В конструкторе, когда я добавляю два элемента к ObservableCollection, привязанному к присоединенному свойству TextBlock, присоединенное свойство обновляется. Но когда я добавляю элементы к той же ObservableCollection позже в другом методе, присоединенное свойство не обновляется.
XAML :
<TextBlock local:TextBlockExtensions.BindableInlines="{Binding StatusInlines}" />
TextBlockExtensions.cs :
public class TextBlockExtensions : BaseViewModel
{
public static IEnumerable<Inline> GetBindableInlines(DependencyObject obj)
{
return (IEnumerable<Inline>)obj.GetValue(BindableInlinesProperty);
}
public static void SetBindableInlines(DependencyObject obj, IEnumerable<Inline> value)
{
obj.SetValue(BindableInlinesProperty, value);
}
public static readonly DependencyProperty BindableInlinesProperty =
DependencyProperty.RegisterAttached("BindableInlines", typeof(IEnumerable<Inline>), typeof(TextBlockExtensions), new PropertyMetadata(null, OnBindableInlinesChanged));
private static void OnBindableInlinesChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var Target = d as TextBlock;
if (Target != null)
{
Target.Inlines.Clear();
Target.Inlines.AddRange((System.Collections.IEnumerable)e.NewValue);
}
}
}
ViewModel :
public ObservableCollection<Inline> StatusInlines { get; set; } = new ObservableCollection<Inline>();
...
// works in the constructor (called twice)
StatusInlines.Add(new Run($"{ text }{ Environment.NewLine }") { ToolTip = "tooltip" });
...
// does not work later in other methods
StatusInlines.Add(new Run($"{ text }{ Environment.NewLine }") { ToolTip = "tooltip" });
BaseViewModel.cs (от angelsix):
public class BaseViewModel : INotifyPropertyChanged
{
#region Protected Members
/// <summary>
/// A global lock for property checks so prevent locking on different instances of expressions.
/// Considering how fast this check will always be it isn't an issue to globally lock all callers.
/// </summary>
protected object mPropertyValueCheckLock = new object();
#endregion
/// <summary>
/// The event that is fired when any child property changes its value
/// </summary>
public event PropertyChangedEventHandler PropertyChanged = (sender, e) => { };
/// <summary>
/// Call this to fire a <see cref="PropertyChanged"/> event
/// </summary>
/// <param name="name"></param>
public void OnPropertyChanged(string name)
{
PropertyChanged(this, new PropertyChangedEventArgs(name));
}
#region Command Helpers
/// <summary>
/// Runs a command if the updating flag is not set.
/// If the flag is true (indicating the function is already running) then the action is not run.
/// If the flag is false (indicating no running function) then the action is run.
/// Once the action is finished if it was run, then the flag is reset to false
/// </summary>
/// <param name="updatingFlag">The boolean property flag defining if the command is already running</param>
/// <param name="action">The action to run if the command is not already running</param>
/// <returns></returns>
protected async Task RunCommandAsync(Expression<Func<bool>> updatingFlag, Func<Task> action)
{
// Lock to ensure single access to check
lock (mPropertyValueCheckLock)
{
// Check if the flag property is true (meaning the function is already running)
if (updatingFlag.GetPropertyValue())
return;
// Set the property flag to true to indicate we are running
updatingFlag.SetPropertyValue(true);
}
try
{
// Run the passed in action
await action();
}
finally
{
// Set the property flag back to false now it's finished
updatingFlag.SetPropertyValue(false);
}
}
/// <summary>
/// Runs a command if the updating flag is not set.
/// If the flag is true (indicating the function is already running) then the action is not run.
/// If the flag is false (indicating no running function) then the action is run.
/// Once the action is finished if it was run, then the flag is reset to false
/// </summary>
/// <param name="updatingFlag">The boolean property flag defining if the command is already running</param>
/// <param name="action">The action to run if the command is not already running</param>
/// <typeparam name="T">The type the action returns</param>
/// <returns></returns>
protected async Task<T> RunCommandAsync<T>(Expression<Func<bool>> updatingFlag, Func<Task<T>> action, T defaultValue = default(T))
{
// Lock to ensure single access to check
lock (mPropertyValueCheckLock)
{
// Check if the flag property is true (meaning the function is already running)
if (updatingFlag.GetPropertyValue())
return defaultValue;
// Set the property flag to true to indicate we are running
updatingFlag.SetPropertyValue(true);
}
try
{
// Run the passed in action
return await action();
}
finally
{
// Set the property flag back to false now it's finished
updatingFlag.SetPropertyValue(false);
}
}
#endregion
}