tui-cs/Terminal.Gui · error · ArgumentException

Steps must be greater than 0.

Error message

Steps must be greater than 0.

What it means

Thrown by the Gradient constructor when any value in the steps collection is less than 1. Steps define how many interpolated colors to generate between adjacent stops, so zero or negative steps are meaningless. It is an ArgumentException. Note a single step value is auto-expanded across all stop pairs when there are more than two stops.

Source

Thrown at Terminal.Gui/Drawing/Gradient.cs:79

    {
        _stops = stops.ToList ();

        if (_stops.Count < 1)
        {
            throw new ArgumentException ("At least one color stop must be provided.");
        }

        _steps = steps.ToList ();

        // If multiple colors and only 1 step assume same distance applies to all steps
        if (_stops.Count > 2 && _steps.Count == 1)
        {
            _steps = Enumerable.Repeat (_steps.Single (), _stops.Count () - 1).ToList ();
        }

        if (_steps.Any (step => step < 1))
        {
            throw new ArgumentException ("Steps must be greater than 0.");
        }

        if (_steps.Count != _stops.Count - 1)
        {
            throw new ArgumentException ("Number of steps must be N-1");
        }

        _loop = loop;
        Spectrum = GenerateGradient (_steps);
    }

    /// <summary>
    ///     Returns the color to use at the given part of the spectrum
    /// </summary>
    /// <param name="fraction">
    ///     Proportion of the way through the spectrum, must be between
    ///     0 and 1 (inclusive).  Returns the last color if <paramref name="fraction"/> is
    ///     <see cref="double.NaN"/>.

View on GitHub (pinned to 2e47b11478)

Solutions

1. Clamp each step to at least 1: steps = steps.Select(s => Math.Max(1, s)).
2. Validate step values before constructing the Gradient.
3. Ensure the source dimension used to derive steps is >= 2.

Example fix

// before
var g = new Gradient(stops, new[] { width - 1 });

// after
int step = Math.Max(1, width - 1);
var g = new Gradient(stops, new[] { step });

steps = steps.Select(s => Math.Max(1, s)).ToList();

static bool AllStepsPositive(IEnumerable<int> steps) => steps.All(s => s >= 1);

try { g = new Gradient(stops, steps); } catch (ArgumentException) { g = new Gradient(stops, Enumerable.Repeat(1, stops.Count()-1)); }

When it happens

Trigger: Calling new Gradient(stops, new[] { 0 }), new Gradient(stops, new[] { -1 }), or a steps list where any element is <= 0.

Common situations: Computing step counts from sizes/dimensions that can be zero (e.g. width-1 on a 1-cell area), config providing 0, or arithmetic underflow.

Related errors

• At least one color stop must be provided.
• Number of steps must be N-1
• Fraction must be between 0 and 1.
• start must be greater than or equal to 0
• Provided text is too short to be any known color format.

AI-assisted analysis of tui-cs/Terminal.Gui@2e47b11478 (2026-08-13). Data as JSON: /api/errors/740f25036cf15dd4. Report an issue: GitHub.