ThemeGradient

open class ThemeGradient: NSGradient

ThemeGradient is a NSGradient subclass that dynamically changes its colors whenever a new theme is make current.

Theme-aware means you don’t need to check any conditions when choosing which gradient to draw. E.g.:

ThemeGradient.rainbowGradient.draw(in: bounds, angle: 0)

The drawing code will draw with different gradient depending on the selected theme. Unless some drawing cache is being done, there’s no need to refresh the UI after changing the current theme.

Defining theme-aware gradients

The recommended way of adding your own dynamic gradients is as follows:

1. Add a ThemeGradient class extension (or TKThemeGradient category on Objective-C) to add class methods for your gradients. E.g.:

   In Swift:

   extension ThemeGradient {
   
       static var brandGradient: ThemeGradient {
          return ThemeGradient.gradient(with: #function)
       }
   
   }
   

   In Objective-C:

   @interface TKThemeGradient (Demo)
   
   + (TKThemeGradient*)brandGradient;
   
   @end
   
   @implementation TKThemeGradient (Demo)
   
   + (TKThemeGradient*)brandGradient {
      return [TKThemeGradient gradientWithSelector:_cmd];
   }
   
   @end
   

2. Add Class Extensions on any Theme you want to support (e.g., LightTheme and DarkTheme - TKLightTheme and TKDarkTheme on Objective-C) to provide instance methods for each theme gradient class method defined on (1). E.g.:

   In Swift:

   extension LightTheme {
   
       var brandGradient: NSGradient {
          return NSGradient(starting: NSColor.white, ending: NSColor.black)
       }
   
       }
   
       extension DarkTheme {
   
       var brandGradient: NSGradient {
          return NSGradient(starting: NSColor.black, ending: NSColor.white)
       }
   
   }
   

   In Objective-C:

   @interface TKLightTheme (Demo) @end
   
   @implementation TKLightTheme (Demo)
   
   - (NSGradient*)brandGradient
   {
      return [[NSGradient alloc] initWithStartingColor:[NSColor whiteColor] endingColor:[NSColor blackColor]];
   }
   
   @end
   
   @interface TKDarkTheme (Demo) @end
   
   @implementation TKDarkTheme (Demo)
   
   - (NSGradient*)brandGradient
   {
      return [[NSGradient alloc] initWithStartingColor:[NSColor blackColor] endingColor:[NSColor whiteColor]];
   }
   
   @end
   

3. If supporting UserTheme‘s, define properties on user theme files (.theme) for each theme gradient class method defined on (1). E.g.:

   displayName = Sample User Theme
   identifier = com.luckymarmot.ThemeKit.SampleUserTheme
   darkTheme = false
   
   orangeSky = rgb(160, 90, 45, .5)
   brandGradient = linear-gradient($orangeSky, rgb(200, 140, 60))
   

Fallback colors

Unimplemented properties/methods on target theme class will default to fallbackGradient. This too, can be customized per theme.

Please check ThemeColor for theme-aware colors and ThemeImage for theme-aware images.