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Improve console contrast: add 256-color ANSI support with improved 16-color fallback #3077

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Improve console contrast: add 256-color ANSI support with improved 16-color fallback #3077

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Improve console log contrast: add 256-color support with 16-color fal…
PatriciaBucataru Apr 9, 2026
071ea8b
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timcassell Apr 10, 2026
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58 changes: 49 additions & 9 deletions src/BenchmarkDotNet/Loggers/ConsoleLogger.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
using BenchmarkDotNet.Detectors;
using BenchmarkDotNet.Detectors;
using BenchmarkDotNet.Extensions;
using BenchmarkDotNet.Helpers;
using BenchmarkDotNet.Portability;
Expand All @@ -21,6 +21,17 @@ public sealed class ConsoleLogger : ILogger
return !(OsDetector.IsAndroid() || OsDetector.IsIOS() || RuntimeInformation.IsWasm || OsDetector.IsTvOS());
});

private static readonly Lazy<bool> ConsoleSupports256Colors = new(() =>
{

var colorTerm = Environment.GetEnvironmentVariable("COLORTERM");
if (colorTerm == "truecolor" || colorTerm == "24bit")
return true;

var term = Environment.GetEnvironmentVariable("TERM");
return term != null && term.Contains("256color");
});

private readonly bool unicodeSupport;
private readonly Dictionary<LogKind, ConsoleColor> colorScheme;

Expand Down Expand Up @@ -54,6 +65,15 @@ private void Write(LogKind logKind, Action<string> write, string text)
return;
}

if (ConsoleSupports256Colors.Value)
{
var colorIndex = Get256Color(logKind);
Console.Write($"\x1b[38;5;{colorIndex}m");
write(text);
Console.Write("\x1b[0m");
return;
}

var colorBefore = Console.ForegroundColor;

try
Expand All @@ -71,20 +91,40 @@ private void Write(LogKind logKind, Action<string> write, string text)
}

private ConsoleColor GetColor(LogKind logKind) =>
colorScheme.ContainsKey(logKind) ? colorScheme[logKind] : DefaultColor;
colorScheme.TryGetValue(logKind, out ConsoleColor value) ? value : DefaultColor;

private static int Get256Color(LogKind logKind)
{
var scheme = Create256ColorScheme();
return scheme.TryGetValue(logKind, out int value) ? value : 252;
}

private static Dictionary<LogKind, ConsoleColor> CreateColorfulScheme() =>
new Dictionary<LogKind, ConsoleColor>
new()
{
{ LogKind.Default, ConsoleColor.Gray },
{ LogKind.Help, ConsoleColor.DarkGreen },
{ LogKind.Help, ConsoleColor.Cyan },
{ LogKind.Header, ConsoleColor.Magenta },
{ LogKind.Result, ConsoleColor.DarkCyan },
{ LogKind.Statistic, ConsoleColor.Cyan },
{ LogKind.Info, ConsoleColor.DarkYellow },
{ LogKind.Result, ConsoleColor.Blue },
{ LogKind.Statistic, ConsoleColor.DarkCyan },
{ LogKind.Info, ConsoleColor.DarkGray },
{ LogKind.Error, ConsoleColor.Red },
{ LogKind.Warning, ConsoleColor.Yellow },
{ LogKind.Hint, ConsoleColor.DarkCyan }
{ LogKind.Warning, ConsoleColor.DarkYellow },
{ LogKind.Hint, ConsoleColor.DarkMagenta }
};

private static Dictionary<LogKind, int> Create256ColorScheme() =>
new()
{
{ LogKind.Default, 244 }, // mid gray - readable on both
{ LogKind.Help, 36 }, // teal-green
{ LogKind.Header, 127 }, // mid magenta
{ LogKind.Result, 33 }, // mid blue
{ LogKind.Statistic, 30 }, // darker teal - distinct from Result and Help
{ LogKind.Info, 130 }, // dark orange/brown - distinct from Warning
{ LogKind.Error, 160 }, // darker red - visible on white without blinding
{ LogKind.Warning, 166 }, // orange - distinct from Info
{ LogKind.Hint, 98 } // muted purple - distinct from Header
};

[PublicAPI]
Expand Down