update portal-names plugin to avoid drawing labels that overlap

might tweak a bit more...

plugins/portal-names.user.js

@@ -20,13 +20,22 @@
 
 // use own namespace for plugin
 window.plugin.portalNames = function() {};
+
+window.plugin.portalNames.NAME_WIDTH = 80;
+window.plugin.portalNames.NAME_HEIGHT = 23;
+
 window.plugin.portalNames.labelLayers = {};
 window.plugin.portalNames.labelLayerGroup = null;
 
 window.plugin.portalNames.setupCSS = function() {
   $("<style>").prop("type", "text/css").html(''
   +'.plugin-portal-names{'
-    +'font-size:11px;color:#FFFFBB;text-align:center;line-height:12px;'
+    +'color:#FFFFBB;'
+    +'font-size:11px;line-height:12px;'
+    +'text-align:center;padding: 2px;'  // padding needed so shadow doesn't clip
+    +'overflow:hidden;'
+// could try this if one-line names are used
+//    +'white-space: nowrap;text-overflow:ellipsis;'
     +'text-shadow:1px 1px #000,1px -1px #000,-1px 1px #000,-1px -1px #000, 0 0 5px #000;'
     +'pointer-events:none;'
   +'}'
@@ -51,31 +60,96 @@ window.plugin.portalNames.removeLabel = function(guid) {
 }
 
 window.plugin.portalNames.addLabel = function(guid, latLng) {
-  window.plugin.portalNames.removeLabel(guid);
+  var previousLayer = window.plugin.portalNames.labelLayers[guid];
+  if (!previousLayer) {
 
-  var d = window.portals[guid].options.details;
-  var portalName = d.portalV2.descriptiveText.TITLE;
+    var d = window.portals[guid].options.details;
+    var portalName = d.portalV2.descriptiveText.TITLE;
 
-  var label = L.marker(latLng, {
-    icon: L.divIcon({
-      className: 'plugin-portal-names',
-      iconAnchor: [50,0],
-      iconSize: [100,24],
-      html: portalName
-    }),
-    guid: guid,
-  });
-  window.plugin.portalNames.labelLayers[guid] = label;
-  label.addTo(window.plugin.portalNames.labelLayerGroup);
+    var label = L.marker(latLng, {
+      icon: L.divIcon({
+        className: 'plugin-portal-names',
+        iconAnchor: [window.plugin.portalNames.NAME_WIDTH/2,0],
+        iconSize: [window.plugin.portalNames.NAME_WIDTH,window.plugin.portalNames.NAME_HEIGHT],
+        html: portalName
+      }),
+      guid: guid,
+    });
+    window.plugin.portalNames.labelLayers[guid] = label;
+    label.addTo(window.plugin.portalNames.labelLayerGroup);
+  }
 }
 
+window.plugin.portalNames.updatePortalLabels = function() {
+
+  if (Object.keys(window.portals).length > 1000) {
+    // too manuy portals to handle quickly - clear all
+    window.plugin.portalNames.labelLayerGroup.clear();
+    window.plugin.portalNames.labelLayers = {};
+    return;
+  }
+
+  var portalPoints = {};
+
+  for (var guid in window.portals) {
+    var p = window.portals[guid];
+    if (p._map) {  // only consider portals added to the map
+      var point = map.latLngToLayerPoint(p.getLatLng());
+      portalPoints[guid] = point;
+    }
+  }
+
+  var coveredPortals = {};
+
+  for (var guid in portalPoints) {
+    var point = portalPoints[guid];
+    // the bounds used for testing are twice as wide as the portal name marker. this is so that there's no left/right
+    // overlap between two different portals text
+    var largeBounds = L.bounds (
+              point.subtract([window.plugin.portalNames.NAME_WIDTH,0]),
+              point.add([window.plugin.portalNames.NAME_WIDTH,window.plugin.portalNames.NAME_HEIGHT])
+    );
+
+    for (var otherGuid in portalPoints) {
+      if (guid != otherGuid) {
+        var otherPoint = portalPoints[otherGuid];
+
+        if (largeBounds.contains(otherPoint)) {
+          // another portal is within the rectangle for this one's name - so no name for this one
+          coveredPortals[guid] = true;
+          break;
+        }
+      }
+    }
+  }
+
+  for (var guid in coveredPortals) {
+    delete portalPoints[guid];
+  }
+
+  // remove any not wanted
+  for (var guid in window.plugin.portalNames.labelLayers) {
+    if (!(guid in portalPoints)) {
+      window.plugin.portalNames.removeLabel(guid);
+    }
+  }
+
+  // and add those we do
+  for (var guid in portalPoints) {
+    window.plugin.portalNames.addLabel(guid, portals[guid].getLatLng());
+  }
+}
+
+
+
 var setup = function() {
   window.plugin.portalNames.setupCSS();
 
   window.plugin.portalNames.labelLayerGroup = new L.LayerGroup();
   window.addLayerGroup('Portal Names', window.plugin.portalNames.labelLayerGroup, true);
 
-  window.addHook('portalAdded', window.plugin.portalNames.portalAdded);
+  window.addHook('mapDataRefreshEnd', window.plugin.portalNames.updatePortalLabels);
+  window.map.on('overlayadd overlayremove', window.plugin.portalNames.updatePortalLabels);
 }
 
 // PLUGIN END //////////////////////////////////////////////////////////