Many MapStructure/NavDisplay updates

See the clone at https://gitorious.org/fg/canvas-hackers-fgdata/source/topics/canvas-radar:

Nasal/canvas/MapStructure.nas

@@ -1,4 +1,9 @@
+################################################################################
+## MapStructure mapping/charting framework for Nasal/Canvas, by Philosopher
+## See: http://wiki.flightgear.org/MapStructure
+###############################################################################
 var _MP_dbg_lvl = "info";
+#var _MP_dbg_lvl = "alert";
 
 var dump_obj = func(m) {
 	var h = {};
@@ -9,32 +14,41 @@ var dump_obj = func(m) {
 };
 
 ##
-# must be either of:
+# for LOD handling (i.e. airports/taxiways/runways)
-# 1) draw* callback, 2) SVG filename, 3) Drawable class (with styling/LOD support)
+var RangeAware = {
-var SymbolDrawable = {
+ new: func {
-	new: func() {
+	return {parents:[RangeAware] };
  },
+ del: func,
+ notifyRangeChange: func die("RangeAware.notifyRangeChange() must be provided by sub-class"),
 };
 
-## wrapper for each element
+## wrapper for each cached element
-## i.e. keeps the canvas and texture map coordinates
+## i.e. keeps the canvas and texture map coordinates for the corresponding raster image
 var CachedElement = {
-	new: func(canvas_path, name, source, offset) {
+	new: func(canvas_path, name, source, size, offset) {
 		var m = {parents:[CachedElement] };
+		if (isa(canvas_path, canvas.Canvas)) {
+			canvas_path = canvas_path.getPath();
+		}
 		m.canvas_src = canvas_path;
 		m.name = name;
 		m.source = source;
+		m.size = size;
 		m.offset = offset;
 		return m;
 	}, # new()
-	render: func(group) {
+	
+	render: func(group, trans0=0, trans1=0) {
 		# create a raster image child in the render target/group
-		return
+		var n = 	group.createChild("image", me.name)
-		group.createChild("image", me.name)
 			.setFile( me.canvas_src )
-			# TODO: fix .setSourceRect() to accept a single vector for coordinates ...
+			# TODO: fix .setSourceRect() to accept a single vector for texture map coordinates ...
 			.setSourceRect(left:me.source[0],top:me.source[1],right:me.source[2],bottom:me.source[3], normalized:0)
-			.setTranslation(me.offset); # FIXME: make sure this stays like this and isn't overridden
+			.setSize(me.size)
+			.setTranslation(trans0,trans1);
+		n.createTransform().setTranslation(me.offset);
+		return n;
 	}, # render()
 }; # of CachedElement
 
@@ -77,10 +91,13 @@ var SymbolCache = {
 			"view": m.canvas_sz,
 			"mipmapping": 1
 		});
-
+		m.canvas_texture.setColorBackground(0, 0, 0, 0); #rgba
 		# add a placement
 		m.canvas_texture.addPlacement( {"type": "ref"} );
 
+		m.path = m.canvas_texture.getPath();
+		m.root = m.canvas_texture.createGroup("entries");
+
 		return m;
 	},
 	add: func(name, callback, draw_mode=0) {
@@ -90,7 +107,7 @@ var SymbolCache = {
 		# get canvas texture that we use as cache
 		# get next free spot in texture (column/row)
 		# run the draw callback and render into a group
-		var gr = me.canvas_texture.createGroup();
+		var gr = me.root.createChild("group",name);
 		gr.setTranslation( me.next_free[0] + me.image_sz[0]*draw_mode0,
 				           me.next_free[1] + me.image_sz[1]*draw_mode1);
 		#settimer(func debug.dump ( gr.getTransformedBounds() ), 0); # XXX: these are only updated when rendered
@@ -102,17 +119,27 @@ var SymbolCache = {
 		# get the bounding box, i.e. coordinates for texture map, or use the .setTranslation() params
 		var coords = me.next_free~me.next_free;
 		foreach (var i; [0,1])
-			coords[i+2] += me.image_sz[i];
+			coords[i+1] += me.image_sz[i];
+		foreach (var i; [0,1])
+			coords[i*2+1] = me.canvas_sz[i] - coords[i*2+1];
 		# get the offset we used to position correctly in the bounds of the canvas
-		var offset = [me.image_sz[0]*draw_mode0, me.image_sz[1]*draw_mode1];
+		var offset = [-me.image_sz[0]*draw_mode0, -me.image_sz[1]*draw_mode1];
-		# store texture map coordinates in lookup map using the name as identifier
+
-		me.dict[name] = CachedElement.new(me.canvas_texture.getPath(), name, coords, offset );
 		# update next free position in cache (column/row)
 		me.next_free[0] += me.image_sz[0];
 		if (me.next_free[0] >= me.canvas_sz[0])
 		{ me.next_free[0] = 0; me.next_free[1] += me.image_sz[1] }
 		if (me.next_free[1] >= me.canvas_sz[1])
 			die("SymbolCache: ran out of space after adding '"~name~"'");
+
+		# store texture map coordinates in lookup map using the name as identifier
+		return me.dict[name] = CachedElement.new(
+			canvas_path: me.path,
+			name: name,
+			source: coords,
+			size:me.image_sz,
+			offset: offset,
+		);
 	}, # add()
 	get: func(name) {
 		if(!contains(me.dict,name)) die("No SymbolCache entry for key:"~ name);
@@ -131,8 +158,9 @@ var Symbol = {
 		else return class,
 	# Calls corresonding symbol constructor
 	# @param group #Canvas.Group to place this on.
-	new: func(type, group, arg...) {
+	# @param layer The #SymbolLayer this is a child of.
-		var ret = call((var class = me.get(type)).new, [group]~arg, class);
+	new: func(type, group, layer, arg...) {
+		var ret = call((var class = me.get(type)).new, [group, layer]~arg, class);
 		ret.element.set("symbol-type", type);
 		return ret;
 	},
@@ -147,6 +175,7 @@ var Symbol = {
 		die("del() not implemented for this symbol type!"),
 }; # of Symbol
 
+
 Symbol.Controller = {
 # Static/singleton:
 	registry: {},
@@ -176,43 +205,80 @@ Symbol.Controller = {
 var getpos_fromghost = func(positioned_g)
 	return [positioned_g.lat, positioned_g.lon];
 
+# to add support for additional ghosts, just append them to the vector below, possibly at runtime:
+var supported_ghosts = ['positioned','Navaid','Fix','flightplan-leg','FGAirport'];
+var is_positioned_ghost = func(obj) {
+	var gt = ghosttype(obj);
+	foreach(var ghost; supported_ghosts) {
+		if (gt == ghost) return 1; # supported ghost was found
+	}
+	return 0; # not a known/supported ghost
+};
+
 # Generic getpos: get lat/lon from any object:
 # (geo.Coord and positioned ghost currently)
-Symbol.Controller.getpos = func(obj) {
+Symbol.Controller.getpos = func(obj, p=nil) {
-	if (typeof(obj) == 'ghost')
+	if (obj == nil) die("Symbol.Controller.getpos received nil");
-		if (ghosttype(obj) == 'positioned' or ghosttype(obj) == 'Navaid' or ghosttype(obj)=='Fix' or ghosttype(obj)=='flightplan-leg')
+	if (p == nil) {
+		var ret = Symbol.Controller.getpos(obj, obj);
+		if (ret != nil) return ret;
+		if (contains(obj, "parents")) {
+			foreach (var p; obj.parents) {
+				var ret = Symbol.Controller.getpos(obj, p);
+				if (ret != nil) return ret;
+			}
+		}
+		debug.dump(obj);
+		die("no suitable getpos() found! Of type: "~typeof(obj));
+	} else {
+		if (typeof(p) == 'ghost')
+			if ( is_positioned_ghost(p) )
 				return getpos_fromghost(obj);
 			else
-			die("bad ghost of type '"~ghosttype(obj)~"'");
+				die("bad/unsupported ghost of type '"~ghosttype(obj)~"' (see MapStructure.nas Symbol.Controller.getpos() to add new ghosts)");
-	if (typeof(obj) == 'hash')
+		if (typeof(p) == 'hash')
-		if (isa(obj, geo.Coord))
+			if (p == geo.Coord)
 				return subvec(obj.latlon(), 0, 2);
-		if (isa(obj, props.Node))
+			if (p == props.Node)
 				return [
 					obj.getValue("position/latitude-deg")  or obj.getValue("latitude-deg"),
 					obj.getValue("position/longitude-deg") or obj.getValue("longitude-deg")
 				];
-		if (contains(obj,'lat') and contains(obj,'lon'))
+			if (contains(p,'lat') and contains(p,'lon'))
 				return [obj.lat, obj.lon];
-
+		return nil;
-	debug.dump(obj);
+	}
-	die("no suitable getpos() found! Of type: "~typeof(obj));
 };
 
-Symbol.Controller.equals = func(l, r) {
+Symbol.Controller.equals = func(l, r, p=nil) {
 	if (l == r) return 1;
-	var t = typeof(l);
+	if (p == nil) {
-	if (t == 'ghost')
+		var ret = Symbol.Controller.equals(l, r, l);
-		return 0;#l.id == r.id;
+		if (ret != nil) return ret;
-	if (t == 'hash')
+		if (contains(l, "parents")) {
-		if (isa(l, props.Node))
+			foreach (var p; l.parents) {
-			return l.equals(r);
+				var ret = Symbol.Controller.equals(l, r, p);
-		else {
+				if (ret != nil) return ret;
-			foreach (var k; keys(l))
-				if (l[k] != r[k]) return 0;
-			return 1;
 			}
-	die("bad types");
+		}
+		debug.dump(obj);
+		die("no suitable equals() found! Of type: "~typeof(obj));
+	} else {
+		if (typeof(p) == 'ghost')
+			if ( is_positioned_ghost(p) )
+				return l.id == r.id;
+			else
+				die("bad/unsupported ghost of type '"~ghosttype(l)~"' (see MapStructure.nas Symbol.Controller.getpos() to add new ghosts)");
+		if (typeof(p) == 'hash')
+			# Somewhat arbitrary convention:
+			#   * l.equals(r)         -- instance method, i.e. uses "me" and "arg[0]"
+			#   * parent._equals(l,r) -- class method, i.e. uses "arg[0]" and "arg[1]"
+			if (contains(p, "equals"))
+				return l.equals(r);
+			if (contains(p, "_equals"))
+				return p._equals(l,r);
+	}
+	return nil;
 };
 
 
@@ -225,32 +291,28 @@ var assert_ms = func(hash, members...)
 
 
 var DotSym = {
-	parents: [Symbol],
+	parents: [Symbol], # TODO: use StyleableSymbol here to support styling and caching
 	element_id: nil,
 # Static/singleton:
 	makeinstance: func(name, hash) {
 		if (!isa(hash, DotSym))
 			die("OOP error");
-		#assert_ms(hash,
-		#	"element_type", # type of Canvas element
-		#	#"element_id",  # optional Canvas id
-		#	#"init",        # initialize routine
-		#	"draw",         # init/update routine
-		#	#getpos",       # get position from model in [x_units,y_units] (optional)
-		#);
 		return Symbol.add(name, hash);
 	},
 # For the instances returned from makeinstance:
-	# @param group The Canvas group to add this to.
+	# @param group The #Canvas.Group to add this to.
+	# @param layer The #SymbolLayer this is a child of.
 	# @param model A correct object (e.g. positioned ghost) as
 	#              expected by the .draw file that represents
 	#              metadata like position, speed, etc.
 	# @param controller Optional controller "glue". Each method
 	#                   is called with the model as the only argument.
-	new: func(group, model, controller=nil) {
+	new: func(group, layer, model, controller=nil) {
+		if (me == nil) die();
 		var m = {
 			parents: [me],
 			group: group,
+			layer: layer,
 			model: model,
 			controller: controller == nil ? me.df_controller : controller,
 			element: group.createChild(
@@ -274,7 +336,7 @@ var DotSym = {
 		if (me.controller != nil)
 			me.controller.del(me.model);
 		call(func me.model.del(), nil, var err=[]); # try...
-		if (err[0] != "No such member: del") # ... and either catch or rethrow
+		if (size(err) and err[0] != "No such member: del") # ... and either catch or rethrow
 			die(err[0]);
 		me.element.del();
 	},
@@ -297,6 +359,7 @@ var DotSym = {
 		if (size(pos) == 3)
 			var (lat,lon,rotation) = pos;
 		else die("bad position: "~debug.dump(pos));
+		# print(me.model.id, ": Position lat/lon: ", lat, "/", lon);
 		me.element.setGeoPosition(lat,lon);
 		if (rotation != nil)
 			me.element.setRotation(rotation);
@@ -313,20 +376,36 @@ var SymbolLayer = {
 		if ((var class = me.registry[type]) == nil)
 			die("unknown type '"~type~"'");
 		else return class,
-# Non-static:
+# Default implementations/values:
 	df_controller: nil, # default controller
 	df_priority: nil, # default priority for display sorting
+	df_style: nil,
 	type: nil, # type of #Symbol to add (MANDATORY)
 	id: nil, # id of the group #canvas.Element (OPTIONAL)
 	# @param group A group to place this on.
+	# @param map The #Canvas.Map this is a member of.
 	# @param controller A controller object (parents=[SymbolLayer.Controller])
 	#                   or implementation (parents[0].parents=[SymbolLayer.Controller]).
-	new: func(group, controller=nil) {
+	new: func(group, map, controller=nil, style=nil, options=nil) {
+		#print("Creating new Layer instance");
+		if (me == nil) die();
 		var m = {
 			parents: [me],
-			group: group.createChild("group", me.id), # TODO: the id is not properly set, but would be useful for debugging purposes (VOR, FIXES, NDB etc)
+			map: map,
+			group: group.createChild("group", me.type), # TODO: the id is not properly set, but would be useful for debugging purposes (VOR, FIXES, NDB etc)
 			list: [],
+			options: options,
 		};
+		m.setVisible();
+
+		# print("Layer setup options:", m.options!=nil);
+		# do no overwrite the default style if style is nil:
+		if (style != nil and typeof(style)=='hash') {
+			#print("Setting up a custom style!");
+			m.style = style;
+		} else m.style = me.df_style;
+
+		# debug.dump(m.style);
 		m.searcher = geo.PositionedSearch.new(me.searchCmd, me.onAdded, me.onRemoved, m);
 		# FIXME: hack to expose type of layer:
 		if (caller(1)[1] == Map.addLayer) {
@@ -349,10 +428,39 @@ var SymbolLayer = {
 		return m;
 	},
 	update: func() {
+		if (!me.getVisible()) {
+			return;
+		}
+		# TODO: add options hash processing here 
+		var updater = func {
 			me.searcher.update();
 			foreach (var e; me.list)
 				e.update();
+		}
+
+		if (me.options != nil and me.options['update_wrapper'] !=nil) {
+			me.options.update_wrapper( me, updater ); # call external wrapper (usually for profiling purposes)
+			# print("calling update_wrapper!");
+		}
+		else	{
+			# print("not using wrapper");	
+			updater();
+			# debug.dump(me.options);
+		}
+		#var start=systime();
+		#var end=systime();
+		# print(me.type, " layer update:", end-start);
+		# HACK: hard-coded ...
+		#setprop("/gui/navdisplay/layers/"~me.type~"/delay-ms", (end-start)*1000 );
 	},
+	##
+	# useful to support checkboxes in dialogs (e.g. Map dialog)
+	# so that we can show/hide layers directly by registering a listener
+	# TODO: should also allow us to update the navdisplay logic WRT to visibility
+	hide: func me.group.hide(),
+	show: func me.group.show(),
+	getVisible: func me.group.getVisible(),
+	setVisible: func(visible = 1) me.group.setVisible(visible),
 	del: func() {
 		printlog(_MP_dbg_lvl, "SymbolLayer.del()");
 		me.controller.del();
@@ -375,17 +483,27 @@ var SymbolLayer = {
 		}
 		return nil;
 	},
-	searchCmd: func() me.controller.searchCmd(),
+	searchCmd: func() { 
+		var result = me.controller.searchCmd();
+		# some hardening TODO: don't do this always - only do it once during initialization, i.e. layer creation ?
+		var type=typeof(result);
+		if(type != 'nil' and type != 'vector') 
+			die("MapStructure: searchCmd() method MUST return a vector of valid objects or nil! (was:"~type~")");
+		return result;
+	},
 	# Adds a symbol.
-	onAdded: func(model)
+	onAdded: func(model) {
-		append(me.list, Symbol.new(me.type, me.group, model)),
+		printlog(_MP_dbg_lvl, "Adding symbol of type "~me.type);
+		if (model == nil) die("Model was nil for "~debug.string(me.type));
+		append(me.list, Symbol.new(me.type, me.group, me, model));
+	},
 	# Removes a symbol.
 	onRemoved: func(model) {
-		if (me.findsym(model, 1)) die("model not found");
+		printlog(_MP_dbg_lvl, "Deleting symbol of type "~me.type);
-		call(func model.del, nil, var err = []);
+		if (me.findsym(model, 1) == nil) die("model not found");
-		# ignore errors
+		call(func model.del(), nil, var err = []); # try...
-		# TODO: ignore only missing member del() errors? and only from the above line?
+		if (size(err) and err[0] != "No such member: del") # ... and either catch or rethrow
-		# Note: die(err[0]) rethrows it; die(err[0]~"") does not.
+			die(err[0]);
 	},
 }; # of SymbolLayer
 
@@ -406,10 +524,8 @@ SymbolLayer.Controller = {
 	# @param layer The #SymbolLayer this controller is responsible for.
 	new: func(type, layer, arg...)
 		return call((var class = me.get(type)).new, [layer]~arg, class),
-# Non-static:
+# Default implementations:
-	run_update: func() {
+	run_update: func() me.layer.update(),
-		me.layer.update();
-	},
 	# @return List of positioned objects.
 	searchCmd: func()
 		die("searchCmd() not implemented for this SymbolLayer.Controller type!"),
@@ -424,6 +540,10 @@ var CompassLayer = {
 var AltitudeArcLayer = {
 };
 
+###
+# set up a cache for 32x32 symbols
+var SymbolCache32x32 = nil;#SymbolCache.new(1024,32);
+
 var load_MapStructure = func {
 	Map.Controller = {
 	# Static/singleton:
@@ -436,8 +556,41 @@ var load_MapStructure = func {
 			else return class,
 		# Calls corresonding controller constructor
 		# @param map The #SymbolMap this controller is responsible for.
-		new: func(type, layer, arg...)
+		new: func(type, map, arg...) {
-			return call((var class = me.get(type)).new, [map]~arg, class),
+			var m = call((var class = me.get(type)).new, [map]~arg, class);
+			if (!contains(m, "map"))
+				m.map = map;
+			# FIXME: fails on no member
+			elsif (m.map != map and !isa(m.map, map) and (
+			       	m.get_position != Map.Controller.get_position
+			     or m.query_range != Map.Controller.query_range
+			     or m.in_range != Map.Controller.in_range))
+			{ die("m must store the map handle as .map if it uses the default method(s)"); }
+		},
+	# Default implementations:
+		get_position: func() {
+			debug.warn("get_position is deprecated");
+			return me.map.getLatLon()~[me.map.getAlt()];
+		},
+		query_range: func() {
+			debug.warn("query_range is deprecated");
+			return me.map.getRange() or 30;
+		},
+		in_range: func(lat, lon, alt=0) {
+			var range = me.map.getRange();
+			if(range == nil) die("in_range: Invalid query range!");
+			# print("Query Range is:", range );
+			if (lat == nil or lon == nil) die("in_range: lat/lon invalid");
+			var pos = geo.Coord.new();
+			pos.set_latlon(lat, lon, alt or 0);
+			var map_pos = me.map.getPosCoord();
+			if (map_pos == nil)
+				return 0; # should happen *ONLY* when map is uninitialized
+			var distance_m = pos.distance_to( map_pos );
+			var is_in_range = distance_m < range * NM2M;
+			# print("Distance:",distance_m*M2NM," nm in range check result:", is_in_range);
+			return is_in_range;
+		},
 	};
 
 	####### LOAD FILES #######
@@ -448,7 +601,7 @@ var load_MapStructure = func {
 			#print(file);
 			if (name == nil)
 				var name = split("/", file)[-1];
-			if (substr(name, size(name)-4) == ".draw")
+			if (substr(name, size(name)-4) == ".draw") # we don't need this anylonger, right ?
 				name = substr(name, 0, size(name)-5);
 			#print("reading file");
 			var code = io.readfile(file);
@@ -469,25 +622,73 @@ var load_MapStructure = func {
 				return;
 			}
 			#print("calling code");
+		
 			call(code, nil, nil, var hash = {});
-			#debug.dump(keys(hash));
+
+
+
+			# validate  
+			var url = ' http://wiki.flightgear.org/MapStructure#';
+			# TODO: these rules should be extended for all main files lcontroller/scontroller and symbol
+			# TODO move this out of here, so that we can use these checks in other places (i.e. searchCmd validation)
+			var checks = [
+					{ extension:'symbol', symbol:'update', type:'func', error:' update() must not be overridden:', id:300},
+					{ extension:'symbol', symbol:'draw', type:'func', required:1, error:' symbol files need to export a draw() routine:', id:301},
+					{ extension:'lcontroller', symbol:'searchCmd', type:'func', required:1, error:' lcontroller without searchCmd method:', id:100},
+					];
+
+
+			var makeurl = func(scope, id) url ~ scope ~ ':' ~ id; 				
+			var bailout = func(file, message, scope, id) die(file~message~"\n"~makeurl(scope,id) );
+
+			var current_ext = split('.', file)[-1];
+			foreach(var check; checks) {
+				# check if we have any rules matching the current file extension
+				if (current_ext == check.extension) {
+					# check for fields that must not be overridden
+					if (check['error'] != nil and 
+						hash[check.symbol]!=nil and !check['required']  and 
+						typeof(hash[check.symbol])==check.type ) {
+						bailout(file,check.error,check.extension,check.id);
+					}
+
+					# check for required fields
+					if (check['required'] != nil and 
+						hash[check.symbol]==nil and
+						typeof( hash[check.symbol]) != check.type) {
+						bailout(file,check.error,check.extension,check.id);
+					}
+				}
+			}
+			if(file==FG_ROOT~'/Nasal/canvas/map/DME.scontroller')  {
+			# var test = hash.new(nil);
+			# debug.dump( id(hash.new) );
+			}
+			# TODO: call self tests/sanity checks here
+			# and consider calling .symbol::draw() to ensure that certain APIs are NOT used, such as setGeoPosition() and setColor() etc (styling)
+
 			return hash;
 		};
 
+		# sets up a shared symbol cache, which will be used by all MapStructure maps and layers
+		# TODO: need to encode styling information as part of  the keys/hash lookup, name - so that 
+		# different maps/layers do not overwrite symbols accidentally 
+		# 
+		canvas.SymbolCache32x32 = SymbolCache.new(1024,32);
+
 		var load_deps = func(name) {
 			load(FG_ROOT~"/Nasal/canvas/map/"~name~".lcontroller",  name);
 			load(FG_ROOT~"/Nasal/canvas/map/"~name~".symbol", name);
 			load(FG_ROOT~"/Nasal/canvas/map/"~name~".scontroller", name);
 		}
 
-		foreach( var name; ['VOR','FIX','NDB','DME','WPT','TFC'] )
+		# add your own MapStructure layers here, see the wiki for details: http://wiki.flightgear.org/MapStructure
+		foreach( var name; ['APT','VOR','FIX','NDB','DME','WPT','TFC','APS',] )
 			load_deps( name );
 		load(FG_ROOT~"/Nasal/canvas/map/aircraftpos.controller", name);
 
-		###
+		# disable this for now
-		# set up a cache for 32x32 symbols
+		if(0) {
-		var SymbolCache32x32 = SymbolCache.new(1024,32);
-
 			var drawVOR = func(color, width=3) return func(group) {
 					# print("drawing vor");
 					var bbox = group.createChild("path")
@@ -508,24 +709,31 @@ var load_MapStructure = func {
 			var cachedVOR3 = SymbolCache32x32.add( "VOR-GREEN" , drawVOR( color:[0, 1, 0], width: 3),   SymbolCache.DRAW_CENTERED );
 			var cachedVOR4 = SymbolCache32x32.add( "VOR-WHITE" , drawVOR( color:[1, 1, 1], width: 3),   SymbolCache.DRAW_CENTERED );
 
+			# visually verify VORs were placed:
+			# var dlg2 = canvas.Window.new([1024,1024], "dialog");
+			# dlg2.setCanvas(SymbolCache32x32.canvas_texture);
+			
+			# use one:
+			# var dlg = canvas.Window.new([120,120],"dialog");
+			# var my_canvas = dlg.createCanvas().setColorBackground(1,1,1,1);
+			# var root = my_canvas.createGroup();
+
+			# SymbolCache32x32.get(name:"VOR-RED").render( group: root ).setTranslation(60,60);
+		}
+
 		# STRESS TEST
 		if (0) {
-			for(var i=0;i <= 1024/32*4 - 4; i+=1)
+			#for(var i=0;i <= 1024/32*4 - 4; i+=1)
-				SymbolCache32x32.add( "VOR-YELLOW"~i , drawVOR( color:[1, 1, 0], width: 3)   );
+			#	SymbolCache32x32.add( "VOR-YELLOW"~i , drawVOR( color:[1, 1, 0], width: 3)   );
-
-			var dlg = canvas.Window.new([640,320],"dialog");
-			var my_canvas = dlg.createCanvas().setColorBackground(1,1,1,1);
-			var root = my_canvas.createGroup();
-
-			SymbolCache32x32.get(name:"VOR-BLUE").render( group: root ).setGeoPosition(getprop("/position/latitude-deg"),getprop("/position/longitude-deg"));
 		}
 
 	})();
 	#print("finished loading files");
 	####### TEST SYMBOL #######
 
-	canvas.load_MapStructure = func;
+	canvas.load_MapStructure = func; # @Philosopher: is this intended/needed ??
 
 }; # load_MapStructure
 
-setlistener("/nasal/canvas/loaded", load_MapStructure); # end ugly module init listener hack
+setlistener("/nasal/canvas/loaded", load_MapStructure); # end ugly module init listener hack. FIXME: do smart Nasal bootstrapping, quod est callidus!
+# Actually, it would be even better to support reloading MapStructure files, and maybe even MapStructure itself by calling the dtor/del method for each Map and then re-running the ctor

Nasal/canvas/api.nas

@@ -244,6 +244,7 @@ var Element = {
   #
   # @param color  Vector of 3 or 4 values in [0, 1]
   setColorFill: func me.set('fill', _getColor(arg)),
+  getColorFill: func me.get('fill'),
   #
   getTransformedBounds: func me.getTightBoundingBox(),
   # Calculate the transformation center based on bounding box and center-offset
@@ -420,7 +421,7 @@ var Map = {
   df_controller: nil,
   new: func(ghost)
   {
-    return { parents: [Map, Group.new(ghost)], layers:{} }.setController();
+    return { parents: [Map, Group.new(ghost)], layers:{}, controller:nil }.setController();
   },
   del: func()
   {
@@ -437,6 +438,7 @@ var Map = {
   },
   setController: func(controller=nil)
   {
+    if (me.controller != nil) me.controller.del(me);
     if (controller == nil)
       controller = Map.df_controller;
     elsif (typeof(controller) != 'hash')
@@ -447,17 +449,24 @@ var Map = {
     } else {
       if (!isa(controller, Map.Controller))
         die("OOP error: controller needs to inherit from Map.Controller");
-      me.controller = controller.new(me);
+      me.controller = call(func controller.new(me), nil, var err=[]); # try...
-      if (!isa(me.controller, controller))
+      if (size(err)) {
-        die("OOP error: created instance needs to inherit from specific controller class");
+        if (err[0] != "No such member: new") # ... and either catch or rethrow
+          die(err[0]);
+        else
+          me.controller = controller;
+      } elsif (me.controller == nil) {
+        me.controller = controller;
+      } elsif (me.controller != controller and !isa(me.controller, controller))
+        die("OOP error: created instance needs to inherit from or be the specific controller class");
     }
 
     return me;
   },
-  addLayer: func(factory, type_arg=nil, priority=nil)
+  addLayer: func(factory, type_arg=nil, priority=nil, style=nil, options=nil)
   {
     if(contains(me.layers, type_arg))
-      print("addLayer() warning: overwriting existing layer:", type_arg);
+      printlog("warn", "addLayer() warning: overwriting existing layer:", type_arg);
 
     # print("addLayer():", type_arg);
 
@@ -466,29 +475,69 @@ var Map = {
       var type = factory.get(type_arg);
     else var type = factory;
 
-    me.layers[type_arg]= type.new(me);
+    me.layers[type_arg] = type.new(group:me, map:me, style:style,options:options);
     if (priority == nil)
       priority = type.df_priority;
     if (priority != nil)
-      me.layers[type_arg].setInt("z-index", priority);
+      me.layers[type_arg].group.setInt("z-index", priority);
+
     return me;
   },
   getLayer: func(type_arg) me.layers[type_arg],
-  setPos: func(lat, lon, hdg=nil, range=nil)
+
+  setRange: func(range) me.set("range",range),
+  getRange: func me.get('range'),
+
+  setPos: func(lat, lon, hdg=nil, range=nil, alt=nil)
   {
     me.set("ref-lat", lat);
     me.set("ref-lon", lon);
     if (hdg != nil)
       me.set("hdg", hdg);
     if (range != nil)
-      me.set("range", range);
+      me.setRange(range);
+    if (alt != nil)
+      me.set("altitude", hdg);
+  },
+  getPos: func
+  {
+    return [me.get("ref-lat"),
+            me.get("ref-lon"),
+            me.get("hdg"),
+            me.get("range"),
+            me.get("altitude")];
+  },
+  getLat: func me.get("ref-lat"),
+  getLon: func me.get("ref-lon"),
+  getHdg: func me.get("hdg"),
+  getAlt: func me.get("altitude"),
+  getRange: func me.get("range"),
+  getLatLon: func [me.get("ref-lat"), me.get("ref-lon")],
+  getPosCoord: func
+  {
+    var (lat, lon) = (me.get("ref-lat"),
+                      me.get("ref-lon"));
+    var alt = me.get("altitude");
+    if (lat == nil or lon == nil) {
+      if (contains(me, "coord")) {
+        debug.warn("canvas.Map: lost ref-lat and/or ref-lon source");
+      }
+      return nil;
+    }
+    if (!contains(me, "coord")) {
+      me.coord = geo.Coord.new();
+    }
+    me.coord.set_latlon(lat,lon,alt or 0);
+    return me.coord;
   },
   # Update each layer on this Map. Called by
   # me.controller.
-  update: func
+  update: func(predicate=nil)
   {
     foreach (var l; keys(me.layers)) {
       var layer = me.layers[l];
+      # Only update if the predicate allows
+      if (predicate == nil or predicate(layer))
         call(layer.update, arg, layer);
     }
     return me;
@@ -570,7 +619,10 @@ var Text = {
     me.setDouble("max-width", w);
   },
   setColor: func me.set('fill', _getColor(arg)),
-  setColorFill: func me.set('background', _getColor(arg))
+  getColor: func me.get('fill'),
+
+  setColorFill: func me.set('background', _getColor(arg)),
+  getColorFill: func me.get('background'),
 };
 
 # Path
@@ -826,8 +878,10 @@ var Path = {
   },
 
   setColor: func me.setStroke(_getColor(arg)),
-  setColorFill: func me.setFill(_getColor(arg)),
+  getColor: func me.getStroke(), 
 
+  setColorFill: func me.setFill(_getColor(arg)),
+  getColorFill: func me.getColorFill(),
   setFill: func(fill)
   {
     me.set('fill', fill);
@@ -836,6 +890,8 @@ var Path = {
   {
     me.set('stroke', stroke);
   },
+  getStroke: func me.get('stroke'),
+
   setStrokeLineWidth: func(width)
   {
     me.setDouble('stroke-width', width);
@@ -997,6 +1053,7 @@ var Canvas = {
   #
   # @param color  Vector of 3 or 4 values in [0, 1]
   setColorBackground: func () { me.texture.getNode('background', 1).setValue(_getColor(arg)); me; },
+  getColorBackground: func me.texture.get('background'),
   # Get path of canvas to be used eg. in Image::setFile
   getPath: func()
   {

Nasal/canvas/map/APS.lcontroller

@@ -0,0 +1,27 @@
+# See: http://wiki.flightgear.org/MapStructure
+# Class things:
+var name = 'APS';
+var parents = [SymbolLayer.Controller];
+var __self__ = caller(0)[0];
+SymbolLayer.Controller.add(name, __self__);
+SymbolLayer.add(name, {
+	parents: [SymbolLayer],
+	type: name, # Symbol type
+	df_controller: __self__, # controller to use by default -- this one
+});
+var new = func(layer) {
+	layer.searcher._equals = func(a,b) {
+		a == b;
+	}
+	return {
+		parents: [__self__],
+		map: layer.map,
+	};
+};
+var del = func;
+
+var searchCmd = func {
+	var c = me.map.getPosCoord();
+	return [c];
+};
+

Nasal/canvas/map/APS.scontroller

@@ -0,0 +1,9 @@
+# See: http://wiki.flightgear.org/MapStructure
+# Class things:
+var name = 'APS';
+var parents = [Symbol.Controller];
+var __self__ = caller(0)[0];
+Symbol.Controller.add(name, __self__);
+Symbol.registry[ name ].df_controller = __self__;
+var new = func(model) ; # this controller doesn't need an instance
+

Nasal/canvas/map/APS.symbol

@@ -0,0 +1,16 @@
+# See: http://wiki.flightgear.org/MapStructure
+# Class things:
+var name = 'APS';
+var parents = [DotSym];
+var __self__ = caller(0)[0];
+DotSym.makeinstance( name, __self__ );
+
+var element_type = "group";
+var element_id = "airplane";
+
+var init = func {
+	canvas.parsesvg(me.element, "Nasal/canvas/map/boeingAirplane.svg");
+	me.draw();
+};
+var draw = func me.element.setRotation(me.layer.map.getHdg());
+

Nasal/canvas/map/APT.lcontroller

@@ -0,0 +1,35 @@
+# See: http://wiki.flightgear.org/MapStructure
+# Class things:
+var name = 'APT';
+var parents = [SymbolLayer.Controller];
+var __self__ = caller(0)[0];
+SymbolLayer.Controller.add(name, __self__);
+SymbolLayer.add(name, {
+	parents: [SymbolLayer],
+	type: name, # Symbol type
+	df_controller: __self__, # controller to use by default -- this one
+});
+var a_instance = nil;
+var new = func(layer) {
+	var m = {
+		parents: [__self__],
+		layer: layer,
+		map: layer.map,
+		listeners: [],
+	};
+	__self__.a_instance = m;
+	return m;
+};
+var del = func() {
+	#print(name,".lcontroller.del()");
+	foreach (var l; me.listeners)
+		removelistener(l);
+};
+
+var searchCmd = func {
+	#print("Running query:", name);
+	var range = me.map.getRange();
+	if (range == nil) return;
+	return positioned.findAirportsWithinRange(me.map.getPosCoord(), range);
+};
+

Nasal/canvas/map/APT.scontroller

@@ -0,0 +1,13 @@
+# See: http://wiki.flightgear.org/MapStructure
+# Class things:
+var name = 'APT';
+var parents = [Symbol.Controller];
+var __self__ = caller(0)[0];
+Symbol.Controller.add(name, __self__);
+Symbol.registry[ name ].df_controller = __self__;
+var new = func(model) ; # this controller doesn't need an instance
+var LayerController = SymbolLayer.Controller.registry[ name ];
+var isActive = func(model) LayerController.a_instance.isActive(model);
+var query_range = func()
+	die( name~".scontroller.query_range /MUST/ be provided by implementation" );
+

Nasal/canvas/map/APT.symbol

@@ -0,0 +1,52 @@
+# See: http://wiki.flightgear.org/MapStructure
+# Class things:
+var name = 'APT';
+var parents = [DotSym];
+var __self__ = caller(0)[0];
+DotSym.makeinstance( name, __self__ );
+
+var element_type = "group"; # we want a group, becomes "me.element"
+var icon_fix = nil;
+var text_fix = nil;
+
+# add the draw routine from airports-nd.draw here
+var draw = func {
+	if (me.icon_fix != nil) return;
+		var icon_apt = me.element.createChild("path", name ~ " icon" )
+			.moveTo(-17,0)
+			.arcSmallCW(17,17,0,34,0)
+			.arcSmallCW(17,17,0,-34,0)
+			.close()
+			.setColor(0,0.6,0.85)
+			.setStrokeLineWidth(3);
+		var text_apt = me.element.createChild("text", name ~ " label")
+			.setDrawMode( canvas.Text.TEXT )
+			.setTranslation(17,35)
+			.setText(me.model.id)
+			.setFont("LiberationFonts/LiberationSans-Regular.ttf")
+			.setColor(0,0.6,0.85)
+			.setFontSize(28);
+		#me.element.setGeoPosition(lat, lon)
+		#	.set("z-index",1); # FIXME: this needs to be configurable!!
+
+# disabled:
+if(0) {
+	# the fix symbol
+	me.icon_fix = me.element.createChild("path")
+		.moveTo(-15,15)
+		.lineTo(0,-15)
+		.lineTo(15,15)
+		.close()
+		.setStrokeLineWidth(3)
+		.setColor(0,0.6,0.85)
+		.setScale(0.5,0.5); # FIXME: do proper LOD handling here - we need to scale according to current texture dimensions vs. original/design dimensions
+	# the fix label
+	me.text_fix = me.element.createChild("text")
+		.setDrawMode( canvas.Text.TEXT )
+		.setText(me.model.id)
+		.setFont("LiberationFonts/LiberationSans-Regular.ttf")
+		.setFontSize(28)
+		.setTranslation(5,25);
+ }
+};
+

Nasal/canvas/map/DME.lcontroller

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'DME';
 var parents = [SymbolLayer.Controller];
@@ -7,17 +8,39 @@ SymbolLayer.add(name, {
 	parents: [SymbolLayer],
 	type: name, # Symbol type
 	df_controller: __self__, # controller to use by default -- this one
+	df_style: {
+		line_width: 3,
+		scale_factor: 1,
+		animation_test: 0,
+		debug: 1,
+		color_default: [0,0.6,0.85],
+		color_tuned: [0,1,0],
+	}
 });
-var a_instance = nil;
 var new = func(layer) {
 	var m = {
 		parents: [__self__],
 		layer: layer,
+		map: layer.map,
 		listeners: [],
-		query_range_nm: 25,
 		query_type:'dme',
 	};
-	__self__.a_instance = m;
+	##
+	# default styling parameters - can be overridden via addLayer( style:{key:value, ...} )
+
+	if (contains(m.layer,'style')) return m; # we already have a proper style
+
+	# otherwise, set up a default style:
+	m.layer.style={};
+	m.layer.style.debug = 0; # HACK: setting this enables benchmarking and printlog statements
+	m.layer.style.animation_test = 0;
+
+	# these are used by the draw() routines, see DME.symbol
+	m.layer.style.scale_factor = 1.0 ; # applied to the whole group for now
+	m.layer.style.line_width = 3.0; 
+	m.layer.style.color_tuned = [0,1,0]; 
+	m.layer.style.color_default = [0,0.6,0.85]; 
+
 	return m;
 };
 var del = func() {
@@ -26,7 +49,9 @@ var del = func() {
 };
 
 var searchCmd = func {
-	#print("Running query:", me.query_type);
+	printlog(_MP_dbg_lvl, "Running query:", me.query_type);
-	return positioned.findWithinRange(me.query_range_nm, me.query_type); # the range should also be exposed, it will typically be controlled via a GUI widget or NavDisplay switch
+	var range = me.map.getRange();
+	if (range == nil) return;
+	return positioned.findWithinRange(me.map.getPosCoord(), range, me.query_type);
 };
 

Nasal/canvas/map/DME.scontroller

@@ -1,12 +1,9 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'DME';
 var parents = [Symbol.Controller];
 var __self__ = caller(0)[0];
 Symbol.Controller.add(name, __self__);
 Symbol.registry[ name ].df_controller = __self__;
-var new = func(model) ; # this controller doesn't need an instance
+var new = func(model, symbol) ; # this controller doesn't need an instance
-var LayerController = SymbolLayer.Controller.registry[ name ];
-var isActive = func(model) LayerController.a_instance.isActive(model);
-var is_tuned = func()
-	die( name~".scontroller.is_tuned /MUST/ be provided by implementation" );
 

Nasal/canvas/map/DME.symbol

@@ -1,3 +1,15 @@
+# See: http://wiki.flightgear.org/MapStructure
+# This layer is currently being restructured to better support 1) styling, 2) LOD and 3) caching of instanced symbols
+# The corresponding APIs in MapStructure.nas and api.nas should probably be extended acccordingly
+#
+# We can look into adapting the other layers once we have a single use-case that works properly - including styling, LOD and caching -
+# at that point, the framework should have evolved sufficiently. 
+#
+# It would probably be a good idea to incrementally port some other layers and provide the corresponding helpers/APIs, to reduce the amount
+# of specialized/identical code in the .symbol files.
+#  
+
+
 # Class things:
 var name = 'DME';
 var parents = [DotSym];
@@ -5,11 +17,101 @@ var __self__ = caller(0)[0];
 DotSym.makeinstance( name, __self__ );
 
 var element_type = "group"; # we want a group, becomes "me.element"
+
+var timer = nil;
+
+###
+# symbols (canvas groups) managed by this file
+#
 var icon_dme = nil;
 
-var draw = func {
+var scale_animation = 1;
-	# Init
+
-	if (me.icon_dme == nil) {
+var animate = func {
+	if (me.scale_animation >= 1)
+		me.scale_animation -= .5;
+	else
+		me.scale_animation += .5;
+	me.element.setScale( me.scale_animation );
+}
+
+
+var del = func {
+ # me.timer.stop();
+}
+
+# CachedElement
+# StyleAttribute
+# Styleable
+# RangeAwareElement
+
+
+
+# var DMEIcon = StyleableElement.new( [{color:IconColor}, ] );
+
+###
+# helper to tell if the symbol is already initialized or not
+# TODO: encapsulate API-wise (this is a very common thing to do...)
+var is_initialized = func me.icon_dme != nil;
+
+###
+# FIXME: these should probably be part of MapStructure itself
+# TODO: Need to come up with a StyleableElement class for this sort of stuff
+var apply_styling = func {
+	# add all styleable groups here
+
+	# no need to do this whenever draw is called - typically, attributes won't change at all - so this is kinda redundant
+	var current_color = me.icon_dme.getColor();
+	var required_color = nil;
+
+	if (typeof(me.layer.map.controller["is_tuned"]) == 'func' and me.layer.map.controller.is_tuned(me.model.frequency/100))
+	#TODO: once we support caching/instancing, we cannot just change the symbol like this - we need to use a different symbol from the cache instead
+	# which is why these things need to be done ONCE during init to set up a cache entry for each symbol variation to come up with a  corresponding raster image
+	# TODO: API-wise it would make sense to maintain a vector of required keys, so that the style hash can be validated in the ctor of the layer
+	# to ensure that all mandatory fields are supplied 
+		required_color = canvas._getColor( me.layer.style.color_tuned);
+		else
+		required_color = canvas._getColor( me.layer.style.color_default);
+
+	if (current_color != required_color) {
+		# print("Setting color!");
+		# TODO: this is where we would select another cached symbol
+		me.icon_dme.setColor( required_color );
+	}
+	# else print("Not changing color (unnecessary)");
+
+	# debug.dump(me.layer.style);
+}
+
+
+###
+# NOTE: This is only applied during initialization
+# TODO: expose via addLayer/style param
+# TODO: also needs to be aware of current range, so that proper LOD handling can be implemented
+var apply_scale = func {
+	# add all symbols here that need scaling
+	# print("Scaling:", me.layer.style.scale_factor);
+	me.icon_dme.setScale( me.layer.style.scale_factor );
+}
+
+###
+# draw routines must be called here to create a lookup table
+# with different symbols, based on styling (colors etc)
+# because we can no longer change instanced symbols later on 
+# as they will be shared, so we need one cache entry for each 
+# variation in style 
+var init_cache = func {
+
+}
+
+##
+# init is done separately to prepare support for caching (instanced symbols)
+# NOTE: People should not be "hard-coding" things like color/size here
+# these need to be encapsulated via a Hash lookup, so that things can be 
+# easily customized
+#
+var init_symbols = func {
+		# debug.dump(me.layer.style);
 		me.icon_dme = me.element.createChild("path")
 			.moveTo(-15,0)
 			.line(-12.5,-7.5)
@@ -25,11 +127,31 @@ var draw = func {
 			.horiz(-14.5)
 			.vert(-14.5)
 			.close()
-			.setStrokeLineWidth(3);
+			.setStrokeLineWidth( me.layer.style.line_width ); #TODO: this should be style-able 
+
+		# finally scale the symbol as requested, this is done last so that people can override this when creating the layer
+		me.apply_scale();	
+	if (me.layer.style.animation_test) {
+
+		me.timer = maketimer(0.33, func me.animate() );
+		me.timer.start();
 	}
-	if (me.controller != nil and me.controller.is_tuned(me.model.frequency/100))
+}
-		me.icon_dme.setColor(0,1,0);
+
-	else
+var updateRun = func {
-		me.icon_dme.setColor(0,0.6,0.85);
+	# check if the current station is tuned or not - and style the symbol accordingly (color)
+	me.apply_styling(); 
+}
+
+##
+# this method is REQUIRED (basically, the entry point for drawing - most others are just helpers)
+var draw = func {
+	# print("DME:draw()");
+	# Init: will set up the symbol if it isn't already
+	if ( !me.is_initialized() )
+		me.init_symbols();
+
+	# wrapper for custom styling, based on tuned/default colors (see lookup hash above)
+	me.updateRun();	
 };
 

Nasal/canvas/map/FIX.lcontroller

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'FIX';
 var parents = [SymbolLayer.Controller];
@@ -7,27 +8,35 @@ SymbolLayer.add(name, {
 	parents: [SymbolLayer],
 	type: name, # Symbol type
 	df_controller: __self__, # controller to use by default -- this one
+
+	df_style: {
+		line_width: 3,
+		scale_factor: 0.5,
+		debug: 1,
+		color_default: [0, 0.6, 0.85],
+	}
+
 });
-var a_instance = nil;
 var new = func(layer) {
 	var m = {
 		parents: [__self__],
 		layer: layer,
+		map: layer.map,
 		listeners: [],
-		query_range_nm: 25,
 		query_type:'fix',
 	};
-	__self__.a_instance = m;
 	return m;
 };
 var del = func() {
-	#print("VOR.lcontroller.del()");
+	printlog(_MP_dbg_lvl, "VOR.lcontroller.del()");
 	foreach (var l; me.listeners)
 		removelistener(l);
 };
 
 var searchCmd = func {
-	#print("Running query:", me.query_type);
+	printlog(_MP_dbg_lvl, "Running query:", me.query_type);
-	return positioned.findWithinRange(me.query_range_nm, me.query_type); # the range should also be exposed, it will typically be controlled via a GUI widget or NavDisplay switch
+	var range = me.map.getRange();
+	if (range == nil) return;
+	return positioned.findWithinRange(me.map.getPosCoord(), range, me.query_type);
 };
 

Nasal/canvas/map/FIX.scontroller

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'FIX';
 var parents = [Symbol.Controller];
@@ -5,8 +6,4 @@ var __self__ = caller(0)[0];
 Symbol.Controller.add(name, __self__);
 Symbol.registry[ name ].df_controller = __self__;
 var new = func(model) ; # this controller doesn't need an instance
-var LayerController = SymbolLayer.Controller.registry[ name ];
-var isActive = func(model) LayerController.a_instance.isActive(model);
-var query_range = func()
-	die( name~".scontroller.query_range /MUST/ be provided by implementation" );
 

Nasal/canvas/map/FIX.symbol

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'FIX';
 var parents = [DotSym];
@@ -8,23 +9,41 @@ var element_type = "group"; # we want a group, becomes "me.element"
 var icon_fix = nil;
 var text_fix = nil;
 
-var draw = func {
+##
-	if (me.icon_fix != nil) return;
+# used during initialization to populate the symbol cache with a FIX symbol
-	# the fix symbol
+#
-	me.icon_fix = me.element.createChild("path")
+var drawFIX = func(color, width) func(group) {
+
+	var symbol = group.createChild("path")
 		.moveTo(-15,15)
 		.lineTo(0,-15)
 		.lineTo(15,15)
 		.close()
-		.setStrokeLineWidth(3)
+		.setStrokeLineWidth(width)
-		.setColor(0,0.6,0.85)
+		.setColor(color)
 		.setScale(0.5,0.5); # FIXME: do proper LOD handling here - we need to scale according to current texture dimensions vs. original/design dimensions
-	# the fix label
+	return symbol;
+}
+
+var icon_fix_cached = [
+	SymbolCache32x32.add(
+		name: "FIX",
+		callback: drawFIX( color:[0, 0.6, 0.85], width:3 ), # TODO: use the style hash to encapsulate styling stuff
+		draw_mode: SymbolCache.DRAW_CENTERED
+	)
+];
+
+var draw = func {
+	if (me.icon_fix != nil) return; # fix icon already initialized
+	# initialize the fix symbol
+	me.icon_fix = icon_fix_cached[0].render(me.element);
+
+	# non-cached  stuff:
+	# FIXME: labels need to be LOD-aware (i.e. aware of MapController range, so that we can hide/show them)
 	me.text_fix = me.element.createChild("text")
 		.setDrawMode( canvas.Text.TEXT )
 		.setText(me.model.id)
-		.setFont("LiberationFonts/LiberationSans-Regular.ttf")
+		.setFont("LiberationFonts/LiberationSans-Regular.ttf") # TODO: encapsulate styling stuff
-		.setFontSize(28)
+		.setFontSize(28) # TODO: encapsulate styling stuff
 		.setTranslation(5,25);
-};
+}
-

Nasal/canvas/map/NDB.lcontroller

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'NDB';
 var parents = [SymbolLayer.Controller];
@@ -12,8 +13,8 @@ var new = func(layer) {
 	var m = {
 		parents: [__self__],
 		layer: layer,
+		map: layer.map,
 		listeners: [],
-		query_range_nm: 25,
 		query_type:'ndb',
 	};
 	return m;
@@ -24,7 +25,9 @@ var del = func() {
 };
 
 var searchCmd = func {
-	#print("Running query:", me.query_type);
+	printlog(_MP_dbg_lvl, "Running query:", me.query_type);
-	return positioned.findWithinRange(me.query_range_nm, me.query_type); # the range should also be exposed, it will typically be controlled via a GUI widget or NavDisplay switch
+	var range = me.map.getRange();
+	if (range == nil) return;
+	return positioned.findWithinRange(me.map.getPosCoord(), range, me.query_type);
 };
 

Nasal/canvas/map/NDB.scontroller

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'NDB';
 var parents = [Symbol.Controller];
@@ -6,7 +7,4 @@ Symbol.Controller.add(name, __self__);
 Symbol.registry[ name ].df_controller = __self__;
 var new = func(model) ; # this controller doesn't need an instance
 var LayerController = SymbolLayer.Controller.registry[ name ];
-var isActive = func(model) LayerController.a_instance.isActive(model);
-var query_range = func()
-	die( name~".scontroller.query_range /MUST/ be provided by implementation" );
 

Nasal/canvas/map/NDB.symbol

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'NDB';
 var parents = [DotSym];

Nasal/canvas/map/TFC.lcontroller

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'TFC';
 var parents = [SymbolLayer.Controller];
@@ -7,6 +8,7 @@ SymbolLayer.add(name, {
 	parents: [SymbolLayer],
 	type: name, # Symbol type
 	df_controller: __self__, # controller to use by default -- this one
+	df_style: { debug: 0 }, # style to use by default
 });
 
 var model_root = props.globals.getNode("/ai/models/");
@@ -15,30 +17,10 @@ var new = func(layer) {
 	var m = {
 		parents: [__self__],
 		layer: layer,
+		map: layer.map,
 		listeners: [],
-		query_range_nm: 25,
+		searchCmd: searchCmd_default,
 	};
-	# Listen to ai model events
-	append(m.listeners, setlistener(
-		model_root.getNode("model-added"), func(n) {
-			#printlog(_MP_dbg_lvl, "Dynamically adding model at "~n.getValue());
-			var node = props.globals.getNode(n.getValue());
-			var name = node.getName();
-			if (name == "aircraft" or name == "multiplayer")
-				if (m.in_range(node.getValue("position/latitude-deg"), node.getValue("position/longitude-deg")))
-					layer.onAdded(TrafficModel.new(node));
-		}
-	));
-	append(m.listeners, setlistener(
-		model_root.getNode("model-removed"), func(n) {
-			#printlog(_MP_dbg_lvl, "Dynamically deleting model at "~n.getValue());
-			var node = props.globals.getNode(n.getValue());
-			var name = node.getName();
-			if (name == "aircraft" or name == "multiplayer")
-				if (m.in_range(node.getValue("position/latitude-deg"), node.getValue("position/longitude-deg")))
-					layer.onRemoved(TrafficModel.new(node));
-		}
-	));
 	layer.searcher._equals = func(l,r) l.equals(r);
 	return m;
 };
@@ -47,19 +29,6 @@ var del = func() {
 	foreach (var l; me.listeners)
 		removelistener(l);
 };
-var in_range = func(lat,lon,myPositionVec=nil,max_dist_m=nil) {
-	if (lat == nil or lon == nil) return 0;
-	var pos = geo.Coord.new();
-	pos.set_latlon(lat,lon);
-	var myPosition = geo.Coord.new();
-	# FIXME: need a Map Controller for this, and all query_range's/get_position's
-	if (myPositionVec == nil)
-		var myPositionVec = me.get_position();
-	myPosition.set_latlon( myPositionVec[0], myPositionVec[1]);
-	if (max_dist_m == nil)
-		var max_dist_m = me.query_range()*NM2M;
-	return (pos.distance_to( myPosition ) <= max_dist_m )
-};
 
 var TrafficModel = {
 	new: func(node, id=nil, layer=nil) {
@@ -72,43 +41,51 @@ var TrafficModel = {
 			node: node,
 			pos: node.getNode("position",1),
 		};
-		if (m.pos == nil)
-			m.latlon = func [nil,nil,nil];
-		#debug.dump(m); # why doesn't this print?
 		return m;
 	},
 	equals: func(other) other.id == me.id,
-	latlon: func() {
+	latlon: func() { # this makes sure to look like a geo.Coord to MapStructure, but will internally use the AI/MP traffic properties instead
 		return [
 			me.pos.getValue("latitude-deg"),
 			me.pos.getValue("longitude-deg"),
 			me.pos.getValue("altitude-ft")
 		];
 	},
+	# these are helper methods related to TCAS handling (TAs/RAs)
+	get_threat_lvl: func() me.getValue("tcas/threat-level"),
+	get_vspd: func() (me.getValue("velocities/vertical-speed-fps") or 0)*60,
+	get_alt:  func() (me.getValue("position/altitude-ft") or 0),
 };
 
-var searchCmd = func {
+
+##
+# dummy/placeholder (will be overridden in ctor and set to the default callback)
+var searchCmd  = func;
+
+var searchCmd_default = func {
 	# TODO: this would be a good candidate for splitting across frames
-	#print("Doing query: "~name);
+	printlog(_MP_dbg_lvl, "Doing query: "~name);
 
 	var result = [];
-	# FIXME: need a Map Controller for this, and all query_range's/get_position's
+	var models = 0;
-	var myPositionVec = me.get_position();
-	var max_dist_m = me.query_range()*NM2M;
 
 	# AI and Multiplayer traffic
-	foreach (var traffic; [model_root.getChildren("aircraft"), model_root.getChildren("multiplayer")]) {
+	foreach (var t; model_root.getChildren()) {
-		foreach(var t; traffic) {
+		if (!t.getValue("valid")) continue;
-			if (me.in_range(t.getValue("position/latitude-deg"),
+		var t_id = t.getNode("id");
-				            t.getValue("position/longitude-deg"),
+		if (t_id == nil or t_id.getValue() == -1) continue;
-				            myPositionVec,
+		models += 1;
-				            max_dist_m))
+		var (lat,lon) = (t.getValue("position/latitude-deg"),
+		                 t.getValue("position/longitude-deg"));
+		if (lat == nil or lon == nil) {
+			printlog("alert", "lat/lon was nil for AI node "~t.getPath());
+			continue;
+		}
+		if (me.map.controller.in_range(lat, lon))
 			append(result, TrafficModel.new(t, nil, me.layer));
 	}
-	}
 
-	#debug.dump(result);
+	#print("Found "~size(result)~" TrafficModel's in range out of "~models~" total.");
-	#return [];
 	return result;
 };
 

Nasal/canvas/map/TFC.scontroller

@@ -1,12 +1,16 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'TFC';
 var parents = [Symbol.Controller];
 var __self__ = caller(0)[0];
 Symbol.Controller.add(name, __self__);
 Symbol.registry[name].df_controller = __self__;
-var new = func(model) ; # this controller doesn't need an instance
+var new = func(model, symbol) ; # this controller doesn't need an instance
-# XXX: this is more model-ish than controller-ish
+var get_alt_diff = func(model) {
-var get_threat_lvl = func(model) model.getValue("tcas/threat-level");
+	# debug.dump( keys(me) );
-var get_vspd       = func(model) (model.getValue("velocities/vertical-speed-fps") or 0)*60;
+	var model_alt = model.get_alt();
-var get_alt_diff   = func(model) (model.getValue("position/altitude-ft") or 0) - (getprop("/position/altitude-ft") or 0);
+	var alt = getprop("/position/altitude-ft"); # FIXME: hardcoded - right, we should probably generalize the "NDSourceDriver logic found in navdisplay.mfd and make it part of MapStructure
+	if (alt == nil or model_alt == nil) return 0;
+	return alt-model_alt;
+};
 

Nasal/canvas/map/TFC.symbol

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'TFC';
 var parents = [DotSym];
@@ -13,15 +14,15 @@ var arrow_type = nil;
 var draw_tcas_arrow = nil;
 
 var draw = func {
-	if (me.draw_tcas_arrow == nil)
+	if (draw_tcas_arrow == nil)
-		me.draw_tcas_arrow = [
+		draw_tcas_arrow = [
 			draw_tcas_arrow_above_500,
 			draw_tcas_arrow_below_500
 		];
 	#var callsign = me.model.getNode("callsign").getValue();
 	# print("Drawing traffic for:", callsign );
-	var threatLvl = me.controller.get_threat_lvl(me.model);
+	var threatLvl = me.model.get_threat_lvl();
-	var vspeed = me.controller.get_vspd(me.model);
+	var vspeed = me.model.get_vspd();
 	var altDiff = me.controller.get_alt_diff(me.model);
 	# Init
 	if (me.text_tcas == nil) {
@@ -59,7 +60,7 @@ var draw = func {
 			.setColor(1,0,0)
 			.setColorFill(1,0,0);
 		me.text_tcas.setColor(1,0,0);
-		me.arrow_tcas.setColor(1,0,0);
+		me.arrow_tcas[me.arrow_type].setColor(1,0,0);
 	} elsif (threatLvl == 2) {
 		# traffic advisory
 		me.icon_tcas.moveTo(-17,0)
@@ -68,7 +69,7 @@ var draw = func {
 			.setColor(1,0.5,0)
 			.setColorFill(1,0.5,0);
 		me.text_tcas.setColor(1,0.5,0);
-		me.arrow_tcas.setColor(1,0.5,0);
+		me.arrow_tcas[me.arrow_type].setColor(1,0.5,0);
 	} elsif (threatLvl == 1) {
 		# proximate traffic
 		me.icon_tcas.moveTo(-10,0)
@@ -78,6 +79,8 @@ var draw = func {
 			.close()
 			.setColor(1,1,1)
 			.setColorFill(1,1,1);
+		me.text_tcas.setColor(1,1,1);
+		me.arrow_tcas[me.arrow_type].setColor(1,1,1);
 	} else {
 		# other traffic
 		me.icon_tcas.moveTo(-10,0)
@@ -86,6 +89,8 @@ var draw = func {
 			.lineTo(0,17)
 			.close()
 			.setColor(1,1,1);
+		me.text_tcas.setColor(1,1,1);
+		me.arrow_tcas[me.arrow_type].setColor(1,1,1);
 	}
 };
 

Nasal/canvas/map/VOR.lcontroller

@@ -1,17 +1,29 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
+var name ='VOR';
 var parents = [SymbolLayer.Controller];
 var __self__ = caller(0)[0];
-SymbolLayer.Controller.add("VOR", __self__);
+SymbolLayer.Controller.add(name, __self__);
-SymbolLayer.add("VOR", {
+SymbolLayer.add(name, {
 	parents: [SymbolLayer],
-	type: "VOR", # Symbol type
+	type: name, # Symbol type
 	df_controller: __self__, # controller to use by default -- this one
 });
-var a_instance = nil;
 var new = func(layer) {
+
+if(0) {
+	# TODO: generalize and move to MapStructure.nas
+	var required_controllers = [ {name: 'query_range',type:'func'}, ];
+	foreach(var c; required_controllers) {
+		if (!contains(layer.map.controller, c.name) or typeof(layer.map.controller[c.name]) !=c.type)
+		die("Required controller is missing/invalid:"~ c.name ~ ' ['~c.type~']' );
+	}
+}
+	
 	var m = {
 		parents: [__self__],
 		layer: layer,
+		map: layer.map,
 		active_vors: [],
 		navNs: props.globals.getNode("instrumentation").getChildren("nav"),
 		listeners: [],
@@ -26,11 +38,10 @@ var new = func(layer) {
 	}
 	#call(debug.dump, keys(layer));
 	m.changed_freq(update:0);
-	__self__.a_instance = m;
 	return m;
 };
 var del = func() {
-	printlog(_MP_dbg_lvl, "VOR.lcontroller.del()");
+	printlog(_MP_dbg_lvl, name,".lcontroller.del()");
 	foreach (var l; me.listeners)
 		removelistener(l);
 };
@@ -50,6 +61,8 @@ var changed_freq = func(update=1) {
 };
 var searchCmd = func {
 	printlog(_MP_dbg_lvl, "Running query:", me.query_type);
-	return positioned.findWithinRange(100, me.query_type); # the range should also be exposed, it will typically be controlled via a GUI widget or NavDisplay switch
+	var range = me.map.getRange();
+	if (range == nil) return;
+	return positioned.findWithinRange(me.map.getPosCoord(), range, me.query_type);
 };
 

Nasal/canvas/map/VOR.scontroller

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'VOR';
 var parents = [Symbol.Controller];
@@ -5,8 +6,4 @@ var __self__ = caller(0)[0];
 Symbol.Controller.add(name, __self__);
 Symbol.registry[name].df_controller = __self__;
 var new = func(model) ; # this controller doesn't need an instance
-var LayerController = SymbolLayer.Controller.registry[name];
-var isActive = func(model) LayerController.a_instance.isActive(model);
-var query_range = func()
-	die(name~".scontroller.query_range /MUST/ be provided by implementation");
 

Nasal/canvas/map/VOR.symbol

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'VOR';
 var parents = [DotSym];
@@ -5,14 +6,32 @@ var __self__ = caller(0)[0];
 DotSym.makeinstance( name, __self__ );
 
 var element_type = "group"; # we want a group, becomes "me.element"
-var icon_vor = nil;
+var icon_vor = nil;  # a handle to the cached icon
 var range_vor = nil; # two elements that get drawn when needed
 var radial_vor = nil; # if one is nil, the other has to be nil
+var active = -1;
 
-var draw = func {
+###
-	# Init
+# this function returns a new function that renders the symbol
-	if (me.icon_vor == nil) {
+# into a canvas group
-		me.icon_vor = me.element.createChild("path")
+# the signature of the first func should contain all customizable
+# parameters (such as color/width etc)
+#
+# you will typically have one such function for each cacheable symbol 
+# and only call it once during initialization (once for each cached style/variation) 
+# the signature of the 2nd func remains untouched, it's internally used
+#
+# NOTE: callbacks that create symbols for caching MUST render them using a 
+# transparent background !!
+#
+var drawVOR = func(color, width=3) return func(group) {
+
+	# init_calls += 1; # TODO: doing this here is too fragile, this should be done by MapStructure ...
+	#  if( init_calls >= 2) 
+	# 	print("Warning: draw() routine for a cached element has been called more than once, should only happen during reset/reinit");
+
+	# print("drawing vor");
+	var symbol = group.createChild("path")
 		.moveTo(-15,0)
 		.lineTo(-7.5,12.5)
 		.lineTo(7.5,12.5)
@@ -20,13 +39,69 @@ var draw = func {
 		.lineTo(7.5,-12.5)
 		.lineTo(-7.5,-12.5)
 		.close()
-			.setStrokeLineWidth(3)
+		.setStrokeLineWidth(width)
-			.setColor(0,0.6,0.85);
+		.setColor( color );
+
+	return symbol; # make this explicit, not everybody knows Nasal internals inside/out ...
+};
+
+##
+# a vector with pre-created symbols that are cached during initialization
+# this needs to be done for each variation of each symbol, i.e. color/width etc
+# note that scaling should not be done here, likewise for positioning via setGeoPosition()
+# 
+# FIXME: We still need to encode styling information as part of the key/name lookup
+# so that the cache entry's name contains styling info, or different maps/layers may
+# overwrite their symbols
+#
+# icon_vor_cache[0] - inactive symbol
+# icon_vor_cache[1] - active symbol
+var icon_vor_cached = [
+	SymbolCache32x32.add(
+		name: "VOR-INACTIVE",
+		callback: drawVOR( color:[0, 0.6, 0.85], width:3 ),
+		draw_mode: SymbolCache.DRAW_CENTERED
+	),
+	SymbolCache32x32.add(
+		name: "VOR-ACTIVE",
+		callback: drawVOR( color:[0, 1, 0], width:3 ),
+		draw_mode: SymbolCache.DRAW_CENTERED
+	),
+];
+
+##
+# TODO: make this a part of the framework, for use by other layers/symbols etc
+#
+var controller_check = func(layer, controller, arg...) {
+	var ret = call(compile("call(layer.controller."~controller~", arg, layer.controller)", "<test>"), arg, var err=[]);
+
+	if (size(err))
+		if (err[0] == "No such member: "~controller)
+			print("MapStructure Warning: Required controller not found: ", name, ":", controller);
+		else die(err[0]); # rethrow
+
+	return ret; # nil if not found
 }
-	# Update
+
-	if (me.controller.isActive(me.model)) {
+var draw = func {
+	# Init
+	if (0 and me.model.id == "SAC") # hack to test isActive() around KSMF
+		setprop("instrumentation/nav[0]/frequencies/selected-mhz", me.model.frequency/100);
+	var active = controller_check(me.layer, 'isActive', me.model);
+	#print(me.model.id,"/", me.model.frequency/100, " isActive:", active);
+	if (active != me.active) {
+		#print("VOR.symbol: active != me.active: del/render event triggered");
+		if (me.icon_vor != nil) me.icon_vor.del();
+		# look up the correct symbol from the cache and render it into the group as a raster image
+		me.icon_vor = icon_vor_cached[active or 0].render(me.element);
+		me.active = active; # update me.active flag
+	}
+	# Update (also handles non-cached stuff, such as text labels or animations)
+	# TODO: we can use a func generator to pre-create the callback/data structure for this
+	if (active) {
 		if (me.range_vor == nil) { 
-			var rangeNm = me.controller.query_range();
+			# initialize me.range and me.radial_vor
+			var rangeNm = me.layer.map.getRange();
 			# print("VOR is tuned:", me.model.id);
 			var radius = (me.model.range_nm/rangeNm)*345;
 			me.range_vor = me.element.createChild("path")
@@ -37,7 +112,7 @@ var draw = func {
 				.setStrokeDashArray([5, 15, 5, 15, 5])
 				.setColor(0,1,0);
 
-			var course = me.controller.get_tuned_course(me.model.frequency/100);
+			var course = me.layer.map.controller.get_tuned_course(me.model.frequency/100);
 			me.radial_vor = me.element.createChild("path")
 				.moveTo(0,-radius)
 				.vert(2*radius)
@@ -45,13 +120,14 @@ var draw = func {
 				.setStrokeDashArray([15, 5, 15, 5, 15])
 				.setColor(0,1,0)
 				.setRotation(course*D2R);
-			me.icon_vor.setColor(0,1,0);
 		}
 		me.range_vor.show();
 		me.radial_vor.show();
-	} elsif (me.range_vor != nil) {
+	} else { # inactive station (not tuned)
+		if (me.range_vor != nil) {
 			me.range_vor.hide();
 			me.radial_vor.hide();
 		}
+	}
 };
 

Nasal/canvas/map/WPT.lcontroller

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'WPT'; # for waypoints
 var parents = [SymbolLayer.Controller];
@@ -12,8 +13,8 @@ var new = func(layer) {
 	var m = {
 		parents: [__self__],
 		layer: layer,
+		map: layer.map,
 		listeners: [],
-		query_range_nm: 25,
 	};
 	return m;
 };
@@ -24,7 +25,7 @@ var del = func() {
 };
 
 var searchCmd = func {
-	#print("Running query: "~name);
+	printlog(_MP_dbg_lvl, "Running query: "~name);
 	
 	var fp = flightplan();
 	var fpSize = fp.getPlanSize();
@@ -33,6 +34,5 @@ var searchCmd = func {
 		append(result, fp.getWP(i).path()[0] );
 
 	return result;
-	# return positioned.findWithinRange(me.query_range_nm, me.query_type); # the range should also be exposed, it will typically be controlled via a GUI widget or NavDisplay switch
 };
 

Nasal/canvas/map/WPT.scontroller

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'WPT';
 var parents = [Symbol.Controller];

Nasal/canvas/map/WPT.symbol

@@ -1,3 +1,4 @@
+# See: http://wiki.flightgear.org/MapStructure
 # Class things:
 var name = 'WPT';
 var parents = [DotSym];

Nasal/canvas/map/aircraftpos.controller

@@ -3,39 +3,96 @@ var parents = [Map.Controller];
 var __self__ = caller(0)[0];
 Map.Controller.add("Aircraft position", __self__);
 #Map.df_controller = __self__;
-var new = func(map) {
+
+##
+#  encapsulate type of aircraft (main, ai, mp or ai+mp)
+#  This is so that we can use reuse the aircraft controller also 
+#  for AI and/or MP traffic, which may use different properties
+#  and to fix up hard-coded property references in layers like TFC
+var SOURCES = {};
+SOURCES["main"] = {
+	getPosition: func subvec(geo.aircraft_position().latlon(), 0, 2),
+	getAltitude: func getprop('/position/altitude-ft'),
+	getHeading:  func getprop('/orientation/heading-deg'),
+};
+
+# Layers which get updated every frame
+var update_instant = [
+	"TFC",
+];
+
+var new = func(map, source='main') {
+	if (source != 'main') 
+		die ("AI/MP traffic not yet supported (WIP)!");
+
 	var m = {
 		parents: [__self__],
 		map: map,
-		_pos: nil, _time: nil,
+		source: SOURCES[source], # main, ai, mp or ai+mp
+		_pos: nil, _time: nil, _range: nil,
 	};
-	m.timer = maketimer(0, m, update_pos);
+	m.timer1 = maketimer(0, m, update_pos);
-	m.timer.start();
+	m.timer2 = maketimer(0, m, update_layers);
+	m.timer1.start();
+	m.timer2.start();
+	m.update_pos();
 	return m;
 };
 var del = func(map) {
 	if (map != me.map) die();
-	me.timer.stop();
+	me.timer1.stop();
+	me.timer2.stop();
 };
 
 # Controller methods
 var update_pos = func {
-	var (lat,lon) = (var pos = geo.aircraft_position()).latlon();
+	var (lat,lon) = me.source.getPosition();
+	me.map.setPos(lat:lat, lon:lon,
+	              hdg:getprop("/orientation/heading-deg"),
+	              alt:me.source.getAltitude());
+	foreach (var t; update_instant)
+		if ((var l=me.map.getLayer(t)) != nil)
+			l.update();
+};
+var update_layers = func {
+	var pos = me.map.getPosCoord();
 	var time = systime();
-	me.map.setPos(lat, lon, getprop("/orientation/heading-deg"));
+	var range = me.map.getRange();
 	if (me._pos == nil)
 		me._pos = geo.Coord.new(pos);
-	else {
+	# Always update if range changed
-		var dist = me._pos.direct_distance_to(pos);
+	elsif (range == me._range) {
+		var dist_m = me._pos.direct_distance_to(pos);
 		# 2 NM until we update again
-		if (dist < 2 * NM2M) return;
+		if (dist_m < 2 * NM2M) return;
-		# Update at most every 4 seconds to avoid escessive stutter:
+		# Update at most every 4 seconds to avoid excessive stutter:
 		elsif (time - me._time < 4) return;
 	}
-	#print("update aircraft position");
+	printlog(_MP_dbg_lvl, "update aircraft position");
 	var (x,y,z) = pos.xyz();
 	me._pos.set_xyz(x,y,z);
 	me._time = time;
+	me._range = range;
 	me.map.update();
 };
 
+# predicate for the draw controller
+var is_tuned = func(freq) {
+	var nav1=getprop("instrumentation/nav[0]/frequencies/selected-mhz");
+	var nav2=getprop("instrumentation/nav[1]/frequencies/selected-mhz");
+	if (freq == nav1 or freq == nav2) return 1;
+	return 0;
+}
+var get_tuned_course = func(freq) {
+	if (freq == getprop("instrumentation/nav[0]/frequencies/selected-mhz"))
+		return getprop("instrumentation/nav[0]/radials/selected-deg");
+	else
+		return getprop("instrumentation/nav[1]/radials/selected-deg");
+}
+var get_position = func {
+	delete(caller(0)[0], "me"); # remove local me, inherit outer one
+	return [
+		me.aircraft_source.get_lat(), me.aircraft_source.get_lon()
+	];
+}
+

Nasal/canvas/map/airplane-symbol.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 ##
 # draw a single airplane symbol
 #

Nasal/canvas/map/airplane-symbol.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var AirplaneSymbolLayer =  {};
 AirplaneSymbolLayer.new = func(group,name, controller) {
 	var m=Layer.new(group, name, AirplaneSymbolModel);

Nasal/canvas/map/airplane-symbol.model

@@ -1,3 +1,4 @@
+# WARNING: *.model files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var AirplaneSymbolModel = {};
 AirplaneSymbolModel.new = func make( LayerModel, AirplaneSymbolModel );
 

Nasal/canvas/map/airports-nd.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 ##
 # draws a single airport (ND style)
 #

Nasal/canvas/map/airports-nd.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var AirportsNDLayer =  {};
 AirportsNDLayer.new = func(group, name) {
 	var m = Layer.new(group, name, AirportsNDModel );

Nasal/canvas/map/airports-nd.model

@@ -1,3 +1,4 @@
+# WARNING: *.model files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var AirportsNDModel = {};
 AirportsNDModel.new =  func make(AirportsNDModel, LayerModel);
 

Nasal/canvas/map/airports.model

@@ -1,3 +1,4 @@
+# WARNING: *.model files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var AirportModel = {};
 AirportModel.new =  func make(AirportModel, LayerModel);
 

Nasal/canvas/map/altitude-profile.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 ##
 # Draw a altitude profile position on the route with text
 #

Nasal/canvas/map/dme.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 ###
 # 
 # 

Nasal/canvas/map/dme.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var DMELayer =  {};
 DMELayer.new = func(group,name,controller=nil) {
 	var m=Layer.new(group, name, DMEModel, controller);

Nasal/canvas/map/dme.model

@@ -1,3 +1,4 @@
+# WARNING: *.model files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var DMEModel = {};
 DMEModel.new = func make( LayerModel, DMEModel );
 

Nasal/canvas/map/fix.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 ##
 # draw a single fix symbol
 #

Nasal/canvas/map/fixes.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var FixLayer =  {};
 FixLayer.new = func(group,name, controller) {
 	var m=Layer.new(group, name, FixModel);

Nasal/canvas/map/fixes.model

@@ -1,3 +1,4 @@
+# WARNING: *.model files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var FixModel = {};
 FixModel.new = func make( LayerModel, FixModel );
 

Nasal/canvas/map/navaid.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 ##    
 # FIXME: until we have better instancing support for symbols, it would be better to return a functor here
 # so that symbols are only parsed once

Nasal/canvas/map/navaids.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var NavLayer =  {};
 NavLayer.new = func(group,name) {
 	var m=Layer.new(group, name, NavaidModel);

Nasal/canvas/map/navaids.model

@@ -1,3 +1,4 @@
+# WARNING: *.model files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var NavaidModel = {};
 NavaidModel.new = func make(LayerModel, NavaidModel);
 NavaidModel.init = func {

Nasal/canvas/map/navdisplay.mfd

@@ -1,5 +1,6 @@
 # ==============================================================================
 # Boeing Navigation Display by Gijs de Rooy
+# See: http://wiki.flightgear.org/Canvas_ND_Framework
 # ==============================================================================
 
 ##
@@ -44,21 +45,10 @@ var NDStyles = {
 		##
 
 		layers: [
-			{ name:'fixes', disabled:1, update_on:['toggle_range','toggle_waypoints'],
-				predicate: func(nd, layer) {
-					# print("Running fixes predicate");
-					var visible=nd.get_switch('toggle_waypoints') and nd.in_mode('toggle_display_mode', ['MAP']) and (nd.rangeNm() <= 40);
-					if (visible) {
-						# print("fixes update requested!");
-						trigger_update( layer );
-					}
-					layer._view.setVisible(visible);
-				}, # end of layer update predicate
-			}, # end of fixes layer
 			{ name:'FIX', isMapStructure:1, update_on:['toggle_range','toggle_waypoints'],
 				# FIXME: this is a really ugly place for controller code
 				predicate: func(nd, layer) {
-					# print("Running vor layer predicate");
+					# print("Running fix layer predicate");
 					# toggle visibility here
 					var visible=nd.get_switch('toggle_waypoints') and nd.in_mode('toggle_display_mode', ['MAP']) and (nd.rangeNm() <= 40);
 					layer.group.setVisible( nd.get_switch('toggle_waypoints') );
@@ -69,6 +59,7 @@ var NDStyles = {
 					}
 				}, # end of layer update predicate
 			}, # end of FIX layer
+
 			# Should redraw every 10 seconds
 			{ name:'storms', update_on:['toggle_range','toggle_weather','toggle_display_mode'],
 				predicate: func(nd, layer) {
@@ -81,7 +72,8 @@ var NDStyles = {
 					layer._view.setVisible(visible);
 				}, # end of layer update predicate
 			}, # end of storms layer
-			{ name:'airplaneSymbol', update_on:['toggle_display_mode'], 
+
+			{ name:'airplaneSymbol', disabled:1, update_on:['toggle_display_mode'], 
 				predicate: func(nd, layer) {
 					var visible = nd.get_switch('toggle_display_mode') == "PLAN";
 					if (visible) {
@@ -89,78 +81,56 @@ var NDStyles = {
 					} layer._view.setVisible(visible);
 				},
 			},
-			{ name:'airports-nd', update_on:['toggle_range','toggle_airports','toggle_display_mode'],
+			{ name:'APS', isMapStructure:1, update_on:['toggle_display_mode'], 
 				predicate: func(nd, layer) {
-					# print("Running airports-nd predicate");
+					var visible = nd.get_switch('toggle_display_mode') == "PLAN";
-					var visible = nd.get_switch('toggle_airports') and nd.in_mode('toggle_display_mode', ['MAP']);
+					layer.group.setVisible( visible );
 					if (visible) {
-						trigger_update( layer ); # clear & redraw
+						layer.update();
+					}
+				},
+			},
+
+			{ name:'APT', isMapStructure:1, update_on:['toggle_range','toggle_airports','toggle_display_mode'],
+				predicate: func(nd, layer) {
+					# toggle visibility here
+					var visible=nd.get_switch('toggle_airports') and nd.in_mode('toggle_display_mode', ['MAP']);
+					layer.group.setVisible( visible );
+					if (visible) {
+						#print("Updating MapStructure ND layer: APT");
+						layer.update();
 					}
-					layer._view.setVisible( visible );
 				}, # end of layer update predicate
-			}, # end of airports layer
+			}, # end of APT layer
 
 			# Should distinct between low and high altitude navaids. Hiding above 40 NM for now, to prevent clutter/lag.
-			{ name:'vor', disabled:1, update_on:['toggle_range','toggle_stations','toggle_display_mode'],
-				predicate: func(nd, layer) {
-					# print("Running vor layer predicate");
-					var visible = nd.get_switch('toggle_stations') and nd.in_mode('toggle_display_mode', ['MAP']) and (nd.rangeNm() <= 40);
-					if(visible) {
-						trigger_update( layer ); # clear & redraw
-					}
-					layer._view.setVisible( nd.get_switch('toggle_stations') );
-				}, # end of layer update predicate
-			}, # end of VOR layer
 			{ name:'VOR', isMapStructure:1, update_on:['toggle_range','toggle_stations','toggle_display_mode'],
 				# FIXME: this is a really ugly place for controller code
 				predicate: func(nd, layer) {
-					# print("Running vor layer predicate");
 					# toggle visibility here
 					var visible = nd.get_switch('toggle_stations') and nd.in_mode('toggle_display_mode', ['MAP']) and (nd.rangeNm() <= 40);
 					layer.group.setVisible( visible );
 					if (visible) {
 						#print("Updating MapStructure ND layer: VOR");
-						# (Hopefully) smart update
 						layer.update();
 					}
 				}, # end of layer update predicate
 			}, # end of VOR layer
 
-			# Should distinct between low and high altitude navaids. Hiding above 40 NM for now, to prevent clutter/lag.
-			{ name:'dme', disabled:1, update_on:['toggle_range','toggle_stations'],
-				predicate: func(nd, layer) {
-					var visible = nd.get_switch('toggle_stations') and nd.in_mode('toggle_display_mode', ['MAP']) and (nd.rangeNm() <= 40);
-					if(visible) {
-						trigger_update( layer ); # clear & redraw
-					}
-					layer._view.setVisible( nd.get_switch('toggle_stations') );
-				}, # end of layer update predicate
-			}, # end of DME layers
 			{ name:'DME', isMapStructure:1, update_on:['toggle_range','toggle_stations'],
 				# FIXME: this is a really ugly place for controller code
 				predicate: func(nd, layer) {
 					var visible = nd.get_switch('toggle_stations') and nd.in_mode('toggle_display_mode', ['MAP']) and (nd.rangeNm() <= 40);
-					# print("Running vor layer predicate");
 					# toggle visibility here
 					layer.group.setVisible( visible );
 					if (visible) {
 						#print("Updating MapStructure ND layer: DME");
-						# (Hopefully) smart update
 						layer.update();
 					}
 				}, # end of layer update predicate
 			}, # end of DME layer
 
-			{ name:'mp-traffic', update_on:['toggle_range','toggle_traffic'],
+			{ name:'TFC', isMapStructure:1, update_on:['toggle_range','toggle_traffic'],
-				predicate: func(nd, layer) {
-					var visible = nd.get_switch('toggle_traffic');
-					layer._view.setVisible( visible );
-					if (visible) {
-						trigger_update( layer ); # clear & redraw
-					}
-				}, # end of layer update predicate
-			}, # end of traffic  layer
-			{ name:'TFC', disabled:1, isMapStructure:1, update_on:['toggle_range','toggle_traffic'],
 				predicate: func(nd, layer) {
 					var visible = nd.get_switch('toggle_traffic');
 					layer.group.setVisible( visible );
@@ -707,22 +677,15 @@ var update_weather = func {
 }
 update_weather();
 
-# Hack to update airplane symbol location on PLAN mode every second
-var update_apl_sym = func {
-	if (getprop("/instrumentation/efis/mfd/display-mode") == "PLAN")
-		setprop("/instrumentation/efis/mfd/display-mode","PLAN");
-	settimer(update_apl_sym, 5);
-}
-update_apl_sym();
-
 ##
 # TODO:
 # - introduce a MFD class (use it also for PFD/EICAS)
 # - introduce a SGSubsystem class and use it  here
 # - introduce a Boeing NavDisplay class
 var NavDisplay = {
+	# static
+	id:0,
 
-	# reset handler
 	del: func {
 		print("Cleaning up NavDisplay");
 		# shut down all timers and other loops here
@@ -735,6 +698,7 @@ var NavDisplay = {
 		if (me.canvas_handle != nil)
 			me.canvas_handle.del();
 		me.inited = 0;
+		NavDisplay.id -= 1;
 	},
 
 	listen: func(p,c) {
@@ -780,6 +744,7 @@ var NavDisplay = {
 	# TODO: the ctor should allow customization, for different aircraft
 	# especially properties and SVG files/handles (747, 757, 777 etc)
 	new : func(prop1, switches=default_switches, style='Boeing') {
+		NavDisplay.id +=1;
 		var m = { parents : [NavDisplay]};
 
 		m.inited = 0;
@@ -834,7 +799,7 @@ var NavDisplay = {
 
 		return m;
 	},
-	newMFD: func(canvas_group, parent=nil)
+	newMFD: func(canvas_group, parent=nil, options=nil)
 	{
 		if (me.inited) die("MFD already was added to scene");
 		me.inited = 1;
@@ -872,7 +837,6 @@ var NavDisplay = {
 		                      "staArrowL","staArrowR","staToL","staFromL","staToR","staFromR"] )
 			me.symbols[element] = me.nd.getElementById(element).updateCenter();
 
-		# this should probably be using Philosopher's new SymbolLayer ?
 		me.map = me.nd.createChild("map","map")
 			.set("clip", "rect(124, 1024, 1024, 0)")
 			.set("screen-range", "700");
@@ -908,19 +872,40 @@ var NavDisplay = {
 		# so we need some simple way to communicate between frontend<->backend until we have real controllers
 		# for now, a single controller hash is shared by most layers - unsupported callbacks are simply ignored by the draw files
 		#
+
 		var controller = {
+			parents: [canvas.Map.Controller],
+			_pos: nil, _time: nil,
 			query_range: func get_range(),
 			is_tuned:is_tuned,
 			get_tuned_course:get_course_by_freq,
 			get_position: get_current_position,
+			new: func(map) return { parents:[controller], map:map },
+			should_update_all: func {
+				# TODO: this is just copied from aircraftpos.controller,
+				# it really should be moved to somewhere common and reused
+				# and extended to fully differentiate between "static"
+				# and "volatile" layers.
+				var pos = me.map.getPosCoord();
+				if (pos == nil) return 0;
+				var time = systime();
+				if (me._pos == nil)
+					me._pos = geo.Coord.new(pos);
+				else {
+					var dist_m = me._pos.direct_distance_to(pos);
+					# 2 NM until we update again
+					if (dist_m < 2 * NM2M) return 0;
+					# Update at most every 4 seconds to avoid excessive stutter:
+					elsif (time - me._time < 4) return 0;
+				}
+				#print("update aircraft position");
+				var (x,y,z) = pos.xyz();
+				me._pos.set_xyz(x,y,z);
+				me._time = time;
+				return 1;
+			},
 		};
-
+		me.map.setController(controller);
-		# FIXME: MapStructure: big hack
-		canvas.Symbol.Controller.get("VOR").query_range = controller.query_range;
-		canvas.Symbol.Controller.get("VOR").get_tuned_course = controller.get_tuned_course;
-		canvas.Symbol.Controller.get("DME").is_tuned = controller.is_tuned;
-		canvas.SymbolLayer.Controller.get("TFC").query_range = controller.query_range;
-		canvas.SymbolLayer.Controller.get("TFC").get_position = controller.get_position;
 
 		###
 		# set up various layers, controlled via callbacks in the controller hash
@@ -938,11 +923,13 @@ var NavDisplay = {
 			var render_target = (!contains(layer,'not_a_map') or !layer.not_a_map) ? me.map : me.nd;
 
 			var the_layer = nil;
-			if(!layer['isMapStructure'])
+			if(!layer['isMapStructure']) # set up an old layer
 				the_layer = me.layers[layer.name] = canvas.MAP_LAYERS[layer.name].new( render_target, layer.name, controller );
 			else {
 				printlog(_MP_dbg_lvl, "Setting up MapStructure-based layer for ND, name:", layer.name);
-				render_target.addLayer(factory: canvas.SymbolLayer, type_arg: layer.name);
+				var opt = options != nil and options[layer.name] != nil ? options[layer.name] :nil;
+				# print("Options is: ", opt!=nil?"enabled":"disabled");
+				render_target.addLayer(factory: canvas.SymbolLayer, type_arg: layer.name, options:opt);
 				the_layer = me.layers[layer.name] = render_target.getLayer(layer.name);
 			}
 
@@ -990,6 +977,14 @@ var NavDisplay = {
 	# and update each model accordingly
 	update: func() # FIXME: This stuff is still too aircraft specific, cannot easily be reused by other aircraft
 	{
+		var _time = systime();
+
+		# Variables:
+		var userLat = me.aircraft_source.get_lat();
+		var userLon = me.aircraft_source.get_lon();
+		var userGndSpd = me.aircraft_source.get_gnd_spd();
+		var userVSpd = me.aircraft_source.get_vspd();
+		var dispLCD = me.get_switch('toggle_display_type') == "LCD";
 		# Heading update
 		var userHdgMag = me.aircraft_source.get_hdg_mag();
 		var userHdgTru = me.aircraft_source.get_hdg_tru();
@@ -1005,6 +1000,12 @@ var NavDisplay = {
 			var userHdg=userHdgMag;
 			var userTrk=userTrkMag;
 		}
+		# this should only ever happen when testing the experimental AI/MP ND driver hash (not critical)
+		# or when an error occurs (critical)
+		if (!userHdg or !userTrk or !userLat or !userLon) {
+			print("aircraft source invalid, returning !");
+			return;
+		}
 		if (me.aircraft_source.get_gnd_spd() < 80)
 			userTrk = userHdg;
 		
@@ -1020,18 +1021,40 @@ var NavDisplay = {
 			me.symbols.hdgTrk.setText("HDG");
 		}
 
-		var userLat = me.aircraft_source.get_lat();
+		# First, update the display position of the map
-		var userLon = me.aircraft_source.get_lon();
+		var pos = {
-		var userGndSpd = me.aircraft_source.get_gnd_spd();
+			lat: nil, lon: nil,
-		var userVSpd = me.aircraft_source.get_vspd();
+			alt: nil, hdg: nil,
-		var dispLCD = me.get_switch('toggle_display_type') == "LCD";
+			range: nil,
+		};
+		pos.range = me.rangeNm(); # avoid this  here, use a listener instead
+		# reposition the map, change heading & range:
+		if(me.in_mode('toggle_display_mode', ['PLAN'])) {
+			pos.hdg = 0;
+			if (getprop(me.efis_path ~ "/inputs/plan-wpt-index") >= 0) {
+				pos.lat = getprop("/autopilot/route-manager/route/wp["~getprop(me.efis_path ~ "/inputs/plan-wpt-index")~"]/latitude-deg");
+				pos.lon = getprop("/autopilot/route-manager/route/wp["~getprop(me.efis_path ~ "/inputs/plan-wpt-index")~"]/longitude-deg");
+			} else {
+				pos.lat = me.map.getLat();
+				pos.lon = me.map.getLon();
+			}
+		} else {
+			pos.hdg = userHdgTrkTru;
+			pos.lat = userLat;
+			pos.lon = userLon;
+		}
+		call(me.map.setPos, [pos.lat, pos.lon], me.map, pos);
 
-		# this should only ever happen when testing the experimental AI/MP ND driver hash (not critical)
+		# MapStructure update!
-		if (!userHdg or !userTrk or !userLat or !userLon) {
+		if (me.map.controller.should_update_all()) {
-			print("aircraft source invalid, returning !");
+			me.map.update();
-			return;
+		} else {
+			# TODO: ugly list here
+			me.map.update(func(layer) (var n=layer.type) == "TFC" or n == "APS");
 		}
 
+		# Other symbol update
+		# TODO: should be refactored!
 		if(me.in_mode('toggle_display_mode', ['PLAN']))
 			me.map.setTranslation(512,512);
 		elsif(me.get_switch('toggle_centered'))
@@ -1105,22 +1128,8 @@ var NavDisplay = {
 
 		me.symbols.range.setText(sprintf("%3.0f",me.rangeNm()/2));
 
-		# reposition the map, change heading & range:
-		if(me.in_mode('toggle_display_mode', ['PLAN'])) {
-			me.map._node.getNode("hdg",1).setDoubleValue(0);
-			if (getprop(me.efis_path ~ "/inputs/plan-wpt-index") >= 0) {
-				me.map._node.getNode("ref-lat",1).setDoubleValue(getprop("/autopilot/route-manager/route/wp["~getprop(me.efis_path ~ "/inputs/plan-wpt-index")~"]/latitude-deg"));
-				me.map._node.getNode("ref-lon",1).setDoubleValue(getprop("/autopilot/route-manager/route/wp["~getprop(me.efis_path ~ "/inputs/plan-wpt-index")~"]/longitude-deg"));
-			}
-		} else {
-			me.map._node.getNode("ref-lat",1).setDoubleValue(userLat);
-			me.map._node.getNode("ref-lon",1).setDoubleValue(userLon);
-		}
-		# The set range of the map does not correspond to what we see in-sim!!
-		me.map._node.getNode("range",1).setDoubleValue(me.rangeNm()); # avoid this  here, use a listener instead
-
 		# Hide heading bug 10 secs after change
-		var vhdg_bug = getprop("autopilot/settings/heading-bug-deg");
+		var vhdg_bug = getprop("autopilot/settings/heading-bug-deg") or 0;
 		var hdg_bug_active = getprop("autopilot/settings/heading-bug-active");
 		if (hdg_bug_active == nil)
 			hdg_bug_active = 1;
@@ -1149,7 +1158,6 @@ var NavDisplay = {
 			me.symbols.selHdgLine2.setRotation(hdgBugRot);
 			me.symbols.compass.setRotation(-userHdgTrk*D2R);
 			me.symbols.compassApp.setRotation(-userHdgTrk*D2R);
-			me.map._node.getNode("hdg",1).setDoubleValue(userHdgTrkTru);
 		}
 		if(me.get_switch('toggle_centered')) {
 			if (me.in_mode('toggle_display_mode', ['APP','VOR']))
@@ -1336,5 +1344,9 @@ var NavDisplay = {
 		me.symbols['status.wpt'].setVisible( me.get_switch('toggle_waypoints') and me.in_mode('toggle_display_mode', ['MAP']));
 		me.symbols['status.arpt'].setVisible( me.get_switch('toggle_airports') and me.in_mode('toggle_display_mode', ['MAP']));
 		me.symbols['status.sta'].setVisible( me.get_switch('toggle_stations') and  me.in_mode('toggle_display_mode', ['MAP']));
+		# Okay, _how_ do we hook this up with FGPlot?
+		#print("ND update took "~(systime()-_time)~" seconds");
+		setprop("/instrumentation/navdisplay["~ NavDisplay.id ~"]/update-ms", systime() - _time);
+		
 	}
 };

Nasal/canvas/map/parking.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var draw_parking = func(group, apt, lod) {
 	var group = group.createChild("group", "apt-"~apt.id);
 	foreach(var park; apt.parking()) {

Nasal/canvas/map/parking.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 #TODO: use custom Model/DataProvider
 var ParkingLayer = {}; # make(Layer);
 ParkingLayer.new = func(group, name) {

Nasal/canvas/map/route.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 ##
 # Draw a route with tracks and waypoints
 #

Nasal/canvas/map/route.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var RouteLayer =  {};
 
 RouteLayer.new = func(group,name) {

Nasal/canvas/map/route.model

@@ -1,3 +1,4 @@
+# WARNING: *.model files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 
 var RouteModel = {route_monitor:nil};
 RouteModel.new = func make(LayerModel, RouteModel);

Nasal/canvas/map/runway-nd.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 
 var draw_rwy_nd = func (group, rwy, controller=nil, lod=nil) {
  # print("drawing runways-nd");

Nasal/canvas/map/runway-nd.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var RunwayNDLayer = {}; 
  RunwayNDLayer.new = func(group, name) {
         var m=Layer.new(group, name, RunwayNDModel ); 

Nasal/canvas/map/runway-nd.model

@@ -1,3 +1,4 @@
+# WARNING: *.model files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var RunwayNDModel = {};
  RunwayNDModel.new = func make( LayerModel, RunwayNDModel );
 

Nasal/canvas/map/runways.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 
 #TODO: split: draw_single_runway(pos)
 

Nasal/canvas/map/runways.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 #TODO: use custom Model/DataProvider
 var RunwayLayer = {}; # make(Layer);
 RunwayLayer.new = func(group, name) {

Nasal/canvas/map/storm.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 ##
 # draw a single storm symbol
 #

Nasal/canvas/map/storms.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var StormLayer =  {};
 StormLayer.new = func(group,name, controller) {
 	var m=Layer.new(group, name, StormModel);

Nasal/canvas/map/storms.model

@@ -1,3 +1,4 @@
+# WARNING: *.model files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var StormModel = {};
 StormModel.new = func make( LayerModel, StormModel );
 

Nasal/canvas/map/taxiways.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var draw_taxiways = func(group, apt, lod) {     # TODO: the LOD arg isn't stricly needed here, 
                                                 # the layer is a conventional canvas group, so it can access its map 
                                                 # parent and just read the "range" property to do LOD handling

Nasal/canvas/map/taxiways.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 #TODO: use custom Model/DataProvider
 var TaxiwayLayer = {}; # make(Layer);
 TaxiwayLayer.new = func(group, name) {

Nasal/canvas/map/tcas_arrow_a500.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var draw_tcas_arrow_above_500 = func(group, lod=0) {
 	group.createChild("path")
 		.moveTo(0,-17)

Nasal/canvas/map/tcas_arrow_b500.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var draw_tcas_arrow_below_500 = func(group) {
 
 group.createChild("path")

Nasal/canvas/map/test.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 
 #TODO: use custom Model/DataProvider
 var TestLayer = {}; # make(Layer);

Nasal/canvas/map/tower.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var draw_tower = func (group, apt,lod) {
 	var group = group.createChild("group", "tower");
 	# TODO: move to map_elements.nas (tower, runway, parking etc)

Nasal/canvas/map/tower.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var TowerLayer = {};
 TowerLayer.new = func(group, name) {
 	var m=Layer.new(group, name, AirportModel ); #FIXME: AirportModel can be shared by Taxiways, Runways etc!!

Nasal/canvas/map/traffic.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var draw_traffic = func(group, traffic, lod=0)
 {
 		var a = traffic;

Nasal/canvas/map/traffic.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var MPTrafficLayer =  {};
 MPTrafficLayer.new = func(group,name, controller=nil) {
 	var m=Layer.new(group, name, MPTrafficModel);

Nasal/canvas/map/traffic.model

@@ -1,3 +1,4 @@
+# WARNING: *.model files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var MPTrafficModel = {};
 MPTrafficModel.new = func make(LayerModel, MPTrafficModel);
 

Nasal/canvas/map/vor.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var draw_vor = func (group, vor, controller=nil, lod = 0) {
 
 	if (0) {

Nasal/canvas/map/vor.layer

@@ -1,3 +1,4 @@
+# WARNING: *.layer files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var VORLayer =  {};
 VORLayer.new = func(group,name, controller) {
 	var m=Layer.new(group, name, VORModel );

Nasal/canvas/map/vor.model

@@ -1,3 +1,4 @@
+# WARNING: *.model files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 var VORModel = {};
 VORModel.new = func make( LayerModel, VORModel );
 

Nasal/canvas/map/waypoint.draw

@@ -1,3 +1,4 @@
+# WARNING: *.draw files will be deprecated, see: http://wiki.flightgear.org/MapStructure
 ##
 # Draw a waypoint symbol and waypoint name (Gijs' 744 ND.nas code)
 

Nasal/geo.nas

@@ -328,7 +328,8 @@ var viewer_position = func {
 # searchCmd executes and returns the actual search,
 # onAdded and onRemoved are callbacks,
 # and obj is a "me" reference (defaults to "me" in the
-# caller's namespace).
+# caller's namespace). If searchCmd returns nil, nothing
+# happens, i.e. the diff is cancelled.
 var PositionedSearch = {
 	new: func(searchCmd, onAdded, onRemoved, obj=nil) {
 		return {
@@ -351,6 +352,8 @@ var PositionedSearch = {
 		return ret;
 	},
 	diff: func(old, new) {
+		if (new == nil)
+			return [old, [], []];
 		var removed = old~[]; #copyvec
 		var added = new~[];
 		# Mark common elements from removed and added:
@@ -369,6 +372,10 @@ var PositionedSearch = {
 			# Optimized search using C code
 			var old = me.result~[]; #copyvec
 			me.result = call(searchCmd, nil, me.obj);
+			if (me.result == nil)
+			{ me.result = old; return }
+			if (typeof(me.result) != 'vector') die("geo.PositionedSearch(): A searchCmd must return a vector of elements or nil !!"); # TODO: Maybe make this a hash instead to wrap a vector, so that we can implement basic type-checking - e.g. doing isa(PositionedSearchResult, me.result) would be kinda neat and could help troubleshooting
+			else
 			positioned.diff( old,
 			                 me.result,
 			                 func call(me.onAdded, arg, me.obj),