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public abstract class BindableBase : INotifyPropertyChanged | |
{ | |
/// <summary> | |
/// Multicast event for property change notifications. | |
/// </summary> | |
public event PropertyChangedEventHandler PropertyChanged; | |
/// <summary> | |
/// Checks if a property already matches a desired value. Sets the property and | |
/// notifies listeners only when necessary. | |
/// </summary> | |
/// <typeparam name="T">Type of the property.</typeparam> | |
/// <param name="storage">Reference to a property with both getter and setter.</param> | |
/// <param name="value">Desired value for the property.</param> | |
/// <param name="propertyName">Name of the property used to notify listeners. This | |
/// value is optional and can be provided automatically when invoked from compilers that | |
/// support CallerMemberName.</param> | |
/// <returns>True if the value was changed, false if the existing value matched the | |
/// desired value.</returns> | |
protected bool SetProperty<T>(ref T storage, T value, [CallerMemberName] String propertyName = null) | |
{ | |
if (object.Equals(storage, value)) return false; | |
storage = value; | |
this.OnPropertyChanged(propertyName); | |
return true; | |
} | |
/// <summary> | |
/// Notifies listeners that a property value has changed. | |
/// </summary> | |
/// <param name="propertyName">Name of the property used to notify listeners. This | |
/// value is optional and can be provided automatically when invoked from compilers | |
/// that support <see cref="CallerMemberNameAttribute"/>.</param> | |
[NotifyPropertyChangedInvocator] | |
protected void OnPropertyChanged([CallerMemberName] string propertyName = null) | |
{ | |
var eventHandler = this.PropertyChanged; | |
if (eventHandler != null) | |
{ | |
eventHandler(this, new PropertyChangedEventArgs(propertyName)); | |
} | |
} | |
} |
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public static class NotificationExtensions | |
{ | |
/// <summary> | |
/// Subscribe to PropertyChange notifications for the given property. | |
/// </summary> | |
/// <param name="notifier"> | |
/// Implementer of <see cref="INotifyPropertyChanged"/> that the events are going to be coming from. | |
/// </param> | |
/// <param name="propertyExpression"> | |
/// Lambda expression pointing to the property that you want to receive change notifications for. | |
/// </param> | |
/// <param name="handler"> | |
/// Event handler of the PropertyChange notifications. | |
/// </param> | |
public static void SubscribeToChanges<T>( | |
this T notifier, | |
Expression<Func<T, object>> propertyExpression, | |
PropertyChangedEventHandler handler) | |
where T : INotifyPropertyChanged | |
{ | |
MemberExpression memberExpression; | |
var unaryExpression = propertyExpression.Body as UnaryExpression; | |
if (unaryExpression != null) | |
{ | |
memberExpression = (MemberExpression)unaryExpression.Operand; | |
} | |
else | |
{ | |
memberExpression = (MemberExpression)propertyExpression.Body; | |
} | |
var propertyInfo = (PropertyInfo)memberExpression.Member; | |
string propertyName = propertyInfo.Name; | |
notifier.PropertyChanged += (s, e) => | |
{ | |
if (e.PropertyName.Equals(propertyName) || string.IsNullOrEmpty(e.PropertyName)) | |
{ | |
handler(s, e); | |
} | |
}; | |
} | |
} |
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