Add symbol renderer

src/ol/symbols.js

@@ -0,0 +1,46 @@
+goog.provide('ol.symbol');
+
+goog.require('goog.dom');
+goog.require('goog.dom.TagName');
+goog.require('ol.style');
+
+
+/**
+ * @param {number} radius Radius.
+ * @param {?ol.style.Fill} fillStyle Fill style.
+ * @param {?ol.style.Stroke} strokeStyle Stroke style.
+ * @return {ol.style.Image} Image.
+ */
+ol.symbol.renderCircle = function(radius, fillStyle, strokeStyle) {
+
+  var canvas = /** @type {HTMLCanvasElement} */
+      (goog.dom.createElement(goog.dom.TagName.CANVAS));
+  var size = 2 * radius + 1;
+  if (!goog.isNull(strokeStyle) && goog.isDef(strokeStyle.width)) {
+    size += strokeStyle.width;
+  }
+  canvas.height = size;
+  canvas.width = size;
+
+  var context = /** @type {CanvasRenderingContext2D} */
+      (canvas.getContext('2d'));
+  context.arc(size / 2, size / 2, radius, 0, 2 * Math.PI, true);
+
+  if (goog.isDefAndNotNull(fillStyle)) {
+    context.fillStyle = fillStyle.color;
+    context.fill();
+  }
+  if (goog.isDefAndNotNull(strokeStyle)) {
+    context.strokeStyle = strokeStyle.color;
+    context.lineWidth = strokeStyle.width;
+    context.stroke();
+  }
+
+  return {
+    anchor: [size / 2, size / 2],
+    image: canvas,
+    rotation: 0,
+    subtractViewRotation: false
+  };
+
+};