egwcorelib/EgwCoreLib.Razor/InputPercent.razor

@using System.Globalization
<input value="@DisplayValue"
       @onchange="OnChange"
       class="@CssClass" />

@code {
    /// <summary>
    /// Actual bind value
    /// </summary>
    [Parameter]
    public decimal Value { get; set; }

    /// <summary>
    /// Event for value changed
    /// </summary>
    [Parameter]
    public EventCallback<decimal> ValueChanged { get; set; }

    /// <summary>
    /// CssClass for input component
    /// </summary>
    [Parameter]
    public string CssClass { get; set; } = string.Empty;

    /// <summary>
    /// Number of decimal places to display in percentage format.
    /// Example: Decimals=2 → "15.00%".
    /// </summary>
    [Parameter]
    public int Decimals { get; set; } = 2;

    /// <summary>
    /// If true, parsing is always done with InvariantCulture.
    /// If false (default), try CurrentCulture first, then InvariantCulture.
    /// </summary>
    [Parameter]
    public bool ForceInvariantParsing { get; set; } = false;

    /// <summary>
    /// Percentage format string
    /// </summary>
    private string DisplayValue => Value.ToString($"P{Decimals}");

    /// <summary>
    /// Change value event
    /// </summary>
    private async Task OnChange(ChangeEventArgs e)
    {
        var input = e.Value?.ToString()?.Trim();

        if (string.IsNullOrWhiteSpace(input))
        {
            Value = 0;
            await ValueChanged.InvokeAsync(0);
            return;
        }

        // Remove % if present
        var cleaned = input.Replace("%", "").Trim();

        decimal parsed;
        bool success;

        if (ForceInvariantParsing)
        {
            // Option 3: Always invariant
            success = decimal.TryParse(cleaned, NumberStyles.Any, CultureInfo.InvariantCulture, out parsed);
        }
        else
        {
            // Option 2: Try current culture, then invariant
            success = decimal.TryParse(cleaned, NumberStyles.Any, CultureInfo.CurrentCulture, out parsed)
                   || decimal.TryParse(cleaned, NumberStyles.Any, CultureInfo.InvariantCulture, out parsed);
        }

        if (success)
        {
            decimal result = parsed <= 1 ? parsed : parsed / 100;
            Value = result;
            await ValueChanged.InvokeAsync(result);
        }
        else
        {
            // Invalid input → reset to 0
            Value = 0;
            await ValueChanged.InvokeAsync(0);
        }
    }
}