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import {GridLayer} from './GridLayer';
import * as Browser from '../../core/Browser';
import * as Util from '../../core/Util';
import * as DomEvent from '../../dom/DomEvent';
import * as DomUtil from '../../dom/DomUtil';
/*
* @class TileLayer
* @inherits GridLayer
* @aka L.TileLayer
* Used to load and display tile layers on the map. Extends `GridLayer`.
*
* @example
*
* ```js
* L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png?{foo}', {foo: 'bar'}).addTo(map);
* ```
*
* @section URL template
* @example
*
* A string of the following form:
*
* ```
* 'http://{s}.somedomain.com/blabla/{z}/{x}/{y}{r}.png'
* ```
*
* `{s}` means one of the available subdomains (used sequentially to help with browser parallel requests per domain limitation; subdomain values are specified in options; `a`, `b` or `c` by default, can be omitted), `{z}` — zoom level, `{x}` and `{y}` — tile coordinates. `{r}` can be used to add "@2x" to the URL to load retina tiles.
*
* You can use custom keys in the template, which will be [evaluated](#util-template) from TileLayer options, like this:
*
* ```
* L.tileLayer('http://{s}.somedomain.com/{foo}/{z}/{x}/{y}.png', {foo: 'bar'});
* ```
*/
export var TileLayer = GridLayer.extend({
// @section
// @aka TileLayer options
options: {
// @option minZoom: Number = 0
// The minimum zoom level down to which this layer will be displayed (inclusive).
minZoom: 0,
// @option maxZoom: Number = 18
// The maximum zoom level up to which this layer will be displayed (inclusive).
maxZoom: 18,
// @option subdomains: String|String[] = 'abc'
// Subdomains of the tile service. Can be passed in the form of one string (where each letter is a subdomain name) or an array of strings.
subdomains: 'abc',
// @option errorTileUrl: String = ''
// URL to the tile image to show in place of the tile that failed to load.
errorTileUrl: '',
// @option zoomOffset: Number = 0
// The zoom number used in tile URLs will be offset with this value.
zoomOffset: 0,
// @option tms: Boolean = false
// If `true`, inverses Y axis numbering for tiles (turn this on for [TMS](https://en.wikipedia.org/wiki/Tile_Map_Service) services).
tms: false,
// @option zoomReverse: Boolean = false
// If set to true, the zoom number used in tile URLs will be reversed (`maxZoom - zoom` instead of `zoom`)
zoomReverse: false,
// @option detectRetina: Boolean = false
// If `true` and user is on a retina display, it will request four tiles of half the specified size and a bigger zoom level in place of one to utilize the high resolution.
detectRetina: false,
// @option crossOrigin: Boolean = false
// If true, all tiles will have their crossOrigin attribute set to ''. This is needed if you want to access tile pixel data.
crossOrigin: false
},
initialize: function (url, options) {
this._url = url;
options = Util.setOptions(this, options);
// detecting retina displays, adjusting tileSize and zoom levels
if (options.detectRetina && Browser.retina && options.maxZoom > 0) {
options.tileSize = Math.floor(options.tileSize / 2);
if (!options.zoomReverse) {
options.zoomOffset++;
options.maxZoom--;
} else {
options.zoomOffset--;
options.minZoom++;
}
options.minZoom = Math.max(0, options.minZoom);
}
if (typeof options.subdomains === 'string') {
options.subdomains = options.subdomains.split('');
}
// for https://github.com/Leaflet/Leaflet/issues/137
if (!Browser.android) {
this.on('tileunload', this._onTileRemove);
}
},
// @method setUrl(url: String, noRedraw?: Boolean): this
// Updates the layer's URL template and redraws it (unless `noRedraw` is set to `true`).
setUrl: function (url, noRedraw) {
this._url = url;
if (!noRedraw) {
this.redraw();
}
return this;
},
// @method createTile(coords: Object, done?: Function): HTMLElement
// Called only internally, overrides GridLayer's [`createTile()`](#gridlayer-createtile)
// to return an `<img>` HTML element with the appropriate image URL given `coords`. The `done`
// callback is called when the tile has been loaded.
createTile: function (coords, done) {
var tile = document.createElement('img');
DomEvent.on(tile, 'load', Util.bind(this._tileOnLoad, this, done, tile));
DomEvent.on(tile, 'error', Util.bind(this._tileOnError, this, done, tile));
if (this.options.crossOrigin) {
tile.crossOrigin = '';
}
/*
Alt tag is set to empty string to keep screen readers from reading URL and for compliance reasons
http://www.w3.org/TR/WCAG20-TECHS/H67
*/
tile.alt = '';
/*
Set role="presentation" to force screen readers to ignore this
https://www.w3.org/TR/wai-aria/roles#textalternativecomputation
*/
tile.setAttribute('role', 'presentation');
tile.src = this.getTileUrl(coords);
return tile;
},
// @section Extension methods
// @uninheritable
// Layers extending `TileLayer` might reimplement the following method.
// @method getTileUrl(coords: Object): String
// Called only internally, returns the URL for a tile given its coordinates.
// Classes extending `TileLayer` can override this function to provide custom tile URL naming schemes.
getTileUrl: function (coords) {
var data = {
r: Browser.retina ? '@2x' : '',
s: this._getSubdomain(coords),
x: coords.x,
y: coords.y,
z: this._getZoomForUrl()
};
if (this._map && !this._map.options.crs.infinite) {
var invertedY = this._globalTileRange.max.y - coords.y;
if (this.options.tms) {
data['y'] = invertedY;
}
data['-y'] = invertedY;
}
return Util.template(this._url, Util.extend(data, this.options));
},
_tileOnLoad: function (done, tile) {
// For https://github.com/Leaflet/Leaflet/issues/3332
if (Browser.ielt9) {
setTimeout(Util.bind(done, this, null, tile), 0);
} else {
done(null, tile);
}
},
_tileOnError: function (done, tile, e) {
var errorUrl = this.options.errorTileUrl;
if (errorUrl && tile.getAttribute('src') !== errorUrl) {
tile.src = errorUrl;
}
done(e, tile);
},
_onTileRemove: function (e) {
e.tile.onload = null;
},
_getZoomForUrl: function () {
var zoom = this._tileZoom,
maxZoom = this.options.maxZoom,
zoomReverse = this.options.zoomReverse,
zoomOffset = this.options.zoomOffset;
if (zoomReverse) {
zoom = maxZoom - zoom;
}
return zoom + zoomOffset;
},
_getSubdomain: function (tilePoint) {
var index = Math.abs(tilePoint.x + tilePoint.y) % this.options.subdomains.length;
return this.options.subdomains[index];
},
// stops loading all tiles in the background layer
_abortLoading: function () {
var i, tile;
for (i in this._tiles) {
if (this._tiles[i].coords.z !== this._tileZoom) {
tile = this._tiles[i].el;
tile.onload = Util.falseFn;
tile.onerror = Util.falseFn;
if (!tile.complete) {
tile.src = Util.emptyImageUrl;
DomUtil.remove(tile);
delete this._tiles[i];
}
}
}
}
});
// @factory L.tilelayer(urlTemplate: String, options?: TileLayer options)
// Instantiates a tile layer object given a `URL template` and optionally an options object.
export function tileLayer(url, options) {
return new TileLayer(url, options);
}
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