Scroll patch with mouse wheel or trackpad

[brusherru]

It will close #1388

[brusherru]

@nkrkv fixed these issues:

• invert scrolling
• shift key for horizontal scrolling (Windows has the same behavior as a Linux, so I made an exception only for macosx)
• Fix twitching of Patch on doing something before PATCH_UPDATE_OFFSET was dispatched
• normalized scroll speed for all browsers/platforms

I did all these things in separate commits, you can check it out separately. Then I'll squash it all in the one commit.

[nkrkv]

This one feels fragile nevertheless. Can we go on without relying on OS name? For example, the following predicate looks pretty equivalent to me:

event.shiftKey && normalizedWheel.pixelX === 0

In contrast to the current conditional, this will trigger a swap on macOS when a user hold down the Shift key and somehow scrolled strictly horizontally?! Is it ever possible? If so, what’s in the head of this xoder who holds the Shift key while scrolling with a gesture?

[nkrkv]

🙄 now it’s totally broken

My desktop version no longer scrolls at all. The welcoming comment is not centered on startup.

Scrolling in Firefox browser is several times faster than native. Feels very counter-intuitive.

[brusherru]

@nkrkv check it out, please

[nkrkv]

Now it’s pretty usable 👍

However, on Firefox I get more coarse scrolling than on Desktop and Chrome (~1.9x faster). Not a big deal and we can leave it as is I think.

The feature should be confirmed to work fine on Windows and ThinkPad. Would you check Windows? And I forgot my ThinkPad, again, today 🙈

[nkrkv]

Tested it on ThinkPad with a touchpad and trackpoint. Both work fine 👍

Let’s wait for feedback from @joepie91 if he has time for testing until the end of this week. If not, let’s merge and open a new issue if something is wrong.

[joepie91]

I've been working with it a bit on my desktop today (ie. with a regular mouse), and there it worked fine. I'll probably have time to test it on my laptop tomorrow, and I'll report back then.

I do keep running into weird intermittent scrolling issues with the project explorer and inspector; I'm up to three different mystery issues now. The specific issues I've been running into:

1. No scrolling at all in the Inspector pane (Inspector scrolling is broken #1423)
2. When scrolling rapidly and nearing the end of the content in the project explorer, it suddenly jumps to the end, skipping a part of the content. Same for scrolling towards the start.
3. When clicking an item when the content exceeds the project browser pane size, the pane jumps to a different scroll position.

Annoyingly, none of these issues are reliably reproducible, and I have no idea whether they're a consequence of the patch panning or a totally unrelated issue (eg. a wonky pane scrolling implementation). I don't think they should be a blocker, unless you have a reason to believe that it might be related to patch panning.

[brusherru]

@joepie91 thanks for the reports and test on the desktop. Will you test it on your Thinkpad?

About project browser and inspector — we'll inspect it and try to fix with another pull request. Looks like the problem is in the "custom scroll" component 🤔

[nkrkv]

@brusherru I think we should rebase & merge this PR. In case of any flaws, a new issue might be open.

[joepie91]

Apologies for the delay :)

I've tested it on my laptop for a bit, and the scrolling works fine. It does get a bit laggy/jittery when I scroll quickly; I'm not sure whether that's due to the scrolling code, or whether it's just a general performance issue. Looking at my process manager, it starts eating a core when that happens.

[joepie91]

Hmm, another issue: if you pan too far away from the contents, it can be difficult to find the contents again, given that it's an infinite canvas and there doesn't seem to be a 'return to center' button or anything. I guess that's a broader panning UX issue though, and not specific to this PR.

[nkrkv]

Thanks for testing!

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