ALKMaps.Layer.BaseMap

Instances of ALKMaps.Layer.BaseMap are used to display data from ALK Web Service Create a new ALK Map layer with the ALKMaps.Layer.BaseMap constructor.

Inherits from

ALKMaps.Layer.Grid

Summary

ALKMaps.Layer.BaseMap	Instances of ALKMaps.Layer.BaseMap are used to display data from ALK Web Service Create a new ALK Map layer with the ALKMaps.Layer.BaseMap constructor.
Constants
DEFAULT_PARAMS	{Object} Hashtable of default parameter key/value pairs
Properties
reproject	Deprecated.
isBaseLayer	{Boolean} Default is true for WMS layer
encodeBBOX	{Boolean} Should the BBOX commas be encoded?
noMagic	{Boolean} If true, the image format will not be automagicaly switched from image/jpeg to image/png or image/gif when using TRANSPARENT=TRUE.
yx	{Object} Keys in this object are EPSG codes for which the axis order is to be reversed (yx instead of xy, LatLon instead of LonLat), with true as value.
singleTile	{Boolean} Use tiles for single image dynamic map.
tileOrigin	{ALKMaps.LonLat} Tile origin
zoomOffset	{Number} If your cache has more zoom levels than you want to provide access to with this layer, supply a zoomOffset.
transparentOverlayLayer	{ALKMaps.Layer.BaseMap} Transparent overlay on satellite map.
Constructor
ALKMaps.Layer.BaseMap	Create a new WMS layer object
Functions
setMap
destroy	Destroy this layer
clone	Create a clone of this layer
reverseAxisOrder	Returns true if the axis order is reversed for the WMS version and projection of the layer.
getURL	Return a GetMap query string for this layer
getXYZ	Calculates x, y and z for the given bounds.
mergeNewParams	Catch changeParams and uppercase the new params to be merged in before calling changeParams on the super class.
getFullRequestString	Combine the layer’s url with its params and these newParams.
changeStyle	Used to switch map styles.
setVisibility	Change layer visibility.
afterAdd	When satellite layer is added as a base layer, add the transparent layer at the same time.
cloneOverlayLayer	Clones the base map layer with some modifications.

Constants

DEFAULT_PARAMS

{Object} Hashtable of default parameter key/value pairs

Properties

reproject

Deprecated. {Boolean} Try to reproject this layer if its coordinate reference system is different than that of the base layer. Default is false. Set this in the layer options. Should be set to false in most cases.

isBaseLayer

{Boolean} Default is true for WMS layer

encodeBBOX

{Boolean} Should the BBOX commas be encoded? The WMS spec says ‘no’, but some services want it that way. Default false.

noMagic

{Boolean} If true, the image format will not be automagicaly switched from image/jpeg to image/png or image/gif when using TRANSPARENT=TRUE. Also isBaseLayer will not changed by the constructor. Default false.

yx

{Object} Keys in this object are EPSG codes for which the axis order is to be reversed (yx instead of xy, LatLon instead of LonLat), with true as value. This is only relevant for WMS versions >= 1.3.0.

singleTile

{Boolean} Use tiles for single image dynamic map.

tileOrigin

{ALKMaps.LonLat} Tile origin

zoomOffset

{Number} If your cache has more zoom levels than you want to provide access to with this layer, supply a zoomOffset. This zoom offset is added to the current map zoom level to determine the level for a requested tile. For example, if you supply a zoomOffset of 3, when the map is at the zoom 0, tiles will be requested from level 3 of your cache. Default is 0 (assumes cache level and map zoom are equivalent). Using zoomOffset is an alternative to setting <serverResolutions> if you only want to expose a subset of the server resolutions.

transparentOverlayLayer

{ALKMaps.Layer.BaseMap} Transparent overlay on satellite map. It is a special layer that is added by the system. User doesnt need to know the existence of this layer usually.

Constructor

ALKMaps.Layer.BaseMap

Create a new WMS layer object

Examples

The code below creates a simple WMS layer using the image/jpeg format.

// Todo: this is not the case any more.
var wms = new ALKMaps.Layer.BaseMap("NASA Global Mosaic",
                                   "http://wms.jpl.nasa.gov/wms.cgi",
                                   {layers: "modis,global_mosaic"});

Note the 3rd argument (params). Properties added to this object will be added to the WMS GetMap requests used for this layer’s tiles. The only mandatory parameter is “layers”. Other common WMS params include “transparent”, “styles” and “format”. Note that the “srs” param will always be ignored. Instead, it will be derived from the baseLayer’s or map’s projection.

The code below creates a transparent WMS layer with additional options.

var wms = new ALKMaps.Layer.BaseMap("NASA Global Mosaic",
                                   {
                                      layers: "modis,global_mosaic",
                                      transparent: true,
                                      style: ALKMaps.STYLE.CLASSIC,
                                      region: "NA" // Valid values are NA, EU, OC and SA. Optional and default to NA for now.
                                   }, {
                                       opacity: 0.5,
                                       singleTile: true
                                   });

Note that by default, a WMS layer is configured as baseLayer. Setting the “transparent” param to true will apply some magic (see noMagic). The default image format changes from image/jpeg to image/png, and the layer is not configured as baseLayer.

Parameters

name	{String} A name for the layer
params	{Object} An object with key/value pairs representing the GetMap query string parameters and parameter values.
options	{Object} Hashtable of extra options to tag onto the layer. These options include all properties listed above, plus the ones inherited from superclasses.

Functions

setMap

setMap: function( map )

destroy

destroy: function()

Destroy this layer

clone

clone: function( obj )

Create a clone of this layer

Returns

{ALKMaps.Layer.BaseMap} An exact clone of this layer

reverseAxisOrder

reverseAxisOrder: function()

Returns true if the axis order is reversed for the WMS version and projection of the layer.

Returns

{Boolean} true if the axis order is reversed, false otherwise.

getURL

getURL: function( bounds )

Return a GetMap query string for this layer

Parameters

bounds

{ALKMaps.Bounds} A bounds representing the bbox for the request.

Returns

{String} A string with the layer’s url and parameters and also the passed-in bounds and appropriate tile size specified as parameters.

getXYZ

Calculates x, y and z for the given bounds.

Parameters

bounds

{ALKMaps.Bounds}

Returns

{Object}

an object with x, y and z properties.

mergeNewParams

mergeNewParams: function( newParams )

Catch changeParams and uppercase the new params to be merged in before calling changeParams on the super class.

Once params have been changed, the tiles will be reloaded with the new parameters.

Parameters

newParams

{Object} Hashtable of new params to use

getFullRequestString

getFullRequestString: function( newParams,
altUrl )

Combine the layer’s url with its params and these newParams.

Add the SRS parameter from projection -- this is probably more eloquently done via a setProjection() method, but this works for now and always.

Parameters

newParams	{Object}
altUrl	{String} Use this as the url instead of the layer’s url

Returns

{String}

changeStyle

changeStyle: function( style )

Used to switch map styles. Map will redraw.

Parameters

style

{ALKMaps.STYLE} Such as ALKMaps.STYLE.SATELLITE, ALKMaps.STYLE.DEFAULT and more

setVisibility

setVisibility: function( visibility )

Change layer visibility. When satellite layer visibility is changed, update the transparent layers visibility at the same time.

parameters

visibility

{Boolean} true: make the layer visibale.

afterAdd

afterAdd: function()

When satellite layer is added as a base layer, add the transparent layer at the same time.

cloneOverlayLayer

cloneOverlayLayer: function()

Clones the base map layer with some modifications. Mainly used for overlaying transparent map on satellite map at this time.