background: extensive animated image support

[evencewang]

shrunk.mp4

Summary

• Support for animated wallpapers along with caching support.
• Wallpaper picker lazy-loads previews without blocking.
• Preview viewport thumbnails could opt in / out of animation, defaulted to off.
• Playback on / off support, currently pausing playback on lock, and resumes after unlock.
• The related cli PR is here: background: extensive animated image support cli#68

Changes

• cachingimagemanager.hpp + cachingimagemanager.cpp + CachingImage.qml reworked to show cached static frame 0 while animated frames decode.
  • Because of CachingImage.qml change, gifs are now also supported for .face (profile avatar). See video above when I lock my screen, I am using the same gif as the background, but they are unrelated, and you could use anything you would like for the profile avatar.
  • If we should guard against it being used for UI icons, let me know.
• WallpaperList.qml addition to drive previews off immediately after index changes, scrolling to animated images will show a static preview right away.
• modules/background/Wallpaper.qml + Background.qml populated with lock scope and gates playback pause/resume upon lock/unlock.

Testing

• QT_LOGGING_TO_CONSOLE=1 quickshell -c caelestia when I had the logs to launch wallpaper picker, picking the animated wallpaper and set it, then watch the playback pause kick in while locked, and resumed after unlock.
• Scrolling through the wallpaper selection viewport without selecting, landing on animated images will immediately kick off the preview (could use more testing).

Known issues:

• Like static images, the caching of the thumbnail sometimes show an empty black rectangle, caching part should receive attention.

[evencewang]

@Gitkubikon
Sorry! I had just seen that you had a PR open as well. 😢 I was working on this as a small extension for myself which is why I didn't check, and it blew out to be slightly more comprehensive than I thought it was going to be.
Would love your feedback on this as well since you have worked on this, and potentially improving on this feature collaboratively.