定义
public class NumericValidationBehavior : Behavior<Entry>
{
protected override void OnAttachedTo(Entry entry)
{
entry.TextChanged += OnEntryTextChanged;
base.OnAttachedTo(entry);
}
protected override void OnDetachingFrom(Entry entry)
{
entry.TextChanged -= OnEntryTextChanged;
base.OnDetachingFrom(entry);
}
void OnEntryTextChanged(object sender, TextChangedEventArgs args)
{
double result;
bool isValid = double.TryParse (args.NewTextValue, out result);
((Entry)sender).TextColor = isValid ? Color.Default : Color.Red;
}
}
使用
<Entry Placeholder="Enter a System.Double">
<Entry.Behaviors>
<local:NumericValidationBehavior />
</Entry.Behaviors>
</Entry>
