Method _setOpen

src/material/sidenav/drawer.ts:577–619

* Toggles the opened state of the drawer. * @param isOpen Whether the drawer should open or close. * @param restoreFocus Whether focus should be restored on close. * @param focusOrigin Origin to use when restoring focus.

(
    isOpen: boolean,
    restoreFocus: boolean,
    focusOrigin: Exclude<FocusOrigin, null>,
  )

   * @param focusOrigin Origin to use when restoring focus.
   */
  private _setOpen(
    isOpen: boolean,
    restoreFocus: boolean,
    focusOrigin: Exclude<FocusOrigin, null>,
  ): Promise<MatDrawerToggleResult> {
    if (isOpen === this.opened) {
      return Promise.resolve(isOpen ? 'open' : 'close');
    }

    this._opened.set(isOpen);
    this._getContent()?._drawerToggled(this);

    if (this._container?._transitionsEnabled) {
      // Note: it's important to set this as early as possible,
      // otherwise the animation can look glitchy in some cases.
      this._setIsAnimating(true);

      // Previously we dispatched this in a `transitionrun` event, but it might not fire
      // if the element is hidden (see #32992). Since this event is load-bearing for the
      // margin calculations, we need it to fire consistently.
      setTimeout(() => this._animationStarted.next());
    } else {
      // Simulate the animation events if animations are disabled.
      setTimeout(() => {
        this._animationStarted.next();
        this._animationEnd.next();
      });
    }

    this._elementRef.nativeElement.classList.toggle('mat-drawer-opened', isOpen);

    if (!isOpen && restoreFocus) {
      this._restoreFocus(focusOrigin);
    }

    // Needed to ensure that the closing sequence fires off correctly.
    this._changeDetectorRef.markForCheck();
    this._updateFocusTrapState();

    return new Promise<MatDrawerToggleResult>(resolve => {
      this.openedChange.pipe(take(1)).subscribe(open => resolve(open ? 'open' : 'close'));
    });
  }

  /** Gets the current content element. */
  private _getContent() {