d2phap/ImageGlass · error · ArgumentException

Zoom factor '{factorStr}' is not a valid float. ----------

Error message

Zoom factor '{factorStr}' is not a valid float.

----------
👉🏼 Method: IG_SetZoom

What it means

Thrown by the string overload of IG_SetZoom when float.TryParse(factorStr) fails. The parse is culture-sensitive (no InvariantCulture supplied), so the accepted decimal separator depends on the current culture. A null, empty, or non-numeric string raises ArgumentException.

Source

Thrown at source/ImageGlass.Lib/Common/ServiceProviders/AppAPIs/AppAPIProvider.cs:1202

        });

        if (result.ExitCode != DialogExitCode.OK) return;

        if (float.TryParse(result.InputValue.Trim(), out var newZoom))
        {
            Viewer.ZoomFactor = newZoom / 100f;
        }
    }


    /// <summary>
    /// Zoom to the current cursor location by the given factor.
    /// </summary>
    public void IG_SetZoom(string? factorStr)
    {
        if (!float.TryParse(factorStr, out var factor))
        {
            throw new ArgumentException($"""
                Zoom factor '{factorStr}' is not a valid float.

                ----------
                👉🏼 Method: {nameof(IG_SetZoom)}
                """,
                nameof(factorStr));
        }

        IG_SetZoom(factor);
    }

    /// <summary>
    /// Zoom to the current cursor location by the given factor.
    /// </summary>
    public static void IG_SetZoom(float factor)
    {
        _ = Viewer.ZoomToPoint(factor);
    }

View on GitHub (pinned to 4a3c4fecef)

Solutions

Pass a plain numeric string matching the current culture's decimal separator, or normalize to the current culture before calling.
Validate with float.TryParse (same overload the method uses) before invoking, and call the float overload directly.
Strip '%', spaces, and quotes upstream before parsing.

Example fix

// before
api.IG_SetZoom(userInput);

// after
var cleaned = userInput?.Trim().TrimEnd('%');
if (float.TryParse(cleaned, out var factor))
{
    api.IG_SetZoom(factor);
}

Defensive patterns

Strategy: validation

Validate before calling

var cleaned = factorStr?.Trim().TrimEnd('%');
if (!float.TryParse(cleaned, out var factor))
    throw new ArgumentException("Zoom factor must be numeric.");
api.IG_SetZoom(factor);

Type guard

static bool IsValidZoomFactor(string? s, IFormatProvider? p = null)
    => float.TryParse(s?.Trim().TrimEnd('%'), out _);

Try / catch

try { api.IG_SetZoom(factorStr); }
catch (ArgumentException ex) when (ex.ParamName == nameof(factorStr))
{ /* reject; note culture may be the cause */ }

Prevention

Strip '%', spaces, and quotes before parsing.
Remember the parse is culture-sensitive; match the user locale's decimal separator.
Validate with the same float.TryParse overload upstream.

When it happens

Trigger: Calling IG_SetZoom(string) with '1.5' in a comma-decimal locale (e.g., de-DE) where '.' is not accepted; '150%' with the percent sign; '' ; 'zoom'; a value with a thousands separator.

Common situations: Hard-coded '1.5' from an English-locale config breaks when the app runs under a European locale; user input copied with a percent sign; CLI argument with surrounding quotes/spaces.

Related errors

AI-assisted analysis of d2phap/ImageGlass@4a3c4fecef (2026-08-13). Data as JSON: /api/errors/bf77ef6dd6f6afb9. Report an issue: GitHub.