Function _openMenu

src/material/menu/menu-trigger-base.ts:196–258

Internal method to open menu providing option to auto focus on first item.

(autoFocus: boolean)

  /** Internal method to open menu providing option to auto focus on first item. */
  protected _openMenu(autoFocus: boolean): void {
    if (this._triggerIsAriaDisabled()) {
      return;
    }

    const menu = this._menu;

    if (this._menuOpen || !menu) {
      return;
    }

    this._pendingRemoval?.unsubscribe();
    const previousTrigger = PANELS_TO_TRIGGERS.get(menu);
    PANELS_TO_TRIGGERS.set(menu, this);

    // If the same menu is currently attached to another trigger,
    // we need to close it so it doesn't end up in a broken state.
    if (previousTrigger && previousTrigger !== this) {
      previousTrigger._closeMenu();
    }

    const overlayRef = this._createOverlay(menu);
    const overlayConfig = overlayRef.getConfig();
    const positionStrategy = overlayConfig.positionStrategy as FlexibleConnectedPositionStrategy;

    this._setPosition(menu, positionStrategy);

    if (this._canHaveBackdrop) {
      overlayConfig.hasBackdrop =
        menu.hasBackdrop == null ? !this._triggersSubmenu() : menu.hasBackdrop;
    } else {
      overlayConfig.hasBackdrop = menu.hasBackdrop ?? false;
    }

    // We need the `hasAttached` check for the case where the user kicked off a removal animation,
    // but re-entered the menu. Re-attaching the same portal will trigger an error otherwise.
    if (!overlayRef.hasAttached()) {
      overlayRef.attach(this._getPortal(menu));
      menu.lazyContent?.attach(this.menuData);
    }

    this._closingActionsSubscription = this._menuClosingActions().subscribe(() =>
      this._closeMenu(),
    );
    menu.parentMenu = this._triggersSubmenu() ? this._parentMaterialMenu : undefined;
    menu.direction = this.dir;

    if (autoFocus) {
      menu.focusFirstItem(this._openedBy || 'program');
    }

    this._setIsMenuOpen(true);

    if (menu instanceof MatMenu) {
      menu._setIsOpen(true);
      menu._directDescendantItems.changes.pipe(takeUntil(menu.close)).subscribe(() => {
        // Re-adjust the position without locking when the amount of items
        // changes so that the overlay is allowed to pick a new optimal position.