Canvas renderer differences

[npezza93]

Details

• Browser and browser version: electron 22.2
• OS version: macOS ventura
• xterm.js version: 5.2 beta 22

Steps to reproduce

Inside neovim I'm seeing differences in rendering between webgl and canvas. The window in the top half of the screenshot is webgl and the canvas one is the bottom half. Both of these instances are rendering the exact same tmux session so they should look identical. Couple things to note:

For the first screenshot:

• Spacing around the nav tabs at the top. There's less spacing on the left of the number while there is more on the right side. The webgl version looks correct but the canvas one seems off.
• The light gray vertical gutter at 80 chars is missing in the canvas renderer but is visible in the webgl renderer.
• The light gray horizontal highlight where the cursor isn't visible in the canvas renderer but is on the webgl one.

For the second screenshot:
I entered visual mode in neovim and you'll in the webgl renderer the hightlight stopped where the characters stopped whereas the canvas one went all the way to the end of the line. Also at the beginning of the lines the canvas one skipped the empty spaces but the webgl one highlighted the empty space.

1. Open a file in neovim

[davidfiala]

Where you see the background colors continuing on beyond where you expect them, I've covered this in a specific, simpler bug with PoC: #4417

[Tyriar]

duplicate of #4120