external: quick fix for L.CanvasIconLayer

IITC-CE/Leaflet.Canvas-Markers#14
Solves performance issue caused by several large overlapping canvases,
observed in some browsers (especially while zooming/panning).

As it appeared, not all browsers canvas implementations are equal.
Issues reported for FF, Safari, and not up-to-date Android WebView.

TODO: reimplement the fix in better way

core/external/leaflet.canvas-markers.js

@@ -111,13 +111,22 @@ function layerFactory (L) {
             this._latlngsIdx = new LatLngsIndex();
         },
 
+        _checkDisplay() {
+            if (this._latlngsIdx._total) {
+                this._container.style.display = 'initial';
+            } else {
+                this._container.style.display = 'none';
+            }
+        },
+
         onAdd: function () {
             L.Renderer.prototype.onAdd.call(this);
             L.DomUtil.toBack(this._container);
         },
 
         _initContainer: function () {
             L.Canvas.prototype._initContainer.call(this);
+            this._checkDisplay();
         },
 
         onRemove: function () {
@@ -331,6 +340,7 @@ function layerFactory (L) {
                 this._pointsIdx.insert(marker, batch);
             }
             this._latlngsIdx.insert(marker, batch);
+            this._checkDisplay();
         },
 
         // Adds single layer at a time. Less efficient for rBush
@@ -396,12 +406,14 @@ function layerFactory (L) {
             }).forEach(function (el) {
                 this._latlngsIdx.remove(el);
             }, this);
+            this._checkDisplay();
         },
 
         removeMarker: function (marker, redraw) {
             var latlng = marker.getLatLng();
             var isDisplaying = this._map && this._map.getBounds().pad(this.options.padding).contains(latlng);
             this._latlngsIdx.remove(marker);
+            this._checkDisplay();
 
             if (isDisplaying && redraw) {
                 this._redraw();
@@ -426,6 +438,7 @@ function layerFactory (L) {
             this._latlngsIdx.clear();
             this._pointsIdx.clear();
             this._clear();
+            this._checkDisplay();
             return this;
         }
     });

core/external/versions.md

@@ -41,6 +41,8 @@
 * https://github.com/IITC-CE/Leaflet.Canvas-Markers
   leaflet.canvas-markers.js: 12fb5afd0a8cb7101a2e8f931e20be76818fe917
   (https://github.com/Spaction/Leaflet.Canvas-Markers/pull/3)
+  + quickfix https://github.com/IITC-CE/Leaflet.Canvas-Markers/pull/14
+  https://github.com/IITC-CE/Leaflet.Canvas-Markers/blob/83d8ea3f0fb4d7e242914a9021270326a7a5c03b/src/plugin/leaflet.canvas-markers.js
   used in: ornaments.js