Getting theme colors in Visual Studio Classifier extension

Question

I'm building a syntax highlighting extension for the Properties language in Visual Studio and already built the classifier/tagger. I'm stuck however at setting/choosing the right colors for the different tags (i.e. keys, values, comments).

I'd like to make the colors follow the current theme of Visual Studio. Right now they're hard-coded (see ForegroundColor = ...):

[Export(typeof(EditorFormatDefinition))]
[ClassificationType(ClassificationTypeNames = "PropertiesKeyTypeDefinition")]
[Name("PropertiesKeyFormat")]
[Order(Before = Priority.Default)]
internal sealed class PropertiesKey : ClassificationFormatDefinition {
    public PropertiesKey() {
        DisplayName = "Properties Key";
        ForegroundColor = Color.FromRgb(86, 156, 214);
    }
}

What I've found so far:

This question presumes my question is already answered.
This answer shows where in the registry the colors could be stored, but that's not a reliable solution.
This question addresses colors for WPF (not my case)
There's the Extensibility Tools extension with the Theme Swatches which show the colors from EnvironmentColors, however I don't know how to use the C# code it provides

If possible, I'd like to use the colors used for 'Keyword', 'String' and 'Comment' colors which can be found in VS in Tools -> Options -> Environment -> Fonts and Colors, again, in accordance with the current theme.

score 2 · Accepted Answer · answered Feb 19 '19 at 10:58

Based on the EnvironmentColors you can get a ThemeResourceKey.

That key can than be transformed into a SolidColorBrush using this function:

private static SolidColorBrush ToBrush(ThemeResourceKey key)
{
    var color = VSColorTheme.GetThemedColor(key);
    return new SolidColorBrush(Color.FromArgb(color.A, color.R, color.G, color.B));
}

So assigning it to your foreground becomes:

[Export(typeof(EditorFormatDefinition))]
[ClassificationType(ClassificationTypeNames = "PropertiesKeyTypeDefinition")]
[Name("PropertiesKeyFormat")]
[Order(Before = Priority.Default)]
internal sealed class PropertiesKey : ClassificationFormatDefinition {
    public PropertiesKey() {
        DisplayName = "Properties Key";
        ForegroundColor = ToBrush(EnvironmentColors.ClassDesignerCommentTextColorKey);
    }
 }

Documentation:

ThemeResouceKey

VSColorTheme.GetThemedColor

Extra:

This might be helpful in selecting the right ThemeResourceKey

VS Colors