139 lines
3.5 KiB
JavaScript
139 lines
3.5 KiB
JavaScript
/**
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* @module ol/TileQueue
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*/
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import {inherits} from './index.js';
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import TileState from './TileState.js';
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import {listen, unlisten} from './events.js';
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import EventType from './events/EventType.js';
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import PriorityQueue from './structs/PriorityQueue.js';
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/**
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* @typedef {function(module:ol/Tile~Tile, string, module:ol/coordinate~Coordinate, number): number} PriorityFunction
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*/
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/**
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* @constructor
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* @extends {module:ol/structs/PriorityQueue~PriorityQueue.<Array>}
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* @param {module:ol/TileQueue~PriorityFunction} tilePriorityFunction
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* Tile priority function.
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* @param {function(): ?} tileChangeCallback
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* Function called on each tile change event.
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* @struct
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*/
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const TileQueue = function(tilePriorityFunction, tileChangeCallback) {
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PriorityQueue.call(
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this,
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/**
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* @param {Array} element Element.
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* @return {number} Priority.
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*/
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function(element) {
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return tilePriorityFunction.apply(null, element);
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},
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/**
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* @param {Array} element Element.
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* @return {string} Key.
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*/
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function(element) {
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return /** @type {module:ol/Tile~Tile} */ (element[0]).getKey();
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});
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/**
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* @private
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* @type {function(): ?}
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*/
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this.tileChangeCallback_ = tileChangeCallback;
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/**
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* @private
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* @type {number}
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*/
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this.tilesLoading_ = 0;
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/**
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* @private
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* @type {!Object.<string,boolean>}
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*/
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this.tilesLoadingKeys_ = {};
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};
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inherits(TileQueue, PriorityQueue);
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/**
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* @inheritDoc
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*/
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TileQueue.prototype.enqueue = function(element) {
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const added = PriorityQueue.prototype.enqueue.call(this, element);
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if (added) {
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const tile = element[0];
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listen(tile, EventType.CHANGE,
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this.handleTileChange, this);
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}
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return added;
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};
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/**
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* @return {number} Number of tiles loading.
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*/
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TileQueue.prototype.getTilesLoading = function() {
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return this.tilesLoading_;
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};
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/**
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* @param {module:ol/events/Event~Event} event Event.
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* @protected
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*/
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TileQueue.prototype.handleTileChange = function(event) {
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const tile = /** @type {module:ol/Tile~Tile} */ (event.target);
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const state = tile.getState();
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if (state === TileState.LOADED || state === TileState.ERROR ||
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state === TileState.EMPTY || state === TileState.ABORT) {
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unlisten(tile, EventType.CHANGE,
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this.handleTileChange, this);
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const tileKey = tile.getKey();
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if (tileKey in this.tilesLoadingKeys_) {
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delete this.tilesLoadingKeys_[tileKey];
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--this.tilesLoading_;
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}
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this.tileChangeCallback_();
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}
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};
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/**
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* @param {number} maxTotalLoading Maximum number tiles to load simultaneously.
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* @param {number} maxNewLoads Maximum number of new tiles to load.
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*/
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TileQueue.prototype.loadMoreTiles = function(maxTotalLoading, maxNewLoads) {
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let newLoads = 0;
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let abortedTiles = false;
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let state, tile, tileKey;
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while (this.tilesLoading_ < maxTotalLoading && newLoads < maxNewLoads &&
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this.getCount() > 0) {
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tile = /** @type {module:ol/Tile~Tile} */ (this.dequeue()[0]);
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tileKey = tile.getKey();
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state = tile.getState();
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if (state === TileState.ABORT) {
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abortedTiles = true;
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} else if (state === TileState.IDLE && !(tileKey in this.tilesLoadingKeys_)) {
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this.tilesLoadingKeys_[tileKey] = true;
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++this.tilesLoading_;
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++newLoads;
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tile.load();
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}
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}
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if (newLoads === 0 && abortedTiles) {
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// Do not stop the render loop when all wanted tiles were aborted due to
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// a small, saturated tile cache.
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this.tileChangeCallback_();
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}
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};
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export default TileQueue;
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