Maps display

    9:- module(map,
   10	  [
   11	    geo_map//1,
   12	    average_geopoints/2
   13	  ]).   14
   15:- use_module(library(http/html_write)).   16:- use_module(library(settings)).   17
   18:- use_module(weblog(info/maps/google/gmap)).   19:- use_module(weblog(info/maps/leaflet/leafletmap)).   20
   21
   22:- meta_predicate geo_map(1, ?, ?).

 geo_map(+Generator:closure)// is det

Geomap (map of Earth) component.

Generator is an arity n term that corresponds to an arity n+1 predicate.

geo_map//1 will repeatedly query Generator for information and build up the map. The final argument may be

• provider(-Name) one of leaflet or google. default google
• id(-ID) The map div id and javascript variable name will be set to this. default lmap or gmap depending on provider. must be valid javascript identifier as atom.
• zoom(Zoom) The zoom level. Provider specific how this maps to a viewport. Default 14
• center(Lat, Long) center map view here. defaults to average of points
• point(-Lat, -Long) A marker will be placed at this point
• icon_for(+point(Lat, Long), -IconName) icon to use for this point. default is provider default icon.
• tooltip_for(+point(Lat, Long), -ToolTipText) contents of tooltip default is no tooltip
• popup_for(-HTML, +point(Lat, Long)) termerized HTML to put in popup
• style(-Style) only meaningful for leaflet, is cloudmade style number
• maptype(-Type) only meaningful for google maps, is the constant for google.maps.MapTypeId (one of 'HYBRID', 'ROADMAP', 'SATELLITE', 'TERRAIN')

Defining icon types means binding an icon/3 for each type, then binding all the properties

• icon(-Name, -ImageSource, -ShadowSource) Defines an icon type name. The actual javascript names are common for all maps with same provider, so you should only define the icons for each map provider once.

Defining an icon requires that the following be defined for each icon type name:

• * icon_size(+Name, X, Y) size of icon image
• * shadow_size(+Name, X, Y) size of shadow image
• * icon_anchor(+Name, X, Y) offset from UL of image to the point touching the spot on the map
• * shadow_anchor(+Name, X, Y) offset from UL of shadow image to the point touching the spot on map
• * popup_anchor(+Name, X, Y) offset from the point touching map to where the popup appears (so, eg, Y coord is often negative)

  @tbd add an example to docs

*/

   90geo_map(Generator) -->
   91	{
   92	     (	 call(Generator, provider(P))
   93	     ;
   94		 P = google
   95	     )
   96	},
   97	make_geo_map(P, Generator).
   98
   99geo_map(_Generator) -->
  100	{
  101		throw(error(domain_error(list, 'provider'), context(geo_map//2,
  102				   'invalid provider')))
  103	},
  104	html([p('error - cannot make map')]).
  105
  106
  107make_geo_map(leaflet, Generator) -->
  108	lmap(Generator).
  109make_geo_map(google, Generator) -->
  110	gmap(Generator).

 average_geopoints(+Points:list, -MeanPoint:point) is det

returns 0,0 for empty list */

  116average_geopoints([] , point(0.0, 0.0)) :- !.
  117average_geopoints(Coordinates, point(ALat, ALong)) :-
  118	sum_geopoints(Coordinates, 0, SumLat, 0, SumLong),
  119	length(Coordinates, Count),
  120	ALat is SumLat/Count,
  121	ALong is SumLong/Count.
  122
  123sum_geopoints([], Lat, Lat, Long, Long).
  124sum_geopoints([point(Lat, Long)|T], Lat0, LatS, Long0, LongS) :-
  125	Lat1 is Lat0+Lat,
  126	Long1 is Long0+Long,
  127	sum_geopoints(T, Lat1, LatS, Long1, LongS)