feat: camera init and camera error events triggered on window

aframe/examples/marker-events.html

@@ -4,6 +4,16 @@
 <script src="../build/aframe-ar.js"></script>
 <!-- Register an aframe component that allows reacting to marker events -->
 <script>
+    window.addEventListener('camera-init', (data) => {
+        console.log('camera-init', data);
+        // TODO: Add your own code
+    })
+
+    window.addEventListener('camera-error', (error) => {
+        console.log('camera-error', error);
+        // TODO: Add your own code e.g. splash screen, message to user, etc.
+    })
+
 	AFRAME.registerComponent('registerevents', {
 		init: function () {
 			var marker = this.el;
@@ -50,7 +60,7 @@
 				<a-torus-knot radius='0.26' radius-tubular='0.05'>
 					<a-animation attribute="rotation" to="360 0 0" dur="5000" easing='linear' repeat="indefinite"></a-animation>
 				</a-torus-knot>
-			</a-box>			
+			</a-box>
 		</a-marker>
 
 		<!-- add a simple camera -->

three.js/src/threex/threex-artoolkitsource.js

@@ -157,6 +157,8 @@ ARjs.Source.prototype._initSourceWebcam = function(onReady, onError) {
 	// init default value
 	onError = onError || function(error){
 		alert('Webcam Error\nName: '+error.name + '\nMessage: '+error.message)
+		const event = new CustomEvent('camera-error', {error});
+		window.dispatchEvent(event);
 	}
 
 	var domElement = document.createElement('video');
@@ -211,10 +213,12 @@ ARjs.Source.prototype._initSourceWebcam = function(onReady, onError) {
 			// set the .src of the domElement
             domElement.srcObject = stream;
 
+			const event = new CustomEvent('camera-init', {stream});
+			window.dispatchEvent(event);
 			// to start the video, when it is possible to start it only on userevent. like in android
 			document.body.addEventListener('click', function(){
 				domElement.play();
-			})
+			});
 			// domElement.play();
 
 // TODO listen to loadedmetadata instead