feature: preview sddm themes

[heeeeeeeeeeh]

Did you check the docs?

• I have read all the Hyde docs

Is your feature request related to a problem? Please describe.

When selecting a theme with Hyde sddm select, I want to see a preview of the themes in fzf.

Describe the solution you'd like

I kinda got it working by stripping down the sddm project https://github.com/heeeeeeeeeeh/sddm-preview. Here's some recording if you like it I can make a pull request.
first time run:

vid1.mp4

second time when all the screenshots are taken.

vid2.mp4

Describe alternatives you've considered

I tried the first answer here:
https://stackoverflow.com/questions/17146747/capture-qml-drawing-buffer-without-displaying
but the screenshot would come out wonk. Maybe there is a way to capture a QQuickView without having to show it.

Additional context

No response

[kRHYME7]

sddm have preview option, Whyyyyy

[heeeeeeeeeeh]

Before I did this, I tried searching if sddm could give an image of the theme but I couldn't find any. there is --test-mode but that opens up a new window, and I wanted the preview to be within the fzf window

[heeeeeeeeeeh]

though I suppose you can run sddm-greeter --test-mode and take a screenshot of the window. The only thing I could done better with my solution is if I could have figured out how to not show the view.

[heeeeeeeeeeh]

not sure if this is a good idea but sddm could be ran though xvfb
xvfb-run -s "-screen 0 1920x1080x24" test.sh /usr/share/sddm/themes
test.sh can be something like this:

#!/usr/bin/env bash
if [ -n "$1" ]; then
  theme=--theme" $1"
fi
sddm-greeter --platform xcb --test-mode $theme &
while ! xwininfo -root -tree | grep -q "Qt Selection Owner for sddm-greeter"; do
  sleep .5
done
scrot ff.png
kill %1