openlayers
Version:
Build tools and sources for developing OpenLayers based mapping applications
124 lines (107 loc) • 3.25 kB
JavaScript
goog.provide('ol.TileQueue');
goog.require('ol');
goog.require('ol.Tile');
goog.require('ol.events');
goog.require('ol.events.EventType');
goog.require('ol.structs.PriorityQueue');
/**
* @constructor
* @extends {ol.structs.PriorityQueue.<Array>}
* @param {ol.TilePriorityFunction} tilePriorityFunction
* Tile priority function.
* @param {function(): ?} tileChangeCallback
* Function called on each tile change event.
* @struct
*/
ol.TileQueue = function(tilePriorityFunction, tileChangeCallback) {
ol.structs.PriorityQueue.call(
this,
/**
* @param {Array} element Element.
* @return {number} Priority.
*/
function(element) {
return tilePriorityFunction.apply(null, element);
},
/**
* @param {Array} element Element.
* @return {string} Key.
*/
function(element) {
return /** @type {ol.Tile} */ (element[0]).getKey();
});
/**
* @private
* @type {function(): ?}
*/
this.tileChangeCallback_ = tileChangeCallback;
/**
* @private
* @type {number}
*/
this.tilesLoading_ = 0;
/**
* @private
* @type {!Object.<string,boolean>}
*/
this.tilesLoadingKeys_ = {};
};
ol.inherits(ol.TileQueue, ol.structs.PriorityQueue);
/**
* @inheritDoc
*/
ol.TileQueue.prototype.enqueue = function(element) {
var added = ol.structs.PriorityQueue.prototype.enqueue.call(this, element);
if (added) {
var tile = element[0];
ol.events.listen(tile, ol.events.EventType.CHANGE,
this.handleTileChange, this);
}
return added;
};
/**
* @return {number} Number of tiles loading.
*/
ol.TileQueue.prototype.getTilesLoading = function() {
return this.tilesLoading_;
};
/**
* @param {ol.events.Event} event Event.
* @protected
*/
ol.TileQueue.prototype.handleTileChange = function(event) {
var tile = /** @type {ol.Tile} */ (event.target);
var state = tile.getState();
if (state === ol.Tile.State.LOADED || state === ol.Tile.State.ERROR ||
state === ol.Tile.State.EMPTY || state === ol.Tile.State.ABORT) {
ol.events.unlisten(tile, ol.events.EventType.CHANGE,
this.handleTileChange, this);
var tileKey = tile.getKey();
if (tileKey in this.tilesLoadingKeys_) {
delete this.tilesLoadingKeys_[tileKey];
--this.tilesLoading_;
}
this.tileChangeCallback_();
}
ol.DEBUG && console.assert(Object.keys(this.tilesLoadingKeys_).length === this.tilesLoading_);
};
/**
* @param {number} maxTotalLoading Maximum number tiles to load simultaneously.
* @param {number} maxNewLoads Maximum number of new tiles to load.
*/
ol.TileQueue.prototype.loadMoreTiles = function(maxTotalLoading, maxNewLoads) {
var newLoads = 0;
var tile, tileKey;
while (this.tilesLoading_ < maxTotalLoading && newLoads < maxNewLoads &&
this.getCount() > 0) {
tile = /** @type {ol.Tile} */ (this.dequeue()[0]);
tileKey = tile.getKey();
if (tile.getState() === ol.Tile.State.IDLE && !(tileKey in this.tilesLoadingKeys_)) {
this.tilesLoadingKeys_[tileKey] = true;
++this.tilesLoading_;
++newLoads;
tile.load();
}
ol.DEBUG && console.assert(Object.keys(this.tilesLoadingKeys_).length === this.tilesLoading_);
}
};