Method _getPreviewInsertionPoint

src/cdk/drag-drop/drag-ref.ts:1570–1597

Gets the element into which the drag preview should be inserted.

(
    initialParent: HTMLElement,
    shadowRoot: ShadowRoot | null,
  )

  /** Gets the element into which the drag preview should be inserted. */
  private _getPreviewInsertionPoint(
    initialParent: HTMLElement,
    shadowRoot: ShadowRoot | null,
  ): HTMLElement {
    const previewContainer = this._previewContainer || 'global';

    if (previewContainer === 'parent') {
      return initialParent;
    }

    if (previewContainer === 'global') {
      const documentRef = this._document;

      // We can't use the body if the user is in fullscreen mode,
      // because the preview will render under the fullscreen element.
      // TODO(crisbeto): dedupe this with the `FullscreenOverlayContainer` eventually.
      return (
        shadowRoot ||
        documentRef.fullscreenElement ||
        (documentRef as any).webkitFullscreenElement ||
        (documentRef as any).mozFullScreenElement ||
        (documentRef as any).msFullscreenElement ||
        documentRef.body
      );
    }

    return coerceElement(previewContainer);
  }

  /** Lazily resolves and returns the dimensions of the preview. */
  private _getPreviewRect(): DOMRect {