Author Scrolling in long-strip manhua/webtoons on mobile
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I’m using the MangaDex PWA on iOS, and there’s this scrolling bug that makes it really frustrating to read manhua. Whenever a new image loads further down the page, the reader immediately scrolls back up the page. If multiple images load in quick succession, you can be scrolling down, but the page will scroll up twice as fast. It can even take you to the previous chapter if you hit the top of the page.

You either have to wait for the entire chapter to load or constantly fight the reader.
Last edited 17 days ago by verdare.
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I thought I was the only one suffering from this. (I am on Android)

It had been literally more than THREE minutes and I still haven't finished this chapter due to this annoying bug.

What a way to destroy a supposed great reading experience.

MangaDex staff I hope you are seeing this and will fix it ASAP.
Holo
Administrator
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@teasday
Teasday
Developer
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@verdare @NIKAtheWorm People have brought this up a few times, but it's been a while since the last time so I assumed it was no longer an issue. Currently, though, I don't really have access to an iOS Safari and this doesn't happen on any Android Chrome or Firefox that I know of so it's pretty tough to test for. I wouldn't have any idea whether something I did fixed it or not.

It doesn't help that frankly I don't know what I could do to fix the issue as described. I have no idea why images being rendered would cause the browser to jump all the way back to the top of the page, I can't think of anything that I wrote that would cause that to happen.

Until I can think of some way of actually debugging this, I'm not sure there's much I can do about it.
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@NIKAtheWorm What browser are you using on Android?
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@verdare I'm using Chrome
I know someone else who also experiences the same thing on iOS + Safari lately too
Last edited 7 days ago by NIKAtheWorm.
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@Teasday Thank you for your prompt reply !

I do understand that fixing a bug is not exactly easy, but I appreciate the fact that you guys have been trying to do something to fix it.
Another thing regarding the bug to take note of again, just like what OP has mentioned, is that it often takes you to the previous chapter(s) whenever you try to scroll through the long strips

I also wanted to say sorry if my comment earlier seemed very hostile; was just really frustrated earlier regarding the bug.

But then again, thank you very much for all your efforts so far !
Teasday
Developer
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To be honest, I'm thinking I should probably mark this as "won't try to fix" and hope it magically goes away in the next major version since I'm going to rewrite the whole thing anyway.
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Just to add some more info, I just tried replicating this bug on desktop Safari, Chrome, and Firefox. No dice. The scrollbar does appear to be jumping up, but the page doesn't actually scroll. It seems this synchronization (or whatever you'd call it) is broken on the mobile version. It's overcompensating for the amount of new page that's actually being generated at the bottom.

@Teasday If you are rewriting the whole thing, please have this bug in mind and keep an eye out for it.
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Just a little theory regarding this mobile scrolling bug that I have been observing for the past 2 days of reading long strip webcomics is that when I scroll on the right-side of the screen, the bug frequently happens but if I scroll on the left-side of the screen it does not happen as much.

I assume it has to do with the [Bring Page to Top] button, which is present on the right-hand side of site.
Teasday
Developer
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@NIKAtheWorm If it doesn't happen "as much" (meaning it does still happen occasionally) then I doubt the Go To Top button has anything to do with it. It shouldn't really work anyway when it's not visible, but maybe I should explicitly disable the click event when it isn't just in case things aren't working as they should on some browsers.
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I guess iOS Safari isn’t tested by devs, so issues are expected.

My Safari on iOS crashes on some mangas.
This one https://mangadex.org/title/41519/kusozako-choroin-nishiga-hachi
crashes browser on default reader, but works okay on the legacy one. My guess is image size / RAM issue.
Teasday
Developer
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@dube posted:

crashes browser on default reader, but works okay on the legacy one. My guess is image size / RAM issue.

Yeah, it's probably due to how the large images are loaded into memory in the default reader, and iOS Safari can't handle it because of the arbitrary limits they put in place. When you say it works okay on the legacy one, do you mean with or without long strip?
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https://mangadex.org/title/41564/she-is-still-cute-today

Legacy - works in both modes
Default - I have to switch from default (for this manga) long strip setting to a single page and not swipe before that or it will crash

https://mangadex.org/title/41519/kusozako-choroin-nishiga-hachi
Looks like a quality overkill: single page is a 5k x 6k PNG. IMO a waste of storage and bandwidth.

Legacy - works in both modes although fast swiping can crash the Safari
Default - crashes even in a single page mode
Teasday
Developer
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Thanks, good to know.