Bug 495369

Summary: Wallpapers KCM does not fade in the new wallpaper when making a selection, as "old" wallpaper settings does.
Product: [Applications] systemsettings Reporter: breineke93
Component: kcm_wallpaperAssignee: Plasma Bugs List <plasma-bugs-null>
Status: CONFIRMED ---    
Severity: minor CC: meven29, meven, nate
Priority: NOR    
Version First Reported In: git-stable-Plasma/6.2   
Target Milestone: ---   
Platform: Fedora RPMs   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: Recording of behavior

Description breineke93 2024-10-26 07:35:51 UTC
Created attachment 175246 [details]
Recording of behavior

SUMMARY
The new wallpapers KCM does not support fading in the new wallpaper when a new selection is made unlike the "old" way of settting the wallpaper, which was a really nice touch.

STEPS TO REPRODUCE
1a. Open wallpapers KCM
2b. Select new wallpaper
vs.
1b. Open desktop settings via right-click menu on desktop
2b. Select new wallpaper

OBSERVED RESULT
When selecting a new wallpaper in the desktop settings window, a nice transition shows the new wallpaper in effect before clicking apply. When selecting a new wallpaper in the wallpaper KCM, no effect is shown and the new wallpaper is applied without transition when clicking apply.

EXPECTED RESULT
Upon selecting a new wallpaper in the wallpapers KCM, a transition to the selected wallpaper occurs before clicking apply.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora KDE 40
KDE Plasma Version: 6.2.1
KDE Frameworks Version: 6.7.0
Qt Version: 6.7.2
Comment 1 Méven Car 2024-10-27 16:42:05 UTC
Technical details:
The wallpaper kcm uses dbus to send wallpaper configuration plasmashell process.
The plasma wallpaper window is able to change directly within plasmashell process the wallpaper (with the animation) without affecting the wallpaper settings.
We would need to change the dbus interface to mimic this, have a "setWallpaperPreview" that changes the wallpaper without changing the settings.
The initial kcm implementation would be a pointer where to plug the things together:
https://invent.kde.org/plasma/plasma-workspace/-/merge_requests/3395