added RUNTIME_STEP_START and RUNTIME_STEP_STOP events

Author: fath11

src/engine/runtime.js

@@ -919,6 +919,22 @@ class Runtime extends EventEmitter {
         return 'RUNTIME_DISPOSED';
     }
 
+    /**
+     * Event name when _step() has been called.
+     * @const {string}
+     */
+    static get RUNTIME_STEP_START () {
+        return 'RUNTIME_STEP_START';
+    }
+
+    /**
+     * Event name when _step() has finished all processing within the function.
+     * @const {string}
+     */
+    static get RUNTIME_STEP_END () {
+        return 'RUNTIME_STEP_END';
+    }
+
     /**
      * Event name for reporting that a block was updated and needs to be rerendered.
      * @const {string}
@@ -2563,6 +2579,11 @@ class Runtime extends EventEmitter {
      * inactive threads after each iteration.
      */
     _step () {
+        // RUNTIME_STEP_START runs before BEFORE_EXECUTE
+        // this runs before any processing of this new step
+        this.frameLoop._stepCounter++;
+        this.emit(Runtime.RUNTIME_STEP_START);
+
         if (this.interpolationEnabled) {
             interpolate.setupInitialState(this);
         }
@@ -2646,6 +2667,9 @@ class Runtime extends EventEmitter {
         if (this.interpolationEnabled) {
             this._lastStepTime = Date.now();
         }
+
+        // RUNTIME_STEP_END runs after AFTER_EXECUTE
+        this.emit(Runtime.RUNTIME_STEP_END);
     }
 
     /**