MaterialTextField TextChanged infinite loop

[thiagoparabas]

When trying to directly change the text in the change, it goes into infinite loop.

private void OnEntryTextChanged(object sender, TextChangedEventArgs args)
        {
            var entry = sender as MaterialTextField;

            var text = entry?.Text;

            if (string.IsNullOrWhiteSpace(text) || _positions == null)
                return;

            if (text.Length > _mask.Length)
            {
                entry.Text = text.Remove(text.Length - 1);
                return;
            }

            foreach (var position in _positions)
                if (text.Length >= position.Key + 1)
                {
                    var value = position.Value.ToString();
                    if (text.Substring(position.Key, 1) != value)
                        text = text.Insert(position.Key, value);
                }

            if (entry.Text != text)
                entry.Text = text;
        }

[contrix09]

Hi. In what line does the looping occur. I tried to replicate the looping, and it happens when you set the Text property of the text field. Heres the code:

private void MaterialTextField_TextChanged(object sender, TextChangedEventArgs e)
{
    const int maxLength = 4;
    var entry = sender as MaterialTextField;

    var text = entry.Text ?? string.Empty;

    if(text.Length > maxLength)
    {
        entry.Text = entry.Text.Substring(0, maxLength);
    }
}

[contrix09]

After some investigation, the looping was caused by the TextChanged event of the text field. It fires when the Text property is about to change, not when it has changed.

Can you provide the other field declarations (_positions and _mask) from your code above so I can test it.

[thiagoparabas]

Yes, sure, following:

This is my behavior

public class MaskedBehavior : Behavior<MaterialTextField>
{
    private string _mask = "";
    public string Mask
    {
        get => _mask;
        set
        {
            _mask = value;
            SetPositions();
        }
    }

    protected override void OnAttachedTo(MaterialTextField entry)
    {
        entry.TextChanged += OnEntryTextChanged;
        base.OnAttachedTo(entry);
    }

    protected override void OnDetachingFrom(MaterialTextField entry)
    {
         entry.TextChanged -= OnEntryTextChanged;
         base.OnDetachingFrom(entry);
    }

    IDictionary<int, char> _positions;

    void SetPositions()
    {
        if (string.IsNullOrEmpty(Mask))
        {
            _positions = null;
            return;
        }

        var list = new Dictionary<int, char>();
        for (var i = 0; i < Mask.Length; i++)
            if (Mask[i] != 'X')
                list.Add(i, Mask[i]);

        _positions = list;
    }

    private void OnEntryTextChanged(object sender, TextChangedEventArgs args)
    {
        var entry = sender as MaterialTextField;

        var text = entry.Text;

        if (string.IsNullOrWhiteSpace(text) || _positions == null)
            return;

        if (text.Length > _mask.Length)
        {
            entry.Text = text.Remove(text.Length - 1);
            return;
        }

        foreach (var position in _positions)
            if (text.Length >= position.Key + 1)
            {
                var value = position.Value.ToString();
                if (text.Substring(position.Key, 1) != value)
                    text = text.Insert(position.Key, value);
            }

        if (entry.Text != text)
            entry.Text = text;
    }
}