chore(igxOverlay): onPosition added, WIP

projects/igniteui-angular/src/lib/directives/toggle/toggle.directive.ts

@@ -35,6 +35,7 @@ export class IgxToggleDirective implements IToggleView, OnInit, OnDestroy {
     private _overlayOpenedSub: Subscription;
     private _overlayClosingSub: Subscription;
     private _overlayClosedSub: Subscription;
+    private _overlayPositionSub: Subscription;
 
     /**
      * Emits an event after the toggle container is opened.
@@ -112,6 +113,9 @@ export class IgxToggleDirective implements IToggleView, OnInit, OnDestroy {
     @Output()
     public onClosing = new EventEmitter<CancelableEventArgs>();
 
+    @Output()
+    public onPosition = new EventEmitter();
+
     private _collapsed = true;
     /**
      * @hidden
@@ -183,6 +187,12 @@ export class IgxToggleDirective implements IToggleView, OnInit, OnDestroy {
             return;
         }
 
+        this._overlayPositionSub = this.overlayService.onPosition
+            // .pipe(...this._overlaySubFilter)
+            .subscribe(() => {
+                this.onPosition.emit();
+            });
+
         if (this._overlayId) {
             this.overlayService.show(this._overlayId, overlaySettings);
         } else {
@@ -281,6 +291,7 @@ export class IgxToggleDirective implements IToggleView, OnInit, OnDestroy {
         this.clearSubscription(this._overlayOpenedSub);
         this.clearSubscription(this._overlayClosingSub);
         this.clearSubscription(this._overlayClosedSub);
+        this.clearSubscription(this._overlayPositionSub);
     }
 
     private clearSubscription(subscription: Subscription) {

projects/igniteui-angular/src/lib/drop-down/drop-down.base.ts

@@ -416,6 +416,9 @@ export abstract class IgxDropDownBase implements OnInit, IToggleView {
         if (eventArgs.cancel) {
             return;
         }
+`    }
+
+    onTogglePosition() {
         this.scrollToItem(this.selectedItem);
     }
 

projects/igniteui-angular/src/lib/drop-down/drop-down.component.html

@@ -1,5 +1,5 @@
 <div class="igx-drop-down__list" igxToggle [style.maxHeight]="maxHeight"
-    (onOpening)="onToggleOpening($event)" (onOpened)="onToggleOpened()"
+    (onOpening)="onToggleOpening($event)" (onOpened)="onToggleOpened()" (onPosition)="onTogglePosition()"
     (onClosing)="onToggleClosing($event)" (onClosed)="onToggleClosed()">
     <ng-container *ngIf="!collapsed">
         <ng-content></ng-content>

projects/igniteui-angular/src/lib/services/overlay/overlay.ts

@@ -91,6 +91,8 @@ export class IgxOverlayService implements OnDestroy {
      */
     public onAnimation = new EventEmitter<OverlayAnimationEventArgs>();
 
+    public onPosition = new EventEmitter();
+
     constructor(
         private _factoryResolver: ComponentFactoryResolver,
         private _appRef: ApplicationRef,
@@ -177,6 +179,7 @@ export class IgxOverlayService implements OnDestroy {
                 document,
                 true,
                 settings.positionStrategy.settings.minSize);
+            this.onPosition.emit();
             settings.scrollStrategy.initialize(this._document, this, id);
             settings.scrollStrategy.attach();
         }