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Winforms data binding: Can a TypeConverter be used instead of the Format/Parse events?

In a Winforms form, I want to provide visual cues to the user when an input field contains an invalid value. To that end, I want to bind the ForeColor property of a input field's label to the (boolean) IsPropertyValid property of the underlying model such that the label turns red when IsPropertyValid == false.

What I currently have is an event handler for the binding's Format event:

Controls["dateOfBirthLabel"].DataBindings["ForeColor"].Format += convertBoolToColor;
// (dateOfBirthLabel.ForeColor is bound to a boolean IsDateOfBirthValid property.)

void convertBoolToColor(object sender, ConvertEventArgs e)
{
    e.Value = (bool)e.Value ? Color.Black : Color.Red;
}

If I wanted to do this in WPF, I suppose I would spe开发者_运维技巧cify a custom value converter (bool to Color) directly with the binding in the XAML. Most importantly, I wouldn't have to refer to a specific control via its name.

I would like to do the same thing with my Winforms form. Ideally, I could specify a TypeConverter object for a particular binding directly in the Forms Designer. Is this possible?


My previous answer (now deleted) was incorrect: This can be done, using a custom TypeConverter.

First, one needs a suitable converter. (Unlike with XAML, one does not implement a IValueConverter, but derive from TypeConverter.) For example:

// using System;
// using System.ComponentModel;
// using System.Drawing;
// using System.Globalization;

sealed class BooleanToColorConverter : TypeConverter
{
    public override bool CanConvertTo(ITypeDescriptorContext context,
                                      Type destinationType)
    {
        return destinationType == typeof(Color);
    }

    public override object ConvertTo(ITypeDescriptorContext context,
                                     CultureInfo culture,
                                     object value, 
                                     Type destinationType)
    {
        return (bool)value ? Color.Green : Color.Red;
    }
}

Next, (and also unlike with XAML data binding,) this converter is not applied to the binding itself; it must be attached to the data source's property using the [TypeConverter] attribute:

// using System.ComponentModel;

partial class DataSource : INotifyPropertyChanged
{
    [TypeConverter(typeof(BooleanToColorConverter))] // <-- add this! 
    public bool IsValid { get { … } set { … } }
}

Finally, formatting must be enabled on the data binding:

// Control control = …;
// DataSource dataSource = …;

control.DataBindings.Add("ForeColor", dataSource, "IsValid", formattingEnabled: true);
//                                                           ^^^^^^^^^^^^^^^^^^^^^^^

Note that this example only deals with one-way (data source to control) data binding. For two-way data binding, you would additionally have to override the TypeConverter.ConvertFrom and TypeConverter.CanConvertFrom methods.


c.DataBindings.Add("Checked", dataSource, dataMember, true, DataSourceUpdateMode.OnPropertyChanged );


class Someclass
{
[TypeConverter(typeof(IntBoolConverter))]
        public int p_isEnable
        {
            get { return nc_isEnable; }
            set { m_isEnable= value); }
        }
}
 public class IntBoolConverter:TypeConverter
    {
        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
        {

            if (sourceType == typeof(bool))
            {
                return true;
            }
            return base.CanConvertFrom(context, sourceType);
        }

        public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
        {
            if (destinationType == typeof(int))
            {
                return true;
            }
            return base.CanConvertFrom(context, destinationType);
        }

        public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
        {
            if (value is bool)
            {
                var objectToInt = value.ObjectToBool();
                return objectToInt;
            }
            return base.ConvertFrom(context, culture, value);
        }
        public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
        {
            if (destinationType == typeof(bool))
            {
                return value.ObjectToBool();
            }
            return base.ConvertTo(context, culture, value, destinationType);
        }
    }
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