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using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
namespace Xamarin.Forms
{
[ContentProperty("Spans")]
public class FormattedString : INotifyPropertyChanged
{
readonly SpanCollection _spans = new SpanCollection();
public FormattedString()
{
_spans.CollectionChanged += OnCollectionChanged;
}
public IList<Span> Spans
{
get { return _spans; }
}
public event PropertyChangedEventHandler PropertyChanged;
public static explicit operator string(FormattedString formatted)
{
return formatted.ToString();
}
public static implicit operator FormattedString(string text)
{
return new FormattedString { Spans = { new Span { Text = text } } };
}
public override string ToString()
{
return string.Concat(Spans.Select(span => span.Text));
}
void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
if (e.OldItems != null)
{
foreach (object item in e.OldItems)
{
var bo = item as Span;
if (bo != null)
bo.PropertyChanged -= OnItemPropertyChanged;
}
}
if (e.NewItems != null)
{
foreach (object item in e.NewItems)
{
var bo = item as Span;
if (bo != null)
bo.PropertyChanged += OnItemPropertyChanged;
}
}
OnPropertyChanged("Spans");
}
void OnItemPropertyChanged(object sender, PropertyChangedEventArgs e)
{
OnPropertyChanged("Spans");
}
void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(propertyName));
}
class SpanCollection : ObservableCollection<Span>
{
protected override void InsertItem(int index, Span item)
{
if (item == null)
throw new ArgumentNullException("item");
base.InsertItem(index, item);
}
protected override void SetItem(int index, Span item)
{
if (item == null)
throw new ArgumentNullException("item");
base.SetItem(index, item);
}
}
}
}
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