Flickering Cursor about beacon

[Malabarba]

No, that shouldn't happen. Do you think you can narrow down the situation where it's happening?

[clemera]

It happens all the time, only sometimes not. I have recorded it so you can better see what I mean. The following is a video file, Github supports only image files so I uploaded it as a png.

I'm on Emacs 24.5.1.

[Malabarba]

I see. That might be a redisplay bug. =/

Could you try the followiung?

• start Emacs with emacs -Q,
• load the seq.el file
• load the beacon.el file
• Try to reproduce this again.

Does it happen?

[clemera]

Yes, it still happens. I'm on Linux. I don't know much about Emacs internals and don't know what redisplay bug means. If you have ideas how I could investigate further let me know, thanks for the help.

[Malabarba]

Redisplay is basically when Emacs draws the screen.

Here's one more thing to try. Evaluate the following code:

(defun redisplay-command ()
  (interactive)
  (redisplay))
(global-set-key [f6] #'redisplay-command)

This makes it so that F6 triggers a redisplay. Ideally, this should have no visual effect.
Hit F6 a few times while paying attention to the cursor. Try to see if the cursor flickers at any moment.

[clemera]

Just tried it, the cursor is not flickering on redisplay.

[Malabarba]

Ok, one more thing to try.

1. Disable beacon-mode
2. Hit M-: and type (beacon--shine), this will leave a permanent beacon at point.
3. Without moving the cursor, hit F6 several times and see if the cursor flickers.

[clemera]

No it does not flicker in this case. I already get used to the flickering ,maybe I should consider it a feature ;)

[Malabarba]

Something else just occurred to me. This could be due to the beacon animation happening so fast than redisplay can't keep up. So maybe slowing down the animation will help. You can do that by decreasing beacon-size or increasing beacon-blink-duration.

[clemera]

Thanks, indeed with a value of 0.8 for beacon-blink-duration the problem disappears.

Do you have an idea why my redisplay is to slow? Seems to work for others. I thought maybe it is something with evil mode and using different cursor styles but the problem occurs when I disable evil-mode, as well.

[Malabarba]

It could be that redisplay is doing too much work, but there could be many different causes for that.
Try turning on the profiler with M-x profiler-start. Then evaluate (dotimes (i 50) (redisplay)) in the scratch buffer, and finally do M-x profiler-report.

[clemera]

Thanks I didn't knew about that! Very useful, although I can not find the cause. Will report it here if I find it.