feat: Theme manager

[VasigaranAndAngel]

Theme manager to the application, enabling support for customizable themes.

this theme manager will be easily accessible once the settings window and theme settings in it are implemented. until then, we'll need to manually edit the config.ini file to set theme settings.

---

to test:

1. add new group and values as below in your config.ini:

   [Appearance]
   DarkMode=auto
   DarkThemeFile=path_to/dark_theme.ini
   LightThemeFile=path_to/light_theme.ini
   

   • DarkMode=auto will set the dark mode to system. available values: true, false and auto
   
   

2. set up theme files:
   the theme files should be like below (in .ini format):

   [ColorRoleName]
   ColorGroupName = Color
   

   • ColorRoleName is the name of the color role (e.g. Window, Button, etc.)
   • ColorGroupName is the name of the color group (e.g. Active, Inactive or Disabled)
   • Color is the color value in the QColor supported format (e.g. #RRGGBB, blue, etc.)
   
   
   sample theme.ini i made this beautiful theme 😎

   [Button]
   Active=green
   Inactive=purple
   Disabled=#101010
   
   [Base]
   Active=cyan
   
   [Text]
   Active=black
   
   [Window]
   Active=orange
   

   available roles

   • WindowText
   • Button
   • Light
   • Midlight
   • Dark
   • Mid
   • Text
   • BrightText
   • ButtonText
   • Base
   • Window
   • Shadow
   • Highlight
   • HighlightedText
   • Link
   • LinkVisited
   • AlternateBase
   • NoRole
   • ToolTipBase
   • ToolTipText
   • PlaceholderText
   • Accent not sure if QPalette and/or widgets gets accent from system, even if this is set
   available groups

   • Active: if focused
   • Inactive: normal
   • Disabled: if disabled

tnx ❤️

[seakrueger]

Getting theme management and switching under control will be good to have, thanks. Unfortunately, currently, I'm unsure how to test this? I'd like to see the stock themes moved to the theme file format.
It also seems you are defining your own theming file format. Is there a reason/advantage to doing this rather than using QSS files (Qt Style Sheets, Qt's file format for theming)?

[seakrueger]

I'd like to see this file moved into a ThemeManager class, rather than having this executed on import.

[VasigaranAndAngel]

or should i just move this line into Ui_MainWindow?

[VasigaranAndAngel]

Unfortunately, currently, I'm unsure how to test this? I'd like to see the stock themes moved to the theme file format.

this theme manager will be useful once the settings window and theme settings in it is implemented. until then, we'll need to manually edit the config.ini file to set theme files.
explicitly setting a stock theme in Qt will make that theme the default. when saving theme colors to the theme.ini file, all default values will be removed because the QPalette is currently being used as the theme palette and most of the QPalette colors are not yet applied to any widgets.

It also seems you are defining your own theming file format. Is there a reason/advantage to doing this rather than using QSS files (Qt Style Sheets, Qt's file format for theming)?

if we use QSS, it will bring lot of customization options. but we would also need to ensure that every widget respects those customizations. to keep theme management as simple as possible, theme manager uses QSettings to save and load themes from .ini files and relies on QPalette to apply colors to widgets.

thank you so much for the reviews ❤️. i'll update and ping you for rereview.

[Computerdores]

I have been trying it out and seems to work well, however whenever I open TS the Appearance role disappears from the config and I have to add it again before starting TS for the Theme to work

[VasigaranAndAngel]

I have been trying it out and seems to work well, however whenever I open TS the Appearance role disappears from the config and I have to add it again before starting TS for the Theme to work

it's because opening library clears all settings. #622

[CyanVoxel]

Could this be updated now that #622 is merged to make is easier to review?