Viewport scrolling issue with C-d/C-u

I noticed that @zbw8388 made a branch on their fork that made me realize a bug I missed when merging #919 and #885 - when scrolling with C-u/C-d, the veiwport is wrong.

This is because neovim internally scrolls the content while using C-u, so that the cursor position stays the same relative to the window. However, vscode moves the cursor and does not scroll the content. This causes the viewport to be unsynced.

I can think of three solutions:

• sync neovim scroll with vscode. This could be done with win_viewport, or winsaveview. This would also remove the need for a custom implementation of C-e/C-y/zt/zb/zz. I believe @asvetliakov said this could cause jitter, but we can try.
• modify vscode scrolling strategy. There might be a vscode api option where moving the cursor long distances will scroll the content instead of moving the cursor
• modify neovim scrolling strategy. Make neovim scroll how vscode does, which only scrolls the content if needed

I think the first option is ideal, if it doesn’t rely on too much code.

[tobealive]

As vscode is generally a bit troublesome with keyboard scrolling, I wrote a plugin recently that I think works fairly well. Maybe it also improves the experience for others who use vscode-neovim until there is a final implementation and solution. https://github.com/tobealive/german-scroll.code

And so great to see the skyrocketing development in recent days. I think slowly but steady, you make it better than the VSCodeVim extension 😊

[theol0403]

@zbw8388 thanks for working on this too!

I vote that we let neovim handle all scrolling. This will let us remove all custom scrolling implementations (zz, C-e, etc). I think that switching to neovim-like behaviour where the content is scrolled instead of the cursor is a good feature.

I’m not sure if the jumplist note is relevant, but we should see if we can work around that if it is an issue. It might be worth it to look into if we can use neovim jumplist again (and also support jumplist from outline view).

If we can remove jitter, and let neovim handle all scrolling, that would be ideal.

I’m not very experienced with synchronization, but it seems like you are quite good with that!

I’m a little lost as to how to fix the current issues in my branch. Your branch (with a few tweaks from mine) seems to work very well to fix the original issue, but mine seems to have a lot of bugs (jitter, incorrect scrolling, etc). I think implementing a lock like you said would be a good next step.