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if (result === null) return
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fetch(self.url,{headers:{Range:'bytes=' + result[0] + '-' + (result[0]+result[1]-1)}}).then(resp => {
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return resp.arrayBuffer()
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}).then(buf => {
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var blob = new Blob( [buf], { type: "image/png" } )
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var imageUrl = window.URL.createObjectURL(blob)
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tile.src = imageUrl
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done(error,tile)
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})
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})
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return tile
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},
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_removeTile: function (key) {
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var tile = this._tiles[key]
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if (!tile) { return }
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tile.el.width = 0
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tile.el.height = 0
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tile.el.deleted = true
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L.DomUtil.remove(tile.el)
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delete this._tiles[key]
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this.fire('tileunload', {
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tile: tile.el,
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coords: this._keyToTileCoords(key)
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})
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},
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})
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return new cls(options)
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}
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}
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