openseadragon/src/osmtilesource.js
2013-02-19 22:53:54 -05:00

107 lines
3.2 KiB
JavaScript

(function( $ ){
/**
* A tilesource implementation for OpenStreetMap. Adopted from Rainer Simon
* project http://github.com/rsimon/seajax-utils.
*
* Note 1. Zoomlevels. Deep Zoom and OSM define zoom levels differently. In Deep
* Zoom, level 0 equals an image of 1x1 pixels. In OSM, level 0 equals an image of
* 256x256 levels (see http://gasi.ch/blog/inside-deep-zoom-2). I.e. there is a
* difference of log2(256)=8 levels.
*
* Note 2. Image dimension. According to the OSM Wiki
* (http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames#Zoom_levels)
* the highest Mapnik zoom level has 256.144x256.144 tiles, with a 256x256
* pixel size. I.e. the Deep Zoom image dimension is 65.572.864x65.572.864
* pixels.
*
* @class
* @extends OpenSeadragon.TileSource
* @param {Number|Object} width - the pixel width of the image or the idiomatic
* options object which is used instead of positional arguments.
* @param {Number} height
* @param {Number} tileSize
* @param {Number} tileOverlap
* @param {String} tilesUrl
*/
$.OsmTileSource = function( width, height, tileSize, tileOverlap, tilesUrl ) {
var options;
if( $.isPlainObject( width ) ){
options = width;
}else{
options = {
width: arguments[0],
height: arguments[1],
tileSize: arguments[2],
tileOverlap: arguments[3],
tilesUrl: arguments[4]
};
}
//apply default setting for standard public OpenStreatMaps service
//but allow them to be specified so fliks can host there own instance
//or apply against other services supportting the same standard
if( !options.width || !options.height ){
options.width = 65572864;
options.height = 65572864;
}
if( !options.tileSize ){
options.tileSize = 256;
options.tileOverlap = 0;
}
if( !options.tilesUrl ){
options.tilesUrl = "http://tile.openstreetmap.org/";
}
options.minLevel = 8;
$.TileSource.apply( this, [ options ] );
};
$.extend( $.OsmTileSource.prototype, $.TileSource.prototype, {
/**
* Determine if the data and/or url imply the image service is supported by
* this tile source.
* @function
* @name OpenSeadragon.OsmTileSource.prototype.supports
* @param {Object|Array} data
* @param {String} optional - url
*/
supports: function( data, url ){
return (
data.type &&
"openstreetmaps" == data.type
);
},
/**
*
* @function
* @name OpenSeadragon.OsmTileSource.prototype.configure
* @param {Object} data - the raw configuration
* @param {String} url - the url the data was retreived from if any.
* @return {Object} options - A dictionary of keyword arguments sufficient
* to configure this tile sources constructor.
*/
configure: function( data, url ){
return data;
},
/**
* @function
* @name OpenSeadragon.OsmTileSource.prototype.getTileUrl
* @param {Number} level
* @param {Number} x
* @param {Number} y
*/
getTileUrl: function( level, x, y ) {
return this.tilesUrl + (level - 8) + "/" + x + "/" + y + ".png";
}
});
}( OpenSeadragon ));