中心Mat菜单,中心MatMenu覆盖到按钮

我选择指令是因为 MatMenuTrigger Directive ,复制材料来源使用的逻辑是有意义的。

到目前为止,这是我提出的方法,我不确定这样进入课堂本身是否“可以接受”,或者这样做是否有任何负面影响。

我愿意就这种方法进行建设性的讨论,以提出任何建议或改进。

斯塔克闪电战

https://stackblitz.com/edit/angular-jpgjdc-nqmyht?embed=1&file=app/center-matmenu.directive.ts

基本上我是在分离 matMenuTrigger 把它放在 div 包装 mat-menu

• 我也在分配 menuTrigger 到a templateRef 上 并将其作为输入传递给我的 center-mat-menu 选择器

<button mat-button [center-mat-menu]="menuTrigger">Menu</button>
<div #menuTrigger="matMenuTrigger" [matMenuTriggerFor]="menu">
 <mat-menu #menu="matMenu">

从那里我创建了一个听众通过 @HostListener

@HostListener('click', ['$event'])

然后复制 马特纽特里格 指令来操纵位置、初始化菜单并在单击时激发打开的动画。

这基本上是 openMenu() 方法 menu-trigger.ts source,除非我在初始化菜单后和调用之前操作左和上样式 this.menuTrigger.menu['_startAnimation'](); 打开菜单。

menu-trigger.ts

我将源按钮的维度存储到变量和 要计算的初始化菜单的宽度 left

@Directive({
  selector: '[center-mat-menu]'
})
export class CenterMatmenuDirective {
  overlayRef: OverlayRef;
  overlayConf: OverlayConfig;
  dropDown: HTMLElement;
  overlayPositionBox: HTMLElement;
  menu: MatMenuPanel;
  button: HTMLElement;
  buttonWidth: number;
  buttonLeft: number;
  buttonBottom: number;

  @Input('center-mat-menu') private menuTrigger: MatMenuTrigger;

  constructor(private _menuButton: ElementRef, private _renderer: Renderer2) { }

  @HostListener('click', ['$event'])
  onclick(e) {
    this._setVariables();
    //menu not opened by keyboard down arrow, have to set this so MatMenuTrigger knows the menu was opened with a mouse click
    this.menuTrigger['_openedBy'] = e.button === 0 ? 'mouse' : null;

    this._overrideMatMenu();

    this.dropDown = this.overlayRef.overlayElement.children[0].children[0] as HTMLElement;
    this.overlayPositionBox = this.overlayRef.hostElement;

    setTimeout(() => {
      this._styleDropDown(this.dropDown);
      this._setOverlayPosition(this.dropDown, this.overlayPositionBox);
      this._openMenu();
    })
  }

  private _setVariables() {
    const config = this.menuTrigger['_getOverlayConfig']();
    this.menuTrigger['_overlayRef'] = this.menuTrigger['_overlay'].create(config);
    this.overlayRef = this.menuTrigger['_overlayRef'];
    this.overlayConf = this.overlayRef.getConfig();
    this.overlayRef.keydownEvents().subscribe();
    this.menu = this.menuTrigger.menu;
    this._setButtonVars();
  }

  private _setButtonVars() {
    this.button = this._menuButton.nativeElement;
    this.buttonWidth = this.button.getBoundingClientRect().width;
    this.buttonLeft = this.button.getBoundingClientRect().left;
    this.buttonBottom = this.button.getBoundingClientRect().bottom;
  }

  private _overrideMatMenu() {
    let strat = this.overlayConf.positionStrategy as FlexibleConnectedPositionStrategy;
    this.menuTrigger['_setPosition'](strat);
    strat.positionChanges.subscribe(() => {
      this._setButtonVars();
      this._setOverlayPosition(this.dropDown, this.overlayPositionBox);
    })
    this.overlayConf.hasBackdrop = this.menu.hasBackdrop == null ?
      !this.menuTrigger.triggersSubmenu() : this.menu.hasBackdrop;
    this.overlayRef.attach(this.menuTrigger['_getPortal']());

    if (this.menu.lazyContent) {
      this.menu.lazyContent.attach()
    }

    this.menuTrigger['_closeSubscription'] = this.menuTrigger['_menuClosingActions']().subscribe(() => {
      this.menuTrigger.closeMenu();
    });
    this.menuTrigger['_initMenu']();
  }

  private _styleDropDown(dropDown: HTMLElement) {
    this._renderer.setStyle(this._renderer.parentNode(dropDown), 'transform-origin', 'center top 0px');
  }

  private _setOverlayPosition(dropDown: HTMLElement, overlayPositionBox: HTMLElement) {
    let dropDownleft = ((this.buttonWidth / 2 + this.buttonLeft) - dropDown.offsetWidth / 2);

    this._renderer.setStyle(overlayPositionBox, 'top', this.buttonBottom + 5 + 'px');
    this._renderer.setStyle(overlayPositionBox, 'left', dropDownleft + 'px');
    this._renderer.setStyle(overlayPositionBox, 'height', '100%');
  }

  private _openMenu() {
    this.menuTrigger.menu['_startAnimation']();
  }
}