I have a text box for entering hex values for specifying color. I have a Validator that validates that the string is a valid hex color value. And a converter that converts a string like "FF0000" to "#FFFF0000" .NET color object. I want to only convert values when the data is valid as if data is invalid, I will get an exception from the converter. How can I do that?
Code below just FYI
XAML
<TextBox x:Name="Background" Canvas.Left="328" Canvas.Top="33" Height="23" Width="60">
<TextBox.Text>
<Binding Path="Background">
<Binding.ValidationRules>
<validators:ColorValidator Property="Background" />
</Binding.ValidationRules>
<Binding.Converter>
<converters:ColorConverter />
</Binding.Converter>
</Binding>
</TextBox.Text>
</TextBox>
Validator
class ColorValidator : ValidationRule
{
public string Property { get; set; }
public ColorValidator()
{
Property = "Color";
}
public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
{
string entry = (string)value;
Regex regex = new Regex(@"[0-9a-fA-F]{6}");
if (!regex.IsMatch(entry)) {
return new ValidationResult(false, string.Format("{0} should be a 6 character hexadecimal color value. Eg. FF0000 for red", Property));
开发者_Python百科 }
return new ValidationResult(true, "");
}
}
Converter
class ColorConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
string entry = ((Color)value).ToString();
return entry.Substring(3);
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
string entry = (string)value;
return (Color)System.Windows.Media.ColorConverter.ConvertFromString("#FF" + entry);
}
}
You can use Binding.DoNothing or DependencyProperty.UnsetValue as the return value in your converter.
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
string entry = (string)value;
Regex regex = new Regex(@"[0-9a-fA-F]{6}");
if (!regex.IsMatch(entry)) {
return Binding.DoNothing;
return entry.Substring(3);
}
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