Font rendering issues with ligatures enabled

[Eugeny]

Compare font weight for a and a-.

The font is Fira Code.

[Eugeny]

Strangely enough, this only happens with -, but not =, although both can form a ligature.

[Tyriar]

What version of xterm.js? Is this in Terminus?

[Tyriar]

Also what rendererType are you using?

[Eugeny]

Sorry - it's xterm 3.13.2, with canvas renderer. You should be able to see it live by grabbing the latest Terminus build.

This behaviour seems to be new in the 3.13.x series.

[jerch]

Cant repro this either with your latest terminus build. Font weight is right for me (tested with echo -e '\x1b[1m a= a- ==' and echo -e '\x1b[0m a= a- ==').

[Eugeny]

This doesn't happen on Windows for me either - only macOS seems to be affected

[Tyriar]

I can't get ligatures to work?

[Eugeny]

Not even after restarting the app?

[Tyriar]

@Eugeny oh that did it.

Cannot repro 😕

[Eugeny]

I'm seeing the difference in brightness of a in a= and a- on the bottom line

[Tyriar]

Oh I see

[Tyriar]

They both seem to be drawing with the same properties. Below logs ctx.font, ctx.fillStyle, ctx.textBaseline, chars, x, y

[Eugeny]

It somewhat looks like the fatter A is just being rendered twice, and the overdraw results in a wider outline where it's antialiased

[Tyriar]

Hmm, maybe we are somehow drawing things wrong normally and the char joiner one is doing it right. I've seem comments that regular text rendering is more heavy than it should be 🤔

[Eugeny]

Can confirm that this doesn't happen with the webgl renderer (all characters seem to be drawn extra-bold there)

[Tyriar]

Closing as won't fix since we want to phase the canvas renderer out in favor of webgl and dom only