Subpixel antialiasing isn't consistently applied to all text in document

[adamsiembida]

• Using Atom 1.0.0.
• Using Windows 7.
• The effect seems to happen on both of my monitors:
  • Primary monitor is 1920 x 1200 resolution.
  • Secondary monitor is 1280 x 1024 resolution.
• Using One Light for both UI Theme and Syntax Theme, but it also happens if I use Atom Light on both.
• Running atom --safe didn't make any difference (still has the same alternating blurry).

It seems that when editing some files, that subpixel antialiasing works for a couple lines, then doesn't work for a couple lines, then works for a few lines, then doesn't ...

When you zoom in, you can see that lines 34-36 are working properly, but then line 37 doesn't have subpixel antialiasing applied.

The strange thing is that if I make a document of all "a" characters, for example, it all looks blurry, but at least it is consistent.

If I fill the document with all "0" characters, it looks like the top few lines are blurry, but the rest renders correctly.

[50Wliu]

@as-cii this seems like your territory :).

[as-cii]

Hey @w1res, thanks for reporting this issue.

Other Windows users have been experiencing a similar problem (#3869 (comment)) but found out it was related to the DPI settings. Would you be willing to check that setting out in your Windows configuration?

Thank you!

[adamsiembida]

I'm getting a value of 1 for window.devicePixelValue (from within the Atom console).

I haven't read too much about using Atom (so this might not be the right way to change it), but I added window.devicePixelRatio = 1.5; to init.coffee and restarted Atom. It didn't seem to make any change in appearance. Is that the right place to change it?

[as-cii]

Thanks @w1res, sorry for letting you wait so long! 🙏

I'm getting a value of 1 for window.devicePixelValue (from within the Atom console).

I assume you are talking about window.devicePixelRatio here. If yes, then DPI settings are definitely not the culprit here but it rather seems like something is screwing up subpixel anti-aliasing. I am starting to think this may actually be caused by highlight decorations.

Have you been able to reproduce this since you first reported? I have just noticed you had the spell-check package enabled in the second screenshot you posted. Could you try disabling it and see if it helps in a similar document (e.g. a document made of a characters only)?

[50Wliu]

I may be hitting this as well; will try to write up some repro steps later on.

[adamsiembida]

@as-cii @50Wliu I disabled off spell-check and now everything looks uniformly sharp across all lines. It seems like you were correct in guessing that it might be related.

In fact, I can have the Settings open in one tab, and the file open in the other, and when I enable/disable the spell-check package (and go back and forth between the tabs), I can see the issue return and then go away.

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