Add ol.BrowserFeature.HAS_WEBGL

src/ol/browserfeature.js

@@ -1,5 +1,9 @@
 goog.provide('ol.BrowserFeature');
 
+goog.require('goog.dom');
+goog.require('goog.dom.TagName');
+goog.require('ol.webgl');
+
 
 /**
  * @define {boolean} Assume touch.
@@ -27,3 +31,29 @@ ol.BrowserFeature.HAS_TOUCH = ol.ASSUME_TOUCH ||
     (goog.global.document &&
     'ontouchstart' in goog.global.document.documentElement) ||
     !!(goog.global.navigator.msPointerEnabled);
+
+
+/**
+ * True if browser supports WebGL.
+ * @const
+ * @type {boolean}
+ * @todo stability experimental
+ */
+ol.BrowserFeature.HAS_WEBGL = (
+    /**
+     * @return {boolean} WebGL supported.
+     */
+    function() {
+      if (!('WebGLRenderingContext' in goog.global)) {
+        return false;
+      }
+      try {
+        var canvas = /** @type {HTMLCanvasElement} */
+            (goog.dom.createElement(goog.dom.TagName.CANVAS));
+        return !goog.isNull(ol.webgl.getContext(canvas, {
+          failIfMajorPerformanceCaveat: true
+        }));
+      } catch (e) {
+        return false;
+      }
+    })();