adding svg layer...

ref #5587

modules/svg/geolocate.js

@@ -0,0 +1,91 @@
+
+export function svgGeolocate(projection, context, dispatch) {
+    var throttledRedraw = _throttle(function () { dispatch.call('change'); }, 1000);
+    var minZoom = 12;
+    var layer = d3_select(null);
+    var _mapillary;
+
+
+    function init() {
+        if (svgGeolocate.initialized) return;  // run once
+        svgGeolocate.enabled = false;
+        svgGeolocate.initialized = true;
+    }
+
+    function showLayer() {
+        layer.attr('display', 'block'); 
+        layerOn();
+    }
+
+
+    function hideLayer() {
+        throttledRedraw.cancel();
+        layer
+            .transition()
+            .duration(250)
+            .style('opacity', 0)
+            .on('end', function() {});
+    }
+
+    function layerOn() {
+        layer
+            .style('opacity', 0)
+            .transition()
+            .duration(250)
+            .style('opacity', 1)
+            .on('end', function () { dispatch.call('change'); });
+
+    }
+
+    function layerOff() {
+        // layer.selectAll('.viewfield-group').remove();
+        layer.style('display', 'none');
+    }
+
+    function update(location) {
+
+        var groups = layer.selectAll('.markers').selectAll('.viewfield-group')
+            .data([location]);
+
+    }
+
+    function drawLocation(selection) {
+        var enabled = svgGeolocate.enabled;
+
+        layer = selection.selectAll('.layer-mapillary-signs')
+            .data([]);
+
+        layer.exit()
+            .remove();
+
+        layer = layer.enter()
+            .append('g')
+            .attr('class', 'layer-geolocate-point')
+            .style('display', enabled ? 'block' : 'none')
+            .merge(layer);
+
+        if (enabled) {
+            layerOn();
+            update();
+        } else {
+            layerOff();
+        }
+    }
+
+    drawLocation.enabled = function(_) {
+        if (!arguments.length) return svgGeolocate.enabled;
+        svgGeolocate.enabled = _;
+        if (svgGeolocate.enabled) {
+            showLayer();
+        } else {
+            hideLayer();
+        }
+        dispatch.call('change');
+        return this;
+    };
+
+
+
+    init();
+    return drawLocation;
+}