Method _createOverlay

src/material/tooltip/tooltip.ts:498–584

Create the overlay config and position strategy

(origin?: {x: number; y: number})

  /** Create the overlay config and position strategy */
  private _createOverlay(origin?: {x: number; y: number}): OverlayRef {
    if (this._overlayRef) {
      const existingStrategy = this._overlayRef.getConfig()
        .positionStrategy as FlexibleConnectedPositionStrategy;

      if ((!this.positionAtOrigin || !origin) && existingStrategy._origin instanceof ElementRef) {
        return this._overlayRef;
      }

      this._detach();
    }

    const scrollableAncestors = this._injector
      .get(ScrollDispatcher)
      .getAncestorScrollContainers(this._elementRef);

    const panelClass = `${this._cssClassPrefix}-${PANEL_CLASS}`;

    // Create connected position strategy that listens for scroll events to reposition.
    const strategy = createFlexibleConnectedPositionStrategy(
      this._injector,
      this.positionAtOrigin ? origin || this._elementRef : this._elementRef,
    )
      .withTransformOriginOn(`.${this._cssClassPrefix}-tooltip`)
      .withFlexibleDimensions(false)
      .withViewportMargin(this._viewportMargin)
      .withScrollableContainers(scrollableAncestors)
      .withPopoverLocation('global');

    strategy.positionChanges.pipe(takeUntil(this._destroyed)).subscribe(change => {
      this._updateCurrentPositionClass(change.connectionPair);

      if (this._tooltipInstance) {
        if (change.scrollableViewProperties.isOverlayClipped && this._tooltipInstance.isVisible()) {
          // After position changes occur and the overlay is clipped by
          // a parent scrollable then close the tooltip.
          this._ngZone.run(() => this.hide(0));
        }
      }
    });

    this._overlayRef = createOverlayRef(this._injector, {
      direction: this._dir,
      positionStrategy: strategy,
      panelClass: this._overlayPanelClass ? [...this._overlayPanelClass, panelClass] : panelClass,
      scrollStrategy: this._injector.get(MAT_TOOLTIP_SCROLL_STRATEGY)(),
      disableAnimations: this._animationsDisabled,
      eventPredicate: this._overlayEventPredicate,
    });

    this._updatePosition(this._overlayRef);

    this._overlayRef
      .detachments()
      .pipe(takeUntil(this._destroyed))
      .subscribe(() => this._detach());

    this._overlayRef