Add Custom Color Scheme Support

[AIIX]

• Color schemes allow skills to utilise a common color scheme and standardise color usage in skills, This PR adds supports for Mycroft.ColorScheme.

• Mycroft.ColorScheme provides 3 colors:

  • Mycroft.ColorScheme.primaryColor
  • Mycroft.ColorScheme.secondaryColor
  • Mycroft.ColorScheme.textColor

• By default Mycroft.ColorScheme will use Kirigami Theme using the Complementary color set to define the three colors, mapped as when useCustomTheme is set to false:

  • Mycroft.ColorScheme.primaryColor == Kirigami.Theme.backgroundColor
  • Mycroft.ColorScheme.secondaryColor == Kirigami.Theme.highlightColor
  • Mycroft.ColorScheme.textColor == Kirigami.Theme.textColor

• Any platform can define its own set of colors by setting the "useCustomTheme" property to true and providing the color configurations in HexArgb (hexadecimal quad format #AARRGGBB where the first two represent the alpha channel)

• The configuration can be provided in /etc/xdg/kde.org/mycroft-gui.conf or /$USER/.config/kde.org/mycroft-gui.conf

Example Configuration:

[General]
useCustomTheme=true
primaryColor=#ff2a2e32
secondaryColor=#ff35bfa4
textColor=#fffcfcfc

Example Usage In Skills:

Mycroft.CardDelegate {

    Rectangle {
       id: exampleRect
       ... 
       radius: 20
       color: Mycroft.ColorScheme.secondaryColor

        Button {
            ...
             background: Rectangle {
                 color: Mycroft.ColorScheme.primaryColor
             }
             contentItem: Text {
                  text: "60-30-10 Color Scheme Usage Example"
                 color: Mycroft.ColorScheme.textColor
             } 
         }
    }
} 

[AIIX]

Closing this in favour of using Kirigami PlatformTheme Plugin to reduce duplication work and since every platform might want to implement it differently, it would probably be best for the platform to export their own PlatformTheme plugin and use Kirigami.Theme roles as required,

An example PlatformTheme plugin implementation can be found https://github.com/OpenVoiceOS/mycroft-embedded-shell/pull/3

[krisgesling]

Yeah cool, if we can achieve this through a plugin that doesn't need to be embedded in the framework that sounds great.

I love the idea, I've just been thinking about the specifics of how we'd use it, what we'd want the colors called etc. This way we don't need to make a decision for all projects :clap: