Barra de rolagem personalizada em Angular

Depois que o Edge se juntou às valentes fileiras dos navegadores Chromium, a personalização das barras de rolagem via CSS está ausente apenas no Firefox. Isso é ótimo, mas, além do Firefox, a solução CSS tem muitas limitações. Veja que magia negra você precisa usar para desaparecer. Para obter controle total sobre a aparência, você ainda precisa recorrer ao JavaScript. Vamos ver como fazê-lo através do componente Angular em um bom caminho.

Magia CSS

, , . -, . . scrollbar-width, Firefox. Edge IE -ms-overflow-style. IE , position: sticky. Chrome Safari ::-webkit-scrollbar.

-, , . , - position: fixed . : .

position: sticky display: flex . :

<div class="bars">...</div>
<div class="content"><ng-content></ng-content></div>

. , - z-index: 1000, 1001, 9999. , position: relative, z-index: 0. - .

z-index: 1, , 100%. :

, . . margin-right: -100%, «» .

, , float, 100%, (max-height, flex: 1 ).

Angular

Angular, , . . . , . :

<div class="bars">
    <div *ngIf="hasVerticalBar" class="bar">
        <div
            class="thumb"
            [class.thumb_active]="verticalThumbActive"
            [style.height.%]="verticalView"
            [style.top.%]="verticalThumb"
        ></div>
    </div>
</div>

:

  //     
  get verticalScrolled(): number {
    const {
      scrollTop,
      scrollHeight,
      clientHeight
    } = this.elementRef.nativeElement;

    return scrollTop / (scrollHeight - clientHeight);
  }

  //    
  get verticalSize(): number {
    const { clientHeight, scrollHeight } = this.elementRef.nativeElement;

    return Math.ceil(clientHeight / scrollHeight * 100);
  }

  //     
  get verticalPosition(): number {
    return this.verticalScrolled * (100 - this.verticalSize);
  }

  //   ,  
  get hasVerticalBar(): boolean {
    return this.verticalSize < 100;
  }

, , — . . , .

mousedown , mousemove mouseup .

:

        <div
            #vertical
            class="thumb"
            [class.thumb_active]="verticalThumbActive"
            [style.height.%]="verticalSize"
            [style.top.%]="verticalPosition"
            (mousedown)="onVerticalStart($event)"
            (document:mousemove)="onVerticalMove($event, vertical)"
        ></div>

mouseup:

  @HostListener('document:mouseup)
  onDragEnd() {
    this.verticalThumbActive = false;
  }

  onVerticalStart(event: MouseEvent) {
    event.preventDefault();

    const { target, clientY } = event;
    const { top, height } = target.getBoundingClientRect();

    this.verticalThumbDragOffset = (clientY - top) / height;
    this.verticalThumbActive = true;
  }

  onVerticalMove(
    { clientY }: MouseEvent,
    { offsetHeight }: HTMLElement
  ) {
    if (!this.verticalThumbActive) {
      return;
    }

    const { nativeElement } = this.elementRef;
    const { top, height } = nativeElement.getBoundingClientRect();
    const maxScrollTop = nativeElement.scrollHeight - height;
    const scrolled =
      (clientY - top - offsetHeight * this.verticalThumbDragOffset) /
      (height - offsetHeight);

    nativeElement.scrollTop = maxScrollTop * scrolled;
  }

.

Angular

, . mousemove . . , Angular , . @tinkoff/ng-event-plugins, . .silent @shouldCall :

(document:mousemove.silent)="onVerticalMove($event, vertical)"

  @shouldCall(isActive)
  @HostListener('init.end', ['$event'])
  @HostListener('document:mouseup.silent')
  onDragEnd() {
    this.verticalThumbActive = false;
  }

  @shouldCall(isActive)
  @HostListener('init.move', ['$event'])
  onVerticalMove(
    { clientY }: MouseEvent,
    { offsetHeight }: HTMLElement
  ) {
    const { nativeElement } = this.elementRef;
    const { top, height } = nativeElement.getBoundingClientRect();
    const maxScrollTop = nativeElement.scrollHeight - height;
    const scrolled =
      (clientY - top - offsetHeight * this.verticalThumbDragOffset) /
      (height - offsetHeight);

    nativeElement.scrollTop = maxScrollTop * scrolled;
  }

: Angular 10 markDirty(this) @shouldCall @HostListener(‘init.xxx’, [‘$event’]), , — .

, . . , . ResizeObserver @ng-web-apis/resize-observer, . Stackblitz.

Edit:

, , . . Output fromEvent, :

  @Output()
  dragged = fromEvent(
    this.elementRef.nativeElement,
    'mousedown'
  ).pipe(
    switchMap(event => {
      event.preventDefault();

      const clientRect = event.target.getBoundingClientRect();
      const offsetVertical = getOffsetVertical(event, clientRect);
      const offsetHorizontal = getOffsetHorizontal(event, clientRect);

      return fromEvent(this.documentRef, 'mousemove').pipe(
        map(event => this.getScrolled(event, offsetVertical, offsetHorizontal)),
        takeUntil(fromEvent(this.documentRef, 'mouseup'))
      );
    })
  );

. , .