Wierd Artifacting and broken fonts after scrolling

[smit2909]

Describe the bug

• On scrolling through files, weird artefacts, like colour from status line remains persistent
• The fonts become completely illegible blurry

To Reproduce Steps to reproduce the behavior:

1. Go to Terimal, open any file in neovide
2. Scroll down using j or shift + ] or any other key
3. See error

Expected behavior Fonts and lines should not be cut off after scrolling

Screenshots If applicable, add screenshots to help explain your problem.

Look at line 210 in below screenshot

Desktop (please complete the following information):

• OS: [Ubuntu 20.10], using xmonad
• Neovide Version: latest commit from master
• Neovim Version 0.5

[Kethku]

What font are you using

[smit2909]

Here a bunch that very consistently show such behaviour

• FiraCode Nerd Font
• Sauce Code Pro
• Jetbrains Mono
• Cascadia Code PL
• Ubuntu Mono / Nerd Font
• CodeNewRoman Nerd Font

This behaviour occurs regardless of the multigrid flag

[doums]

Hi, I observe the same bug here. I use JetbrainsMono.

• Arch Linux
• Neovide 0.7.0
• neovim (build myself)

  NVIM v0.5.0-dev+1450-g5aaa1a1c0
  Build type: Release
  LuaJIT 2.1.0-beta3

  I use no desktop environment, just a window manager dwm. My compositor is picom.

[Kethku]

i can repro something like this on windows now. The trick was dpi scaling had to be enabled, so it looks like this has to do with the renderer's interaction with scaling.

[last-partizan]

Yes, it seems related to scaling. I tried to reproduce bug with scaling set to 1, and was not able to. At 1 it works fine.

When using wayland it renders at 1 regardless of system-wide scaling.

I'll try to dig this issue.

[doums]

What scaling setting are you talking about ? Because I far as I know the only scaling setting I set myself are some env variables for GTK and QT

QT_AUTO_SCREEN_SCALE_FACTOR 1
GDK_SCALE 2
GDK_DPI_SCALE 0.5

and dpi for X11

Xft.dpi: 120

[last-partizan]

I'm talking about this scaling: https://docs.rs/winit/0.22.2/winit/window/struct.Window.html#method.scale_factor

If you're using x11, it's calculated from DPI.

[last-partizan]

As workaround you can set WINIT_X11_SCALE_FACTOR=1 and just set bigger font size.

[last-partizan]

@doums try running latest version with neovide --log, and then show me grep scale neovide_rCURRENT.log. And what exact font and font size are you using?

Issue is affecting some font sizes more than others, and i want to find some good combinations to reproduce it.

[last-partizan]

@Kethku I'm pretty sure it's some sort of rounding issue. window.scale_factor() sometimes passed as f64 and sometimes as f32. And multiplied by font size in some parts. And with scaling like 1 or 2 it works perfectly fine.

Maybe you have some ideas/hints?

[last-partizan]

@Kethku i'm worried abount those lines:

In src/renderer/mod.rs:draw_frame there is root_canvas.scale((scaling, scaling)); And in src/renderer/rendered_window.rs:handle_window_draw_command there is canvas.scale((scaling, scaling));

If i comment out one of them, it scales in half, if i comment both - it scales in half more. Is it supposed to work this way?

[last-partizan]

When i get these artifacts, cursor is rendered at slightly different (and i think, correct?) position.

And when i change mode to visual and make a selection, line gets rerendered at same position as cursor, without artifacts.

[Kethku]

I introduced a fix for this here: https://github.com/Kethku/neovide/pull/791 which removes the scroll performance optimization which seems to cause the issue. Could you try it and or review the change? I know you've been looking into this @last-partizan

[last-partizan]

https://github.com/Kethku/neovide/pull/793

Here is another fix. @doums @smit2909 please, try it.

[doums]

bug seems to be fixed in #793 good job !

But I can't build main, it's failing with

error: checksum for `skia-safe v0.40.2` changed between lock files

[last-partizan]

@doums Merged fix

[doums]

main is still broken

[smit2909]

793

Here is another fix. @doums @smit2909 please, try it.

Awsome! Working like a charm @last-partizan . No more broken fonts. I am on 755-scale-factor branch though. I didnt build after the merge into main.

[last-partizan]

@doums are you sure?

https://github.com/Kethku/neovide/commit/5c5cf9088da9ce205f2225ca969fcf2f251e4c12

Does git log includes this commit?

[last-partizan]

Just to be clear, #793 is not merged yet.

I just merged fixes for broken main branch.

[doums]

@doums are you sure?

5c5cf90

Does git log includes this commit?

I was talking about artifact bug on main branch. Yes the build is fixed of main branch and yes it includes the commit.

[last-partizan]

This should be fixed now on main.