Strange scrollbar thumb behavior in Firefox

sir-boformer commented 6 years ago

Bug Report or Feature Request (mark with an `x`)

- [x] bug report -> please search issues before submitting
- [ ] feature request
- [ ] question

OS and Version?

Windows 10

Versions

Angular 6.0.0. ngx-scrollbar 2.0.1

Repro steps

Press scrollbar thumb in Firefox, move mouse.

Video

https://imgur.com/1G7Hj37

MurhafSousli commented 6 years ago

@sir-boformer It is working fine on my end. Can reproduce it?

sir-boformer commented 6 years ago

Tested on two different machines with Firefox 59.0.3 and 60.0.1.

Smooth scrolling (default) is enabled on both machines. (general.smoothScroll: true in about:config)

I also created a new blank angular project:

ng new ngx-scrollbar-test --style scss
yarn add ngx-scrollbar

app.module.ts

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { ScrollbarModule } from 'ngx-scrollbar';

import { AppComponent } from './app.component';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    ScrollbarModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

app.component.html

<ng-scrollbar style="width: 640px; height: 480px">
 <div>
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  Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis.   
  At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, At accusam aliquyam diam diam dolore dolores duo eirmod eos erat, et nonumy sed tempor et et invidunt justo labore Stet clita ea et gubergren, kasd magna no rebum. sanctus sea sed takimata ut vero voluptua. est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat.   
  Consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus.   
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  Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat.   
  Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi.   
  Nam liber tempor cum soluta nobis eleifend option congue nihil imperdiet doming id quod mazim placerat facer possim assum. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo
 </div>
</ng-scrollbar>

MurhafSousli commented 6 years ago

I tested both the demo and stackblitz on firefox! no problem with the scroll

can you reproduce your issue in stackblitz?

sir-boformer commented 6 years ago

It's the same on Stackblitz: https://imgur.com/a/kDVTgD4

I also tested it with a completely isolated Firefox installation on my dev server (Firefox 59.0.2 (32-Bit)), with the same issue.

sir-boformer commented 6 years ago

Are you also using Windows? Maybe it's a specific FF on Windows issue.

Edit: It also happens in x direction

sir-boformer commented 6 years ago

I found the cause of the issue:

DOM Event Objects like Mouse Events are mutable, and Firefox is reusing/resetting the event objects.

  private thumbYWorker(e: any) {

    const startDrag = (event: any) => {

      console.log('offsetY', e.offsetY) // <--- This is always 0 in Firefox

      this._prevPageY = this._thumbSizeY - e.offsetY;
      ...
    };

   ...
}

To fix this problem, all you have to do is store a copy of the event values you want to use in the nested listeners:

  private thumbYWorker(e: any) {

    const downOffsetY = e.offsetY; // copy value here

    const startDrag = (event: any) => {

      this._prevPageY = this._thumbSizeY - downOffsetY;
      ...
    };

   ...
}

MurhafSousli commented 6 years ago

I noticed now, thanks for the PR! Updated in 2.0.2

MurhafSousli / ngx-scrollbar