/// <summary>
/// Initializes a new instance of the <see cref="CF.Xamarin.Forms.Classes.PropertyChangeListener"/> class.
/// </summary>
/// <param name="owner">Owner.</param>
/// <param name="callback">Callback.</param>
public void Listen <TModel>(Expression <Func <TModel, object> > property, object owner, Action callback)
{
if (callback == null)
{
throw new ArgumentNullException("callback");
}
if (owner == null)
{
throw new ArgumentNullException("owner");
}
_notifyChangedObject = owner as INotifyPropertyChanged;
if (_notifyChangedObject == null)
{
throw new ArgumentNullException("owner as IPropertyNotifyChanged");
}
_propertyName = PropertyNameHelper.GetPropertyName <TModel>(property);
if (string.IsNullOrEmpty(_propertyName))
{
throw new ArgumentException("property");
}
_callback = callback;
// Hook up event
_notifyChangedObject.PropertyChanged += HandlePropertyChangedEventHandler;
// Start by updating:
_callback();
}
/// <summary>
/// Calls the notify property changed event if it is attached. By using some
/// Expression/Func magic we get compile time type checking on our property
/// names by using this method instead of calling the event with a string in code.
/// </summary>
/// <param name="property">Property.</param>
protected override void RaisePropertyChangedEvent(Expression <Func <object> > property)
{
base.RaisePropertyChangedEvent(property);
var propertyName = PropertyNameHelper.GetPropertyName <BaseModel>(property);
CheckDependantProperties(propertyName);
}
/// <summary>
/// Adds a dependency between a property and another property. Whenever the property changes, the command's
/// state will be updated
/// </summary>
/// <param name="property">Source property.</param>
/// <param name="dependantProperty">Target property.</param>
private void AddPropertyDependency(Expression <Func <object> > property,
Expression <Func <object> > dependantProperty)
{
AddPropertyDependency(PropertyNameHelper.GetPropertyName <BaseModel>(property),
PropertyNameHelper.GetPropertyName <BaseModel>(dependantProperty));
}
/// <summary>
/// Returns the name of the member
/// </summary>
/// <returns>The of.</returns>
/// <param name="prop">Property.</param>
public string NameOf <TModel>(Expression <Func <TModel, object> > property)
{
return(PropertyNameHelper.GetPropertyName <TModel> (property));
}
/// <summary>
/// Calls the notify property changed event if it is attached. By using some
/// Expression/Func magic we get compile time type checking on our property
/// names by using this method instead of calling the event with a string in code.
/// </summary>
/// <param name="property">Property.</param>
protected virtual void RaisePropertyChangedEvent(Expression <Func <object> > property)
{
RaisePropertyChangedEvent(PropertyNameHelper.GetPropertyName <BaseNotifyPropertyChangedObject>(property));
}