/// <summary>
/// Notifies multiple property changed
/// </summary>
/// <param name="propertyChanged">The property changed event handler that the propertyChangedImplementation holds</param>
/// <param name="sender">The event sender, optional because it is not required for the Xamarin.Forms view to react to a property changed</param>
/// <param name="properties"></param>
/// <remarks>This extension method does not set the event `sender` when notifying property changed. This has not proven to a problem when we created the extension, but be aware of it if you end up with something strange. Set <see cref="sender"/> if you need to make sure that we send the event sender</remarks>
public static void RaiseForEach(this PropertyChangedEventHandler propertyChanged, object?sender = null, params string[] properties)
{
foreach (var property in properties)
{
propertyChanged.Raise(property, sender);
}
}
public static void Raise <T>(this PropertyChangedEventHandler handler, object sender, params Expression <Func <T> >[] propertyExpressions)
{
foreach (var propertyExpression in propertyExpressions)
{
handler.Raise <T>(sender, propertyExpression);
}
}
/// <summary>
/// Sets a value to a backing field if it passes a equality check and notifies property changed.
/// </summary>
/// <typeparam name="S">The type of the property</typeparam>
/// <param name="backingStore">The backing store that will hold the value of the property</param>
/// <param name="value">The new value that should be set</param>
/// <param name="propertyChanged">The property changed event handler that the propertyChangedImplementation holds</param>
/// <param name="sender">The event sender, optional because it is not required for the Xamarin.Forms view to react to a property changed</param>
/// <param name="propertyName">A nullable property name, if left empty it will pick the caller member name</param>
/// <remarks>This method does a equality check to see if the value has changed, if you need to notify property changed when the value has not changed, please use <see cref="Raise"/></remarks>
/// <remarks>This extension method does not set the event `sender` when notifying property changed. This has not proven to a problem when we created the extension, but be aware of it if you end up with something strange. Set <see cref="sender"/> if you need to make sure that we send the event sender</remarks>
/// <returns>A boolean value to indicate that the property changed has been invoked</returns>
public static bool RaiseWhenSet <S>(this PropertyChangedEventHandler propertyChanged, ref S backingStore, S value, object?sender = null, [CallerMemberName] string propertyName = "")
{
if (EqualityComparer <S> .Default.Equals(backingStore, value))
{
return(false);
}
backingStore = value;
propertyChanged?.Raise(propertyName, sender);
return(true);
}
public static bool SetPropertyValueAndNotify <T>(this PropertyChangedEventHandler handler, INotifyPropertyChanged sender, ref T storage, T value, [CallerMemberName] String propertyName = null)
{
if (object.Equals(storage, value))
{
return(false);
}
storage = value;
handler.Raise(sender, propertyName);
return(true);
}
public static void Raise(this PropertyChangedEventHandler handler, object sender, Expression <Func <object> > propertyExpression)
{
if (handler == null || propertyExpression == null)
{
return;
}
var propertyBodyExpression = propertyExpression.Body;
var propertyAccessExpression = propertyBodyExpression.NodeType == ExpressionType.MemberAccess
? (MemberExpression)propertyBodyExpression
: (MemberExpression)((UnaryExpression)propertyBodyExpression).Operand;
handler.Raise(sender, propertyAccessExpression.Member.Name);
}
public static void Raise <T>(this PropertyChangedEventHandler handler, object sender, Expression <Func <T> > propertyExpression)
{
var body = propertyExpression.Body as MemberExpression;
if (body == null)
{
throw new ArgumentException("'propertyExpression' should be a member expression");
}
var expression = body.Expression as ConstantExpression;
if (expression == null)
{
throw new ArgumentException("'propertyExpression' body should be a constant expression");
}
handler.Raise(sender, body.Member.Name);
}
public void Raise_WhenPropertySelectorReturnsNull_DoesNothing()
{
var handler = new PropertyChangedEventHandler(delegate { });
handler.Raise(() => null);
}
static public void Raise(this PropertyChangedEventHandler handler, object sender, string propertyName)
{
handler.Raise(sender, new PropertyChangedEventArgs(propertyName));
}
/// <summary>
/// Notifies property changed.
/// </summary>
/// <param name="propertyChangedImplementation">The property changed implementation, this is normally a view model </param>
/// <param name="propertyChanged">The property changed event handler that the propertyChangedImplementation holds</param>
/// <param name="propertyName">A nullable property name, if left empty it will pick the caller member name</param>
public static void OnPropertyChanged(this INotifyPropertyChanged propertyChangedImplementation, PropertyChangedEventHandler?propertyChanged, [CallerMemberName] string propertyName = "")
{
propertyChanged?.Raise(propertyName, propertyChangedImplementation);
}
public static void Raise <PropertyType>(this PropertyChangedEventHandler onPropertyChanged, object sender, Expression <Func <PropertyType> > propertyExpression)
{
onPropertyChanged.Raise(sender, propertyExpression.GetMemberName());
}
protected virtual void OnPropertyChanged(string propertyName)
{
_propertyChanged.Raise(this, propertyName);
}
