First pass at #386, fallback message may need work

.settings/settings.json

@@ -1,4 +1,5 @@
 // Place your settings in this file to overwrite default and user settings.
 {
-	"editor.tabSize": 3
+	"editor.tabSize": 3,
+	"editor.insertSpaces": true
 }

GruntFile.js

@@ -85,6 +85,13 @@ module.exports = function (grunt) {
       // Shell Commands
       //
       shell: {
+
+         //
+         // Execute a small server
+         //
+         server: {
+            command: 'python -m SimpleHTTPServer 8089'
+         },
 
          //
          // Execute TypeScript compiler against Excalibur core
@@ -214,6 +221,8 @@ module.exports = function (grunt) {
 
    grunt.registerTask('compile', ['shell:tsc', 'minified', 'concat', 'copy', 'shell:nuget'])
 
+   grunt.registerTask('server', [])
+
    // Travis task - for Travis CI
    grunt.registerTask('travis', 'default');
 };

src/engine/Engine.ts

@@ -16,6 +16,7 @@
 /// <reference path="Loader.ts" />
 /// <reference path="Promises.ts" />
 /// <reference path="Util/Util.ts" />
+/// <reference path="Util/Detector.ts" />
 /// <reference path="Binding.ts" />
 /// <reference path="TileMap.ts" />
 /// <reference path="Label.ts" />
@@ -402,6 +403,9 @@ module ex {
 
       // this is a reference to the current requestAnimationFrame return value
       private _requestId: number;
+
+      // this determines whether excalibur is compatible with your browser
+      private _compatible: boolean;
 
       // loading
       private _loader: ILoadable;
@@ -449,8 +453,24 @@ module ex {
             displayMode = options.displayMode;
          }
 
+         // Check compatibility 
+         if(!(this._compatible = (new ex.Detector()).compatible())) {
+            var message = document.createElement('div');
+            message.innerText = 'Sorry, your browser does not support all the features needed for Excalibur';
+            document.body.appendChild(message);
+
+            if(canvasElementId) {
+               var canvas = document.getElementById(canvasElementId);
+               if(canvas) {
+                  canvas.parentElement.removeChild(canvas);
+               }
+            }
+
+            return;
+         }
+
          this._logger = Logger.getInstance();
-
+         
          this._logger.info('Powered by Excalibur.js visit", "http://excaliburjs.com", "for more information.');
 
          this._logger.debug('Building engine...');
@@ -478,7 +498,7 @@ module ex {
             this._logger.debug('Engine viewport is fullscreen');
             this.displayMode = DisplayMode.FullScreen;
          }
-
+                  
 
          this._loader = new Loader();
 
@@ -1015,6 +1035,11 @@ module ex {
        * [[Sound]], or [[Texture]].
        */
       public start(loader?: ILoadable) : Promise<any> {
+         if(!this._compatible) {
+            var promise = new Promise();
+            return promise.reject('Excalibur is incompatible with your browser');
+         }
+
          var loadingComplete: Promise<any>;
          if (loader) {
             loader.wireEngine(this);

src/engine/Util/Detector.ts

@@ -0,0 +1,84 @@
+/// <reference path="Log.ts" />
+module ex {
+
+   export class Detector {
+
+      // critical browser features required for ex to run
+      private _criticalTests = {
+         // Test canvas/2d context support
+         canvasSupport: function() {
+            var elem = document.createElement('canvas');
+            return !!(elem.getContext && elem.getContext('2d'));
+         },
+
+         // Test array buffer support ex uses for downloading binary data
+         arrayBufferSupport: function() {
+            var xhr = new XMLHttpRequest();
+            xhr.open('GET', '/');
+            try {
+               xhr.responseType = 'arraybuffer';
+            } catch (e) {
+               return false;
+            }
+            return xhr.responseType === 'arraybuffer';
+         },
+
+         // Test data urls ex uses for sprites
+         dataUrlSupport: function() {
+            var canvas = document.createElement('canvas');
+            return canvas.toDataURL('image/png').indexOf('data:image/png') === 0;
+         },
+
+         // Test object url support for loading
+         objectUrlSupport: function() {
+            return 'URL' in window && 'revokeObjectURL' in URL && 'createObjectURL' in URL;
+         },
+
+         // RGBA support for colors
+         rgbaSupport: function() {
+            var style = document.createElement('a').style;
+            style.cssText = 'background-color:rgba(150,255,150,.5)';
+
+            return ('' + style.backgroundColor).indexOf('rgba') > -1;
+         }
+      };
+
+      // warnings excalibur performance will be degraded
+      private _warningTest = {
+         webAudioSupport: function() {
+            return !!((<any>window).AudioContext || 
+                     (<any>window).webkitAudioContext || 
+                     (<any>window).mozAudioContext || 
+                     (<any>window).msAudioContext || 
+                     (<any>window).oAudioContext);
+         },
+         webglSupport: function() {
+            var elem = document.createElement('canvas');
+            return !!(elem.getContext && elem.getContext('webgl'));
+         }
+      };
+
+      public compatible(): boolean {			
+         // Critical test will for ex not to run
+         for(var test in this._criticalTests) {
+            if(!this._criticalTests[test]()) {
+               ex.Logger.getInstance().error('Critical browser feature test for Excalibur failed:', 
+                  test, 'Excalibur cannot run!');
+               return false;
+            }
+         }
+
+         // Warning tests do not for ex to return false to compatibility
+         for(var warning in this._warningTest) {
+            if(!this._warningTest[warning]()) {
+               ex.Logger.getInstance().warn('Warning browser feature test for Excalibur failed:', 
+                  warning, 'Excalibur performance will be degraded');
+            }
+         }
+
+         return true;
+      }
+
+   }
+
+}