Implement as dynamic setting of the map bounds.

assets/maps/src/Map.calculateFeatureBounds.js

@@ -0,0 +1,69 @@
+/**
+ * Extend map so that it can calculate their bounds depending of the features with the property affectBounds.
+ */
+L.Map.include({
+    _dynamicBounds: null,
+
+    /**
+     * Calculate feature bounds.
+     *
+     * Use this method without any arguments to scan the whole map for features.
+     *
+     * If a layer is passed then only this layer is used if the map option adjustBounds is set or the force flag
+     * is given.
+     *
+     * @param {L.Layer} layer Optional limit to a layer.
+     * @param {bool}    force Force scaning of a layer no matter if adjustBounds is set.
+     *
+     * @return void
+     */
+    calculateFeatureBounds: function(layer, force) {
+        if (layer) {
+            if (!this.options.adjustBounds && !force) {
+                return;
+            }
+
+            this._scanForBounds(layer);
+        } else {
+            this.eachLayer(this._scanForBounds, this);
+        }
+
+        if (this._dynamicBounds) {
+            this.fitBounds(this._dynamicBounds);
+        }
+    },
+
+    /**
+     * Scan recursively for bounds in a layer and extend _dynamicBounds if any found.
+     *
+     * @param {L.Layer} layer The layer
+     * @private
+     */
+    _scanForBounds: function(layer) {
+        var source;
+
+        if (layer.feature && layer.feature.properties && layer.feature.properties.affectBounds) {
+            if (layer.getBounds) {
+                source = layer.getBounds();
+
+                if (source.isValid()) {
+                    if (this._dynamicBounds) {
+                        this._dynamicBounds.extend(source);
+                    } else {
+                        this._dynamicBounds = L.latLngBounds(source.getSouthWest(), source.getNorthEast());
+                    }
+                }
+            } else if (layer.getLatLng) {
+                source = layer.getLatLng();
+
+                if (this._dynamicBounds) {
+                    this._dynamicBounds.extend(source);
+                } else {
+                    this._dynamicBounds = L.latLngBounds(source, source);
+                }
+            }
+        } else if (layer.eachLayer) {
+            layer.eachLayer(this._scanForBounds, this);
+        }
+    }
+});