When choosing a dark background color for the lock screen, the black font is hard to read. There should just be an option to choose the font color (and possibly the font). The same applies for sddm as well, at least for the breeze-design with custom background image.
Currently the only option is to change the wallpaper you use (either by modding it to include lighter sections in the area where the dark text is or changing it entirely). The issue isn't that there is anything blocking a way to set it from a design perspective but rather where to include it currently and how hard it is to do from a technical standpoint. We have a massive problem with settings - and there has been quite the discussion about SDDM/Lockscreen/Wallpaper-settings which will probably affect this. Adding it in the "set wallpaper" section for Lockscreen and SDDM seems like a good temporary solution (since they are mostly empty space currently) but then again what will happen with the work when those are redesigned? TL;DR from a design perspective nothing blocks the idea that you can change font colour - at the same time, the programmers will have to reply on how complex it is to add - and whether the risk of a future overhaul will make that effort worthless.
An easy colorchooser next to the wallpaper-chooser (or even color chooser in case of the lockscreen) would be a good start. Stuff like font type may be better off in full themes (didn't try to use other sddm themes, yet). Another option may be choosing a dark/light color based on the average color of the wallpaper, but i see several possiblities for this to fail.
Dublicate / same kind of as Bug 369676 - White lockscreen text's readability depends on background - https://bugs.kde.org/show_bug.cgi?id=369676
The readability issue is gone with Bug 369676. I am not sure if the bug should stay open for the possiblity to configure colors for better theming.
Certain elements on the lock screen respect the active color theme--such as the Unlock button and the textfield. I think it would make the most sense to continue in this vein and make them ALL respect the theme, rather than adding an additional UI to change the color of only some of the elements on the lock screen.
(In reply to Nate Graham from comment #5) > Certain elements on the lock screen respect the active color theme--such as > the Unlock button and the textfield. I think it would make the most sense to > continue in this vein and make them ALL respect the theme, rather than > adding an additional UI to change the color of only some of the elements on > the lock screen. By my knowledge: Text is using complementary normal text color. Password field is using view normal background color. Password text is using view normal text color. Unlock button is using button normal background color. Unlock text is using button normal text color. Earlier: https://forum.kde.org/viewtopic.php?f=14&t=151172
They do all respect the theme. The only difference is they're in the colour group "Complementary"