[Feature request] Support mouse scrolling

[akinsho]

Hi,

So I want to preface this by saying that I realise that I can remap the mouse scroll wheel commands, and I've been doing that for years with various smooth scroll plugins.

So why does this need a different solution?

1. <c-u> and <c-d> are too aggressive for a touch bad where depending on how much force you use you could end up scrolling a huge amount which was unintended.
2. <c-e> and <c-y> are too small and adding a count helps slightly, but currently in this plugins once you hit the top or bottom plus/minus the scroll off the cursor line begins to jitter wildly.
3. Maybe you could take advantage of the new mousescroll option and use that to control how much scrolling happens?

There might be other ways to handle this, but I wonder if a dedicated command might not give a better result. One that can be sufficiently granular for mouse scrolling? Perhaps not, I have never properly looked into this sort of thing so no idea what's possible.

[declancm]

Hi @akinsho! Just so I'm understanding correctly, are you wanting a smooth scroll for the ~3 line jumps that the mouse scrolls to make it completely smooth?

I'll look into the <c-e> and <c-y> to improve them so hopefully you will be able to use them for mouse scrolling :).

This could work but it scrolls the cursor instead of scrolling the screen (always_scroll = true should be set if you want smooth scrolling constantly):

vim.keymap.set({ 'n', 'x' }, '<ScrollWheelUp>', "<Cmd>lua Scroll('3k', 0, 0, 15)<CR>")
vim.keymap.set({ 'n', 'x' }, '<ScrollWheelDown>', "<Cmd>lua Scroll('3j', 0, 0, 15)<CR>")

[akinsho]

@declancm so when using a trackpad, the line jumps that the mouse does can easily build up into a really long scroll which is jittery/non-smooth by default. Also, re the size of the scroll with the recently added mousescroll option on nvim nightly as user can set this value themselves to say mousescroll=ver:1,hor:3 so it can be made even more granular.

I had tried the j, k mapping similar to the ones you had without the final argument or the always scroll and had noticed the behaviour with the cursor which had been off-putting. I'll try again with those options set.

I also tried the recent changes to <c-e> and <c-y> but still find them to be jittering at the tail end. By jittery here, I mean that it seems like the cursor line is jumping between the last two lines, so they appear to flicker. You can reproduce it by just spamming <c-y> in a large file and wait till the cursor reaches your scroll off position, then it will start.

[akinsho]

Just tried out your mapping and that works quite well 👍🏿, one thing that's a little unfortunate is that a small swipe upwards on my trackpad can send the scroll going for ages like dozens of events were sent and so a fairly light swipe can mean I can't stop scrolling till I hit C-C I wonder if this can be throttled in nvim 🤔

[declancm]

So i think i fixed the <c-y> and <c-e> visual glitch when the count is 1 in 2806c5ddec9afee34acb4fd6c03e32f6cf902f66 :). I'll try looking into a way to use the mousescroll option for vertical and horizontal scrolling with the mouse wheel

[akinsho]

@declancm thanks for tweaking both of those. That fixes the visual glitch 👍🏿 . One thing I'm noticing using these keys though is that if sort of feels less smooth the way I have it set up. I'm not sure if it's just a matter of me configuring something but scrolling feels less smooth than other scroll motions.

I'm using

        vim.keymap.set({ 'n', 'x' }, '<ScrollWheelUp>', "<Cmd>lua Scroll('<c-e>', 0, 0, 3)<CR>")
        vim.keymap.set({ 'n', 'x' }, '<ScrollWheelDown>', "<Cmd>lua Scroll('<c-y>', 0, 0, 3)<CR>")

[declancm]

So those keymaps would just be equivalent to the following keymaps because there is no count:

vim.keymap.set({ 'n', 'x' }, '<ScrollWheelUp>', '<c-e>')
vim.keymap.set({ 'n', 'x' }, '<ScrollWheelDown>', '<c-y>')

I just did some testing and you can actually use:

vim.keymap.set({ 'n', 'x' }, '<ScrollWheelUp>', "<Cmd>lua Scroll('<ScrollWheelUp>')<CR>")
vim.keymap.set({ 'n', 'x' }, '<ScrollWheelDown>', "<Cmd>lua Scroll('<ScrollWheelDown>')<CR>")

This should respect the mousescroll settings and do horizontal scrolling.

The plugin works by first scrolling to the correct line number and then scrolling the window. This makes it look a bit jumpy when using a heap of small movements together as it was designed for large movements. I'll try looking into making this smoother to better support wheel scrolling :)

[akinsho]

Just tried that out and it works, except the jitter in the cursor line is back, as was the case for <C-E> and <C-Y>.

[declancm]

Hi @akinsho !

Could you please try the feature branch of this plugin? I have implemented smooth scrolling for the scroll wheel without the jitter in these commits: 204a6522d76977952184b688956a4c71267fd102 1f7d1ca8e917d2b79cd37d8acd02bf35fb6db511. Could you test if it's up to your standards before I merge with master? :)

[akinsho]

@declancm that works really nicely thanks 👍🏿