Add snapping to synthetic points example (to be removed)

examples/synthetic-points.js

@@ -3,6 +3,7 @@ goog.require('ol.Map');
 goog.require('ol.Overlay');
 goog.require('ol.RendererHint');
 goog.require('ol.View2D');
+goog.require('ol.geom.LineString');
 goog.require('ol.geom.Point');
 goog.require('ol.layer.Vector');
 goog.require('ol.shape');
@@ -37,10 +38,11 @@ var styles = {
   })]
 };
 
+var vectorSource = new ol.source.Vector({
+  features: features
+});
 var vector = new ol.layer.Vector({
-  source: new ol.source.Vector({
-    features: features
-  }),
+  source: vectorSource,
   styleFunction: function(feature, resolution) {
     return styles[feature.get('size')];
   }
@@ -61,6 +63,60 @@ var map = new ol.Map({
   overlays: [popup]
 });
 
+var point = null;
+var line = null;
+var displaySnap = function(coordinate) {
+  var closestFeature = vectorSource.getClosestFeatureToCoordinate(coordinate);
+  if (closestFeature === null) {
+    point = null;
+    line = null;
+  } else {
+    var geometry = closestFeature.getGeometry();
+    var closestPoint = geometry.getClosestPoint(coordinate);
+    if (point === null) {
+      point = new ol.geom.Point(closestPoint);
+    } else {
+      point.setCoordinates(closestPoint);
+    }
+    if (line === null) {
+      line = new ol.geom.LineString([coordinate, closestPoint]);
+    } else {
+      line.setCoordinates([coordinate, closestPoint]);
+    }
+  }
+  map.requestRenderFrame();
+};
+
+$(map.getViewport()).on('mousemove', function(evt) {
+  var coordinate = map.getEventCoordinate(evt.originalEvent);
+  displaySnap(coordinate);
+});
+
+map.on('singleclick', function(evt) {
+  var coordinate = evt.getCoordinate();
+  displaySnap(coordinate);
+});
+
+var imageStyle = ol.shape.renderCircle(10, null, new ol.style.Stroke({
+  color: 'rgba(255,255,0,0.9)',
+  width: 3
+}));
+var strokeStyle = new ol.style.Stroke({
+  color: 'rgba(255,255,0,0.9)',
+  width: 3
+});
+map.on('postcompose', function(evt) {
+  var render = evt.getRender();
+  if (point !== null) {
+    render.setImageStyle(imageStyle);
+    render.drawPointGeometry(point);
+  }
+  if (line !== null) {
+    render.setFillStrokeStyle(null, strokeStyle);
+    render.drawLineStringGeometry(line);
+  }
+});
+
 $(map.getViewport()).on('mousemove', function(e) {
   var pixel = map.getEventPixel(e.originalEvent);