cursor "bolds" some characters when sub-pixel smoothing is on

[Ben Aisen]

Binary package hint: emacs-snapshot

When sub-pixel smoothing is on, the character to the left of the cursor sometimes becomes "bold" when the cursor blinks on and off. This effect is cumulative and disappears when the cursor is moved over the character but not when it is moved away. Also, it doesn't seem to happen if the cursor is over whitespace.

Without sub-pixel smoothing, this doesn't happen.

Screenshot is attached. Here the cursor is over the "t" in "exists" in line 3; compare the two "s" shapes.

Using emacs-snapshot version 1:20080228-1ubuntu1 on hardy.

[Ben Aisen (beinsane11)]

Apparently this is a bug in the Xft LCD filtering. Putting this in .Xresources and running xrdb -merge .Xresources seems to fix the problem:

Xft.lcdfilter: lcdfilterlegacy

[rfvuhbtg (rfvuhbtg)]

The lcdfilter legacy appears to fix the "bolding" problem, but on my laptop it makes the fonts look absolutely horrendous. Distractingly so. It would be good to get a proper fix out for this soon.

[Ben Aisen (beinsane11)]

It seems I was wrong - the "bolding" doesn't appear on the "s" with the legacy filter on, but continues to appear on other characters like "2", even without subpixel rendering on. (Turning antialias off or using a bitmap font instead of Vera solves this problem, but looks awful and defeats the purpose of using bleeding-edge Emacs to begin with.) Looks like it's a weird emacs/Xft internal thing. Should we forward this upstream?

[rfvuhbtg (rfvuhbtg)]

The problem is pretty bad. It was enough to force me to learn vim until this gets fixed. Vim/Gvim doesn't seem to have any problems with font-smoothing, but then, I don't know what it uses for font rendering. Since a lot of programmers use emacs, and those same programmers spend hours each day starting at the editor windows, it would be good to get this fixed soon, especially since this is a regression from previous Ubuntu versions.

[Ben Aisen (beinsane11)]

Apparently this is fixed in current CVS.

[rfvuhbtg (rfvuhbtg)]

Would someone be kind enough to package up an updated and fixed ubuntu deb?

[rfvuhbtg (rfvuhbtg)]

Well, I can confirm that the bug is fixed in the current cvs emacs. Unfortunately, I don't know how to generate a deb file from what I've compiled.

If any Ubuntu maintainers see this, all you really have to do is rebuild the emacs-snapshot debs from cvs and update the repositories and that should solve this bug report.

[Ben Aisen (beinsane11)]

Fixed in Intrepid package.

[rfvuhbtg (rfvuhbtg)]

Could we get this backported to the Hardy packages? (Seeing as how Hardy is an LTS release and not everyone will be upgrading it any time soon)