private static string?GetResolvedTextColor(FrameworkElement frameworkElement, string?background)
{
if (background is null ||
!TryGetColor(frameworkElement, LIGHT_TEXT_KEY, out var lightColor) ||
!TryGetColor(frameworkElement, DARK_TEXT_KEY, out var darkColor) ||
!TryGetColor(frameworkElement, background, out var backgroundColor) ||
backgroundColor.A != 255)
{
return(null);
}
var lightContrast = ColorExtensions.ContrastWith(lightColor, backgroundColor);
var darkContrast = ColorExtensions.ContrastWith(darkColor, backgroundColor);
return(lightContrast > darkContrast ? LIGHT_TEXT_KEY : DARK_TEXT_KEY);
}
public override object Convert(object value, Type targetType, object?parameter, CultureInfo culture)
{
var color = value as Color? ??
(value as SolidColorBrush)?.Color ??
throw new ArgumentException($"{nameof(value)} must be of type {nameof(Color)} or {nameof(SolidColorBrush)}", nameof(value));
if (color.A != 255)
{
throw new NotSupportedException($"{nameof(value)} must be nontransparant to use in a {nameof(ContrastTextColorConverter)}");
}
var lightColor = Application.Current.FindResource <Color>(LIGHT_TEXT_KEY);
var darkColor = Application.Current.FindResource <Color>(DARK_TEXT_KEY);
var lightContrast = ColorExtensions.ContrastWith(lightColor, color);
var darkContrast = ColorExtensions.ContrastWith(darkColor, color);
var contrastColor = lightContrast > darkContrast ? lightColor : darkColor;
if (targetType.IsAssignableFrom(typeof(SolidColorBrush)))
{
return(new SolidColorBrush(contrastColor));
}
else if (targetType.IsAssignableFrom(typeof(Color)))
{
return(contrastColor);
}
else if (value is SolidColorBrush)
{
return(new SolidColorBrush(contrastColor));
}
else
{
return(contrastColor);
}
}