/
OpenStreetMapImageryProvider.js
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OpenStreetMapImageryProvider.js
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/*global define*/
define([
'../Core/defaultValue',
'../Core/DeveloperError',
'../Core/Event',
'../Core/writeTextToCanvas',
'./ImageryProvider',
'./WebMercatorTilingScheme',
'./Credit'
], function(
defaultValue,
DeveloperError,
Event,
writeTextToCanvas,
ImageryProvider,
WebMercatorTilingScheme,
Credit) {
"use strict";
var trailingSlashRegex = /\/$/;
var defaultCredit = new Credit('MapQuest, Open Street Map and contributors, CC-BY-SA');
/**
* Provides tiled imagery hosted by OpenStreetMap or another provider of Slippy tiles. Please be aware
* that a default-constructed instance of this class will connect to OpenStreetMap's volunteer-run
* servers, so you must conform to their
* <a href='http://wiki.openstreetmap.org/wiki/Tile_usage_policy'>Tile Usage Policy</a>.
*
* @alias OpenStreetMapImageryProvider
* @constructor
*
* @param {String} [description.url='http://tile.openstreetmap.org'] The OpenStreetMap server url.
* @param {String} [description.fileExtension='png'] The file extension for images on the server.
* @param {Object} [description.proxy] A proxy to use for requests. This object is expected to have a getURL function which returns the proxied URL.
* @param {Extent} [description.extent=Extent.MAX_VALUE] The extent of the layer.
* @param {Number} [description.maximumLevel=18] The maximum level-of-detail supported by the imagery provider.
* @param {Credit|String} [description.credit='MapQuest, Open Street Map and contributors, CC-BY-SA'] A credit for the data source, which is displayed on the canvas.
*
* @see ArcGisMapServerImageryProvider
* @see BingMapsImageryProvider
* @see SingleTileImageryProvider
* @see TileMapServiceImageryProvider
* @see WebMapServiceImageryProvider
*
* @see <a href='http://wiki.openstreetmap.org/wiki/Main_Page'>OpenStreetMap Wiki</a>
* @see <a href='http://www.w3.org/TR/cors/'>Cross-Origin Resource Sharing</a>
*
* @example
* // OpenStreetMap tile provider
* var osm = new OpenStreetMapImageryProvider({
* url : 'http://tile.openstreetmap.org/'
* });
*/
var OpenStreetMapImageryProvider = function OpenStreetMapImageryProvider(description) {
description = defaultValue(description, {});
var url = defaultValue(description.url, 'http://tile.openstreetmap.org/');
if (!trailingSlashRegex.test(url)) {
url = url + '/';
}
this._url = url;
this._fileExtension = defaultValue(description.fileExtension, 'png');
this._proxy = description.proxy;
this._tileDiscardPolicy = description.tileDiscardPolicy;
this._tilingScheme = new WebMercatorTilingScheme();
this._tileWidth = 256;
this._tileHeight = 256;
this._maximumLevel = defaultValue(description.maximumLevel, 18);
this._extent = defaultValue(description.extent, this._tilingScheme.getExtent());
this._errorEvent = new Event();
this._ready = true;
var credit = defaultValue(description.credit, defaultCredit);
if (typeof credit === 'string') {
credit = new Credit(credit);
}
this._credit = credit;
};
function buildImageUrl(imageryProvider, x, y, level) {
var url = imageryProvider._url + level + '/' + x + '/' + y + '.' + imageryProvider._fileExtension;
var proxy = imageryProvider._proxy;
if (typeof proxy !== 'undefined') {
url = proxy.getURL(url);
}
return url;
}
/**
* Gets the URL of the service hosting the imagery.
*
* @memberof OpenStreetMapImageryProvider
*
* @returns {String} The URL.
*/
OpenStreetMapImageryProvider.prototype.getUrl = function() {
return this._url;
};
/**
* Gets the proxy used by this provider.
*
* @memberof OpenStreetMapImageryProvider
*
* @returns {Proxy} The proxy.
*
* @see DefaultProxy
*/
OpenStreetMapImageryProvider.prototype.getProxy = function() {
return this._proxy;
};
/**
* Gets the width of each tile, in pixels. This function should
* not be called before {@link OpenStreetMapImageryProvider#isReady} returns true.
*
* @memberof OpenStreetMapImageryProvider
*
* @returns {Number} The width.
*
* @exception {DeveloperError} <code>getTileWidth</code> must not be called before the imagery provider is ready.
*/
OpenStreetMapImageryProvider.prototype.getTileWidth = function() {
if (!this._ready) {
throw new DeveloperError('getTileWidth must not be called before the imagery provider is ready.');
}
return this._tileWidth;
};
/**
* Gets the height of each tile, in pixels. This function should
* not be called before {@link OpenStreetMapImageryProvider#isReady} returns true.
*
* @memberof OpenStreetMapImageryProvider
*
* @returns {Number} The height.
*
* @exception {DeveloperError} <code>getTileHeight</code> must not be called before the imagery provider is ready.
*/
OpenStreetMapImageryProvider.prototype.getTileHeight = function() {
if (!this._ready) {
throw new DeveloperError('getTileHeight must not be called before the imagery provider is ready.');
}
return this._tileHeight;
};
/**
* Gets the maximum level-of-detail that can be requested. This function should
* not be called before {@link OpenStreetMapImageryProvider#isReady} returns true.
*
* @memberof OpenStreetMapImageryProvider
*
* @returns {Number} The maximum level.
*
* @exception {DeveloperError} <code>getMaximumLevel</code> must not be called before the imagery provider is ready.
*/
OpenStreetMapImageryProvider.prototype.getMaximumLevel = function() {
if (!this._ready) {
throw new DeveloperError('getMaximumLevel must not be called before the imagery provider is ready.');
}
return this._maximumLevel;
};
/**
* Gets the minimum level-of-detail that can be requested. This function should
* not be called before {@link OpenStreetMapImageryProvider#isReady} returns true.
*
* @memberof OpenStreetMapImageryProvider
*
* @returns {Number} The minimum level.
*
* @exception {DeveloperError} <code>getMinimumLevel</code> must not be called before the imagery provider is ready.
*/
OpenStreetMapImageryProvider.prototype.getMinimumLevel = function() {
if (!this._ready) {
throw new DeveloperError('getMinimumLevel must not be called before the imagery provider is ready.');
}
return 0;
};
/**
* Gets the tiling scheme used by this provider. This function should
* not be called before {@link OpenStreetMapImageryProvider#isReady} returns true.
*
* @memberof OpenStreetMapImageryProvider
*
* @returns {TilingScheme} The tiling scheme.
* @see WebMercatorTilingScheme
* @see GeographicTilingScheme
*
* @exception {DeveloperError} <code>getTilingScheme</code> must not be called before the imagery provider is ready.
*/
OpenStreetMapImageryProvider.prototype.getTilingScheme = function() {
if (!this._ready) {
throw new DeveloperError('getTilingScheme must not be called before the imagery provider is ready.');
}
return this._tilingScheme;
};
/**
* Gets the extent, in radians, of the imagery provided by this instance. This function should
* not be called before {@link OpenStreetMapImageryProvider#isReady} returns true.
*
* @memberof OpenStreetMapImageryProvider
*
* @returns {Extent} The extent.
*
* @exception {DeveloperError} <code>getExtent</code> must not be called before the imagery provider is ready.
*/
OpenStreetMapImageryProvider.prototype.getExtent = function() {
if (!this._ready) {
throw new DeveloperError('getExtent must not be called before the imagery provider is ready.');
}
return this._extent;
};
/**
* Gets the tile discard policy. If not undefined, the discard policy is responsible
* for filtering out "missing" tiles via its shouldDiscardImage function. If this function
* returns undefined, no tiles are filtered. This function should
* not be called before {@link OpenStreetMapImageryProvider#isReady} returns true.
*
* @memberof OpenStreetMapImageryProvider
*
* @returns {TileDiscardPolicy} The discard policy.
*
* @see DiscardMissingTileImagePolicy
* @see NeverTileDiscardPolicy
*
* @exception {DeveloperError} <code>getTileDiscardPolicy</code> must not be called before the imagery provider is ready.
*/
OpenStreetMapImageryProvider.prototype.getTileDiscardPolicy = function() {
if (!this._ready) {
throw new DeveloperError('getTileDiscardPolicy must not be called before the imagery provider is ready.');
}
return this._tileDiscardPolicy;
};
/**
* Gets an event that is raised when the imagery provider encounters an asynchronous error. By subscribing
* to the event, you will be notified of the error and can potentially recover from it. Event listeners
* are passed an instance of {@link TileProviderError}.
*
* @memberof OpenStreetMapImageryProvider
*
* @returns {Event} The event.
*/
OpenStreetMapImageryProvider.prototype.getErrorEvent = function() {
return this._errorEvent;
};
/**
* Gets a value indicating whether or not the provider is ready for use.
*
* @memberof OpenStreetMapImageryProvider
*
* @returns {Boolean} True if the provider is ready to use; otherwise, false.
*/
OpenStreetMapImageryProvider.prototype.isReady = function() {
return this._ready;
};
/**
* Requests the image for a given tile. This function should
* not be called before {@link OpenStreetMapImageryProvider#isReady} returns true.
*
* @memberof OpenStreetMapImageryProvider
*
* @param {Number} x The tile X coordinate.
* @param {Number} y The tile Y coordinate.
* @param {Number} level The tile level.
*
* @returns {Promise} A promise for the image that will resolve when the image is available, or
* undefined if there are too many active requests to the server, and the request
* should be retried later. The resolved image may be either an
* Image or a Canvas DOM object.
*
* @exception {DeveloperError} <code>requestImage</code> must not be called before the imagery provider is ready.
*/
OpenStreetMapImageryProvider.prototype.requestImage = function(x, y, level) {
if (!this._ready) {
throw new DeveloperError('requestImage must not be called before the imagery provider is ready.');
}
var url = buildImageUrl(this, x, y, level);
return ImageryProvider.loadImage(this, url);
};
/**
* Gets the credit to display when this imagery provider is active. Typically this is used to credit
* the source of the imagery. This function should not be called before {@link OpenStreetMapImageryProvider#isReady} returns true.
*
* @memberof OpenStreetMapImageryProvider
*
* @returns {Credit} The credit, or undefined if no credit exists
*/
OpenStreetMapImageryProvider.prototype.getCredit = function() {
return this._credit;
};
return OpenStreetMapImageryProvider;
});