support creating GrabDragInteraction with state from previous model, #…

…354

Signed-off-by: Michael Kauzmann <[email protected]>

js/common/model/Mass.ts

@@ -175,6 +175,14 @@ export default abstract class Mass extends PhetioObject {
 
   public readonly resetEmitter = new Emitter();
 
+  // MassViews and their GrabDragInteractions are recreated, the mass stores relevant information from one instantiation to
+  // another. These quantities do not need to be PhET-iO stateful, because they are related to usability and
+  // accessibility, and when studio launches a Standard PhET-iO Wrapper, these values should be zeroed out, not preserved
+  // in the state. These values are internal, and should not be read. Instead, get the most up-to-date info from the
+  // view's GrabDragInteraction itself.
+  public numberOfKeyboardGrabs = 0;
+  public numberOfGrabs = 0;
+
   protected constructor( engine: PhysicsEngine, providedOptions: MassOptions ) {
 
     const options = optionize<MassOptions, SelfOptions, PhetioObjectOptions>()( {
@@ -582,6 +590,9 @@ export default abstract class Mass extends PhetioObject {
 
     this.resetPosition();
 
+    this.numberOfGrabs = 0;
+    this.numberOfKeyboardGrabs = 0;
+
     this.resetEmitter.emit();
   }
 

js/common/view/MassView.ts

@@ -157,10 +157,11 @@ export default abstract class MassView extends Disposable {
         onRelease() {
           endKeyboardInteraction();
         },
-        tandem: Tandem.OPT_OUT
+        tandem: Tandem.OPT_OUT,
+        numberOfKeyboardGrabs: mass.numberOfKeyboardGrabs,
+        numberOfGrabs: mass.numberOfGrabs
       } );
 
-
       const myListener = () => {
 
         if ( this.focusablePath && this.grabDragInteraction && !this.focusablePath.isDisposed ) {
@@ -205,6 +206,11 @@ export default abstract class MassView extends Disposable {
       mass.transformedEmitter.addListener( myListener );
 
       this.disposeEmitter.addListener( () => {
+
+        // Keep in sync for the next time this mass will create a new view
+        mass.numberOfKeyboardGrabs = this.grabDragInteraction!.numberOfKeyboardGrabs;
+        mass.numberOfGrabs = this.grabDragInteraction!.numberOfGrabs;
+
         this.grabDragInteraction!.dispose();
         keyboardDragListener.dispose();
         this.focusablePath!.dispose();