Making Material tabs scrollable

问题

I'm using Material tabs in my application (mat-tab s inside mat-tab-group) When there are more tabs than can be displayed, two navigation buttons are shown to display the other tabs:

My requirement is to enable the user to scroll on the tab bar so that other tabs are shown.

I tried to do some css changes but couldn't solve it. It's highly appreciated if any solution or suggestion can be given.

回答1:

Try my solution in this stackblitz demo.

First get a reference to the matTabGroup:

app.component.html

<mat-tab-group #tabGroup>
               ^^^^^^^^^  

app.component.ts

@ViewChild('tabGroup')
tabGroup;

Then listen to the mouse scroll wheel event and trigger a custom scroll function:

app.component.html

<mat-tab-group (wheel)="scrollTabs($event)" #tabGroup>
                        ^^^^^^^^^^^^^^^^^^  

app.component.ts

scrollTabs(event) {
  const children = this.tabGroup._tabHeader._elementRef.nativeElement.children;

  // get the tabGroup pagination buttons
  const back = children[0];
  const forward = children[2];

  // depending on scroll direction click forward or back
  if (event.deltaY > 0) {
    forward.click();
  } else {
    back.click();
  }
}

Disclaimer: This solution is very brittle. The Angular Material tabs do not offer an API for doing this. The solution depends on internal references that might change without notice (e. g. this private variable this.tabGroup._tabHeader). Also, it does not yet stop the page from scrolling and only works with vertical scrolling. (Those two can be addressed though.)

回答2:

Try this pure css solution StackBlitz

Put this code in the same component where mat-tab is used

::ng-deep .mat-tab-header {
  overflow-x: scroll !important;
}

::ng-deep .mat-tab-label-container { 
  overflow: visible !important;
}

::ng-deep .mat-tab-header::-webkit-scrollbar { // TO Remove horizontal scrollbar in tabs
  display: none;
}

回答3:

[Long text solution] My goal was to make mat-tabs scrollable by default, without controls, but with the ability to auto-scroll when clicking on partially visible mat-tab to move it to the visible center-ish viewport.

1) This behavior already partially realized in this example "from the box" - https://stackblitz.com/edit/angular-mat-tabs-scrollalble-initial-behavior. The problem is that you can't scroll backward normally - there some buggy behavior to push tabs to the left. So it does not work as I wanted.

2) The next variant was with scrolling event - take a (wheel)="event" on mat-tab-group - but its also not work with mobile. https://stackblitz.com/edit/angular-mat-tabs-scrollable-by-wheel-event Got it from this awesome comment above.

3) My own scroll of mat-tabs with scrolling on mobile and autoscrolling clicked tab to center of screen' viewport when you click on the tab was not too simple but it works! :)

first, you need to disable "from the box" scrolling when tapping on tabs and pagination buttons:

mat-tabs-override.scss:

$black: #121212;
@mixin media-query-for-mobile {
  @media (max-width: 768px) and (min-width: 1px) {
    @content;
  }
}
mat-tab-group {
  .mat-tab-header {
    .mat-tab-header-pagination {
      display: none !important; // <== disable pagination
    }
    .mat-tab-label-container {
      left: 0px; // if you need to use it on mobile - set left position to 0
      width: 100%;
      .mat-tab-list {
        overflow-x: auto !important; // <== set horisontal scroll bar imperatively
        // below rule prevents sliding of buttons' container - because it not sliding properly - to left it not slide as well
        transform: none !important;
        .mat-tab-labels {
          // some tweaks for tabs - up to you
          @include media-query-for-mobile {
            justify-content: unset !important; 
          }
          .mat-tab-label {
            // min-width: 20% !important;
            padding: 1.25% !important;
            margin: 0px !important;
            text-transform: uppercase;
            color: $black;
            font-weight: 600;
            min-width: 140px !important;
          }
        }
      }
    }
  }
}

in this case you will see that all tabs are similar by width and scrollable on mobile.

Next, you need to make auto-scroll for tabs when you clicking on them and change their position to the center of the screen, based on the current viewport - let's do it!

We can create a directive, which will listen to the main container of <mat-tabs-group>, check width of scrollable container .mat-tab-labels and move the tab to be visible in viewport by auto-scrolling .mat-tabs-labels container to needed way:

directive in template:

<mat-tab-group scrollToCenter>
    <mat-tab label="tab 1"></mat-tab>
    <mat-tab label="tab 2"></mat-tab>
    <mat-tab label="tab 3"></mat-tab>
    <mat-tab label="tab 4"></mat-tab>
    <mat-tab label="tab 5"></mat-tab>
    <mat-tab label="tab 6"></mat-tab>
    <mat-tab label="tab 7"></mat-tab>
    <mat-tab label="tab 8"></mat-tab>
</mat-tab-group>

directive.ts:

import { Directive, ElementRef, OnDestroy } from '@angular/core';
import { fromEvent, Subscription } from 'rxjs';

interface DOMRectI {
  bottom: number;
  height: number;
  left: number; // position start of element
  right: number; // position end of element
  top: number;
  width: number; // width of element
  x?: number;
  y?: number;
}

@Directive({
  // tslint:disable-next-line:directive-selector
  selector: '[scrollToCenter]',
})
export class MatTabScrollToCenterDirective implements OnDestroy {
  isMobile: boolean;
  subs = new Subscription();
  constructor(
    private element: ElementRef
  ) {
    this.subs.add(
      fromEvent(this.element.nativeElement, 'click').subscribe((clickedContainer: MouseEvent) => {
        const scrollContainer = this.element.nativeElement.querySelector('.mat-tab-list');
        const currentScrolledContainerPosition: number = scrollContainer.scrollLeft;

        const newPositionScrollTo = this.calcScrollToCenterValue(clickedContainer, currentScrolledContainerPosition);
      })
    );
  }

/** calculate scroll position to center of viewport */
  calcScrollToCenterValue(clickedContainer, currentScrolledContainerPosition): number {
    const scrolledButton: DOMRectI = (clickedContainer.target as HTMLElement).getBoundingClientRect();
    const leftXOffset = (window.innerWidth - scrolledButton.width) / 2;
    const currentVisibleViewportLeft = scrolledButton.left;
    const neededLeftOffset = currentVisibleViewportLeft - leftXOffset;
    console.log(scrolledButton);
    const newValueToSCroll = currentScrolledContainerPosition + neededLeftOffset;
    return newValueToSCroll;
  }

  ngOnDestroy() {
    this.subs.unsubscribe();
  }
}

And it works! :0 But not in ios and IE... Why? Because ios and IE don't support Element.scroll()

Solution - npm i element-scroll-polyfill and set to polyfills.ts

/** enable polufill for element.scroll() on IE and ios */
import 'element-scroll-polyfill';

Great! but now scroll is not so smooth... IE and ios not support smooth-scroll-behavior.

Solution - npm i smoothscroll-polyfill and add to polyfills.ts

import smoothscroll from 'smoothscroll-polyfill';
// enable polyfill
smoothscroll.polyfill();

Finally it works everywhere. Hope it helps somebody to fix mat-tabs autoscrolling emptiness :)

DEMO Enjoy it :)

来源：https://stackoverflow.com/questions/51544452/making-material-tabs-scrollable